Name: fabrication and testing of photonic thermometers
Uploaded: 2018-10-24T12:30:00.000+00:00
Duration: 8 min 44 s
Description: Watch this Scientific Journal Video about Fabrication and Testing of Photonic Thermometers at JoVE.com

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><tbody><tr><td>&lt;em&gt;Packaging process&lt;/em&gt;</td><td></td><td></td><td></td></tr><tr><td>6-axis stage</td><td>PI instruments</td><td></td><td></td></tr><tr><td>video cameras</td><td></td><td></td><td></td></tr><tr><td>epoxy dispensation system</td><td></td><td></td><td></td></tr><tr><td>Fiber array</td><td></td><td></td><td></td></tr><tr><td>&lt;em&gt;Temperature Measurement&lt;/em&gt;</td><td></td><td></td><td></td></tr><tr><td>Metrology Well</td><td>Fluke</td><td>9170</td><td>Dry well stable to better than .01 K</td></tr><tr><td>Laser</td><td>Newport</td><td>TLB6700</td><td>1520-1570 nm tunable laser</td></tr><tr><td>Wavemeter</td><td>HighFinesse</td><td>WS/7</td><td>100 Hz wavemeter</td></tr><tr><td>Power meter</td><td>Newport</td><td>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...

Watch this Scientific Journal Video about Fabrication and Testing of Photonic Thermometers at JoVE.com

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 ...

fabrication-and-testing-of-photonic-thermometers

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5.8K Views.  University of Maryland. We describe the process of fabrication and testing of photonic thermometers.

Video: Fabrication and Testing of Photonic Thermometers

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.

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 ...

Engineering

Thermal Measurement Techniques in Analytical Microfluidic Devices

Thermal measurement techniques have been used for many applications such as thermal characterization of materials and chemical reaction detection. Micromachining techniques allow reduction of the thermal mass of fabricated structures and introduce the possibility to perform high sensitivity thermal measurements in the micro-scale and nano-scale devices. Combining thermal measurement techniques with microfluidic devices allows performing different analytical measurements with low sample consumption and reduced measurement time by integrating the miniaturized system on a single chip. The procedures of thermal measurement techniques for particle detection, material characterization, and chemical detection are introduced in this paper.

Here, we present three protocols for thermal measurements in microfluidic devices.

Thermal measurement techniques have been used for many applications such as thermal characterization of materials and chemical reaction detection. ...

Fiber Optic Distributed Sensors for High-resolution Temperature Field Mapping

The reliability of computational fluid dynamics (CFD) codes is checked by comparing simulations with experimental data. A typical data set consists chiefly of velocity and temperature readings, both ideally having high spatial and temporal resolution to facilitate rigorous code validation. While high resolution velocity data is readily obtained through optical measurement techniques such as particle image velocimetry, it has proven difficult to obtain temperature data with similar resolution. Traditional sensors such as thermocouples cannot fill this role, but the recent development of distributed sensing based on Rayleigh scattering and swept-wave interferometry offers resolution suitable for CFD code validation work. Thousands of temperature measurements can be generated along a single thin optical fiber at hundreds of Hertz. Sensors function over large temperature ranges and within opaque fluids where optical techniques are unsuitable. But this type of sensor is sensitive to strain and humidity as well as temperature and so accuracy is affected by handling, vibration, and shifts in relative humidity. Such behavior is quite unlike traditional sensors and so unconventional installation and operating procedures are necessary to ensure accurate measurements. This paper demonstrates implementation of a Rayleigh scattering-type distributed temperature sensor in a thermal mixing experiment involving two air jets at 25 and 45 &#176;C. We present criteria to guide selection of optical fiber for the sensor and describe installation setup for a jet mixing experiment. We illustrate sensor baselining, which links readings to an absolute temperature standard, and discuss practical issues such as errors due to flow-induced vibration. This material can aid those interested in temperature measurements having high data density and bandwidth for fluid dynamics experiments and similar applications. We highlight pitfalls specific to these sensors for consideration in experiment design and operation.

We demonstrate use of a fiber optic distributed sensor for mapping the temperature field of mixing air jets. The Rayleigh scattering-based sensor generates thousands of data points along a single fiber to provide exceptional spatial resolution that is unattainable with traditional sensors such as thermocouples.

The reliability of computational fluid dynamics (CFD) codes is checked by comparing simulations with experimental data. A typical data set consists ...

A Simple Dewar/Cryostat for Thermally Equilibrating Samples at Known Temperatures for Accurate Cryogenic Luminescence Measurements

The design and operation of a simple liquid nitrogen Dewar/cryostat apparatus based upon a small fused silica optical Dewar, a thermocouple assembly, and a CCD spectrograph are described. The experiments for which this Dewar/cryostat is designed require fast sample loading, fast sample freezing, fast alignment of the sample, accurate and stable sample temperatures, and small size and portability of the Dewar/cryostat cryogenic unit. When coupled with the fast data acquisition rates of the CCD spectrograph, this Dewar/cryostat is capable of supporting cryogenic luminescence spectroscopic measurements on luminescent samples at a series of known, stable temperatures in the 77-300 K range. A temperature-dependent study of the oxygen quenching of luminescence in a rhodium(III) transition metal complex is presented as an example of the type of investigation possible with this Dewar/cryostat. In the context of this apparatus, a stable temperature for cryogenic spectroscopy means a luminescent sample that is thermally equilibrated with either liquid nitrogen or gaseous nitrogen at a known measureable temperature that does not vary (&#916;T &#60; 0.1 K) during the short time scale (~1-10 sec) of the spectroscopic measurement by the CCD. The Dewar/cryostat works by taking advantage of the positive thermal gradient dT/dh that develops above liquid nitrogen level in the Dewar where h is the height of the sample above the liquid nitrogen level. The slow evaporation of the liquid nitrogen results in a slow increase in h over several hours and a consequent slow increase in the sample temperature T over this time period. A quickly acquired luminescence spectrum effectively catches the sample at a constant, thermally equilibrated temperature.

A simple liquid nitrogen Dewar/cryostat apparatus comprised of a small fused silica optical Dewar, a thermocouple, and a charge-coupled device (CCD) spectrograph are described. The experiments for which this Dewar/cryostat is designed require fast sample loading, freezing, and alignment, accurate and stable sample temperatures, and small size/portability.

The design and operation of a simple liquid nitrogen Dewar/cryostat apparatus based upon a small fused silica optical Dewar, a thermocouple assembly, and ...

Fabrication of an Optical Cell Dryer for the Spectroscopic Analysis Cells

Optical cells, which are experimental instruments, are small, square tubes sealed on one side. A sample is placed in this tube, and a measurement is performed with a spectroscope. The materials used for optical cells generally include quartz glass or plastic, but expensive quartz glass is reused by removing substances, other than liquids, to be analyzed that adhere to the interior of the container. In such a case, the optical cells are washed with water or ethanol and dried. Then, the next sample is added and measured. Optical cells are dried naturally or with a manual hairdryer. However, drying takes time, which makes it one of the factors that increase the experiment time. In this study, the objective is to drastically reduce the drying time with a dedicated automatic dryer that can dry multiple optical cells at once. To realize this, a circuit was designed for a microcomputer, and the hardware using it was independently designed and manufactured.

A protocol for fabricating a device for simultaneously drying multiple optical cells is presented.

Optical cells, which are experimental instruments, are small, square tubes sealed on one side. A sample is placed in this tube, and a measurement is ...

A Silicon-tipped Fiber-optic Sensing Platform with High Resolution and Fast Response

In this article, we introduce an innovative and practically promising fiber-optic sensing platform (FOSP) that we proposed and demonstrated recently. This FOSP relies on a silicon Fabry-Perot interferometer (FPI) attached to the fiber end, referred to as Si-FOSP in this work. The Si-FOSP generates an interferogram determined by the optical path length (OPL) of the silicon cavity. Measurand alters the OPL and thus shifts the interferogram. Due to the unique optical and thermal properties of the silicon material, this Si-FOSP exhibits an advantageous performance in terms of sensitivity and speed. Furthermore, the mature silicon fabrication industry endows the Si-FOSP with excellent reproducibility and low cost toward practical applications. Depending on the specific applications, either a low-finesse or high-finesse version will be utilized, and two different data demodulation methods will be adopted accordingly. Detailed protocols for fabricating both versions of the Si-FOSP will be provided. Three representative applications and their according results will be shown. The first one is a prototype underwater thermometer for profiling the ocean thermoclines, the second one is a flow meter to measure flow speed in the ocean, and the last one is a bolometer used for monitoring exhaust radiation from magnetically confined high-temperature plasma.

This work reports an innovative silicon-tipped fiber-optic sensing platform (Si-FOSP) for high-resolution and fast-response measurement of a variety of physical parameters, such as temperature, flow, and radiation. Applications of this Si-FOSP span from oceanographic research, mechanical industry, to fusion energy research.

In this article, we introduce an innovative and practically promising fiber-optic sensing platform (FOSP) that we proposed and demonstrated recently. This ...

Fabrication of Microscope Stage for Vertical Observation with Temperature Control Function

Samples are usually placed onto a horizontal microscope stage for microscopic observation. However, to observe the influence of gravity on a sample or study afloat behavior, it is necessary to make the microscope stage vertical. To accomplish this, a sideways inverted microscope tilted by 90&#176; has been devised. To observe samples with this microscope, sample containers such as Petri dishes or glass slides must be secured to the stage vertically. A device that can secure sample containers in place on a vertical microscope stage has been developed and is described here. Attachment of this device to the stage allows observation of sample dynamics in the vertical plane. The ability to regulate temperature using a silicone rubber heater also permits observation of temperature-dependent sample behaviors. Furthermore, the temperature data is transferred to an internet server. Temperature settings and log monitoring can be controlled remotely from a PC or smartphone.

Presented here is a protocol using a temperature-controlled microscope stage that allows a sample container to be mounted on a vertical microscope.

Samples are usually placed onto a horizontal microscope stage for microscopic observation. However, to observe the influence of gravity on a sample or ...

Rapid Repetition Rate Fluctuation Measurement of Soliton Crystals in a Microresonator

Temporal solitons have attracted great interest in the past decades for their behavior in a steady state, where the dispersion is balanced by the nonlinearity in a propagation Kerr medium. The development of dissipative Kerr solitons (DKSs) in high-Q microcavities drives a novel, compact, chip-scale soliton source. When DKSs serve as femtosecond pulses, the repetition rate fluctuation can be applied to ultrahigh precision metrology, high-speed optical sampling, and optical clocks, etc. In this paper, the rapid repetition rate fluctuation of soliton crystals (SCs), a special state of DKSs where particle-like solitons are tightly packed and fully occupy a resonator, is measured based on the well-known delayed self-heterodyne method. The SCs are generated using a thermal-controlled method. The pump is a frequency fixed laser with a linewidth of 100 Hz. The integral time in frequency fluctuation measurements is controlled by the length of the delay fiber. For a SC with a single vacancy, the repetition rate fluctuations are ~53.24 Hz within 10 &#181;s and ~509.32 Hz within 125 &#181;s, respectively.

Here, we present a protocol to generate soliton crystals in a butterfly-packaged micro-ring resonator using a thermal tuned method. Further, the repetition rate fluctuations of a soliton crystal with a single vacancy are measured using a delayed self-heterodyne method.

Temporal solitons have attracted great interest in the past decades for their behavior in a steady state, where the dispersion is balanced by the ...

In Situ Surface Temperature Measurement in a Conveyor Belt Furnace via Inline Infrared Thermography

Measuring the surface temperature of objects that are processed in conveyor belt furnaces is an important tool in process control and quality assurance. Currently, the surface temperature of objects processed in conveyor belt furnaces is typically measured via thermocouples. However, infrared (IR) thermography presents multiple advantages compared to thermocouple measurements, as it is a contactless, real-time, and spatially resolved method. Here, as a representative proof-of-concept example, an inline thermography system is successfully installed into an IR lamp powered solar firing furnace, which is used for the contact firing process of industrial Si solar cells. This protocol describes how to install an IR camera into a conveyor belt furnace, conduct a customer correction of a factory calibrated IR camera, and perform the evaluation of spatial surface temperature distribution on a target object.

This protocol describes how to install an infrared camera into a conveyor belt furnace, conduct a customer correction of a factory calibrated IR camera, and evaluate the spatial surface temperature distribution of an object of interest. The example objects are industrial silicon solar cells.

Measuring the surface temperature of objects that are processed in conveyor belt furnaces is an important tool in process control and quality assurance. ...

Fabrication of a Fabry-P&#233;rot Etalon for Application in Trace-Gas Spectroscopy

Fabrication of a Low-Cost, Fiber-Coupled, and Air-Spaced Fabry-P&#233;rot Etalon

Fabry-P&#233;rot etalons (FPE) have found their way into many applications. In fields such as spectroscopy, telecommunications, and astronomy, FPEs are used for their high sensitivity as well as their exceptional filtering capability. However, air-spaced etalons with high finesse are usually built by specialized facilities. Their production requires a clean room, special glass handling, and coating machinery, meaning commercially available FPEs are sold for a high price. In this article, a new and cost-effective method to fabricate fiber-coupled FPEs with standard photonic laboratory equipment is presented. The protocol should serve as a step-by-step guide for the construction and characterization of these FPEs. We hope this&#160;will enable researchers to conduct fast and cost-effective prototyping of FPEs for various fields of application. The FPE, as presented here, is used for spectroscopic applications. As shown in the representative results section via proof of principle measurements of water vapor in ambient air, this FPE has a finesse of 15, which is sufficient for the photothermal detection of trace concentrations of gases.

Author Spotlight: Fabrication of a Low-Cost, Fiber-Coupled, and Air-Spaced Fabry-P&#233;rot Etalon  

This protocol describes the construction of a low-cost, discrete, fiber-coupled, and air-spaced Fabry-Perot etalon with various applications, such as in trace-gas spectroscopy. The fabrication is possible in any facility with standard optical laboratory equipment available.

Fabry-P&#233;rot etalons (FPE) have found their way into many applications. In fields such as spectroscopy, telecommunications, and astronomy, FPEs are ...