Following the publication of a first market survey and a technology roadmap in 1998/2000, the NEXUS Association has continued its efforts on analyzing market opportunities and technology roadmaps for Microsystems (MST) and MEMS products and applications. Directed, primarily, by application-driven technology users, NEXUS has championed such tasks to help provide strategic guidance for industry and research to encourage the uptake of the technology beyond its conventional realm. In this context, NEXUS through its User-Supplier-Clubs (USCs) has produced forecasts addressing the potential of MST/MEMS insertion into telecommunication systems over the next 10 years in the context of functionality advancements and network evolution. The Roadmaps chart forecasts for functionalities, underpinned by MST/MEMS-based solutions and progress for a selection of applications considered of prime importance for the MST/MEMS related markets. The NEXUS Roadmap report will be released in Q1 2003. This presentation will outline the methodologies adopted for the road-mapping activity and provide some of the MOEMS-related results. In addition, further roadmaps on polymer micro-optics and a modular approach for MOEMS manufacturing will be highlighted.

Continued demands for delivery of high performance micro-optoelectromechanical systems (MOEMS) place unprecedented requirements on methods used in their development and operation. Metrology is a major and inseparable part of these methods. Optoelectronic methodology is an essential field of metrology. Due to its scalability, optoelectronic methodology is particularly suitable for testing of MOEMS where measurements must be made with ever increasing accuracy and precision. This was particularly evident during the last few years, characterized by miniaturization of devices, when requirements for measurements have rapidly increased as the emerging technologies introduced new products, especially, optical MEMS. In this paper, a novel optoelectronic methodology for testing of MOEMS is described and its applications are illustrated with representative examples. These examples demonstrate capability to measure submicron deformations of various components of the micromirror device, under operating conditions, and show viability of the optoelectronic methodology for testing of MOEMS.

We report absolute measurements of thermal-mechanical noise in microelectromechanical systems. The measurements are made possible with a simple, high resolution optical technique that has a displacement resolution on the order of hundreds of femtometers per root Hz at frequencies of tens of kHz. The measured noise spectrum agrees with the calculated noise level to within 25%, a discrepancy most likely due to uncertainty in the effective dynamic mass of the vibrating bridge. These measurements demonstrate that thermal-mechanical noise can be the dominant noise source in actuated microelectromechanical devices. This noise will become even more pronounced as the size of mechanical devices continues to shrink.

Robust control and failure assessment of MEMS employed in physically demanding, mission critical applications will allow for higher degrees of quality assurance in MEMS operation. Device fault detection and closed-loop control require detailed knowledge of the operational states of MEMS over the lifetime of the device, obtained by a means decoupled from the system. Preliminary through-wafer optical monitoring research efforts have shown that through-wafer optical probing is suitable for characterizing and monitoring the behavior of MEMS, and can be implemented in an integrated optical monitoring package for continuous in-situ device monitoring. This presentation will discuss research undertaken to establish integrated optical device metrology for closed-loop control of a MUMPS fabricated lateral harmonic oscillator. Successful linear closed-loop control results using a through-wafer optical microprobe position feedback signal will be presented. A theoretical optical output field intensity study of grating structures, fabricated on the shuttle of the resonator, was performed to improve the position resolution of the optical microprobe position signal. Through-wafer microprobe signals providing a positional resolution of 2 μm using grating structures will be shown, along with initial binary Fresnel diffractive optical microelement design layout, process development, and testing results. Progress in the design, fabrication, and test of integrated optical elements for multiple microprobe signal delivery and recovery will be discussed, as well as simulation of device system model parameter changes for failure assessment.

The inherent ability of silicon micromachining to provide a multitude of precision aligned optical components on a single die naturally facilitates optical communication trends towards installing larger cross-connects and transmitting many channels on individual fibers. A micromachined mirror array has been designed and fabricated using the Analog Devices, Inc. (ADI) Optical iMEMS (R) process. The single-chip mirror die consists of 84 mirrors arranged in a linear array with an average pitch of 95 μm. Each mirror is equipped with a pair of polysilicon actuation electrodes located beneath the mirror. These two electrodes allow each mirror to be independently rotated around the axis parallel to the long dimension of the array using off-chip voltage commands. An operating mirror tilt of +/- 2 degrees is achieved with less than 130 volts of actuation. The design objectives including high mirror fill factor, optimal air damping, low mirror-to-mirror cross talk, acceptable voltage levels, and robustness posed significant challenges. This paper will describe how these challenges were overcome using an interdigitated mirror layout. The mirrors were successfully fabricated with good yield and characterized through both customer and ADI testing.

An all-fiber optical switch based on silicon on insulator (SOI) and deep reactive-ion etching (DRIE) technology has been developed. The novel switch is designed for applications requiring high optical power transfer, such as routing in optical energy conversion and transfer systems, while requiring low electrical power for switch actuation. The optical switch was realized by attaching a short optical fiber segment to a large-displacement microactuator, suspended between fixed input and output optical fibers. When the fibers are coaxially aligned, optical transfer is achieved between the fixed input and output fibers. The present work offers the potential for low electrical power operation, high-density array fabrication, fully-integrated manufacturing, and decoupled electromechanical/optical performance. The device concept and fabrication process is described, and optical transfer efficiency results are discussed. Current switches employ integrated electrothermal actuators to move the intermediate optical fiber segment, and switches based on lower-power electrostatic actuators will also be described.

Development of a high power optical micro switch fabricated by deep reactive ion etching (DRIE) in silicon on insulator (SOI) substrates is presented. The devices discussed are a key component in a MEMS-based, Naval safety and arming (S&A) system for use in underwater weapons. Two different optical switching techniques are investigated: moving reflector type and moving fiber type. In each technique, a single pair of multimode optical fibers is used to transmit optical power on the order of 1 W at a working wavelength of 810 nm. For the moving reflector type device, an etched vertical sidewall reflector is electrostatically actuated in and out of the optical path between input and output fibers. For the moving fiber type device, v-beam thermal actuators are used to push cantilevered input and output optical fibers in and out of direct alignment with each other. Fabrication is performed on 100 μm thick silicon substrates with fiber alignment channels, reflectors, and actuators being fabricated at the same time with a single etch step. Device concept, modeling, and initial characterization results will be presented.

The goal of this study is to understand how to optimize the performance of micro-mirrors for a variety of optical microsystem applications. Our approach relies on a number of process variations and mirror designs to ultimately produce relatively large (500μm to mm-scale), smooth (for nm RMS), and flat mirrors (greater than 1m curvature). White-light interferometric measurements, and finite element models are discussed in support of these findings. Stress gradients and residual stresses have been measured for accurate modeling of micro-mirrors. Through this modeling study, we have identified relevant structural parameters that will optimize SUMMiT V MEMS mirrors for optical applications. Ways of mitigating surface topography, print-through effects, and RMS roughness are currently being investigated.

The optical system properties of a reconfigurable surface micromachined micro-electro-mechanical system (MEMS) interconnect are presented. An array of optical signals from a singlemode MT connector is first collimated by a refractive lenslet array. Each beam may be individually redirected by a rotatable, 45 degree flip-up MEMS mirror. The second, complimentary MEMS mirror folds the optical beam back through the lenslet array and couples it into a second fiber row on the MT connector. Much work has been presented promoting the utility of MEMS configurations to manipulate optical signals. This work examines, with ray tracing simulations, the proposed configuration from the detailed optical system perspective.

Despite the recent sag in the optical telecom sector, the development and application of Micro-Opto-Electro-Mechanical Systems (MOEMS)-based devices for optical interconnects continues to expand. The utility of such fundamental research is finding increasing relevance in a variety of technical and commercial areas. This paper will report on the present status of the diffractive and reflective components and arrays that are being developed at the University at Albany’s Institute for Materials (UAIM) NanoFab 200. Selected examples include the current generation of the patented MEMS Compound Grating (MCG) and an innovative micro-scanner device, both of which are being examined for inclusion in prototype interconnect systems. These devices are based on a dual technology development path which includes decreasing feature size and increasing integration level. The MCG prototypes are currently produced with 1-2 micron feature size in 144 element arrays. The surface topology of these components can be controlled using electrostatic attraction to yield both angular deflection and wavelength separation. The optical and mechanical performance of these devices that use either polysilicon or silicon dioxide as a structural material will be reported. Several prototype MCG array architectures have been interfaced with optical sources including VCSEL arrays to test optical interconnect concepts. In addition, recent work on an innovative micro-scanner will be discussed. The micro-scanner is based on a cantilever design with access electrodes to electrostatically control deflection in multiple planes. Details of the components including simulation, fabrication and initial prototype performance tests will be presented.

In this paper, the development of a 1X4 micro optical switch utilizing electrostatic actuation and vertical silicon mirrors was reported. This device was fabricated from silicon-on-insulator (SOI) wafer using a bulk micromachining process, which allowed the fabrication of vertical mirrors and U-grooves through deep reactive ion etching (DRIE) of silicon. A few process steps were required in the fabrication. Moreover, the device was patterned in a single lithographic step. A relatively high yield (up to 70%) was achieved during the microfabrication due to this compact process flow. More importantly, the footprint was less than 13mm². To verify the design, the stress/strain distribution around the actuator was examined using FEM simulation. The relationship between driving voltage and mirror displacement derived from simulation agreed well with the measurement. Tapered lensed singlemode fiber were assembled into U-grooves and positioned passively by fiber stopper. The device was then packaged and pigtailed. Characterization on the mechanical and optical performance of this device show the promising characteristics of this 1×4 optical switch for use in optical networks.

A slow-speed optical fiber cross-connect has been developed around surface-micromachined MEMS mirrors that pop up 45 degrees relative to the substrate and rotate 360 degrees about the normal axis. Various assembly, latching, and rotational mechanisms have been evaluated and tested, with current work focusing on demonstrating functionality. Routing capability has been characterized for 2 × 2 arrays of micromirrors, the feedback from which has been applied to second-generation designs with improved control and greater precision. The cross-connect described here is scalable and represents an important building block in a general-purpose photonic infrastructure.

Have developed relatively simple and compact design of microelectromechanical optical switch of electrostatic type containing cardan structure including two movable elements: the outer one, in central part of which the mirror is formed, and which perform beam scanning along the X axis, and the inner one which deflect beam along the Y axis. The movable elements and the basis are connected successively by the torsion pairs positioned along the mutually perpendicular axes. Originality of the design consists in fabrication of inner element in the form of plate having in its central part the cavity, on the bottom of which the electrodes are formed to turn the inner element. The axes of both pairs of torsions and mirror being positioned in the same plane. The distinctive feature of the switch operation is independence and constancy of the mirror position under any order of signals supply to the control movable and unmoveable electrodes. Corresponding theoretical calculations have been performed, and optimum relations of constructive elements sizes are presented. The switch provides enhancement of spatial addressing precision, reducing of mass and dimension parameters, control apparatus simplification.

A novel Fourier spectrometer using thin film technology was developed. The spectrometer based on a semi transparent thin film detector in combination with a tunable micro machined mirror. The semi transparent detector is introduced into a standing wave created in front of the mirror to sample the profile of the standing wave. Varying the position of the mirror results in a shift of the phase of the standing waves and thus in a change of the optical generation profile within the semi transparent detector. The active region of the sensor (thickness-absorption) is thinner than the wavelength of the incoming light, so that the modulation of the intensity results in a modulation of the overall photocurrent. The spectral information of the incoming light can be determined by the Fourier transformation of the sensor signal. Based on the linear arrangement of the sensor and the mirror, the spectrometer facilitates the realization of 1D and 2D arrays of spectrometers combining medium range spectral resolution with medium range spatial resolution. The novel device is filling the gap between solid-state camera technology with only three-color channels (red, green and blue) but high spatial resolution on one hand and precision spectrometers with high spectral resolution but no spatial resolution on the other hand. An analytical optical model of the spectrometer was applied to evaluate different detector concepts. The model was used to study the performance of different device designs regarding the spectral resolution of the spectrometer, the spectral range and the linearity of the response. The calculations will be compared with experimental results of semi transparent amorphous silicon detectors.

In this paper, we propose a novel miniature MEMS based thermoacoustic cryo-cooler for thermal management of cryogenic electronic devices. The basic idea is to exploit a new way to realize a highly-reliable miniature cryo-cooler, which would allow integration of a cryogenic cooling system directly into a cryogenic electronic device. A vertical comb-drive is proposed as the means to provide an acoustic source through a driving plate to a resonant tube. By exciting a standing wave within the resonant tube, a temperature difference develops across the stack in the tube, thereby enabling heat exchange between two heat exchangers. The use of gray scale technology to fabricate tapered resonant tube provides a way to improve the efficiency of the cooling system, compared with a simple cylinder configuration. Furthermore, a tapered tube leads to extremely strong standing waves with relatively pure waveforms and reduces possible harmonics. The working principle of this device is described here. The fabrication of this device is considered, which is compatible with current MEMS fabrication technology. Finally, the theoretical analysis of key components of this cryo-cooler is presented.

In this paper, we describe the fabrication of cantilevered arrays of tapered near-field probes with pyramidal, sub-micrometer tips that are micromachined from glass substrates. High density data storage and page-oriented retrieval are the potential applications of the described microdevice. Heating and pulling or chemical etching of optic fibers are the common approaches to sub-wavelength aperture fabrication necessary to probe the near-field. Arrays have been previously formed by chemical etching of or film deposition on an opaque substrate and were later coupled to optical fibers for use as near-field probes though; alignment of optical fibers with the apertures for guiding the light to the detector in the far-field is not trivial. Probe arrays described in this work were initially fabricated by dicing a 175-μm thick borosilicate glass substrate using a 250-μm thick resinoid blade and were subsequently tapered and sharpened in a two-step chemical etch process performed at room temperature. The tips were then metallized using a 100nm thick coating of aluminum. Arrays of upto eight 1cm to 2.5 cm long probes with center-to-center spacing of 450 μm and tip sizes of approximately 200 nm were fabricated. Roughness on the vertical sidewall was characterized and the dependence of optical loss coefficients of the light guiding bulk on etch duration was investigated.

A scheme of a novel hybrid integrated micro spectrometer is proposed, which greatly reduces the number of optical units used in the system and can easily realize the integration of the optical unit and the detecting array. At the same time, the effective area of the grating is increased. One model of such device is fabricated. It is about 60mm×40mm×40mm and the volume can be further reduced. In experiments, the spectrum signal of Hg lamp and tungsten lamp is obtained. The result shows that a resolution of 7nm is achieved when a single mode fiber is used as the light input device.

This paper reports the design, modeling, fabrication and testing of a novel variable optical attenuator for multi-channel power equalizers to be used in dense wavelength division multiplexed (DWDM) systems. The attenuator is fabricated by silicon surface micromachining technology and is then manually assembled and integrated with two single mode optical fibers that act as optical input and output. A 40 × 40 μm² mirror coated with gold is driven by a proprietary drawbridge structure to cut partially into the light path between two fibers, enabling the attenuation. The attenuator has a dimension of 0.6 × 1 μm² excluding the fibers. It has 1.5 dB insertion loss and 45 dB attenuation range, and requires only 8 V driving voltage, showing that it is promising for DWDM applications. Optical and mechanical models of the attenuator have also been established. Although the models are developed with the initial intention of modeling the MEMS attenuator, they are also available to the other types of devices in which the preconditions of the models are satisfied.

Two new micromachined VOAs(Variable Optical Attenuator), which have a micromirror with ultra-smooth surface, are presented and are compared with each other with respect to each different actuator type with same mirror structure. A couple of tapered fibers are perpendicularly aligned using the reflection of a micromirror. By moving the micromirror parallel or vertical direction to the mirror surface, some part of transmitting light can be attenuated with the principle of leaked light or misaligned light. This paper shows the two features of performance of the new two type VOAs. The one is that a micromirror with ultra-smooth surface gives the good optical performances of the VOA and the second is that the two new type VOAs have different the optical characteristics, such as polarization dependent loss(PDL), wave dependent loss(WDL) and return loss(RL), because of the different optical path or different optical attenuated method by different actuator. In this paper, the structure of reflector type VOA is fabricated using silicon micromachining process. Using SOI(silicon-on-insulator) wafer with 80μm device layer and 3 μm oxide layer, structure is patterned by ICP (Inductively Coupled Plasma) deep etch process which is followd by thermal oxidation for improved surface roughness, HF oxide layer etching, releasing and Au sputtering to form mirror surfaces and interconnection pads. This paper pays attention to the importance of the final optical fiber alignment, which may play a key role in the optical performance of the VOA.

Tunable lasers have wide applications in DWDM systems to save inventory cost and to improve the optical network functionalities. The Microelectromechanical Systems (MEMS) technology has shown strong promise to miniaturize the conventional mechanical tunable lasers with adding merits of high compactness, high speed, batch production and so on. In this paper, external cavity tunable diode lasers using MEMS movable mirrors and rotary gratings as the external reflectors are presented. One tunable laser of 2 mm × 1.5 mm is formed by integration of a surface-micromachined 3D mirror with a diode laser and an optical fiber. In addition, deep-etched structures such rotary gratings, circular mirror, microlens, and grooves for diode laser and fiber are illustrated to form widely tunable lasers.

This paper presents, for the first time, a micromachined in-plane tunable optical filter (TOF) using thermo-optic effect for wavelength division multiplexed telecommunication. The TOFs are comprised of a Fabry-Perot silicon optical resonator formed between two distributed Bragg reflectors with high-reflectance based on silicon/air-gap pairs. The whole device was vertically fabricated using silicon deep reactive ion etching (DRIE). And input/output optical fibers were easily aligned along with the TOF structure on the substrate by exploiting in-plane fiber alignment. Tunability of the TOFs is experimentally achieved through thermal modulation of optical path length by heating the silicon resonator. As an input voltage increases, a notch of reflectance spectrum shifts to a longer wavelength with a tuning range of 9 nm and 3dB bandwidth of 2nm. The temperature of a silicon resonator was estimated to be about 93°C for the tuning range.

Bionics transfers the principles of success of nature into natural science, engineering disciplines and applications. Often generation and detection of different spectral colors play key roles in communication in both, nature and technology. The latter one refers e.g. to dense wavelength division multiplex optical communication systems. This paper shows interesting parallels in tunable spectral light filtering by butterfly wings and by tunable optical filters used in optical communication systems. In both cases light interferes constructively and destructively with nano- and microstructures of appropriate shape, dimensions and materials. In this paper methodology is strongly emphasized. We demonstrate that tailored scaling allows the effectiveness of physical effects to be enhanced in nature and technology. These principles are rigorously applied in micromachined 1.55μm vertical-resonator-based filters, capable of wide, continuous, monotonic and kink-free tuning by a single control parameter. Tuning is achieved by mechanically actuating one or several membranes embedded by air-gaps in a vertical resonator including two ultra-highly reflective DBR mirrors. The layers of mirrors reveal a very strong refractive index contrast. Filters including InP/air-gap DBR's (3.5 periods) using GaInAs sacrificial layers reveal a continuous tuning of >9% of the absolute wavelength. Varying a reverse voltage (U=0 .. -3.2V) between the membranes, a tuning range up to 142nm was obtained due to electrostatic actuation. Appropriate miniaturization is shown to increase the mechanical stability and the effectiveness of spectral tuning by electrostatic actuation since the relative significance of the fundamental physical forces can be shifted considerably by appropriate scaling.

This contribution deals with design, fabrication and test of a micromachined first order Fabry-Perot-Interferometer (FPI) usable as tunable infrared filter in a spectrometer. The approach discussed here minimizes mirror curvature by using relative thick (300 μm Si ) mirror carriers for the fixed and the movable mirror of the FPI. We use thermally grown λ/4 thick SiO₂ for antireflection layer at the mirror back side and for the first low refractive layer followed by a λ/4 thick polycrystalline silicon high refractive layer. Second and third λ/4 layer pairs of SiO₂ and polycrystalline silicon complete the mirrors. The cavity size is electrostically tuned and capacitively detected by a closed loop control.

The National Science Foundation Center for Adaptive Optics (CfAO) is coordinating a program for the development of spatial light modulators suitable for adaptive optics applications based on micro-optoelectromechanical systems (MOEMS) technology. This collaborative program is being conducted by researchers at several partner institutions including the Berkeley Sensor & Actuator Center, Boston Micromachines, Boston University, Lucent Technologies, the Jet Propulsion Laboratory, and Lawrence Livermore National Laboratory. The goal of this program is to produce MEMS spatial light modulators with several thousand actuators that can be used for high-resolution wavefront control applications that would benefit from low device cost, small system size, and low power requirements. The two primary applications targeted by the CfAO are astronomy and vision science. In this paper, we present an overview of the CfAO MEMS development plan along with details of the current program status.

For the correction of the human eye´s higher order aberrations in vision science we developed a new micromirror device with an monolithically integrated active CMOS address matrix providing a fine segmented array of 240 × 200 mirror elements across an active area of 9.8 × 8.0 mm². The micromirrors possess a piston-type architecture for a pure phase shifting capability and are fabricated by means of aluminum surface-micromachining. Using a basic pixel size of 40 × 40 μm² a mechanical stroke of at least 450 nm is obtained at address voltages below 30V, which is suitable for both active matrix addressing and a modulo 2π phase correction in the visible. Furthermore, an active CMOS address matrix similar to a DRAM was developed providing one switching transistor and one storage capacitor for each mirror cell. Those devices were fabricated within a special high voltage CMOS process providing a full analog address capability of up to 30V at an 8 bit resolution defined by the external driving board. Using interferometric surface profile and laser vibrometer measurements we will present latest experimental results of the mirrors’ electromechanical properties. For the first time those micromirror devices now also have been implemented into an ophthalmic diagnosis system for the measurement and correction of the human eye’s wave aberrations. Therefore, first results of the obtained aberration reduction as well as the impact on vision enhancement will be presented.

The design, fabrication, and preliminary test results of a microelectromechanical, micromachined spatial light modulator (μSLM) with complementary metal-oxide semiconductor (CMOS) electronics, for control of optical phase is presented in this paper. An array of 32×32 piston-motion MEMS mirror segments make up the μSLM. Each mirror segment will be capable of altering the phase of reflected light by up to one wavelength for infrared illumination (? = 1.5 μm). The mirror segments are fabricated from metal in a low temperature process allowing for vertical integration of the μSLM with CMOS based, multi-bit, control electronics. The surface of the CMOS is planarized to facilitate μSLM-CMOS integration. The fabrication process and process development results, test results, including frequency response and electromechanical characterization of the (μSLM) actuators, will be presented.

A large-scale, high speed, high resolution, phase-only microelectromechanical system (MEMS) spatial light modulator (SLM) has been fabricated. Using polysilicon thin film technology, the micro mirror array offers significant improvement in SLM speed in comparison to alternative modulator technologies. Pixel opto-electromechanical characterization has been quantified experimentally on large scale arrays of micro mirrors and results are reported.

The application of adaptive optics in astronomy requires increasingly compact deformable optical components with a high density of actuators, able to provide strokes of several micrometers. The main problem of the use of adaptive optics in more mainstream areas is the cost, the size and consequently the weight of the system. This paper presents the design and the results obtained with the deformable mirror under development. The system will have a continuous reflective membrane of 1 cm² driven by 64 closing gap actuators operating in contact. In the following this type of actuators is called “zipping actuators”. Applying 100 V to some 800 μm wide zipping actuators results in an electrostatic force of 100 μN and a mirror displacement of 6 μm. Recent tests of the electric behaviour show linearity between applied tension and resulting displacement as well as a good reproducibility. We also present analysis and results obtained on silicon or polymer (BCB) membranes which have to be attached on the actuator array. A preliminary assembled component made of one actuator sealed to a 5 μm thick polymer 5 × 5 mm² (BCB) membrane has demonstrated the feasibility of deforming such a small membrane by 3 μm, which is very promising.

We are developing membrane mirrors for use in adaptive optics, particularly in astronomy and vision science. We have micro-fabricated membrane mirrors from single crystal silicon using wet chemical etching and reactive ion etching. Membrane size, tension and operating voltage were selected to allow greater deformation of the mirror surface at low operating voltage than previous membrane mirror designs. Mirror devices consist of independently fabricated membrane and electrode array chips that are flip chip bonded together. We have fabricated electrode arrays with 256 and 1024 electrodes, and active diameters ranging from 6-10 mm (comparable to the size of the human pupil). Membrane-electrode hybrids are mounted to ceramic packages, wire bonded, and driven by off chip, D/A electronics. These devices are milestones in the development of an electret membrane mirror.

Adaptive optics systems are used to maintain an optical system at its optimum performance through real time corrections of a wavefront. Deformable mirrors have traditionally been relatively large, expensive devices, suitable for systems such as large telescopes. The objective of the present work is to expand the range of systems that can employ adaptive optics by developing a small, low-cost MEMS deformable mirror. This deformable mirror uses a continuous membrane and has 61 actuators arranged in to approximate a circular pattern. Each actuator has an associated spring suspension, allowing it to push as well as pull on the membrane, producing locally convex or concave curvature. The folded springs are positioned so as to maximize the lateral stability. Maximum actuator displacement is six microns at less than 200 volts. The actuator resonant frequency, is greater than 10 kHz, allowing high-frequency updates of the mirror shape. To operate at high speed, the device must be sealed in a low-pressure environment. Each microactuator uses a vertical comb drive to achieve large travel at a reasonable voltage. The continuous membranes are made of silicon or silicon nitride. Both the actuator and membrane are fabricated with bulk micromachine process technologies. The design targets laser based communication specifications and medical imaging applications.

Large-stroke micromachined deformable mirror technology can boost the imaging performance of an otherwise non-rigid, lower-quality telescope structure. The proposed deformable mirror concept in this paper combines a microfabricated large-stroke piezoelectric actuator with a reflective membrane “transferred” in its entirety from a separate wafer. This process allows the large-stroke actuation of the continuous membrane and can provide the necessary large wavefront correction. The micromachined deformable mirror approach allows mass-production of actuators as well as scalable structures with, high actuator densities. The piezoelectric unimorph actuator design approach delivers large actuator stroke with a highly localized influence function, while maintaining a surface figure of optical quality. Both of these component fabrication techniques are easily scaled to accommodate deformable mirrors with very large areas.

This work presents a nodal model for continuous face sheet deformable mirrors that can be solved quickly on a desktop computer. This network of simple cubic stiffening elements can more accurately simulate deflections resulting from complex loading conditions than a membrane model and is much easier to implement than a non-linear finite element model. The deflections predicted by the model are compared to expected behavior and to FEM results for a simple system. While restoring forces due to pre-stress and deformation-induced stress are fairly accurately modeled, resistance due to bending is only accurately modeled for specialized devices.

A surface-micromachined focusing mirror with variable focal length, which is controlled by adjusting the mirror’s curvature, is fabricated and characterized. The bowl-shaped micromirror, which is fabricated from the micro bilayer circular plate, focuses light beam through thermal actuation of the external heat source. Both the initial and operational curvatures are manipulated by the residual stresses in two layers of the mirror. Improper stresses would lead to the failure of the bowl-shaped structure. We analyze and design geometrical dimensions for simultaneously avoiding the structure failure and increasing the tuning range of the focal length. The interferometer has been used to measure the focal length and the focusing ability. Mirrors with nominal focal lengths approximately 730 μm, and tuning ranges of about 50 microns were demonstrated. The measurement directly through optical approach has also been tried, but requires further investigation, because the laser beam affects the focusing of the micromirror seriously.

We have developed an approach for processing communication signals in the optical domain using a DLP digital mirror array driven by a Digital Signal Processor (DSP). In optical communication systems, modulation rates of 10 GB/s and above are common, hence, direct processing of Dense Wavelength Division Multiplexed (DWDM) optical signals without undergoing Optical to Electrical conversion has become a key requirement for cost effective deployment of dynamic optical networks. This work will discuss primarily applications of Optical Signal Processing (OSP) to coherent DWDM signals. Optical Signal Processing has also found applications in spectroscopy, microscopy, sensing, optical correlation, and testing.

A novelle concept for miniaturized multimode fiber optical switches is presented, which can be applied for the whole spectrum of fiber core diameter and numerical aperture. It is particularly useful for large core high numerical aperture fibers used for applications in illumination systems, sensing and optical spectrometers. Because of relaxed positioning tolerances - compared to singlemode setups - most existing solutions are based on moving fibers or fiber collimators leading to devices with excellent optical parameters. Due to the mechanical properties of the fibers it is difficult to use these switching principles for fibers with large diameter. The system we present is based on fixed fibers, each having a collimating lens. A following imaging system projects the incoming optical beam to a tilting high-reflectivity micromirror placed in the focal plane. The reflected beam travels back through the imaging system targeting an output fiber which is addressed by the angle position of the mirror. Due to the folded optics design both input and output channels are located on the same side of the device. Special emphasis was taken on the chromatic dispersion behaviour of the setup leading to a broad spectral range. We present the optical and mechanical design considerations and experimental results obtained with first realized prototypes of 1×4 and 1×8 style switches for 400μm core diameter multimode fibers.