The authors acknowledge the NIST/CNST NanoFab facility for providing opportunity to fabricate silicon photonic temperature sensors and Wyatt Miller and Dawn Cross for assistance in setting up the experiments.

1. Device Fabrication
Note: Silicon photonic devices can be fabricated using silicon-on-insulator (SOI) wafers applying conventional CMOS-technology via photo- or electron beam lithography followed by inductive plasma reactive ion etch (ICP RIE) of 220 nm-thick topmost silicon layer. After ICP RIE etch the devices can be top-cladded with a thin polymer film or SiO2 protective layer. Below are the main steps of in fabrication of SOI photonic devices.
<ol>
	<li>Clean an SOI wafer in a piranha solution for 10 min, a mixture 4:1 of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2), followed by a deionized (DI) water rinse for 1 min and nitrogen gas blow dry.</li>
	<li>Spin coat about 20-50 mL of maN 2405 e-beam resist onto the wafer at 4,000 rpm for 60 s, followed by a hotplate bake at 90 &#176;C for 15 min.</li>
	<li>Expose the device pattern on to the spin-coated resist using e-beam lithography and develop the resist. The usual base exposure dose is about 600 &#181;C/cm2. Develop with MIF-319 developer for 60 s, followed by a 60 s water rinse.</li>
	<li>Perform an ICP RIE etch of the 220 nm thick silicon layer to remove the unprotected silicon. Use a pseudo-Bosch process with C4F8: 57 SCCM / SF6: 33 SCCM, ICP power: 3,000 W; RIE power: 15 W; pressure 10 mTorr, temperature: 15 &#176;C; Etch rate: approximately 5-6 nm/s</li>
	<li>Dissolve the resist mask in pure acetone for 1 h, followed by an isopropanol rinse, a 60 s DI water rinse and nitrogen gas blow dry.</li>
	<li>Deposit a 1 &#181;m thick protective top-layer on the wafer (a thin polymer film) via a spin coating (spin coat 20-50 mL PMMA at 4,000 rpm for 60 s followed by a hotplate bake at 180 &#176;C for 2 min).</li>
	<li>Dice the wafer with a wafer dicing saw (saw blade thickness: 35 &#181;m) into small easy to handle chips (e.g., 20 mm &#215; 20 mm).</li>
</ol>
2. Photonic Chip Packaging
Note: The fabricated photonic chips are packaged on a custom design packaging setup where a custom-built packaging setup is used to align and bond an array of optical fibers to a photonic chip. The packaging setup shown on Figure 1 consists of (i) 6-axis micro-positioning stage, that allows 6-degree of freedom movement (X, Y, Z coordinates, and three corresponding angles of rotation relative to X, Y, Z coordinates) with submicron precision; (ii) on-stage integrated Peltier module that allows to heat or cool the top stage platform; (iii) v-groove array holder arm; epoxy adhesive micro-dispensing module; (iv) ultra violet (UV) light exposure module to cure UV adhesives, and (v) four high magnification digital cameras for top, front, and two side angle views. Optical fibers package in v-groove array are procured from a commercial source.
<ol>
	<li>Rough alignment procedure
	<ol>
		<li>Place the photonic chip on the 6-axis stage, and orient the chip so the on-chip input/output ports are aligned with the v-groove array.</li>
		<li>Turn on vacuum suction through on-stage integrated vacuum pumping port to hold the chip in place.</li>
		<li>Use the top-view digital camera to locate and place the photonic devices of interest in the center of the 6-axis stage.</li>
		<li>Position the v-groove array holder arm close to the chip and use vacuum suction through an integrated pumping port to hold the array in place.</li>
		<li>Use the side-view digital cameras as a visual feedback to help position the fiber array above the on-chip grating couplers.</li>
		<li>Raise the 6-axis stage to bring the photonic chip to within 10 &#181;m of the fiber array&#39;s bottom edge. 
		NOTE: The edge of the v-groove fiber array should be roughly aligned (within 50 &#181;m to 100 &#181;m accuracy) relative to on-chip alignment marks. This procedure brings the optical fiber facets within a relative proximity of the corresponding grating couplers.</li>
	</ol>
	</li>
	<li>Automated optimal alignment
	<ol>
		<li>Once a rough manual alignment is achieved, activate the automated search using the vendor supplied software for the 6-axis stage. 
		NOTE: This algorithm performs a pre-defined walk over the 6-degrees of movements (translational and rotational) until the maximum transmission of broadband light through the chip&#39;s input and output ports is achieved. It should take no longer than 20 s to 30 s.</li>
	</ol>
	</li>
	<li>Photonic chip testing 
	NOTE: Once the optimal alignment is achieved, check device viability before proceeding with the bonding.
	<ol>
		<li>Use the on-stage integrated Peltier module to thermally cycle the chip&#39;s temperature while recording the spectral response. For thermal cycling, we used a custom script written in LabView.</li>
		<li>Analyze the recorded spectra is to verify the temperature sensitivity of the device (recommended values are 70 pm/&#176;C to 80 pm/&#176;C). 
		NOTE: The laser spectrometer has been described elsewhere in detail2. The recorded spectra are analyzed to determine the temperature sensitivity of the device which should be in the 70 pm/&#176;C to 80 pm/&#176;C range.</li>
	</ol>
	</li>
	<li>Bonding of optical fibers
	<ol>
		<li>Slowly lower the array down to the chip surface.</li>
		<li>Carefully position the epoxy filled syringe in close vicinity of the fiber array&#39;s edge using another XYZ micron precision stage.</li>
		<li>Dispense a single micro-droplet of an epoxy and initiate the curing process (either via UV irradiation or a thermal cycling).</li>
		<li>Periodically run the automated alignment (peaking/maximization) routine to prevent drift induced loss of signal until such a time that the epoxy starts to harden. 
		NOTE: After epoxy curing the photonic chip performance and light coupling efficiency are tested again by recording transmission spectra of the device at different temperatures. Light coupling efficiency typically increases after the bonding process, likely because the refractive index matched optical epoxy reduces reflection losses at the fiber-chip interface.</li>
	</ol>
	</li>
	<li>Packaging of Photonic Thermometer
	<ol>
		<li>Place the fiber bonded photonic chip on a copper cylinder (h = 25 mm, dia.= 5.79 mm) with a small amount (about 1 mg) of thermal grease applied to the copper mounting surface. 
		NOTE: Thermal grease ensures good even thermal contact between the metal heat conductor and the chip. Furthermore, thermal grease provides a weak adhesion between the two parts which facilitates the process of lowering the copper cylinder-chip assembly down a glass tube (h = 50 mm; inner dia. = 6.0 mm).</li>
		<li>Gently lower the chip-copper cylinder down the glass tube.</li>
		<li>Backfill the glass tube with Argon gas and seal with a rubber cork.</li>
	</ol>
	</li>
</ol>
3. Temperature Measurement
<ol>
	<li>Place the packaged photonic thermometer (glass tube + copper cylinder + fiber coupled photonic device) into a metrology temperature dry well (temperature should be stable to within 1 mK).</li>
	<li>Using the custom-built computer program set the settling time (20 min to 30 min), number of thermal cycles (minimum 3), temperature step size (1 &#176;C to 5 &#176;C), number of consecutive scans (minimum recommendation 5) and laser power (exact power delivered is specific to individual cases but generally is in the nanowatt to microwatt range). 
	NOTE: A calibrated platinum resistance thermometer bonded to the copper cylinder is used to concurrently record the bath temperature as the photonic measurements are carried out.</li>
</ol>

<ol>
	<li>Price, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Platinum+resistance+Thermometer.">The Platinum resistance Thermometer.</a> Platinum Metals Review. 3 (3), 78-87 (1959).</li><li>Xu, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultra-Sensitive+Chip-Based+Photonic+Temperature+Sensor+Using+Ring+Resonator+Structures.">Ultra-Sensitive Chip-Based Photonic Temperature Sensor Using Ring Resonator Structures.</a> Optics Express. 22, 3098-3104 (2014).</li><li>Donner, J. S., Thompson, S. A., Kreuzer, M. P., Baffou, G., Quidant, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mapping+Intracellular+Temperatrure+Using+Green+Flurorescent+Protein.">Mapping Intracellular Temperatrure Using Green Flurorescent Protein.</a> Nano Letters. 12 (4), 2107-2111 (2012).</li><li>Ahmed, Z., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Towards+Photonics+Enabled+Quantum+Metrology+of+Temperature,+Pressure+and+Vacuum.">Towards Photonics Enabled Quantum Metrology of Temperature, Pressure and Vacuum.</a> arXiv:1603.07690 [physics.optics]. , (2016).</li><li>Ahmed, Z., Filla, J., Guthrie, W., Quintavall, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fiber+Bragg+Gratings+Based+Thermometry.">Fiber Bragg Gratings Based Thermometry.</a> NCSL International Measure. 10, 24-27 (2015).</li><li>Hill, K. O., Meltz, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fiber+Bragg+Grating+Technology+Fundamental+and+Overview.">Fiber Bragg Grating Technology Fundamental and Overview.</a> J. of Lightwave Technology. 15, 1263-1275 (1997).</li><li>Liacouras, P. C., Grant, G., Choudhry, K., Strouse, G. F., Ahmed, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fiber+Bragg+Gratings+Embedded+in+3D-printed+Scaffolds.">Fiber Bragg Gratings Embedded in 3D-printed Scaffolds.</a> NCSL International Measure. 10 (2), 50-52 (2015).</li><li>Klimov, N. N., Mittal, S., Berger, M., Ahmed, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On-chip+silicon+waveguide+Bragg+grating+photonic+temperature+sensor.">On-chip silicon waveguide Bragg grating photonic temperature sensor.</a> Optical Letters. 40 (17), 3934-3936 (2015).</li><li>Klimov, N. N., Purdy, T., Ahmed, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On-Chip+Silicon+Photonic+Thermometers:+from+Waveguide+Bragg+Grating+to+Ring+Resonators+sensors.">On-Chip Silicon Photonic Thermometers: from Waveguide Bragg Grating to Ring Resonators sensors.</a> Proceedings. , (2015).</li><li>Kim, G. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Silicon+photonic+temperature+sensor+employing+a+ring+resonator+manufactured+using+a+standard+CMOS+process.">Silicon photonic temperature sensor employing a ring resonator manufactured using a standard CMOS process.</a> Optical Express. 18 (21), 22215-22221 (2010).</li><li>Purdy, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermometry+with+Optomechanical+Cavities.">Thermometry with Optomechanical Cavities.</a> , STu1H.2 (2016).</li></ol>

The authors have nothing to disclose.
Certain equipment or materials are identified in this paper in order to specify the experimental procedure adequately. Such identification is not intended to imply endorsement by the National Institute of Standards and Technology, nor is it intended to imply that the materials or equipment identified are necessarily the best available.

The objective of this experiment was to quantify the temperature dependent response of a photonic thermometer. For quantitative measurements of temperature, it is prudent to utilize a stable heat source such as a metrology grade deep dry well, small volume sensors, ensure good thermal contact between the well and the sensor, and minimize heat loses to the environment. These requirements are easily met by bonding optical fibers to the chip, effectively creating a packaged device that can be lowered deep into the metrology...

The gold standard for temperature metrology, the platinum resistance thermometer, was first proposed by Sir Siemens in 1871 with Callender1 developing the first device in 1890. Since that time incremental progress in the design and manufacturing of thermometers has delivered a wide range of temperature measurement solutions. The standard platinum resistance thermometer (SPRT) is the interpolating instrument for realizing International Temperature Scale (ITS-90) and its dissemination using resistance thermometry. Today, more than a century after its invention, resistance thermometry plays a crucial role in various aspects of industry and everyday technology ranging from biomedicine to manufacturing process control, to energy production and consumption. Although well-calibrated industrial resistance thermometers can measure temperature with uncertainties as small as 10 mK, they are sensitive to mechanical shock, thermal stress and environmental variables such as humidity and chemical contaminants. Consequently, resistance thermometers require periodic (and costly) off-line recalibrations. These fundamental limitations of resistance thermometry have produced considerable interest in developing photonic temperature sensors2 that can deliver similar to better measurement capabilities whislt being more robust against mechanical shock. Such a devcie will appeal to national and industrial labs and those interested in long-term monitoring where instrument drift can negatively impact productivity.
In recent years a wide variety of novel photonic thermometers have been proposed including photosensitive dyes3, sapphire-based microwave whispering gallery mode resonator4, fiber optic sensors5,6,7, and on-chip silicon nano-photonic sensors8,9,10. At NIST, our efforts are aimed at developing low-cost, readily-deployable, novel temperature sensors and standards that are easily manufactured using existing technologies, such as CMOS-compatible manufacturing. A particular focus has been the development of silicon photonic devices. We have demonstrated that these devices can be used to measure temperature over the ranges of -40 &#176;C to 80 &#176;C and 5 &#176;C to 165 &#176;C with uncertainties that are comparable to legacy devices8. Furthermore, our results suggest that with a better process control device interchangeability on the order of 0.1 &#176;C uncertainty is achievable (i.e. the uncertainty of temperature measurement using nominal coefficients not calibration determined coefficients).

<table border="0" cellpadding="0" cellspacing="0" width="672">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Packaging process</td>
			<td style="width:99px;"></td>
			<td style="width:119px;"></td>
			<td style="width:239px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">6-axis stage</td>
			<td style="width:99px;">PI instruments</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">video cameras</td>
			<td style="width:99px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">epoxy dispensation system</td>
			<td style="width:99px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Fiber array</td>
			<td style="width:99px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Temperature Measurement</td>
			<td style="width:99px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Metrology Well</td>
			<td style="width:99px;">Fluke</td>
			<td align="right" style="width:119px;">9170</td>
			<td>Dry well stable to better than .01 K</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Laser</td>
			<td style="width:99px;">Newport</td>
			<td style="width:119px;">TLB6700</td>
			<td>1520-1570 nm tunable laser</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:216px;">Wavemeter</td>
			<td style="width:99px;">HighFinesse</td>
			<td style="width:119px;">WS/7</td>
			<td>100 Hz wavemeter</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Power meter</td>
			<td style="width:99px;">Newport</td>
			<td style="width:119px;">1936-R</td>
			<td>power meter with broad range</td>
		</tr>
	</tbody>
</table>

fabrication and testing of photonic thermometers

In recent years, a push for developing novel silicon photonic devices for telecommunications has generated a vast knowledge base that is now being leveraged for developing sophisticated photonic sensors. Silicon photonic sensors seek to exploit the strong confinement of light in nano-waveguides to transduce changes in physical state to changes in resonance frequency. In the case of thermometry, the thermo-optic coefficient, i.e., changes in refractive index due to temperature, causes the resonant frequency of the photonic device such as a Bragg grating to drift with temperature. We are developing a suite of photonic devices that leverage recent advances in telecom compatible light sources to fabricate cost-effective photonic temperature sensors, which can be deployed in a wide variety of settings ranging from controlled laboratory conditions, to the noisy environment of a factory floor or a residence. In this manuscript, we detail our protocol for the fabrication and testing of photonic thermometers.

As shown in Figure 2, the ring resonator transmission spectra shows a narrow dip in transmission corresponding to the resonance condition. The resonance fringe shifts to longer wavelengths as temperature is increased from 20 &#176;C to 105 &#176;C in 5 &#176;C increments. The transmission spectrum is fitted to a polynomial function from which the peak center is extracted. The polynomial fit was found to give the most consistent results in the presence of a sl...

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Fabrication and Testing of Photonic Thermometers

We describe the process of fabrication and testing of photonic thermometers.

In recent years, a push for developing novel silicon photonic devices for telecommunications has generated a vast knowledge base that is now being ...

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5.7K Views.  University of Maryland. We describe the process of fabrication and testing of photonic thermometers.

Video: Fabrication and Testing of Photonic Thermometers

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Flow-pattern Guided Fabrication of High-density Barcode Antibody Microarray

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Preparation of Hollow Polystyrene Particles and Microcapsules by Radical Polymerization of Janus Droplets Consisting of Hydrocarbon and Fluorocarbon Oils

In this article, we have demonstrated a method for producing hollow particles and microcapsules using oil droplets consisting of hydrocarbon oil (styrene) and fluorocarbon oil (perfluoro-n-octane, PFO) in aqueous surfactant (sodium dodecylsulfate, SDS) solutions. Since fluorocarbon oils are immiscible with hydrocarbon oils, the two oils are separated. Emulsions are prepared by stirring styrene/PFO/aqueous SDS solution mixtures at 80 &#176;C. The type of emulsions and the morphology of droplets in the emulsions are observed by light microscope and scanning confocal fluorescence microscope. It is found that oil droplets with Janus-type morphologies consisting of mutually immiscible styrene and PFO are formed in aqueous SDS solutions. Polystyrene particles are fabricated by radical polymerization of the ternary mixtures of styrene/PFO/aqueous SDS solution at 80 &#176;C. The morphologies of the polystyrene are confirmed by scanning electron microscopy and scanning transmission electron microscopy observations. These observations show the preparation of hollow polystyrene particles with a single hole on the surface. To our knowledge, this method is a novel strategy using the immiscibility of hydrocarbon and fluorocarbon oils. The hollow particles can also be applied to the preparation of microcapsules.

A protocol for the fabrication of hollow polymer particles and microcapsules by radical polymerization using emulsions consisting of styrene, perfluoro-n-octane, and aqueous SDS (sodium dodecylsulfate) solution is presented.

In this article, we have demonstrated a method for producing hollow particles and microcapsules using oil droplets consisting of hydrocarbon oil (styrene) ...

Fabrication and Testing of Catalytic Aerogels Prepared Via Rapid Supercritical Extraction

Protocols for preparing and testing catalytic aerogels by incorporating metal species into silica and alumina aerogel platforms are presented. Three preparation methods are described: (a) the incorporation of metal salts into silica or alumina wet gels using an impregnation method; (b) the incorporation of metal salts into alumina wet gels using a co-precursor method; and (c) the addition of metal nanoparticles directly into a silica aerogel precursor mixture. The methods utilize a hydraulic hot press, which allows for rapid (&#60;6 h) supercritical extraction and results in aerogels of low density (0.10 g/mL) and high surface area (200-800 m2/g). While the work presented here focuses on the use of copper salts and copper nanoparticles, the approach can be implemented using other metal salts and nanoparticles. A protocol for testing the three-way catalytic ability of these aerogels for automotive pollution mitigation is also presented. This technique uses custom-built equipment, the Union Catalytic Testbed (UCAT), in which a simulated exhaust mixture is passed over an aerogel sample at a controlled temperature and flow rate. The system is capable of measuring the ability of the catalytic aerogels, under both oxidizing and reducing conditions, to convert CO, NO and unburned hydrocarbons (HCs) to less harmful species (CO2, H2O and N2). Example catalytic results are presented for the aerogels described.

Here we present protocols for preparing and testing catalytic aerogels by incorporating metal species into silica and alumina aerogel platforms. Methods for preparing materials using copper salts and copper-containing nanoparticles are featured. Catalytic testing protocols demonstrate the effectiveness of these aerogels for three-way catalysis applications.

Protocols for preparing and testing catalytic aerogels by incorporating metal species into silica and alumina aerogel platforms are presented. Three ...

Iron Nanowire Fabrication by Nano-Porous Anodized Aluminum and its Characterization

Magnetic nanowires possess unique properties that have attracted the interest of different fields of research, including basic physics, biomedicine, and data storage. We demonstrate a fabrication method for iron (Fe) nanowires&#160;via electrochemical deposition into anodic&#160;alumina oxide (AAO) templates. The templates are fabricated by anodization of aluminum (Al) discs, and the pore length and diameter are controlled by changing the anodizing conditions. Pores with an average diameter of around 120 nm are created using oxalic acid as the electrolyte. Using this method, cylindrical nanowires are synthesized, which are released by dissolving the alumina using a selective chemical etchant.

In this work, we describe a&#160;protocol to fabricate iron nanowires, including the formation of the porous alumina membrane that is used as the template, electrodeposition into templates using electrolyte solution, and the release of the nanowires into the solution.

Magnetic nanowires possess unique properties that have attracted the interest of different fields of research, including basic physics, biomedicine, and ...