An electroactive polymer (EAP)-based MOEMS spatial light modulator (SLM), which shows high reliability and fast response speed, is reported in this work. The reliability is achieved by designing the SLM without direct contact between electrodes and deformable EAP surface; while the fast response speed is obtained by optimizing the microstructure of the EAP material. The concept of SLM, material optimization approach, fabrication processes, as well as characterization methods, are described. The SLM is driven by relatively low voltage, which is 200 V dc and 60 V ac and the response time is 35 μs. The manufactured SLM shows no degradation or breakdown after millions of actuation cycles, indicating a good reliability of the device.
We report a polymer based multiple diffraction modulator, in which PDMS (polydimethylsiloxane) is utilized as the
actuation material, for speckle reduction. The properties of the PDMS are characterized based on its response time and
deformability, which are the key properties concerned in this work. The structure dependent properties of PDMS are
discussed. Using the described technique, the PDMS satisfy the system demand.
The modulator is used to create real-time diffraction patterns by dynamic gratings formed by flexible PDMS. The
diffracted light passes through a diffuser, which is placed after the modulator, and induces speckle patterns on the screen.
Speckle-reduction is achieved by adding the time-varying speckle patterns in the integration time of the detector. It is
observed that using the modulator which has two gratings, the speckle contrast ratio reaches to 50%, which shows fair
agreement with the simulation.
An array of diffraction gratings and a Random Phase Plate (RPP) are used to suppress laser speckle effect. Dynamic
diffraction spots are generated on the surface of the RPP, after which the scattering lights are perceived by a detector.
Speckle Contrast Ratio (CR) and Number of Independent Speckle Patterns (NISP) with different gratings rotation
orientations (θ), gratings frequencies (grooves per millimeter: f), diameters of laser beam (D), and distances between the array of diffraction gratings and the RPP (Z) are calculated based on ZEMAX simulations, and an optimized model is proposed.
Cost efficient integration technologies and materials for manufacturing of uncooled infrared bolometer focal plane arrays
(FPA) are presented. The technology platform enables 320x240 pixel resolution with a pitch down to 20 μm and very
A heterogeneous 3D MEMS integration technology called SOIC (Silicon-On-Integrated-Circuit) is used to combine high
performance Si/SiGe bolometers with state-of-the-art electronic read-out-integrated-circuits.
The SOIC integration process consists of: (a) Separate fabrication of the CMOS wafer and the MEMS wafer. (b)
Adhesive wafer bonding. (c) Sacrificial removal of the MEMS handle wafer. (d) Via-hole etching. (e) Via formation and
MEMS device definition. (f) Sacrificial etching of the polymer adhesive. We will present an optimized process flow that
only contains dry etch processes for the critical process steps. Thus, extremely small, sub-micrometer feature sizes and
vias can be implemented for the infrared bolometer arrays.
The Si/SiGe thermistor is grown epitaxially, forming a mono-crystalline multi layer structure. The temperature
coefficient of resistance (TCR) is primarily controlled by the concentration of Ge present in the strained SiGe layers.
TCR values of more than 3%/K can be achieved with a low signal-to-noise ratio due to the mono-crystalline nature of the
material. In addition to its excellent electrical properties, the thermistor material is thermally stable up to temperatures
above 600 °C, thus enabling the novel integration and packaging techniques described in this paper.
Vacuum sealing at the wafer level reduces the overall costs compared to encapsulation after die singulation. Wafer
bonding is performed using a Cu-Sn based metallic bonding process followed by getter activation at ≥350 °C achieving a
pressure in the 0.001 mbar range. After assembling, the final metal phases are stable and fully compatible with hightemperature
processes. Hermeticity over the product lifetime is accomplished by well-controlled electro-deposition of
metal layers, optimized bonding parameters and a suitable bond frame design.
In this paper, we report surface and electromechanical properties of polydimethylsiloxane (PDMS)
films prepared by a modified molding technique. The film with thickness = 4 μm was deposited on
oxidized silicon wafer by the modified molding technique and corresponding elastic modulus of the bulk
PDMS materials is equal to 36 kPa. Surface morphology of the film was examined by optical
interferometer and Scanning Electron Microscope (SEM). Its roughness is ~ 10 nm and wave-liked
structures were locally observed on the film surface. In order to investigate electromechanical performance
of the film, sandwich structured multilayer films Au (patterned electrodes, 150 nm) /PDMS (4 μm) /Au
(top un-patterned electrode, 50 nm) were deposited on the oxidized silicon wafer. The displacement ratios
of the PDMS film parallel to electric fields were characterized from 0 V/μm to 52.5 V/μm and maximum
value of the displacement ratio reaches ~ 5.0 %. Meanwhile, the rising and falling response time of the
PDMS films are reported as a function of applied electric fields. Since the good light reflection of top gold
electrode and displacement ratio of the sandwich-structured films, the multilayer films device might be a
proper candidate for the application of spatial light modulator.
We report on device properties of tunable spatial light modulators for high-resolution optical applications by a novel
fabrication process. Thin polydimethylsiloxane (PDMS) films (4ìm-13ìm) were sandwiched between a flexible gold
film(50nm) and a rigid substrate with a comb-like electrode either by compression molding or spin coating. By applying
voltage between the upper gold film and underlying electrode, the initial plane PDMS surface changes into a form of
grating. Far-field scattering pattern with high order light components was observed by illumination at the continuously
reflective gold film with laser beam. Characterization was done by measuring the grating profile of the PDMS and the
response time. The PDMS deformation was demonstrated to increase with driving voltage. The deformation for 6ìm
thick PDMS is measured around 100nm when driving voltage is applied as 230V. Modeling and simulation of the
modulator electro-mechanical behavior was done for varies structure design. The simulation results showed fair
agreement with the experimental results. The response time, which defines how fast the PDMS response to the applied
voltage, was measured as a function of the driving voltage. The measured rise time is around 1 micorseconds and the fall
time is around 0.2 microseconds.