This work was funded by Startup funding from the University of Illinois at Urbana-Champaign, DARPA ORCHID program through a grant from AFOSR, the National Science Foundation through grant CMMI-1265164, and the National Science Foundation Graduate Research Fellowship program. We acknowledge enlightening discussions with Prof. Jack Harris, Prof. Pierre Meystre, Dr. Matt Eichenfield, Prof. Taher Saif, and Prof. Rashid Bashir.

1. Fabrication of Ultra-high-Q Microfluidic Resonators
<ol>
	<li>Preparation of capillary manufacturing setup
	<ol>
		<li>Fabricate the microfluidic optomechanical resonator in the following way &#8211; Heat a glass capillary preform with approximately 10 W of CO2 laser radiation at 10.6 microns wavelength, and draw out the heated capillary linearly using motorized translation stages. Figure 1 shows the arrangement of the linear translation stages, the lasers, and the location of the capillary preform before the pulling process.</li>
		<li>Program suitable automation software to simultaneously control the two CO2 lasers (for heating) and the two linear stages. The two linear stages perform the drawing process for the laser-heated capillary.</li>
		<li>One of the linear stages must be fast (e.g. 5 mm/sec) for the linear drawing process. Feed in more material to the heating zone with the second, slower linear stage (e.g. 0.5 mm/sec) since the capillary preform material gets depleted during the pulling process.</li>
		<li>Align the sample holders on the linear stages along both vertical and horizontal axes.</li>
		<li>Carefully align both CO2 laser beams such that they target the same spot in space (between the sample holders). A piece of card paper or heat sensitive paper is useful for this process. Do not forget to use eye protection for laser safety. Do not lower eyes to table level. Use suitable beam blocks, fume exhaust, and fire protection.</li>
		<li>Select reasonable parameters for the drawing process. For example, the following parameters reliably produce a good capillary size &#8212; 10 mm/sec pulling speed, 0.5 mm/sec feed-in speed, 3 sec preheating time, 4.5 W preheating powers for both lasers, and 5 W heating powers for both lasers.</li>
		<li>Modulation of the laser power during pulling can be used to control the capillary radius lengthwise during the drawing process to form the &#8216;bottle&#8217; resonators. An example is shown in Figure 2d. Select the proper modulation parameters: 3 Hz frequency, 6 W and 3 W for laser powers, and 50% duty cycle.</li>
	</ol>
	</li>
	<li>Fabrication of microfluidic optomechanical resonators
	<ol>
		<li>Cut a sufficiently long segment (about 2-4 cm) of fused silica capillary such that it can reach the two holders attached to the linear translation stages.</li>
		<li>Mount the capillary sample on the sample holders such that the laser target zone is roughly in the middle of the capillary. Readjust CO2 laser alignment if needed.</li>
		<li>Pull the capillary using the parameters as stated in 1.1.6. First preheat the capillary for a few seconds (Figure 2a), and then pull it with or without laser modulation (parameters in 1.1.7) as needed.</li>
		<li>Remove the drawn capillary (Figure 2b) from the sample holder. Handle the sample with gloves at the two thick ends only, in order not to contaminate the clean resonator surface.</li>
		<li>Vary the pulling parameters to fabricate capillaries with different diameters. Typically outer diameter varies from 30 &#181;m to 200 &#181;m depending on pulling conditions.</li>
	</ol>
	</li>
	<li>Mounting the fabricated device for testing
	<ol>
		<li>Prepare an E shape glass holder (Figure 2c). Cut three 1 cm x 0.5 cm and one 3 cm x 0.5 cm glass pieces from glass slides. Assemble them into an E shape using glass adhesive or superglue.</li>
		<li>Cut a length of microfluidic capillary out of the drawn sample. This length should be longer than the distance between two adjacent glass branches on the E shape holder.</li>
		<li>Glue the microcapillary device onto the holder using optical adhesive while making sure to keep a portion hanging uncontaminated between two branches of the E shape holder. Cure the optical adhesive with a LED UV curing light source for 10 sec. Figures 2c and 2d show the finished product.</li>
		<li>Carefully insert both ends of the mounted resonator into two slightly larger plastic tubes (e.g. 200 &#181;m in inner diameter). Glue and UV cure both ends to the plastic tubes with optical adhesive.</li>
		<li>Clamp the E shape structure from the third (free) glass branch to a clamped mounting device for testing. The optical quality factor of the final microfluidic resonator depends on how well the fabrication lasers were aligned and how stable their power levels were.</li>
	</ol>
	</li>
</ol>
2. Experimental Setup for Optomechanical Testing
<ol>
	<li>Fabrication of tapered optical fiber
	<ol>
		<li>Prepare a single mode telecom-band optical fiber of desired length (e.g. a few feet). Fiber segment should be long enough to be both mounted in the tapering area and connected to the setup (Figure 4). The tapering method explained here is similar to what is suggested and demonstrated in 22.</li>
		<li>Connect the prepared fiber segment to the rest of the experimental setup using any convenient fiber-splicing method.</li>
		<li>Mount the spliced fiber segment onto two linear pullers that face each other.</li>
		<li>Strip off the fiber jacket in the center of the mounted fiber fragment to expose cladding area. This is where taper will be fabricated. Clean the stripped area with methanol.</li>
		<li>Turn on the tunable laser to see real-time transmission on an oscilloscope. Make sure to set attenuators so that photodetectors are not damaged.</li>
		<li>Place a narrow nozzle hydrogen gas burner immediately underneath the unjacketed portion of the fiber. Follow all recommended safety procedures when working with pressurized flammable gases such as hydrogen. Other &#8220;clean burning&#8221; sources of flame or ceramic heaters could also be used.</li>
		<li>Before lighting up the gas, check the flow rate so that flame will not be too large (a 1-2 cm tall flame is adequate). Note that the flame is mostly invisible but may be seen as a faint orange glow in a dark room. The hydrogen flow rate should be set to a point where lighted flame will adequately soften the glass fiber.</li>
		<li>Light up the flame. As soon as flame is on, start pulling the fiber using motorized stages. Appropriate pulling speed depends on flow rate of hydrogen gas and vicinity of the flame. NOTE: Transmission through the fiber will begin to show temporal oscillation behavior as pulling continues. This indicates multimode operation.</li>
		<li>When oscillatory behavior stops and shows an unchanging signal over time, stop pulling and turn-off the flame immediately. This is when single-mode taper is obtained. Check the transmission. If transmission is too low, repeat the procedure from 2.1.1. with modified gas flow rate, flame size, and flame location. On occasion, low transmission could be due to bad alignment at step 2.1.3. or due to contamination of the exposed cladding.</li>
		<li>If resultant transmission through the taper is satisfactory, wait a few minutes to cool down the taper.</li>
		<li>Inspect the taper under a microscope. For 1,550 nm operational wavelength, typical diameter of the single-mode taper is in the order of 1-2 &#181;m.</li>
	</ol>
	</li>
	<li>Taper-coupling to WGR and searching for electronic signals indicating vibration
	<ol>
		<li>Set up the experiment in the configuration shown in Figure 3. Mechanical vibrations can be generated through both SBS and RP by the same experimental configuration. In order to clearly detect back-scattered signals as in the case of backward-SBS4,21, use a circulator between taper and tunable laser.</li>
		<li>Before turning on the tunable IR laser, make sure to set attenuators in place so that photodetectors are not damaged.</li>
		<li>Turn on and stabilize the tunable IR laser. A function generator is used to sweep the frequency of the input IR laser.</li>
		<li>Mount the resonator holder on a nanopositioning stage. Carefully bring the resonator close to the tapered fiber in order to obtain evanescent coupling. As the laser frequency is swept, optical resonances will appear as dips in transmission in the oscilloscope, as in Figure 2b of 22.</li>
		<li>Connect the photodetector output to an electrical spectrum analyzer (ESA), where the temporal interference (i.e. beat note) between the input laser light and the scattered light can be observed. This temporal interference occurs at the mechanical oscillation frequency. The &#8220;peak hold&#8221; function on the spectrum analyzer is often useful in the initial search for mechanical vibrations.</li>
		<li>Use higher input power while performing the initial search for mechanical vibration, especially when liquids are present inside the device. NOTE: Typically, input power in the order of 100 &#181;W to the device is sufficient to excite mechanical vibration.</li>
		<li>If mechanical oscillation is observed, attempt to lock to the relevant optical mode by turning off the laser frequency scan and controlling the laser wavelength in CW mode. Here, both oscilloscope and spectrum analyzer are useful in tandem. Periodic signals appear on the oscilloscope when a mechanical mode is present, as seen in Figure 5 and 1,6.</li>
	</ol>
	</li>
</ol>
3. Measuring Optomechanical Vibrations
<ol>
	<li>Optical and electronic signature of radiation pressure (RP) modes
	<ol>
		<li>As described in 2.2, mechanical oscillations will be observed when the taper and device are correctly coupled, the device optical and mechanical modes have sufficient Q-factors, and sufficient input optical power is provided. If oscillations in the range of 10 MHz - 1 GHz are not observed, attempt to change polarization to investigate different resonances, or increase the input power from tunable laser in order to overcome the minimum threshold for oscillation. When increasing the input power, always be careful not to saturate the photodetectors. Also, as described in 8, coupling distance is a key factor for exciting different RP modes.</li>
		<li>If mechanical modes are still not observed, try measuring optical quality factor. For microfluidic optomechanical resonators, results show that optical quality factor of 106 is sufficient to excite parametric oscillations13. 
		NOTE: Usually, RP modes will manifest as electronic oscillations on the spectrum analyzer accompanied by their harmonics, as seen in Figure 5. Representative results will be discussed in section 4.</li>
		<li>Use a scanning Fabry-Perot interferometer or high-resolution optical spectrum analyzer to detect the optical side bands that are generated due to amplitude and phase modulation, which is in turn induced by the periodic cavity deformation. An example measurement may be seen in Figure 3h of 1.</li>
	</ol>
	</li>
	<li>Optical and electronic signature of whispering-gallery acoustic modes
	<ol>
		<li>The acoustic frequency of backward-SBS for silica glass is approximately 11 GHz when a 1.5 micron pump laser is used4,23. Use a circulator that monitors the back-scattered light and some small amount of Rayleigh-scattered pump, to observe electronic signals for these vibrational modes. Use a high-resolution optical spectrum analyzer to resolve the scattered light. An example measurement is shown in Figure 2 of 4.</li>
		<li>Use the beat note between forward scattered light and the pump laser to observe lower frequency (sub-1 GHz) whispering-gallery acoustic modes.</li>
		<li>Due to the lower mechanical rigidity in the breathing direction, the signal from SBS is sometimes weaker than the signal from the RP modes. Again, sweep the laser at slow speed, and use &#8220;peak hold&#8221; on the spectrum analyzer to help in finding the SBS signal.</li>
		<li>Note that unlike RP-excited breathing modes, SBS-excited whispering-gallery acoustic modes do not exhibit harmonics in the optical and electronic spectra (unless cascaded excitation takes place4,24). Instead only one Stokes sideband appears for SBS modes.</li>
	</ol>
	</li>
</ol>

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We have nothing to disclose.

We have fabricated and tested a new device that bridges between cavity optomechanics and microfluidics by employing high-Q optical resonances to excite (and interrogate) mechanical vibration. It is surprising that multiple excitation mechanisms are available in the very same device, which generate a variety of mechanical vibrational modes at rates spanning 2 MHz to 11,300 MHz. Centrifugal radiation pressure supports both wineglass modes and breathing modes in the 2-200 MHz span, Forward stimulated Brillouin scattering al...

Cavity optomechanics studies the parametric coupling between phonon modes and photon modes in microresonators by means of radiation pressure (RP)1-3 and stimulated Brillouin scattering (SBS)4-6. SBS and RP mechanisms have been demonstrated in many different optical systems, such as fibers7, microspheres4,6,8, toroids1,9, and crystalline resonators5,10. Through this photon-phonon coupling, both cooling11 and excitation6,10 of mechanical modes have been demonstrated. However, almost all reported optomechanics experiments are with solid phases of matter. This is because direct liquid immersion of the optomechanical devices results in greatly increased radiative acoustic loss because of the higher impedance of liquids compared against air. In addition, in some situations dissipative loss mechanisms in liquids may exceed the radiative acoustic losses.
Recently, a new type of hollow optomechanical oscillator with a microcapillary geometry was introduced12-15, and which by design is equipped for microfluidic experiments. The diameter of this capillary is modulated along its length to form multiple &#8216;bottle resonators&#8217; that simultaneously confine optical whispering-gallery resonances16 as well as mechanical resonant modes17. Multiple families of mechanical resonant modes participate, including breathing modes, wine-glass modes, and whispering-gallery acoustic modes. The wine-glass (standing-wave) and whispering-gallery acoustic (traveling-wave) resonances are formed when a vibration with integer multiple of acoustic wavelengths occurs around the device circumference. Light is evanescently coupled into the optical whispering-gallery modes of these &#8216;bottles&#8217; by means of a tapered optical fiber18. Confinement of the liquid inside19,20 the capillary resonator, as opposed to outside it, enables high mechanical- and optical- quality factors simultaneously, which allows the optical excitation of mechanical modes by means of both RP and SBS. As has been shown, these mechanical excitations are able to penetrate into the fluid within the device12,13, forming a shared solid-liquid resonant mode, thus enabling an opto-mechanical interface to the fluidic environment within.
In this paper we describe fabrication, RP and SBS actuation, and representative measurement results for this novel optomechanical system. Specific material and tool lists are also provided.

<table border="0" cellpadding="0" cellspacing="0" style="width:647px;" width="647">
	<tbody>
		<tr>
			<td>Tunable IR laser</td>
			<td>Newfocus</td>
			<td>TLB-6328</td>
			<td></td>
		</tr>
		<tr>
			<td>Photodetectors</td>
			<td>Newfocus</td>
			<td>1811-FC (Low speed 125MHz) / 1611-FC-AC (High speed 1GHz)</td>
			<td></td>
		</tr>
		<tr>
			<td>Optical fiber</td>
			<td>Corning</td>
			<td>SMF28</td>
			<td></td>
		</tr>
		<tr>
			<td>Silica capillary</td>
			<td>PolyMicro</td>
			<td>TSP700850</td>
			<td></td>
		</tr>
		<tr>
			<td>10.6 um wavelength CO2 laser</td>
			<td>Synrad</td>
			<td>48-1KWM and 48-2KWM</td>
			<td></td>
		</tr>
		<tr>
			<td>UV-curing optical adhesive</td>
			<td>Thorlabs</td>
			<td>NOA81</td>
			<td></td>
		</tr>
		<tr>
			<td>Tubing</td>
			<td>Tygon</td>
			<td>EW-06418-01</td>
			<td></td>
		</tr>
		<tr>
			<td>Syringes</td>
			<td>B-D</td>
			<td>YO-07940-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Needles</td>
			<td>Weller</td>
			<td>KDS201P</td>
			<td></td>
		</tr>
		<tr>
			<td>Electrical spectrum analyzer</td>
			<td>Agilent Technologies</td>
			<td>N9010A (EXA Signal Analyzer)</td>
			<td></td>
		</tr>
		<tr>
		</tr>
		<tr>
			<td>Tektronix</td>
			<td>6114A (RSA, Real-time spectrum analyzer)</td>
			<td></td>
		</tr>
		<tr>
			<td>Optical spectrum analyzer</td>
			<td>Advantest</td>
			<td>Q8384</td>
			<td></td>
		</tr>
		<tr>
			<td>Oscilloscope</td>
			<td>Tektronix</td>
			<td>DPO 4104B-L</td>
			<td></td>
		</tr>
		<tr>
			<td>Gold mirrors</td>
			<td>II-VI Infrared</td>
			<td>836627</td>
			<td></td>
		</tr>
		<tr>
			<td>Linear stage (slow)</td>
			<td>DryLin</td>
			<td>H1W1150</td>
			<td></td>
		</tr>
		<tr>
			<td>Linear stage (fast)</td>
			<td>PBC Linear</td>
			<td>MTB055D-0902-14F12</td>
			<td></td>
		</tr>
		<tr>
			<td>Fabry Perot optical spectrum analyser</td>
			<td>Thorlabs</td>
			<td>SA 200-14A (FSR: 1.5 GHz)</td>
			<td></td>
		</tr>
	</tbody>
</table>

fabrication and testing of microfluidic optomechanical oscillators

Cavity optomechanics experiments that parametrically couple the phonon modes and photon modes have been investigated in various optical systems including microresonators. However, because of the increased acoustic radiative losses during direct liquid immersion of optomechanical devices, almost all published optomechanical experiments have been performed in solid phase. This paper discusses a recently introduced hollow microfluidic optomechanical resonator. Detailed methodology is provided to fabricate these ultra-high-Q microfluidic resonators, perform optomechanical testing, and measure radiation pressure-driven breathing mode and SBS-driven whispering gallery mode parametric vibrations. By confining liquids inside the capillary resonator, high mechanical- and optical- quality factors are simultaneously maintained.

The capillaries produced by this method are thin (between 30 &#181;m and 200 &#181;m), clear, and very flexible, but are sufficiently robust for direct handling. It is important to protect the outer surface of the capillary device against dust and water (moisture) in order to maintain a high optical quality factor (Q). By dipping one end of the capillary in water and blowing air through the capillary by means of a syringe, it can be verified whether the capillary is through or whether was sealed off during fabrication du...

Watch this Scientific Journal Video about Fabrication and Testing of Microfluidic Optomechanical Oscillators at JoVE.com

Fabrication and Testing of Microfluidic Optomechanical Oscillators

Parametric optomechanical excitations have recently been experimentally demonstrated in microfluidic optomechanical resonators by means of optical radiation pressure and stimulated Brillouin scattering. This paper describes the fabrication of these microfluidic resonators along with methodologies for generating and verifying optomechanical oscillations.

Cavity optomechanics experiments that parametrically couple the phonon modes and photon modes have been investigated in various optical systems including ...

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12.1K Views.  University of Illinois at Urbana-Champaign. Parametric optomechanical excitations have recently been experimentally demonstrated in microfluidic optomechanical resonators by means of optical radiation pressure and stimulated Brillouin scattering. This paper describes the fabrication of these microfluidic resonators along with methodologies for generating and verifying optomechanical oscillations. 

Video: Fabrication and Testing of Microfluidic Optomechanical Oscillators

Simulation, Fabrication and Characterization of THz Metamaterial Absorbers

Metamaterials (MM), artificial materials engineered to have properties that may not be found in nature, have been widely explored since the first theoretical1 and experimental demonstration2 of their unique properties. MMs can provide a highly controllable electromagnetic response, and to date have been demonstrated in every technologically relevant spectral range including the optical3, near IR4, mid IR5 , THz6 , mm-wave7 , microwave8 and radio9 bands. Applications include perfect lenses10, sensors11, telecommunications12, invisibility cloaks13 and filters14,15. We have recently developed single band16, dual band17 and broadband18 THz metamaterial absorber devices capable of greater than 80% absorption at the resonance peak. The concept of a MM absorber is especially important at THz frequencies where it is difficult to find strong frequency selective THz absorbers19. In our MM absorber the THz radiation is absorbed in a thickness of ~ &lambda;/20, overcoming the thickness limitation of traditional quarter wavelength absorbers. MM absorbers naturally lend themselves to THz detection applications, such as thermal sensors, and if integrated with suitable THz sources (e.g. QCLs), could lead to compact, highly sensitive, low cost, real time THz imaging systems.

This protocol outlines the simulation, fabrication and characterization of THz metamaterial absorbers. Such absorbers, when coupled with an appropriate sensor, have applications in THz imaging and spectroscopy.

Metamaterials (MM),  artificial materials engineered to have properties that may not be found in  nature, have been widely explored since the first ...

Fabrication And Characterization Of Photonic Crystal Slow Light Waveguides And Cavities

Slow light has been one of the hot topics in the photonics community in the past decade, generating great interest both from a fundamental point of view and for its considerable potential for practical applications. Slow light photonic crystal waveguides, in particular, have played a major part and have been successfully employed for delaying optical signals1-4 and the enhancement of both linear5-7 and nonlinear devices.8-11
Photonic crystal cavities achieve similar effects to that of slow light waveguides, but over a reduced band-width. These cavities offer high Q-factor/volume ratio, for the realization of optically12 and electrically13 pumped ultra-low threshold lasers and the enhancement of nonlinear effects.14-16 Furthermore, passive filters17 and modulators18-19 have been demonstrated, exhibiting ultra-narrow line-width, high free-spectral range and record values of low energy consumption.
To attain these exciting results, a robust repeatable fabrication protocol must be developed. In this paper we take an in-depth look at our fabrication protocol which employs electron-beam lithography for the definition of photonic crystal patterns and uses wet and dry etching techniques. Our optimised fabrication recipe results in photonic crystals that do not suffer from vertical asymmetry and exhibit very good edge-wall roughness. We discuss the results of varying the etching parameters and the detrimental effects that they can have on a device, leading to a diagnostic route that can be taken to identify and eliminate similar issues.
The key to evaluating slow light waveguides is the passive characterization of transmission and group index spectra. Various methods have been reported, most notably resolving the Fabry-Perot fringes of the transmission spectrum20-21 and interferometric techniques.22-25 Here, we describe a direct, broadband measurement technique combining spectral interferometry with Fourier transform analysis.26 Our method stands out for its simplicity and power, as we can characterise a bare photonic crystal with access waveguides, without need for on-chip interference components, and the setup only consists of a Mach-Zehnder interferometer, with no need for moving parts and delay scans.
When characterising photonic crystal cavities, techniques involving internal sources21 or external waveguides directly coupled to the cavity27 impact on the performance of the cavity itself, thereby distorting the measurement. Here, we describe a novel and non-intrusive technique that makes use of a cross-polarised probe beam and is known as resonant scattering (RS), where the probe is coupled out-of plane into the cavity through an objective. The technique was first demonstrated by McCutcheon et al.28 and further developed by Galli et al.29

Use of photonic crystal slow light waveguides and cavities has been widely adopted by the photonics community in many differing applications. Therefore fabrication and characterization of these devices are of great interest. This paper outlines our fabrication technique and two optical characterization methods, namely: interferometric (waveguides) and resonant scattering (cavities).

Slow light has been one of the hot topics in the photonics community in the past decade, generating great interest both from a fundamental point of view ...

Fabrication of VB2/Air Cells for Electrochemical Testing

A technique to investigate the properties and performance of new multi-electron metal/air battery systems is proposed and presented. A method for synthesizing nanoscopic VB2 is presented as well as step-by-step procedure for applying a zirconium oxide coating to the VB2 particles for stabilization upon discharge. The process for disassembling existing zinc/air cells is shown, in addition construction of the new working electrode to replace the conventional zinc/air cell anode with a the nanoscopic VB2 anode. Finally, discharge of the completed VB2/air battery is reported. We show that using the zinc/air cell as a test bed is useful to provide a consistent configuration to study the performance of the high-energy high capacity nanoscopic VB2 anode.

Fabrication of VB2/Air Cells for Electrochemical Testing

A protocol is presented to study multi-electron metal/air battery systems by using previous technology developed for the zinc/air cell. Electrochemical testing is then performed on fabricated batteries to evaluate performance.

A technique to investigate the properties and performance of new multi-electron metal/air battery systems is proposed and presented. A method for ...

Quantum State Engineering of Light with Continuous-wave Optical Parametric Oscillators

Engineering non-classical states of the electromagnetic field is a central quest for quantum optics1,2. Beyond their fundamental significance, such states are indeed the resources for implementing various protocols, ranging from enhanced metrology to quantum communication and computing. A variety of devices can be used to generate non-classical states, such as single emitters, light-matter interfaces or non-linear systems3. We focus here on the use of a continuous-wave optical parametric oscillator3,4. This system is based on a non-linear &#967;2 crystal inserted inside an optical cavity and it is now well-known as a very efficient source of non-classical light, such as single-mode or two-mode squeezed vacuum depending on the crystal phase matching. 
Squeezed vacuum is a Gaussian state as its quadrature distributions follow a Gaussian statistics. However, it has been shown that number of protocols require non-Gaussian states5. Generating directly such states is a difficult task and would require strong &#967;3 non-linearities. Another procedure, probabilistic but heralded, consists in using a measurement-induced non-linearity via a conditional preparation technique operated on Gaussian states. Here, we detail this generation protocol for two non-Gaussian states, the single-photon state and a superposition of coherent states, using two differently phase-matched parametric oscillators as primary resources. This technique enables achievement of a high fidelity with the targeted state and generation of the state in a well-controlled spatiotemporal mode.

We describe the reliable generation of non-Gaussian states of traveling optical fields, including single-photon states and coherent state superpositions, using a conditional preparation method operated on the non-classical light emitted by optical parametric oscillators. Type-I and type-II phase-matched oscillators are considered and common procedures, such as the required frequency filtering or the high-efficiency quantum state characterization by homodyning, are detailed.

Engineering non-classical states of the electromagnetic field is a central quest for quantum optics1,2. Beyond their fundamental significance, such states ...

Fabrication and Characterization of Superconducting Resonators

Superconducting microwave resonators are of interest for a wide range of applications, including for their use as microwave kinetic inductance detectors (MKIDs) for the detection of faint astrophysical signatures, as well as for quantum computing applications and materials characterization. In this paper, procedures are presented for the fabrication and characterization of thin-film superconducting microwave resonators. The fabrication methodology allows for the realization of superconducting transmission-line resonators with features on both sides of an atomically smooth single-crystal silicon dielectric. This work describes the procedure for the installation of resonator devices into a cryogenic microwave testbed and for cool-down below the superconducting transition temperature. The set-up of the cryogenic microwave testbed allows one to do careful measurements of the complex microwave transmission of these resonator devices, enabling the extraction of the properties of the superconducting lines and dielectric substrate (e.g., internal quality factors, loss and kinetic inductance fractions), which are important for device design and performance.

Superconducting microwave resonators are of interest for detection of light, quantum computing applications and materials characterization. This work presents a detailed procedure for fabrication and characterization of superconducting microwave resonator scattering parameters.

Superconducting microwave resonators are of interest for a wide range of applications, including for their use as microwave kinetic inductance detectors ...

Solvent Bonding for Fabrication of PMMA and COP Microfluidic Devices

Thermoplastic microfluidic devices offer many advantages over those made from silicone elastomers, but bonding procedures must be developed for each thermoplastic of interest. Solvent bonding is a simple and versatile method that can be used to fabricate devices from a variety of plastics. An appropriate solvent is added between two device layers to be bonded, and heat and pressure are applied to the device to facilitate the bonding. By using an appropriate combination of solvent, plastic, heat, and pressure, the device can be sealed with a high quality bond, characterized as having high bond coverage, bond strength, optical clarity, durability over time, and low deformation or damage to microfeature geometry. We describe the procedure for bonding devices made from two popular thermoplastics, poly(methyl-methacrylate) (PMMA), and cyclo-olefin polymer (COP), as well as a variety of methods to characterize the quality of the resulting bonds, and strategies to troubleshoot low quality bonds. These methods can be used to develop new solvent bonding protocols for other plastic-solvent systems.

Solvent bonding is a simple and versatile method for fabricating thermoplastic microfluidic devices with high quality bonds. We describe a protocol to achieve strong, optically clear bonds in PMMA and COP microfluidic devices that preserve microfeature details, by a judicious combination of pressure, temperature, an appropriate solvent, and device geometry.

Thermoplastic microfluidic devices offer many advantages over those made from silicone elastomers, but bonding procedures must be developed for each ...

Subsurface Defect Localization by Structured Heating Using Laser Projected Photothermal Thermography

The presented method is used to locate subsurface defects oriented perpendicularly to the surface. To achieve this, we create destructively interfering thermal wave fields that are disturbed by the defect. This effect is measured and used to locate the defect. We form the destructively interfering wave fields by using a modified projector. The original light engine of the projector is replaced with a fiber-coupled high-power diode laser. Its beam is shaped and aligned to the projector&#39;s spatial light modulator and optimized for optimal optical throughput and homogeneous projection by first characterizing the beam profile, and, second, correcting it mechanically and numerically. A high-performance infrared (IR) camera is set up according to the tight geometrical situation (including corrections of the geometrical image distortions) and the requirement to detect weak temperature oscillations at the sample surface. Data acquisition can be performed once a synchronization between the individual thermal wave field sources, the scanning stage, and the IR camera is established by using a dedicated experimental setup which needs to be tuned to the specific material being investigated. During data post-processing, the relevant information on the presence of a defect below the surface of the sample is extracted. It is retrieved from the oscillating part of the acquired thermal radiation coming from the so-called depletion line of the sample surface. The exact location of the defect is deduced from the analysis of the spatial-temporal shape of these oscillations in a final step. The method is reference-free and very sensitive to changes within the thermal wave field. So far, the method has been tested with steel samples but is applicable to different materials as well, in particular to temperature sensitive materials.

This method aims at locating vertical subsurface defects. Here, we couple a laser with a spatial light modulator and trigger its video input to heat a sample surface deterministically with two anti-phased modulated lines while acquiring highly resolved thermal images. The defect position is retrieved from evaluating thermal wave interference minima.

The presented method is used to locate subsurface defects oriented perpendicularly to the surface. To achieve this, we create destructively interfering ...

Focused Ion Beam Fabrication of LiPON-based Solid-state Lithium-ion Nanobatteries for In Situ Testing

Solid-state electrolytes are a promising replacement for current organic liquid electrolytes, enabling higher energy densities and improved safety of lithium-ion (Li-ion) batteries. However, a number of setbacks prevent their integration into commercial devices. The main limiting factor is due to nanoscale phenomena occurring at the electrode/electrolyte interfaces, ultimately leading to degradation of battery operation. These key problems are highly challenging to observe and characterize as these batteries contain multiple buried interfaces. One approach for direct observation of interfacial phenomena in thin film batteries is through the fabrication of electrochemically active nanobatteries by a focused ion beam (FIB). As such, a reliable technique to fabricate nanobatteries was developed and demonstrated in recent work. Herein, a detailed protocol with a step-by-step process is presented to enable the reproduction of this nanobattery fabrication process. In particular, this technique was applied to a thin film battery consisting of LiCoO2/LiPON/a-Si, and has further been previously demonstrated by in situ cycling within a transmission electron microscope.

Focused Ion Beam Fabrication of LiPON-based Solid-state Lithium-ion Nanobatteries for In Situ Testing

A protocol for the fabrication of electrochemically active LiPON-based solid-state lithium-ion nanobatteries using a focused ion beam is presented.

Solid-state electrolytes are a promising replacement for current organic liquid electrolytes, enabling higher energy densities and improved safety of ...

Scalable Stamp Printing and Fabrication of Hemiwicking Surfaces

Hemiwicking is a process where a fluid wets a patterned surface beyond its normal wetting length due to a combination of capillary action and imbibition. This wetting phenomenon is important in many technical fields ranging from physiology to aerospace engineering. Currently, several different techniques exist for fabricating hemiwicking structures. These conventional methods, however, are often time consuming and are difficult to scale-up for large areas or are difficult to customize for specific, nonhomogeneous patterning geometries. The presented protocol provides researchers with a simple, scalable, and cost-effective method for fabricating micro-patterned hemiwicking surfaces. The method fabricates wicking structures through the use of stamp printing, polydimethylsiloxane (PDMS) molding, and thin-film surface coatings. The protocol is demonstrated for hemiwicking with ethanol on PDMS micropillar arrays coated with a 70 nm thick aluminum thin-film.

A simple protocol is provided for the fabrication of hemiwicking structures of varying sizes, shapes, and materials. The protocol uses a combination of physical stamping, PDMS molding, and thin-film surface modifications via common materials deposition techniques.

Hemiwicking is a process where a fluid wets a patterned surface beyond its normal wetting length due to a combination of capillary action and imbibition. ...

Method Development for Contactless Resonant Cavity Dielectric Spectroscopic Studies of Cellulosic Paper

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of data that can be obtained from an individual sample and renders it difficult to produce statistically relevant data for unique and rare materials. Resonant cavity dielectric spectroscopy is a non-destructive, contactless technique which can simultaneously interrogate both sides of a sheeted material and provide measurements which are suitable for statistical interpretations. This offers analysts the ability to quickly discriminate between sheeted materials based on composition and storage history. In this methodology article, we demonstrate how contactless resonant cavity dielectric spectroscopy may be used to differentiate between paper analytes of varying fiber species compositions, to determine the relative age of the paper, and to detect and quantify the amount of post-consumer waste (PCW) recycled fiber content in manufactured office paper.

A protocol for the non-destructive analysis of the fiber content and relative age of paper.

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of ...