This PDF file contains the front matter associated with SPIE Proceedings Volume 10116, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and Conference Committee listing.

Due to their advances in achieving large focal-length tuning ranges with compact structures, solid tunable lenses based on the Alvarez-Lohmann principle show a promising potential in various applications, especially modern miniature imaging systems. In this paper, we report miniature endoscopic systems integrated with solid tunable lenses for optical adjustable focusing or zooming. The solid tunable lenses are designed according to the improved Alvarez-Lohmann principle, where two independent extended polynomials are employed to govern the two freeform surfaces, respectively. Slim piezo benders aligned along the optical axis are utilized to drive the solid tunable lenses to move laterally. An image fiber bundle is used to transmit the images captured by the optical system to the external cameras. Results show that the endoscopic system is equipped with a capability of optical power tuning from about 135 diopters to about 205 diopters when there is a single solid tunable lens integrated in the system, which enables it to achieve adjustable focus for objects located at different positions. The integration of two solid tunable lenses and two fixed lenses further enables the endoscopic system to have the optical-zooming capability. A zoom ratio of 3x and a maximum full field of view as high as about 80 degrees are realized experimentally. The cross sectional diameter of the endoscopic probe is controlled below 4 mm. The captured images are clear and sharp. Such adjustable-focus or zoom endoscopic systems would be useful in future medical or industrial applications.

Electrostatic actuation is highly efficient at micro and nanoscale. However, large deflection in common electrostatically driven MEMS requires large electrode separation and thus high driving voltages. To offer a solution to this problem we developed a novel electrostatic actuator class, which is based on a force-to-stress transformation in the periodically patterned upper layer of a silicon cantilever beam. We report on advances in the development of such electrostatic bending actuators. Several variants of a CMOS compatible and RoHS-directive compliant fabrication processes to fabricate vertical deflecting beams with a thickness of 30 μm are presented. A concept to extend the actuation space towards lateral deflecting elements is introduced. The fabricated and characterized vertical deflecting cantilever beam variants make use of a 0.2 μm electrode gap and achieve deflections of up to multiples of this value. Simulation results based on an FE-model applied to calculate the voltage dependent curvature for various actuator cell designs are presented. The calculated values show very good agreement with the experimentally determined voltage controlled actuation curvatures. Particular attention was paid to parasitic effects induced by small, sub micrometer, electrode gaps. This includes parasitic currents between the two electrode layers. No experimental hint was found that such effects significantly influence the curvature for a control voltage up to 45 V. The paper provides an outlook for the applicability of the technology based on specifically designed and fabricated actuators which allow for a large variety of motion patterns including out-of-plane and in-plane motion as well as membrane deformation and linear motion.

A MEMS scanner with a high level of motion freedom has been developed. It includes a 2D mechanical tilting capability of +/- 15°, a piston motion of 50μm and a focus/defocus control system of a 2mm diameter mirror. The tilt and piston motion is achieved with an electromagnetic actuation (moving magnet) and the focus control with a deformation of the reflective surface with pneumatic actuation. This required the fabrication of at least one channel on the compliant membrane and a closed cavity below the mirror surface and connected to an external pressure regulator (vacuum to several bars). The fabrication relies on 3 SOI wafers, 2 for forming the compliant membranes and the integrated channel, and 1 to form the cavity mirror. All wafers were then assembled by fusion bonding. Pneumatic actuation for focus control can be achieved from front or back side; function of packaging concept. A reflective coating can be added at the mirror surface depending of the application. The tilt and piston actuation is achieved by electromagnetic actuation for which a magnet is fixed on the moving part of the MEMS device. Finally the MEMS device is mounted on a ceramic PCB, containing the actuation micro-coils. Concept, fabrication, and testing of the devices will be presented. A case study for application in an endoscope with an integrated high power laser and a MEMS steering mechanism will be presented.

In this paper we present a 2D raster scanning quasi-static/resonant micro mirror being controlled in both axes in closed-loop with on-chip piezo-resistive sensor feedback. While the resonant axis oscillates with a given frequency, the quasi-static axis allows static as well as dynamic deflection up to its eigenfrequency because of its staggered vertical comb (SVC) drive arrangement. Due to the high quality factor of the very low damped spring-masssystem, an adapted trajectory planning using jerk limitation is applied for the quasi-static axis [1]. Nevertheless, inaccuracies of the applied nonlinear micro mirror model and external disturbances lead to undesired residual oscillation in open-loop control mode. To achieve high precise and fast beam positioning, we implement a flatness-based control algorithm with feedback to on-chip piezo-resistive deflection sensors. In comparison to previous work [2, 3], we developed a micro controller setup for driving the microscanner, that is equipped with an analog Bessel filter increasing the sensor signal quality significantly. In this study we demonstrate a small size and low power micro mirror driver including high-voltage generation and a microcontroller for real-time control as well as a head circuit board for high resolution sensing. We discuss experimental results of open-loop and closed-loop control for 2D raster scanning operation. Finally, the outlook is given to the intrinsic capability to compensate temperature drifts influencing the piezo-resistive sensor signal.

Previously, the realization and closed loop control of a MEMS scanner integrating position sensors made with piezoresistive sensors was presented. It consisted of a silicon compliant membrane with integrated position sensors, on which a mirror and a magnet were assembled. This device was mounted on a PCB containing coils for electromagnetic actuation. In this work, the reliability of such system was evaluated through thermal and mechanical analysis. The objective of thermal analysis was to evaluate the lifetime of the MEMS scanner and is consisting of temperature cycling (-40°C to 100°C) and accelerated electrical endurance (100°C with power supplied to all electrical components). The objective of mechanical analysis was to assess the resistance of the system to mechanical stress and is consisting of mechanical shock and vibration. A high speed camera has been used to observe the behavior of the MEMS scanner. The use of shock stopper to improve the mechanical resistance has been evaluated and had demonstrated a resistance increase from 250g to 900g. The minimum shock resistance required for the system is 500g for transportation and 1000g for portative devices.

2D quasistatic (point-to-point) gimbal-less MEMS mirrors enable programmable, arbitrary control of laser beam position and velocity - up to their maximum limits. Hence, they provide the ability to track targets, point lasercom beams, and to scan uniform velocity lines over objects in laser imaging. They are becoming increasingly established in applications including 3D scanning, laser marking and 3D printing, biomedical imaging, communications, and LiDAR. With the increased utility in applications that demand larger mirror sizes and larger overall angle*diameter (θ*D) figures of merit, the technology is continuously pushed against its limit. As a result we have implemented mirrors with larger diameters including 5.0mm, 6.4mm, and 7.5mm, and have designed actuators with larger torque and angles to match the Θ*D demand. While the results have been very positive in certain application cases, a limitation for their more wide-spread use has been the relatively high susceptibility of large- θ*D mirrors to shock and vibrations. On the other hand, one of the challenges of MEMS mirrors of small diameters is their lower optical power tolerance simply due to their smaller area and heat removal ability. Although they can be operated at up to 2-3W of CW laser power, new developments in dynamic solid state lighting in e.g. headlights demand operation at up to 10W or beyond.

In this work we study and present several package-level approaches to increase mechanical damping, shock robustness, and laser power tolerance. Specifically, we study back-filling of MEMS packages with different gases as well as with different (increased) pressures to control damping and in turn increase robustness and useable bandwidth. Additionally, we study the effects of specialized mechanical structures which were designed and fabricated to modify packages to significantly reduce volumes of space around moving structures.

In their standard form and packaging the MEMS mirrors tested in this study typically measure quality factors of 75-100. Increases of pressure up to 50psi have shown relatively modest reductions of the overall quality factor to the 40-50 range. Backfilling of packages with heavier inert gasses such as Ar and SF₆ results in lowering of the quality factor down to 20-30 range. Mechanical modifications of the package with special structures and reduced air-gap to the window yielded the best results, reducing the quality factor to ~9-14. Combination of specialized packaging structures and gas backfill and pressure control could provide a very efficient heat transfer from the mirror and the desired near-critical damping, but has not been demonstrated yet. The increased performance does not change the compactness and low power consumption - the improved MEMS mirrors still consume <1mW. So far, designs with mirror sizes through 3.0mm diameter with increased damping have passed 500G shock tests.

In terms of improved heat removal we have found that the packaging improvement greatly increased optical power tolerance of MEMS mirrors from few Watts of CW laser power to <10 Watts. The exact numbers for the upper limit are not yet available - in samples where the heat removing structure was added and air was replaced with Helium, our setup with 3 combined lasers was not able to damage any samples.

We revisit the scaling laws in micro-optical systems to highlight new phenomena arising beyond a conventional optical regime, especially when the size of the system approaches to the operational wavelength. Our goal is to visualize the impact of the scaling effect in the micrometer-sized domain. First, we will show where the conventional optical regime fades away and unexpected responses arise. We will show this by using a ball-lens as an example. Second, we discuss the scaling effect in the Fresnel number of lens systems. Moving toward wavelength-scale microlenses, a specific value of Fresnel numbers leads to a giant focal shift with strong focal power. Our study will give comprehensive insights into the birth of unanticipated phenomena in miniaturized optical systems.

Lenticular type multi-view display is one of the most popular ways for implementing three dimensional display. This method has a simple structure and exhibits a high luminance. However, fabricating the lenticular lens is difficult because it requires optically complex calculations. 2D-3D conversion is also impossible due to the fixed shape of the lenticular lens. Electrowetting based liquid lenticular lens has a simple fabrication process compared to the solid lenticular lens and the focal length of the liquid lenticular lens can be changed by applying the voltage. 3D and 2D images can be observed with a convex and a flat lens state respectively. Despite these advantages, the electrowetting based liquid lenticular lens demands high driving voltage and low breakdown voltage with a single dielectric layer structure. A certain degree of thickness of the dielectric layer is essential for a uniform operation and a low degradation over time. This paper presents multilayer dielectric structure which results in low driving voltage and the enhanced dielectric breakdown. Aluminum oxide (Al2O3), silicon oxide (SiO2) and parylene C were selected as the multilayer insulators. The total thickness of the dielectric layer of all samples was the same. This method using the multilayer dielectric structure can achieve the lower operating voltage than when using the single dielectric layer. We compared the liquid lenticular lens with three kinds of the multilayer dielectric structure to one with the parylene C single dielectric layer in regard to operational characteristics such as the driving voltage and the dielectric breakdown.

These days micro lens array is used in various fields such as fiber coupling, laser collimation, imaging and sensor system and beam homogenizer, etc. One of important thing in using micro lens array is, choice of its pitch. Especially imaging systems like integral imaging or light-field camera, pitch of micro lens array defines the system property and thus it could limit the variability of the system. There are already researches about lens array using liquid, and droplet control by electrowetting. This paper reports the result of combining them, the liquid lens array that could vary its pitch by electrowetting.

Since lens array is a repeated system, realization of a small part of lens array is enough to show its property. The lens array is composed of nine (3 by 3) liquid droplets on flat surface. On substrate, 11 line electrodes are patterned along vertical and horizontal direction respectively. The width of line electrodes is 300um and interval is 200um. Each droplet is positioned to contain three electrode lines for both of vertical and horizontal direction. So there is one remaining electrode line in each of outermost side for both direction. In original state the voltage is applied to inner electrodes. When voltage of outermost electrodes are turned on, eight outermost droplets move to outer side, thereby increasing pitch of lens array. The original pitch was 1.5mm and it increased to 2.5mm after electrodes of voltage applied is changed.

This study introduces a 3D lenticular system and its fabrication method operating with liquids. The lenses of the lenticular system consists of two immiscible liquids requiring a good uniformity of their amount. The amount is controlled by an opened structures fabricated by silicon KOH etching process. For the fabrication, a low pressure silicon nitride (LSN) is deposited on a bare <1 0 0> silicon wafer followed by a photolithography and a reactive ion etching (RIE) remaining a 200nm LSN layer. A KOH etching process is done for 2 hours with a KOH solution of 40wt% in deionized water. To fabricate the opened structure, a time controlling is required not to be fully etched. The finalized silicon wafer is sputtered by a copper layer as a seed layer for an electroplating. By the electroplating with nickel, a master mold is made. To get the high transparency, poly methyl methacrylate (PMMA) is chosen for the substrate and a hot embossing process is done by fabricated nickel mold with PMMA. The PMMA is coated by gold as an electrode and parylene C and Teflon multi-layer as dielectric layers. For two immiscible liquids, deionized water and a mixture of dodecane and 1-Chloronaphthalene are used. The dosing process is done in underwater environment and the mixed oil is dosed uniformly as the oil has tendency to spread onto the substrate. After sealing the active liquid lenticular devices is fabricated and good uniformity is achieved.

A miniaturized adaptive-focus camera objective featuring a gravity-immune liquid-tunable aspherical lens is presented. The lens, which has an aperture size of 3 mm, a nominal focal length of 8mm and an optimum tuning range between 7.2 to 8.8 mm, is experimentally demonstrated to have diffraction-limited performance at the nominal focal length with identical performance for vertical and horizontal lens orientations, leading to a drastic reduction in spherical aberration compared to conventional liquid-tunable lenses. The camera objective comprises three fixed elements and a tunable lens, arranged on a 5×5×13 mm platform. It provides a viewing angle of 40° imaged on a 3 mm sensor. By tuning the lens in its optimum operation range, the object distance can be shifted from 5mm to infinity.

A fluid-filled micro-lens concept with an electrically driven polymer actuator was developed in view of optimization of its variation in focal length. The high strain electrostrictive terpolymer P(VDF-TrFE-CFE) was first used in the actuator design for this purpose. Our study showed that the electric field-induced strain in polymer thin films could be even further enhanced by mixing high-k BaTiO3 nanoparticles in the terpolymer. A newly developed nanocomposite P(VDF-TrFE-CFE) / BaTiO3 ring-shaped actuator was implemented into the 3 mm aperture, liquid-filled micro-lens concept. The micro-lens was fabricated in a wafer-level process flow, which included micromachining of fluidic chambers on silicon wafers, thin film nanocomposite actuator processing, assembly through wafer bonding and chip filling with liquids. Particular characteristics of the nanocomposite were taken into account such as the homogeneous nanoparticle dispersion into the thin film with impact on thin film dielectric breakdown, electrode adherence as well as nanocomposite film etching. Variable focal length micro-lenses conceps with a single fluidic chamber but also with two fluidic chambers (a design, which can potentially improve the lens membrane stability) were fabricated and characterized. We could demonstrate a wide focal length variation of tens of diopters first for a single chamber plano-convex micro-lens obtained by adjusting the voltage applied on the integrated actuator.

In this work we demonstrate a highly flexible laser imaging system for 3D sensing applications such as in tracking of VR/AR headsets, hands and gestures. The system uses a MEMS mirror scan module to transmit low power laser pulses over programmable areas within a field of view and uses a single photodiode to measure the reflected light. User can arbitrarily select the number of pixels to scan over an area and can thus obtain images of target objects at arbitrarily fast rates. The work builds on the previously presented “MEMSEye” laser tracking technology which uses a fast steering MEMS scan module with a modulated laser, and a tuned photosensor to acquire and track a retroreflector-marked object. To track VR/AR headsets, hands and similar objects with multiple markers or no markers at all, a single-point tracking methodology is not sufficient. Cameras could be more appropriate in such multi-point imaging cases but suffer from low frame rates, dependence on ambient lighting, and relatively low resolution when without zooming and panning capability. A hybrid method can address the problem by providing a system with its own light source (laser beam), and with full programmability of the pixel locations and scans such that frame rates of >100 Hz are possible over specific areas of interest. With a modest 1 Mpixel rate of measurement, scanning a sub-region of the field of view with 64 x 64 pixels results in ~200Hz update. Multiple such modules can be used to scan and image or track objects with multiple markers and fully obtain their position and attitude in a room with sub-5ms updates. Furthermore the room itself could be imaged and measured with wall markers or in conjunction with a camera for a total 3D scanning solution. Proof of concept demonstrator is presented here with pixel rates of only 30k-50k per second due to limitations of the present prototype electronics, resulting in refresh rates that are significantly lower than possible with the MEMS mirror scan modules.

We experimentally demonstrate electro-optic modulation in thin film lithium niobate microdisk resonators with an integrated bottom electrode fabricated from a z-cut Lithium Niobate on Insulator wafer. The structure consisted of a 400nm thick crystalline z-cut lithium niobate/2um SiO2/20nm Cr/100nm Au/10nm Cr film stack on top of a z-cut lithium niobate handle wafer. The integrated bottom electrode is located 2um beneath the resonator. This proximity, coupled with positioning an electrical probe close to the top of the resonator, allows large optical frequency shifts with low voltages. We observed a 0.111pm/V resonance shift of vertically polarized (TM) optical whispering gallery modes, with the voltage applied perpendicular to the wafer surface. This corresponds to a shift of one optical linewidth at an applied voltage of 180V, using the r33 component of the eletro-optic tensor. We observed a smaller shift of 0.066pm/V for the radially polarized (TE) modes, using the r13 component of the electro-optic tensor. The experiment was performed using a 1550nm tunable laser that was coupled to the optical resonator modes using a tapered optical fiber. To measure the electro-optic shift of the resonance, a voltage was applied across the device via DC probe tips and the peak shift was calibrated with a Toptica WS6 IR wavemeter with 200 MHz absolute accuracy. We also present a finite element model that accurately predicts the resonance shift as a function of applied voltage for both polarizations.

Continuous and accurate monitoring of acceleration and temperature inside large turbo- and hydro-generators is of crucial importance to prevent extremely expensive system damages and false positives. Development of optical, metalfree sensors for such systems has gained a lot of attention due to the fact that they are resistant to typically very strong electromagnetic fields and that they are non-conductive. We present miniature temperature and accelerometer optical sensors using a common silicon MEMS platform. A linear response with a deviation as small as 1% between set and measured accelerations has been obtained in an acceleration range 0-40g. Preliminary tests for temperature sensors indicate a linear response with sensitivity better than 1°C in a range of 20°C to 150°C.

The full complex, spatial modulation of light at high frame rates is essential for a variety of applications. In particular, emerging techniques applied to scattering media, such as Digital Optical Phase Conjugation and Wavefront Shaping, request challenging performance parameters. They refer to imaging tasks inside biological media, whose characteristics concerning the transmission and reflection of scattered light may change over time within milliseconds. Thus, these methods call for frame rates in the kilohertz range. Existing solutions typically over frame rate capabilities below 100 Hz, since they rely on liquid crystal spatial light modulators (SLMs). We propose a diffractive MEMS optical system for this application range. It relies on an analog, tilt-type micro mirror array (MMA) based on an established SLM technology, where the standard application is grayscale amplitude control. The new MMA system design allows the phase manipulation at high-speed as well.

The article studies properties of the appropriate optical setup by simulating the propagation of the light. Relevant test patterns and sensitivity parameters of the system will be analyzed. Our results illustrate the main opportunities of the concept with particular focus on the tilt mirror technology. They indicate a promising path to realize the complex light modulation at frame rates above 1 kHz and resolutions well beyond 10,000 complex pixels.

VTT’s Fabry-Perot interferometers (FPI) technology enables creation of small and cost-efficient microspectrometers and hyperspectral imagers – these robust and light-weight sensors are currently finding their way into a variety of novel applications, including emerging medical products, automotive sensors, space instruments and mobile sensing devices. This presentation gives an overview of our core FPI technologies with current advances in generation of novel sensing applications including recent mobile technology demonstrators of a hyperspectral iPhone and a mobile phone CO2 sensor, which aim to advance mobile spectroscopic sensing.

A novel miniaturized near-infrared spectrometer readily mountable to wearable devices for continuous monitoring of individual’s key bio-markers was proposed. Spectrum is measured by sequential illuminations with LED’s, having independent spectrum profiles and a continuous detection of light radiations from the skin tissue with a single cell PD. Based on Tikhonov regularization with singular value decomposition, a spectrum resolution less than 10nm was reconstructed based on experimentally measured LED profiles. A prototype covering first overtone band (1500-1800nm) where bio-markers have pronounced absorption peaks was fabricated and verified of its performance. Reconstructed spectrum shows that the novel concept of miniaturized spectrometer is valid.

We present an optical spectroscopic technique, making use of both Raman signals and fluorescence spectroscopy, for the identification of five brands of commercially available extra-virgin olive-oil (EVOO). We demonstrate our technique on both a ‘bulk-optics’ free-space system and a compact device. Using the compact device, which is capable of recording both Raman and fluorescence signals, we achieved an average sensitivity and specificity of 98.4% and 99.6% for discrimination, respectively. Our approach demonstrates that both Raman and fluorescence spectroscopy can be used for portable discrimination of EVOOs which obviates the need to use centralised laboratories and opens up the prospect of in-field testing. This technique may enable detection of EVOO that has undergone counterfeiting or adulteration. One of the main challenges facing Raman spectroscopy for use in quality control of EVOOs is that the oxidation of EVOO, which naturally occurs due to aging, causes shifts in Raman spectra with time, which implies regular retraining would be necessary. We present a potential method of analysis to minimize the effect that aging has on discrimination efficiency; we show that by discarding the first principal component, which contains information on the variations due to oxidation, we can improve discrimination efficiency thus improving the robustness of our technique.

In this work, we report carbon dioxide gas sensing in the ambient air in the mid-infrared range around 4250 nm using MEMS FTIR spectrometer. The core engine of the spectrometer is a scanning Michelson interferometer fabricated using deep etching technology on silicon-on-insulator wafer. The measured Signal-to-Noise Ratio (SNR) is 24 dB at a wavelength of 4250 nm and the spectral resolution is about 60 cm^-1. A free-space gas cell using CaF₂ lenses with lightgas interaction lengths of 12 cm and 120 cm is demonstrated. The results demonstrate about 400 ppm concentration detection in the ambient air. The theoretical sensitivity limit based on the achieved SNR and resolution is about 15 ppm.

MOEMS Deformable Mirrors (DM) are key components for next generation optical instruments implementing innovative adaptive optics systems, in existing telescopes as well as in the future ELTs. Due to the wide variety of applications, these DMs must perform at room temperature as well as in cryogenic and vacuum environment. Ideally, the MOEMS-DMs must be designed to operate in such environment. This is unfortunately usually not the case. We will present some major rules for designing / operating DMs in cryo and vacuum. Next step is to characterize with high accuracy the different DM candidates. We chose to use interferometry for the full characterization of these devices, including surface quality measurement in static and dynamical modes, at ambient and in vacuum/cryo. Thanks to our previous set-up developments, we are placing a compact cryo-vacuum chamber designed for reaching 10-6 mbar and 160K, in front of our custom Michelson interferometer, able to measure performances of the DM at actuator/segment level as well as whole mirror level, with a lateral resolution of 2μm and a sub-nanometric zresolution. Using this interferometric bench, we tested the PTT 111 DM from Iris AO: this unique and robust design uses an array of single crystalline silicon hexagonal mirrors with a pitch of 606μm, able to move in tip, tilt and piston with strokes from 5 to 7μm, and tilt angle in the range of +/- 5mrad. They exhibit typically an open-loop flat surface figure as good as < 20nm rms. A specific mount including electronic and opto-mechanical interfaces has been designed for fitting in the test chamber. Segment deformation, mirror shaping, open-loop operation are tested at room and cryo temperature and results are compared. The device could be operated successfully at 160K. An additional, mainly focus-like, 500 nm deformation is measured at 160K; we were able to recover the best flat in cryo by correcting the focus and local tip-tilts on some segments. Tests on DM with different mirror thicknesses (25μm and 50μm) and different coatings (silver and gold) are currently under way. Finally, the goal of these studies is to test DMs in cryo and vacuum conditions as well as to improve their architecture for staying efficient in harsh environment.

Spaceborne assessment of fire characteristics relies on radiance measurement of fire pixels and non-fire pixels mainly in the midwave infrared (MWIR). Because ambient temperature non-fire pixels have low thermal emission in this spectral range, it remains a challenge to retrieve fire characteristics with the desired accuracy. This paper reports on uncooled microbolometers specially designed with low noise equivalent power (NEP) to enable fire diagnosis at MWIR wavelengths. Each microbolometer forming a 512x3 format array includes a Wheatstone bridge of one active, one blind, and two thermally shunted pixels followed by its own signal chain. Design analyses suggest the conditions for achieving the best NEP performance are: (i) the active, blind, and one shunt pixel have equal electrical resistances while the other shunt pixel has a larger resistance; (ii) the temperature difference between the active pixel and heat sink corresponds to about one-third the heat sink temperature; and (iii) the active and blind pixels have low thermal mass and conductance. Hardwired devices having different structural layouts were prepared for the validation of physical parameters and performance so that the suitable designs could be identified. After this, focal planes of 512x3 microbolometers were fabricated on readout electronics to allow further performance evaluation and development of staggered 1017x3 format arrays for a planned mission. The active pixel designs on the fabricated arrays exhibit a MWIR absorptance as high as 0.83 through implementation of a Salisbury screen absorber, a thermal conductance of ~ 67 nW/K, and a response time shorter than 10 ms. Their responsivities are found to be in good agreement with predictions of the design analysis. The effectiveness of an Al shield platform erected above the blind pixel was investigated, showing that certain designs are capable of attenuating the incident power by up to 24 times. Under optimal operating conditions an NEP of ~ 64 pW was derived from measurements in the spectral range of 3.4-4.2 um, which was corroborated by the probing results obtained on the on-wafer focal plane arrays. When using these arrays with an F/1 telescope to retrieve scenes of 400 K from low Earth orbits, a noise equivalent temperature difference of ~ 320 mK can be achieved.

We present the basic characteristics of amplitude modulation cantilever with optical waveguide in liquid. This optical waveguide cantilever-based transducer can be used for small particle detection or biological sensing in liquid environments. Essentially, the SiON waveguide embedded in the SiO² cantilever is designed and fabricated to detect the biomolecular interaction or small particle in the liquid. For a measurement, the actuation based on amplitude modulation is applied for a stable oscillation of the cantilever in liquid environment. Finally, modulated output signal of optical waveguide cantilever were measured and analyzed.

In cavity optomechanics the state of a mechanical element can be manipulated by interfacing it with light via radiation pressure, electrostriction, or related phenomena. The majority of mechanical elements employed in optomechanical systems to date are solid objects (membranes, nanowires, mirrors, etc); however fluids can also be used as a mechanical element. Compared to solids, fluids have an advantage: they readily achieve precise alignment with the optical cavity, as the fluid can conformally fill or coat the optical cavity. However, almost all optomechanical systems need to be cooled to sub-Kelvin temperatures in order for quantum effects to be observed. Liquid helium is the only fluid that doesn't solidify under its own pressure at these temperatures. Additionally, helium has almost no optical absorption, high thermal conductivity and very low acoustic loss at cryogenic temperatures. We have developed an optomechanical system in which the mechanical mode is a standing density wave in superfluid helium inside a 70 μm long Fabry-Perot cavity. The optical mode is also a mode of the same cavity. Thus, the system is completely self-aligned. In this system, we used electrostriction to drive the mechanical mode with light by modulating the optical intensity. We also observed the mode's undriven Brownian motion and from that extracted it mean phonon number. We measured phonon number as low as n_ac=11. The optomechanical effects of optical spring and optical damping were observed, and agreed well with the predictions of conventional optomechanical theory.