The authors gratefully acknowledge financial support from Air Force Research Laboratory contract FA8650-14-C-6571 and from DAQRI LLC.

1. Initial Preparation
Note: Begin with a new X-cut lithium niobate wafer. It should be optical grade, 1 mm thick, clean, with nothing deposited on the surface, both sides polished, and the top side marked.
<ol>
	<li>Using an Electron Beam Evaporator or equivalent machine at a vacuum of 50 &#181;Torr, evaporate 200 nm of aluminum on the wafer at 5 &#197;/sec. To replicate the presented results, position the wafer constellation 65 cm above the aluminum crucible.</li>
	<li>Spin on 30 drops of a positive photo resist, such as AZ3330, at 3,000 rpm for 60 sec. Softbake the resist at 90 &#176;C for 60 sec. Note: For a detailed description of the mechanics of spinning polymer films see the work by C. J. Lawrence21.</li>
	<li>Using the proper mask, such as the &#34;Mask 1. Proton Exchange Mask.dxf&#34; file supplied in the appendix, expose the wafer using a mask aligner with a 350 W mercury bulb or its equivalent for 10 sec as per machine specifications. Ensure that the wafer is aligned so that the waveguides are parallel to the y-axis.</li>
	<li>Develop the resist in a positive photoresist developer for 60 sec. Hard bake the wafer for 60 sec at 110 &#176;C. Etch away the exposed aluminum completely by submerging it for 2 min in a 1 L solution aluminum etch heated to 50 &#176;C. 
	CAUTION: Aluminum etch is toxic, corrosive and harmful. See MSDS for proper handling and storage of this chemical. Use proper personal protective equipment for acid when handling this chemical.</li>
	<li>Remove the photoresist mask with a rinse of acetone followed by isopropyl alcohol (IPA).</li>
	<li>Using a 0.016 in. thick diamond blade with an exposure depth of 0.165 in. on an automatic dicing saw, cut the wafer into 10 x 15 mm2 devices with the long dimension parallel to the y-axis. 
	Note: The blade will not cut all the way through the substrate. To separate each device, simply stress each cut made by the dicing saw. Each 10 x 15 mm2 device will individually go through the remaining steps of the protocol.</li>
</ol>
2. Proton Exchange
<ol>
	<li>Place an individual device in a test tube with a small hole ground into the bottom to allow interaction between the device and all liquid baths.</li>
	<li>Proton exchange the device by immersing it in a 1 L melt of 99% pure benzoic acid at 240 &#176;C. Use an immersion time of 10 min and 10 sec in order to achieve the target depth of 0.4504 &#181;m. 
	Note: The proton exchange immersion time is dictated by the diffusion coefficient, D, which for the authors&#39; melt is currently D = 0.2993. The proton exchange immersion time is calculated using the relation T = d2 / (4D). In this equation, T is the exchange time in hours, d is the waveguide depth in microns, and D is the diffusion coefficient. For a detailed description of the mechanics of proton exchange see the work by J. L. Jackel15.</li>
	<li>Remove the device and allow to cool for 5 min or until cool to the touch. Clean off any benzoic acid residue with a rinse of acetone then IPA.</li>
</ol>
3. Anneal
<ol>
	<li>Place device in a regular test tube and wrap the tube in aluminum foil. Place the tube in a muffle furnace for 45 min at 375 &#176;C. Remove the device and allow to cool for 5 min or until cool to the touch.</li>
</ol>
4. Clean
<ol>
	<li>Clean the aluminum mask from the device using aluminum etch for roughly 2 min at 50 &#176;C. Clean the device in acidic piranha etch to remove any organic residues. 
	CAUTION: Acidic piranha etch is toxic, corrosive and harmful. See MSDS for proper handling and storage of these chemicals. Use proper personal protective equipment for acid when handling these chemicals.</li>
	<li>Rinse the device in acetone, then IPA, and dry with compressed nitrogen.</li>
</ol>
5. Waveguide Measurements
<ol>
	<li>Using any commercial waveguide analyzer measure the characteristics of the proton exchanged waveguide. 
	Note: A good device will have 2 guided modes using a 633 nm laser. See Figure 2 for an example of desired results. If the device shows more than two guided modes for red illumination then the exchange time in step 2.2 should be reduced. Likewise if the device shows less than two guided modes the exchange time should be increased.</li>
</ol>
6. Add Resist
<ol>
	<li>Spin on 4 drops of a Lift Off Resist (LOR) at 3,000 rpm for 60 sec and then bake at 200 &#176;C for 1 hr. Remove and allow the device to cool for 5 min or until cool to the touch. Spin on 4 drops of a 3:1 solution of polymethyl methacrylate (PMMA) and Anisole at 3,000 rpm for 60 sec and then bake at 150 &#176;C for 15 min.</li>
	<li>Remove and allow the device to cool for 5 min or until cool to the touch. Spin on 2 drops of a conductive polymer at 1,000 rpm for 60 sec, then spin at 6,000 rpm for 4 sec to remove any excess.</li>
</ol>
7. Pattern
<ol>
	<li>Use an electron microscope enhanced with a beam blanker to enable writing or an equivalent machine to expose the device.
	<ol>
		<li>Under a vacuum of 50 &#181;Torr, expose the conductive layer to an electron beam with an area dose of 30 &#181;C/cm2 that scans the pattern of the interdigital transducers. To replicate the results use a measured beam current of 410 pA.</li>
		<li>Write the pattern from a .dxf or equivalent file on the electron microscope as per machine specifications. 
		Note: For a detailed description of the E-Beam lithography process see the work done by R. E. Fontana22.</li>
	</ol>
	</li>
</ol>
8. Develop
<ol>
	<li>Remove the conductive layer by rinsing the device in a continuous stream of deionized water for 5sec. Remove the exposed PMMA by dipping the device into 1:3 solution of methyl isobutyl ketone (MIBK) and IPA for 45 sec.
	<ol>
		<li>Remove from the 1:3 solution of MIBK:IPA and rinse with IPA for 5 sec. Dry the device with compressed nitrogen.</li>
	</ol>
	</li>
	<li>Repeat steps 8.1-8.1.1 as necessary to fully develop the PMMA. 
	Note: However expose the device to the solution of MIBK:IPA in 5sec increments only. Complete development should reveal the LOR underneath the PMMA and can be identified by uniform coloration throughout the developed area surrounded by crisp edges and corners. 
	Note: Over development of PMMA leads to small feature blowout and can completely erase the interdigital transducer fingers leaving a single large developed block. Likewise under development leaves non-uniform residues that will decrease the effectiveness of the liftoff process that follows.</li>
	<li>Remove LOR in exposed region by dipping the device into a 1:1 solution of an appropriate developer and deionized water for 25 sec. Remove from the 1:1 solution of an appropriate developer and deionized water. Rinse with IPA for 5 sec.
	<ol>
		<li>Dry with compressed nitrogen. Repeat steps 8.3 as necessary to fully develop the LOR. 
		Note: However expose the device to the solution of an appropriate developer and deionized water in 2 sec increments only. Complete development should reveal the surface of the substrate underneath the LOR. It can be identified by uniform white coloration throughout the developed area while maintaining crisp edges and corners. Failure to develop the LOR properly also leads to the problems discussed in 8.2.3.1. See Figure 3 for an example LOR development process. 
		Note: Switching to a lower ratio of an appropriate developer to deionized water such as 1:2 or 1:3 is helpful as the device nears complete development to allow the fine features to develop without blowing out the device. However, it is not advantageous to start with these doses as total time increases and exceeds the optimal time in the developer.</li>
	</ol>
	</li>
</ol>
9. Deposit Aluminum
<ol>
	<li>Using an Electron Beam Evaporator or equivalent machine at a vacuum of 50 &#181;Torr, evaporate 200 nm of aluminum on the wafer at 5 &#197;/sec.</li>
</ol>
10. Liftoff Aluminum
<ol>
	<li>Fill a large glass dish with 750 ml of water on a hot plate at 90 &#176;C. Insert a plastic buffer into the water dish. In a separate small glass container submerge the device in a 100 ml solution of N-methyl-2-pyrrolidone (NMP).</li>
	<li>Place the container of NMP solution containing the device onto the plastic buffer ensuring that the water level does not exceed the height of the container of NMP. Cover and let sit 3 to 4 hr or until aluminum liftoff is complete. Remove the device from NMP. 
	Note: It is advantageous to clean off large sections of aluminum from the device before removing it from the NMP bath. Do this by using a pipette filled with NMP to squirt the device and knock off any remaining large chunks of unwanted aluminum.</li>
	<li>Rinse the device in IPA and dry with compressed nitrogen. Under a microscope, verify that liftoff is complete. If unwanted residual aluminum remains, wet the device with acetone and very gently brush with a cleanroom swab coated in acetone to remove.</li>
	<li>Rinse in IPA, dry with compressed nitrogen, and recheck under the microscope. Repeat 10.3 and 10.4 as needed.</li>
</ol>
11. Polish the End
<ol>
	<li>Coat the device in a protective film such as a layer of positive photoresist. Clamp the device so that the end with the transducers is exposed for polishing. Using proper polishing procedures23, slowly polish the end of the device to a surface roughness of less than 100 nm, so that no surface defects interfere with the light exiting the device.</li>
	<li>Remove the device from the clamp and clean off the protective film. If photoresist was used as a protective film, a generous rinse in acetone and then IPA will remove it. Dry the sample as necessary with compressed nitrogen.</li>
</ol>
12. Mount on a Breakout Board
<ol>
	<li>If any assembly is required for the RF breakout board, assemble the breakout board according to its specifications.</li>
	<li>Build, out of glass slides, a mounting platform to hold firmly both the RF breakout board and the device. Note: The mounting platform is built in a U shape out of three glass slides: one 75 x 50 x 1 mm3 and two 75 x 25 x 1 mm3.
	<ol>
		<li>Place a generous bead of superglue over the leftmost fourth of the large slide. Place one of the smaller slides over the bead of superglue so that leftmost edge and the bottom edge align with the corresponding edges on the large slide.</li>
		<li>Apply firm and equal pressure to the two slides until the superglue sets, about 15 sec. Repeat the process for the rightmost fourth of the large slide.</li>
	</ol>
	</li>
	<li>Mount the device to the top of the mounting platform with double-sided tape. Make sure the end of the device overhangs the end of the mounting platform so that the mounting platform does not interfere with light exiting the end of the device.</li>
	<li>Mount the RF breakout board to the mounting platform so that it is not in the beam path of the light exiting the device. A simple way to do this is to elevate the breakout board with thick tape so that the bottom of the breakout board is above the top of the device.</li>
	<li>Wire bond the pads on the device to their respective locations on the RF breakout board. Use a 27 nH series inductor to impedance match each transducer to the breakout board inputs.</li>
</ol>
13. Prism Coupling
<ol>
	<li>Select a rutile prism to couple light into the device. The polarization of the light (Transverse Electric) should be parallel to the optical axis of the rutile the optical axis (Z-axis) of the X-cut lithium niobate.</li>
	<li>Clean the contact surfaces of both the device and the prism thoroughly with IPA. Position the prism so that it is centered on the channel to be tested.</li>
	<li>Press the bottom of the prism firmly against the top of the device with a clamping mechanism. Note: Do not overtighten as excessive pressure will crack the substrate and damage the coupling prism.</li>
	<li>If successful, observe a wet spot will appear. 
	Note: A wet spot is a region of frustrated total internal reflection at the interface between the prism and the sample. For an example of proper prism coupling see Figure 4.</li>
</ol>
14. Mount in the Characterization Apparatus
<ol>
	<li>Mount the device on the rotating platform of the Frequency division color characterization apparatus for anisotropic leaky mode light modulators discussed by A. Henrie4. 
	Note: A schematic of the Characterization Apparatus is supplied in Figure 5.</li>
</ol>
15. Align in the Characterization Apparatus
<ol>
	<li>Turn on the laser. To replicate the results presented in this paper use 5 V for 638 nm, 5.5 V for 532 nm, and 6.5 V for 445 nm.</li>
	<li>Attenuate the beam until the intensity of the scattered light is comfortable to the eye. Verify the laser polarization.
	<ol>
		<li>Place a polarizer in the beam path after the half wave plate so that it blocks horizontally polarized light. Rotate the half wave plate to achieve maximum attenuation of the laser light. Remove the polarizer.</li>
	</ol>
	</li>
	<li>Manually rotate the platform so that the angle between the laser and the top surface of the device is set to the proper entrance angle. 
	Note: The proper angle can be found in Table 1 according to the desired testing wavelength and mode.</li>
	<li>Align prism using the linear translation stages when the focal point of the laser passes through the 90&#176; corner of the prism. Note: Increased laser scatter caused by the corner of the prism can sometimes be seen.
	<ol>
		<li>At this point, light should be coupling into the device which can be verified either by the characteristic streak of light caused by scattering in the waveguide or by the characteristic mode lines coming out of the end of the device24 (see Figure 6). 
		Note: If using mode lines to verify coupling, it is helpful to remove the power meter from the beam path. Instead insert a uniformly scattering object, such as a sheet of white paper, into the beam path.</li>
		<li>If no coupling is detected, slowly rotate the device while maintaining the coupling edge of the prism in the focal point of the laser. If after five degrees rotation in either direction no coupling can be detected, remove the device from the rotating platform, remove the prism and return to step 13.</li>
	</ol>
	</li>
	<li>Once coupling is detected, fine tune the rotational platform and linear translation stages to maximize the coupling of the light.</li>
</ol>
16. Attach the RF Input and Enclose the Device
<ol>
	<li>Replace the power meter that was removed during alignment. Also remove any obstructions to the beam path used for alignment purposes.</li>
	<li>Attach the RF input to the device breakout board and turn on the RF signal generator. Make sure the amplifier is powered. Note: To protect the device from burnout, the electrical power of the signal reaching the device should not exceed 1 W.</li>
	<li>Remove any attenuation used for safety during alignment. The laser is now at the optical power levels used for testing. Enclose the entire system in an optically isolating box.</li>
</ol>
17. Run the Provided Testing Program
<ol>
	<li>Obtain a laboratory equipment manager to run the characterization device, such as the LabView file AutomatedDeviceCharacterization.vi provided in the appendix.</li>
	<li>Insert all user parameters into the testing software on the control computer. Note: Figure 7 is supplied for those using the provided experiment control file. It indicates with a yellow box the fields that must be updated before each automated test is run in order for the provided analytical program to run properly in step 19.
	<ol>
		<li>To replicate the results presented in this paper use the following testing parameters: Initial Frequency: 100 MHz, Final Frequency: 800 MHz, Frequency Step: 10, Rough Initial Position: 0, Rough Final Position: 25, and Position Step: 1. Make sure the &#34;Output to File&#34; button is pressed.</li>
	</ol>
	</li>
	<li>Run the testing program. 
	Note: The provided program drives a power meter along a linear track at user defined intervals. At each position the RF input signal is swept through a set of chosen frequencies and power measurements are made. A measurement is also made with the RF input at its lowest frequency setting and lowest output power which has been experimentally determined as equivalent to no input signal4. These measurements are then graphed in real time in a 3D interactive chart.
	<ol>
		<li>Observe the four output files: *config.csv describes the experiment, *data.csv contains the power reading at each frequency, *no_stim.csv contains the background noise reading, and *graph.jpeg contains a copy of the graph on the user interface of the program as it was when the program ended. See Figure 8.</li>
	</ol>
	</li>
	<li>Repeat sections 15-17 for each wavelength and the TE1 mode described in Table 1.</li>
</ol>
18. Analyze the Frequency and Angular Output Profiles
<ol>
	<li>Obtain a statistical analysis program or download the CompareWDMmodes.m MATLab code provided in the appendix.</li>
	<li>In the folder (where the program is located), create a subfolder, &#34;Sample Number&#34; enter the &#34;Sample Number&#34; into the testing program. The sample number is the device identification number.</li>
	<li>In this folder, &#34;Sample Number,&#34; create three subfolders. Name each folder as follows, &#34;Sample Number&#34;_ &#34;Color&#34;_M1_ &#34;Transducer&#34;. The names in &#34;bold and italics&#34; are values entered into the testing program by the user. (e.g. A16_BLUE_M1_T1, C5_RED_M1_T13, or D35_GREEN_M1_T18).</li>
	<li>Into each subfolder, copy the four files created by the testing software that correspond with that particular wavelength, mode, and transducer.</li>
	<li>Open the analytical program and change the user defined variables at the top to reflect the user defined values input into the testing software. 
	Note: If using the provided analytical program and the user defined values in the testing program are &#34;Sample Number&#34;=A16, &#34;Guided Mode&#34;=1, &#34;Transducer&#34;=1 the analytical code would be modified to the following: 
	&#160;&#160;&#160;&#160; % User Defined Variables 
	&#160;&#160;&#160;&#160; series=&#39;A&#39;; 
	&#160;&#160;&#160;&#160; sample=16; 
	&#160;&#160;&#160;&#160; modes=[1]; 
	&#160;&#160;&#160;&#160; transducer=&#39;T1&#39;;</li>
	<li>Run the analytical program. 
	Note: If using the provided analytical code, among other things it creates a figure that compares the normalized frequency response and the angular output for red, green, and blue light. The file it creates is located in the &#34;Sample Number&#34; subfolder. See Figure 9 for an example of the output .</li>
</ol>

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The authors have nothing to disclose.

The design of each device has two critical steps, proton exchange and development of the LOR. Of the two, proton exchange time determines the depth of the waveguide, which in turn determines the number of guided to leaky mode transitions, the controllable frequency bandwidth, and every key design parameter for each color of light. Two guided modes in red is desired. If more exist then bandwidth is sacrificed. If less exist then no guided to leaky mode transition is guaranteed. Follow the note in step 2.2.1 to correct pro...

Most holographic display technologies, such as pixelated light valves as well as MEMs devices and bulk wave acousto-optic modulators, are too complex to allow for broad participation in their development. Pixelated modulators, especially those with filter layers and active back planes may require dozens of patterning steps to build5 and may be limited by fan-out6. The greater the number of patterning steps the higher the device complexity, and the tighter the fabrication protocol must be to achieve reasonable device yield7. Bulk-wave acousto-optic modulators do not lend themselves to wafer based processes8,9. Anisotropic leaky mode modulators, however, require only two patterning steps to fabricate and utilize relatively standard microfabrication techniques10,11. The accessibility of these processes make it possible for any institution with modest fabrication facilities to participate in the development of holographic video display technology12.
The simplicity of device fabrication can be beguiling, however, as the proper function of the devices is strongly dependent upon waveguides which must be carefully measured and adjusted to achieve the desired device characteristics. For example, if the waveguide is too deep, the device&#39;s operational bandwidth will be narrowed13. If the wave guide is too shallow, the device may not work for red illumination. If the waveguide is annealed too long, the shape of the waveguide&#39;s depth profile will be distorted, and the red, green and blue transitions may not sit adjacent in the frequency domain14. In this work the authors present the tools and techniques to perform this characterization.
The leaky mode modulator consists of a proton exchanged waveguide indiffused on the surface of a piezoelectric, x-cut lithium niobate substrate15,16. At one end of the waveguide is an aluminum interdigital transducer, see Figure 1. Light is introduced into the waveguide using a prism coupler17. The transducer then launches surface acoustic waves which interact contralinearly with light in the waveguide along the y-axis. This interaction couples guided light into a leaky mode which leaks out of the waveguide into the bulk and finally exits the substrate from the edge face18,19. This interaction also rotates the polarization from TE polarized guided light to TM polarized leaky mode light. The surface acoustic wave pattern is the hologram, and it is capable of scanning and shaping the output light to form a holographic image.
The waveguide is created by proton exchange. First, aluminum is deposited on the substrate. Then the aluminum is patterned photo-lithographically and etched to expose regions of the substrate to become waveguide channels. The remaining aluminum acts as a hard mask. The substrate is immersed in a melt of benzoic acid which alters the surface index in the exposed regions. The device is removed, cleaned and annealed in a muffle furnace. The final depth of the waveguide determines the number of leaky mode transitions. The waveguide depth also determines the frequency of each guided-to-mode transitions for each color4.
The aluminum transducers are formed by liftoff. After waveguides are formed, an E-beam resist is spun onto the substrate. An interdigital transducer is patterned with an electron beam to form a chirped transducer designed to respond to the 200 MHz band responsible for controlling color in waveguide devices. The finger period is determined by &#923;&#402; = v where, &#923;, is the finger period, v, is the velocity of sound in the substrate and, &#402;, is the radio frequency (RF). The transducer will have an impedance that must be matched to 75 ohms for efficient operation20.
The guided to leaky mode interaction occurs at different frequencies for different wavelengths of illumination light and as a result red, green, and blue light can be controlled in the frequency domain. The surface acoustic wave pattern is generated by an RF signal sent to the interdigital transducer. The RF of the input signal translate to spatial frequencies on the surface acoustic wave pattern. The waveguide can be fabricated so that low frequency signals control the angular sweep and amplitude of red light, while middle frequencies control green light and high frequencies control blue light. The authors have identified a set of waveguide parameters that allow all three of these interactions to be separate and adjacent in the frequency domain so that all three colors can be controlled with a single 200 MHz signal which is the maximum bandwidth of commodity graphics processing units (GPUs).
By matching the bandwidth of a GPU channel to that of a leaky mode modulator, the system becomes fully parallel and highly scalable. By adding bandwidth matched pairs of GPUs and leaky mode modulator channels, one may construct holographic displays of arbitrary size.
After the device is created, it is carefully characterized to verify that the frequencies for guided-to-leaky mode transition are appropriate for frequency control of color. First, the location of the guided modes are determined by a commercial prism coupler to confirm that the waveguide has the appropriate depth and the correct number of guided modes. Then, after the devices are mounted and packaged, they are placed in a custom prism coupler which maps the input frequencies of the scanned output light. The resulting data gives the frequency input response and the angular output response for red, green, and blue light for the device to be tested. If the device has been fabricated correctly, the device input response will be separated in frequency and the output response will be overlapping in angle. When this is confirmed, the device is ready for use in a holographic video display.
The first measurements take place before the device has been packaged. The waveguide depth is determined by a commercial prism coupler. This can be accomplished with just one illumination wavelength (typically 632 nm red) but authors have modified their commercial prism coupler to allow it to gather mode information for red, green and blue light. After packaging, the device undergoes a second measurement in a custom prism coupler which records deflected output light as a function of input RF. A detailed description of these measurements follows. Fabrication steps are also given.

<table border="0" cellpadding="0" cellspacing="0" width="921">
	<tbody>
		<tr height="40">
			<td height="40" style="height:40px;width:243px;">X-Cut Lithium Niobate</td>
			<td style="width:143px;">Gooch and Housego</td>
			<td style="width:147px;">99-00630-01</td>
			<td style="width:391px;">Lithium Niobate 3&#8243; Diameter X-CUT Wafer 1mm Polish/Polish</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:243px;">Positive Photo Resist 1</td>
			<td style="width:143px;">EMD Performance Materials</td>
			<td style="width:147px;">AZ 3330 F Photoresist</td>
			<td style="width:391px;">Used in the creation of the proton exchange mask.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:243px;">Photoresist Developer</td>
			<td style="width:143px;">EMD Performance Materials</td>
			<td style="width:147px;">AZ MIF 300</td>
			<td style="width:391px;">Develops AZ3330 and LOR 3A</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:243px;">Aluminium</td>
			<td style="width:143px;">International Advanced Materials</td>
			<td style="width:147px;">AL13</td>
			<td style="width:391px;">99.999% Pure</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:243px;">Aluminium Etch</td>
			<td style="width:143px;">Transene</td>
			<td style="width:147px;">Type A Aluminum Etchant</td>
			<td style="width:391px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:243px;">Benzoic Acid</td>
			<td style="width:143px;">Sigma Aldrich</td>
			<td style="width:147px;">109479-500G</td>
			<td style="width:391px;">99% Pure</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:243px;">Acetone</td>
			<td style="width:143px;">Fisher Chemical</td>
			<td style="width:147px;">UN1009</td>
			<td style="width:391px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:243px;">IPA</td>
			<td style="width:143px;">Fisher Chemical</td>
			<td style="width:147px;">UN1219</td>
			<td style="width:391px;">99.5% pure Isopropyl Alcohol</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:243px;">Acidic Piranha etch</td>
			<td style="width:143px;">Cyantek Corperation</td>
			<td style="width:147px;">Nanostrip</td>
			<td style="width:391px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:243px;">Under Layer Resist</td>
			<td style="width:143px;">Micro Chem</td>
			<td style="width:147px;">LOR 3A</td>
			<td style="width:391px;">Bottom layer used for liftoff.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:243px;">Positive Photo Resist</td>
			<td style="width:143px;">Micro Chem</td>
			<td style="width:147px;">950 PMMA A9</td>
			<td style="width:391px;">Top layer used for liftoff</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:243px;">Anisole</td>
			<td style="width:143px;">Micro Chem</td>
			<td style="width:147px;">A Thinner</td>
			<td style="width:391px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:243px;">Conductive polymer aqueous solution</td>
			<td style="width:143px;">Mitsubishi Rayon Company</td>
			<td style="width:147px;">AquaSAVE</td>
			<td style="width:391px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:243px;">MIBK (4-Methyl-2-pentanone)</td>
			<td style="width:143px;">Sigma Aldrich</td>
			<td style="width:147px;">360511</td>
			<td style="width:391px;">Develops PMMA</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:243px;">NMP (1-methyl-2-pyrrolidone)</td>
			<td style="width:143px;">Sigma Aldrich</td>
			<td style="width:147px;">328634</td>
			<td style="width:391px;">Used for liftoff</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:243px;">Name of the Equipment</td>
			<td style="width:143px;">Company</td>
			<td style="width:147px;">Catalog Number</td>
			<td style="width:391px;">Comments/ Description</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:243px;">E-beam Evaporator&#160;</td>
			<td style="width:143px;">Denton Vacuum&#160;</td>
			<td style="width:147px;">Integrity 20</td>
			<td style="width:391px;">Any equivalent equipment would suffice.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:243px;">Thin Film Spinner</td>
			<td style="width:143px;">Laurell Technologies Corporation</td>
			<td style="width:147px;">WS-400A-6NPP-LITE</td>
			<td style="width:391px;">Any equivalent equipment would suffice.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:243px;">Mask Aligner&#160;</td>
			<td style="width:143px;">Karl Suss America Inc.</td>
			<td style="width:147px;">MA 150 CC</td>
			<td style="width:391px;">Any equivalent equipment would suffice.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:243px;">Automatic Dicing Saw&#160;</td>
			<td style="width:143px;">Disco Corperation</td>
			<td style="width:147px;">Disco Dad 320</td>
			<td style="width:391px;">Any equivalent equipment would suffice.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:243px;">Muffle Furnace</td>
			<td style="width:143px;">Thermo Scientific</td>
			<td style="width:147px;">FB1415M</td>
			<td style="width:391px;">Any equivalent equipment would suffice.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:243px;">Electron Microscope</td>
			<td style="width:143px;">FEI</td>
			<td style="width:147px;">XL30 ESEM</td>
			<td style="width:391px;">Any equivalent equipment would suffice.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:243px;">Dehydration Oven</td>
			<td style="width:143px;">Lab-Line Instruments&#160;</td>
			<td style="width:147px;">Ultra-Clean 100&#160; (3497M-3)</td>
			<td style="width:391px;">Any equivalent equipment would suffice.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:243px;">Hot Plate</td>
			<td style="width:143px;">Thermo Scientific</td>
			<td style="width:147px;">SP131325</td>
			<td style="width:391px;">Any equivalent equipment would suffice.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:243px;">Polisher</td>
			<td style="width:143px;">Ultra Tec Mfg., Inc.</td>
			<td style="width:147px;">Ultrapol End &#38; Edge Polisher</td>
			<td style="width:391px;">Any equivalent equipment would suffice.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:243px;">Class IIIb 12V RBG Lasers: Wavelengths(nm): 638, 532, and 445</td>
			<td style="width:143px;"></td>
			<td style="width:147px;"></td>
			<td style="width:391px;">Bought second-hand. Probably pulled from a laser projector. Any equivalent equipment would suffice.</td>
		</tr>
		<tr height="60">
			<td height="60" style="height:60px;width:243px;">Signal Generator</td>
			<td style="width:143px;">Agilent</td>
			<td style="width:147px;">8648D</td>
			<td style="width:391px;">Now found at Keysight. Obsolete. Any equivalent equipment would suffice. Needed Frequency sweep 9 KHz-1000 MHz.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:243px;">Signal Amplifier</td>
			<td style="width:143px;">Mini-Circuits</td>
			<td style="width:147px;">TB-17</td>
			<td style="width:391px;">Necessary only to overcome the limitations of the signal generator.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:243px;">Power Meter Controller</td>
			<td style="width:143px;">ThorLabs</td>
			<td style="width:147px;">PM100D</td>
			<td style="width:391px;">With power meter model S130C. Any equivalent equipment would suffice. Needed sensitivity 500pW</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:243px;">Linear Actuator Controller</td>
			<td style="width:143px;">Newport</td>
			<td style="width:147px;">ESP7000</td>
			<td style="width:391px;">With linear actuator model MFN25PP. Any equivalent equipment would suffice. Needs 0.1mm accuracy.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:243px;">AutomatedDeviceCharacterization.vi&#160;</td>
			<td style="width:143px;">LabView</td>
			<td style="width:147px;">Experimental Control Software by BYU</td>
			<td style="width:391px;">Found in the appendix</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:243px;">CompareWDMmodes.m</td>
			<td style="width:143px;">MATLab</td>
			<td style="width:147px;">Analytical Software by BYU</td>
			<td style="width:391px;">Found in the appendix</td>
		</tr>
	</tbody>
</table>

characterization of anisotropic leaky mode modulators for holovideo

Holovideo displays are based on light-bending spatial light modulators. One such spatial light modulator is the anisotropic leaky mode modulator. This modulator is particularly well suited for holographic video experimentation as it is relatively simple and inexpensive to fabricate1-3. Some additional advantages of leaky mode devices include: large aggregate bandwidth, polarization separation of signal light from noise, large angular deflection and frequency control of color1. In order to realize these advantages, it is necessary to be able to adequately characterize these devices as their operation is strongly dependent on waveguide and transducer parameters4. To characterize the modulators, the authors use a commercial prism coupler as well as a custom characterization apparatus to identify guided modes, calculate waveguide thickness and finally to map the device's frequency input and angular output of leaky mode modulators. This work gives a detailed description of the measurement and characterization of leaky mode modulators suitable for full-color holographic video.

The principle results of the protocol above are the guided mode measurement from the commercial prism coupler shown in Figure 2, the single frequency, raw input/output data gathered from the customized prism coupler shown in Figure 8 and the multicolor curves shown in Figure 9. In the following paragraphs we discuss the actionable information produced by each of these outputs.
T...

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Characterization of Anisotropic Leaky Mode Modulators for Holovideo

This work describes fabrication and characterization of anisotropic leaky mode modulators for holographic video.

Holovideo displays are based on light-bending spatial light modulators.  One such spatial light modulator is the anisotropic leaky mode modulator.  This ...

characterization-of-anisotropic-leaky-mode-modulators-for-holovideo

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7.9K Views.  Brigham Young University. This work describes fabrication and characterization of anisotropic leaky mode modulators for holographic video.

Video: Characterization of Anisotropic Leaky Mode Modulators for Holovideo

Development of Whispering Gallery Mode Polymeric Micro-optical Electric Field Sensors

Optical modes of dielectric micro-cavities have received significant attention in recent years for their potential in a broad range of applications. The optical modes are frequently referred to as "whispering gallery modes" (WGM) or "morphology dependent resonances" (MDR) and exhibit high optical quality factors. Some proposed applications of micro-cavity optical resonators are in spectroscopy1, micro-cavity laser technology2, optical communications3-6 as well as sensor technology. The WGM-based sensor applications include those in biology7, trace gas detection8, and impurity detection in liquids9. Mechanical sensors based on microsphere resonators have also been proposed, including those for force10,11, pressure12, acceleration13 and wall shear stress14. In the present, we demonstrate a WGM-based electric field sensor, which builds on our previous studies15,16. A candidate application of this sensor is in the detection of neuronal action potential.
The electric field sensor is based on polymeric multi-layered dielectric microspheres. The external electric field induces surface and body forces on the spheres (electrostriction effect) leading to elastic deformation. This change in the morphology of the spheres, leads to shifts in the WGM. The electric field-induced WGM shifts are interrogated by exciting the optical modes of the spheres by laser light. Light from a distributed feedback (DFB) laser (nominal wavelength of ~ 1.3 &mu;m) is side-coupled into the microspheres using a tapered section of a single mode optical fiber. The base material of the spheres is polydimethylsiloxane (PDMS). Three microsphere geometries are used: (1) PDMS sphere with a 60:1 volumetric ratio of base-to-curing agent mixture, (2) multi layer sphere with 60:1 PDMS core, in order to increase the dielectric constant of the sphere, a middle layer of 60:1 PDMS that is mixed with varying amounts (2% to 10% by volume) of barium titanate and an outer layer of 60:1 PDMS and (3) solid silica sphere coated with a thin layer of uncured PDMS base. In each type of sensor, laser light from the tapered fiber is coupled into the outermost layer that provides high optical quality factor WGM (Q ~ 106). The microspheres are poled for several hours at electric fields of ~ 1 MV/m to increase their sensitivity to electric field.

A high-sensitivity photonic micro sensor was developed for electric field detection. The sensor exploits the optical modes of a dielectric sphere. Changes in the external electric field perturb the sphere morphology leading to shifts in its optical modes. The electric field strength is measured by monitoring these optical shifts.

Optical modes of dielectric micro-cavities have received significant attention in recent years for their potential in a broad range of applications. The ...

Microwave Photonics Systems Based on Whispering-gallery-mode Resonators

Microwave photonics systems rely fundamentally on the interaction between microwave and optical signals. These systems are extremely promising for various areas of technology and applied science, such as aerospace and communication engineering, sensing, metrology, nonlinear photonics, and quantum optics. In this article, we present the principal techniques used in our lab to build microwave photonics systems based on ultra-high Q whispering gallery mode resonators. First detailed in this article is the protocol for resonator polishing, which is based on a grind-and-polish technique close to the ones used to polish optical components such as lenses or telescope mirrors. Then, a white light interferometric profilometer measures surface roughness, which is a key parameter to characterize the quality of the polishing. In order to launch light in the resonator, a tapered silica fiber with diameter in the micrometer range is used. To reach such small diameters, we adopt the "flame-brushing" technique, using simultaneously computer-controlled motors to pull the fiber apart, and a blowtorch to heat the fiber area to be tapered. The resonator and the tapered fiber are later approached to one another to visualize the resonance signal of the whispering gallery modes using a wavelength-scanning laser. By increasing the optical power in the resonator, nonlinear phenomena are triggered until the formation of a Kerr optical frequency comb is observed with a spectrum made of equidistant spectral lines. These Kerr comb spectra have exceptional characteristics that are suitable for several applications in science and technology. We consider the application related to ultra-stable microwave frequency synthesis and demonstrate the generation of a Kerr comb with GHz intermodal frequency.

The customized techniques developed in our lab to build microwave photonics systems based on ultra-high Q whispering gallery mode resonators are presented. The protocols to obtain and characterize these resonators are detailed, and an explanation of some of their applications in microwave photonics is given.

Microwave photonics systems rely fundamentally on the interaction between microwave and optical signals. These systems are extremely promising for various ...

Fabrication and Characterization of Disordered Polymer Optical Fibers for Transverse Anderson Localization of Light

We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. The developed polymer optical fiber is composed of 80,000 strands of poly (methyl methacrylate) (PMMA) and polystyrene (PS) that are randomly mixed and drawn into a square cross section optical fiber with a side width of 250 &mu;m. Initially, each strand is 200 &mu;m in diameter and 8-inches long. During the mixing process of the original fiber strands, the fibers cross over each other; however, a large draw ratio guarantees that the refractive index profile is invariant along the length of the fiber for several tens of centimeters. The large refractive index difference of 0.1 between the disordered sites results in a small localized beam radius that is comparable to the beam radius of conventional optical fibers. The input light is launched from a standard single mode optical fiber using the butt-coupling method and the near-field output beam from the disordered fiber is imaged using a 40X objective and a CCD camera. The output beam diameter agrees well with the expected results from the numerical simulations. The disordered optical fiber presented in this work is the first device-level implementation of 2D Anderson localization, and can potentially be used for image transport and short-haul optical communication systems.

We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. This microstructured fiber can transport a small localized beam with a radius that is comparable to the beam radius of conventional optical fibers.

We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. The developed ...

Construction and Characterization of External Cavity Diode Lasers for Atomic Physics

Since their development in the late 1980s, cheap, reliable external cavity diode lasers (ECDLs) have replaced complex and expensive traditional dye and Titanium Sapphire lasers as the workhorse laser of atomic physics labs1,2. Their versatility and prolific use throughout atomic physics in applications such as absorption spectroscopy and laser cooling1,2 makes it imperative for incoming students to gain a firm practical understanding of these lasers. This publication builds upon the seminal work by Wieman3, updating components, and providing a video tutorial. The setup, frequency locking and performance characterization of an ECDL will be described. Discussion of component selection and proper mounting of both diodes and gratings, the factors affecting mode selection within the cavity, proper alignment for optimal external feedback, optics setup for coarse and fine frequency sensitive measurements, a brief overview of laser locking techniques, and laser linewidth measurements are included.

This is an instructional paper to guide the construction and diagnostics of external cavity diode lasers (ECDLs), including component selection and optical alignment, as well as the basics of frequency reference spectroscopy and laser linewidth measurements for applications in the field of atomic physics.

Since their development in the late 1980s, cheap, reliable external cavity diode lasers (ECDLs) have replaced complex and expensive traditional dye and ...

Mechanical Expansion of Steel Tubing as a Solution to Leaky Wellbores

Wellbore cement, a procedural component of wellbore completion operations, primarily provides zonal isolation and mechanical support of the metal pipe (casing), and protects metal components from corrosive fluids. These are essential for uncompromised wellbore integrity. Cements can undergo multiple forms of failure, such as debonding at the cement/rock and cement/metal interfaces, fracturing, and defects within the cement matrix. Failures and defects within the cement will ultimately lead to fluid migration, resulting in inter-zonal fluid migration and premature well abandonment. Currently, there are over 1.8 million operating wells worldwide and over one third of these wells have leak related problems defined as Sustained Casing Pressure (SCP)1. 
The focus of this research was to develop an experimental setup at bench-scale to explore the effect of mechanical manipulation of wellbore casing-cement composite samples as a potential technology for the remediation of gas leaks. 
The experimental methodology utilized in this study enabled formation of an impermeable seal at the pipe/cement interface in a simulated wellbore system. Successful nitrogen gas flow-through measurements demonstrated that an existing microannulus was sealed at laboratory experimental conditions and fluid flow prevented by mechanical manipulation of the metal/cement composite sample. Furthermore, this methodology can be applied not only for the remediation of leaky wellbores, but also in plugging and abandonment procedures as well as wellbore completions technology, and potentially preventing negative impacts of wellbores on subsurface and surface environments.

This article reports on a laboratory scale investigation of an existing field procedure and its adaptation for sealing of leaky wellbores. It consists of mechanical expansion of metal pipe, which results in an improved metal/cement bond, ultimate sealing of hydraulic pathways and prevention of gas leaks caused by the presence of a microannular channel.

Wellbore cement, a procedural component of wellbore completion operations, primarily provides zonal isolation and mechanical support of the metal pipe ...

Electron Channeling Contrast Imaging for Rapid III-V Heteroepitaxial Characterization

Misfit dislocations in heteroepitaxial layers of GaP grown on Si(001) substrates are characterized through use of electron channeling contrast imaging (ECCI) in a scanning electron microscope (SEM). ECCI allows for imaging of defects and crystallographic features under specific diffraction conditions, similar to that possible via plan-view transmission electron microscopy (PV-TEM). A particular advantage of the ECCI technique is that it requires little to no sample preparation, and indeed can use large area, as-produced samples, making it a considerably higher throughput characterization method than TEM. Similar to TEM, different diffraction conditions can be obtained with ECCI by tilting and rotating the sample in the SEM. This capability enables the selective imaging of specific defects, such as misfit dislocations at the GaP/Si interface, with high contrast levels, which are determined by the standard invisibility criteria. An example application of this technique is described wherein ECCI imaging is used to determine the critical thickness for dislocation nucleation for GaP-on-Si by imaging a range of samples with various GaP epilayer thicknesses. Examples of ECCI micrographs of additional defect types, including threading dislocations and a stacking fault, are provided as demonstration of its broad, TEM-like applicability. Ultimately, the combination of TEM-like capabilities &#8211; high spatial resolution and richness of microstructural data &#8211; with the convenience and speed of SEM, position ECCI as a powerful tool for the rapid characterization of crystalline materials.

The use of electron channeling contrast imaging in a scanning electron microscope to characterize defects in III-V/Si heteroexpitaxial thin films is described. This method yields similar results to plan-view transmission electron microscopy, but in significantly less time due to lack of required sample preparation.

Misfit dislocations in heteroepitaxial layers of GaP grown on Si(001) substrates are characterized through use of electron channeling contrast imaging ...

Automation of Mode Locking in a Nonlinear Polarization Rotation Fiber Laser through Output Polarization Measurements

When a laser is mode-locked, it emits a train of ultra-short pulses at a repetition rate determined by the laser cavity length. This article outlines a new and inexpensive procedure to force mode locking in a pre-adjusted nonlinear polarization rotation fiber laser. This procedure is based on the detection of a sudden change in the output polarization state when mode locking occurs. This change is used to command the alignment of the intra-cavity polarization controller in order to find mode-locking conditions. More specifically, the value of the first Stokes parameter varies when the angle of the polarization controller is swept and, moreover, it undergoes an abrupt variation when the laser enters the mode-locked state. Monitoring this abrupt variation provides a practical easy-to-detect signal that can be used to command the alignment of the polarization controller and drive the laser towards mode locking. This monitoring is achieved by feeding a small portion of the signal to a polarization analyzer measuring the first Stokes parameter. A sudden change in the read out of this parameter from the analyzer will occur when the laser enters the mode-locked state. At this moment, the required angle of the polarization controller is kept fixed. The alignment is completed. This procedure provides an alternate way to existing automating procedures that use equipment such as an optical spectrum analyzer, an RF spectrum analyzer, a photodiode connected to an electronic pulse-counter or a nonlinear detecting scheme based on two-photon absorption or second harmonic generation. It is suitable for lasers mode locked by nonlinear polarization rotation. It is relatively easy to implement, it requires inexpensive means, especially at a wavelength of 1550 nm, and it lowers the production and operation costs incurred in comparison to the above-mentioned techniques.

A protocol to detect and automate mode locking in a pre-adjusted nonlinear polarization rotation fiber laser is presented. The detection of a sudden change in the output polarization state when mode locking occurs is used to command the alignment of an intra-cavity polarization controller in order to find mode-locking conditions.

When a laser is mode-locked, it emits a train of ultra-short pulses at a repetition rate determined by the laser cavity length. This article outlines a ...

Stimulated Stokes and Antistokes Raman Scattering in Microspherical Whispering Gallery Mode Resonators

Dielectric microspheres can confine light and sound for a length of time through high quality factor whispering gallery modes (WGM). Glass microspheres can be thought as a store of energy with a huge variety of applications: compact laser sources, highly sensitive biochemical sensors and nonlinear phenomena. A protocol for the fabrication of both the microspheres and coupling system is given. The couplers described here are tapered fibers. Efficient generation of nonlinear phenomena related to third order optical non-linear susceptibility &#935;(3) interactions in triply resonant silica microspheres is presented in this paper. The interactions here reported are: Stimulated Raman Scattering (SRS), and four wave mixing processes comprising Stimulated Anti-stokes Raman Scattering (SARS). A proof of the cavity-enhanced phenomenon is given by the lack of correlation among the pump, signal and idler: a resonant mode has to exist in order to obtain the pair of signal and idler. In the case of hyperparametric oscillations (four wave mixing and stimulated anti-stokes Raman scattering), the modes must fulfill the energy and momentum conservation and, last but not least, have a good spatial overlap.

Efficient generation of nonlinear phenomena related to third order optical non-linear susceptibility &#935;(3) interactions in triply resonant silica microspheres is presented in this paper. The interactions here reported are: Stimulated Raman Scattering (SRS), and four wave mixing processes comprising Stimulated Anti-stokes Raman Scattering (SARS).

Dielectric microspheres can confine light and sound for a length of time through high quality factor whispering gallery modes (WGM). Glass microspheres ...

A Novel Method for In Situ Electromechanical Characterization of Nanoscale Specimens

Electrically assisted deformation (EAD) is increasingly being used to improve the formability of metals during processes such as sheet metal rolling and forging. Adoption of this technique is proceeding despite disagreement concerning the underlying mechanism responsible for EAD. The experimental procedure described herein enables a more explicit study compared to previous EAD research by removing thermal effects, which are responsible for disagreement in interpreting previous EAD results. Furthermore, as the procedure described here enables EAD observation in situ and in real time in a transmission electron microscope (TEM), it is superior to existing post-mortem methods that observe EAD effects post-test. Test samples consist of a single crystal copper (SCC) foil having a free-standing tensile test section of nanoscale thickness, fabricated using a combination of laser and ion beam milling. The SCC is mounted to an etched silicon base that provides mechanical support and electrical isolation while serving as a heat sink. Using this geometry, even at high current density (~3,500 A/mm2), the test section experiences a negligible temperature increase (&#60;0.02 &#176;C), thus eliminating Joule heating effects. Monitoring material deformation and identifying the corresponding changes to microstructures, e.g. dislocations, are accomplished by acquiring and analyzing a series of TEM images. Our sample preparation and in situ experiment procedures are robust and versatile as they can be readily utilized to test materials with different microstructures, e.g., single and polycrystalline copper.

A Novel Method for In Situ Electromechanical Characterization of Nanoscale Specimens

Isolating electrical and thermal effects on electrically assisted deformation (EAD) is very difficult using macroscopic samples. Metallic sample micro- and nanostructures together with a custom test procedure have been developed to evaluate the impact of applied current on the formation without joule heating and evolution of dislocations on these samples.

Electrically assisted deformation (EAD) is increasingly being used to improve the formability of metals during processes such as sheet metal rolling and ...

Ultrasonic Fatigue Testing in the Tension-Compression Mode

Ultrasonic fatigue testing is one of a few methods which allow investigating fatigue properties in the ultra-high cycle region. The method is based on exposing the specimen to longitudinal vibrations on its resonance frequency close to 20 kHz. With use of this method, it is possible to significantly decrease the time required for the test, when compared to conventional testing devices usually working at frequencies under 200 Hz. It is also used to simulate loading of material during operation in high speed conditions, such as those experienced by components of jet engines or car turbo pumps. It is necessary to operate only in the high and ultra-high cycle region, due to the possibility of extremely high deformation rates, which can have a significant influence on the test results. Specimen shape and dimensions have to be carefully selected and calculated to fulfill the resonance condition of the ultrasonic system; thus, it is not possible to test the full components or specimens of arbitrary shape. Before each test, it is necessary to harmonize the specimen with the frequency of the ultrasonic system to compensate for deviations of the real shape from the ideal one. It is not possible to run a test until a total fracture of the specimen, since the test is automatically terminated after initiation and propagation of the crack to a certain length, when the stiffness of the system changes enough to shift the system out of the resonance frequency. This manuscript describes the process of evaluation of materials' fatigue properties at high-frequency ultrasonic fatigue loading with use of mechanical resonance at a frequency close to 20 kHz. The protocol includes a detailed description of all steps required for a correct test, including specimen design, stress calculation, harmonizing with the resonance frequency, performing the test, and final static fracture.

A protocol for ultrasonic fatigue testing in the high and ultra-high cycle region in axial tension-compression loading mode.

Ultrasonic fatigue testing is one of a few methods which allow investigating fatigue properties in the ultra-high cycle region. The method is based on ...