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We have designed a wafer level chip scale package for a bi-stable SOI-MEMS dc switch using a silicon-glass hermetic seal with through the lid feedthroughs. Bonded at 365 °C, 230 V and 250 kg, they pass the fine/gross leak test after thermal cycling and mechanical shock/vibration according to MIL-STD-833, fulfilling the requirements for biomedical applications. The measured shear strength is 114 ± 26 N in correspondence with the theoretically expected 100 N. Ruthenium microcontacts are a factor of 100 more robust than gold microcontacts, being stable over 106 cycles measured in a N2 atmosphere inside the package presented here. Future work will include a more extensive bond quality assessment and continued microcontact reliability measurements.

In this paper, we have designed a bistable microelectromechanical switch for an implantable lead electrode multiplexer application. Fabrication is based on a single mask process. State changes require an 18 V pulse to the actuators consuming only 0.2 nJ energy. The switch does not consume any energy in either the ON or the OFF state. Total chip size including bond pads is approximately 1.5 mm /spl times/ 1.5 mm. The initial contact resistance is below 5 /spl Omega/ with a contact force in the order of 10 /spl mu/N. The contact resistance stays consistently below 30 /spl Omega/ for the first 40 000 cycles. Breakdown voltage between the two contact members in OFF state is 300 V. We plan to further investigate applicability of this switch in the biomedical field.

This paper reports on a new optical 2/spl times/2 switch for single-mode fibers. The switching principle is based on a vertical micro-mirror which can be moved into the optical path to switch light between two pairs of fibers. The micromirror switch is designed for by-pass applications. When power is turned off the mirror spring back into its rest position and brings the switch into its bar state. This operation is very reliable, since the moving parts do not get into contact. Fabrication is based on the silicon micromachining technology, which allows to integrate the switching mirror, its electrostatic actuator and the alignment grooves for the fibers on the same chip. The mechanical switching principle brings with it a number of optical advantages such as a high crosstalk attenuation above 50 dB and wavelength and polarization insensitivity. At a wavelength of 1310 nm a minimum insertion loss of 0.6 dB was measured in the bar state, i.e. when the mirror is out of the optical path. In the cross state the light is reflected on the gold coated micro-mirror which has a reflectivity of about 80%. The insertion loss of the bar state was thus higher and a minimum value of 1.6 dB could be obtained. The switching time was well below 1 ms.

In this paper, we report on a passive duplexer based on reflective modulation for single-mode fibers. The component integrates a silicon micromechanical modulator and a photoreceiver in a hybrid assembly. Fabricated by the silicon micromachining technology reflective modulators allow a considerable cost reduction of single mode fiber-optic links as compared to systems operating with active light sources at both link terminals. The micromechanical modulator is characterized by a low insertion loss of less than 3 dB and polarization insensitivity. The ON-OFF ratio is typically 9 dB over a wavelength range from 1260 to 1360 nm. The operation frequency is limited by the mechanical movement of the modulator membrane to 1.3-2 MHz. We report on the characterization of fully packaged duplexer components.

Advanced deep reactive ion etching (ADRIE) is a new tool for the fabrication of bulk micromachined devices. Different sensors and actuators which use ADRIE alone or combined with other technologies such as surface micromachining of silicon are presented here. These examples demonstrate the potential and the design freedom of this tool, allowing a large number of different shapes to be patterned and new smart devices to be realized.

The REMO (REflective MOdulator) component is a micromechanical light modulator fabricated by polysilicon surface micromachining. During operation the maximum tensile stress is 130 MPa and the maximum homogeneous electric field is 60 V μm −1 . The effects of these high operation stresses in combination with humid air have been studied. In dry air the mechanical properties of polysilicon meet the requirements for a highly reliable modulator, i.e., the fracture strength is well above the operation stress and slow crack growth is not expected to occur. In dry air no change of the mechanical or the electrical properties can be observed. The combination of cyclic mechanical stress, high electric field and humid air can lead to membrane rupture. On specimens where the stress cycling is stopped before rupture, an increase of the resonance frequency and a permanent electrical polarization of the air-gap capacitor can be observed. This is explained by the formation of a surface oxide. The oxide stiffens the membrane, which results in an increase of the resonance frequency. Trapped charges in the oxide lead to a permanent polarization of the air-gap capacitor.

We report on vertical mirrors fabricated by deep reactive ion etching of silicon. The mirror height is 75 /spl mu/m, covering the fiber core of a single-mode fiber when the latter is placed into a groove of equal depth and etched simultaneously with the mirror. To obtain a uniform etch depth, etching is stopped on a buried oxide layer. Using the buried oxide as a sacrificial layer allows to fabricate mirrors with suspension and actuation structures as well as fiber-alignment grooves in one and the same processing step. A minimal mirror thickness of 2.3 /spl mu/m was achieved, resulting in an aspect ratio higher than 30. The verticality was better than 89.3/spl deg/. In the upper part of the mirror a surface roughness below 40 nm rms was obtained. At a wavelength of 1300 nm the reflectivity of the aluminum-coated mirrors was measured to be higher than 76%. Using a reactive ion etched mirror we have fabricated an optical fiber switch with electrostatic actuation. The coupling loss in the bar state of two packaged prototypes was between 0.6 and 1.7 dB and between 1.4 and 3.4 dB in the cross state. The switching time is below 0.2 ms.

Note: 152 Reference SAMLAB-ARTICLE-1996-008 Record created on 2009-05-12, modified on 2016-08-08

Graded-Index (GRIN) lenses with a diameter of 125 μm are presented. This diameter enables the assembly of the GRIN lenses onto an optical micro-system using the same passive alignment grooves as used for the light carrying optical fibers. In contrast to refractive lenses, GRIN lenses have flat endfaces and the focal distance of a GRIN lens is defined by its length. Therefore, GRIN lenses can be diced from a selected multimode optical fiber with a regular wafer dicing machine. The effects of the resulting surface roughness are reduced by immersing the optical parts into index matching oil, which can not be applied for refractive lenses. This has a further advantage since an anti-reflective coating becomes dispensable. The coupling efficiency of a collimator set-up using the GRIN lenses is studied using paraxial ray calculations. The calculated minimal coupling losses of less than 0.3 dB are in excellent agreement with the measured results. Losses smaller than 2 dB over a coupling length of 2 mm have been measured. © 2006 Optical Society of America.

We present a miniaturized Fourier transform spectrometer (FTS) based on optical microelectromechanical system technology. The FTS is a Michelson interferometer with one scanning mirror. A new type of electrostatic comb drive actuator moves the mirror. We have measured a nonlinearity of the driving system of +/-0.5 mum for a displacement of 38.5 mum . A method is presented to correct the spectrum to get rid of the nonlinearity. The driving reproducibility is +/-25 nm. The measured resolution of the spectrometer after the phase correction is 6 nm at a wavelength of 633 nm.

The design, simulation, fabrication and characterization of micro-GRIN lenses with a diameter of 125 mum is presented. GRIN rods having the same diameter as optical fibers can be passively aligned using U-grooves and microfabricated springs

In this paper a Fabry-Perot modulator fabricated by surface micromachining is presented. The modulator is optimized for a wavelength of 1.3 /spl mu/m and intended for fiber-in-the- loop applications. It consists of a double-supported polysilicon beam separated from an underlying polysilicon electrode by an air gap. The two polysilicon electrodes form the mirrors of the Fabry-Perot cavity. By electrostatic actuation the optical path between the mirrors can be reduced, which results in modulation of the reflectivity. Characterization of the modulator shows a maximum on-off ratio of 9 dB. The observed modulator behaviour indicates a maximum modulation rate of 2.8 Mbit/s.

The REMO (REflective MOdulator) component is a micromechanical light modulator fabricated by polysilicon surface micromachining. Its operation principle is based on a Fabry-Perot consisting of two polysilicon mirrors. In the present paper a systematic study of the effects of high operation stresses in combination with humid air is presented. Slow crack growth is evaluated by visual inspection of precracked structures. Electrical and mechanical drift phenomena are characterized by recording the resonance frequency in vacuum after continuous operation during several weeks.

We report on a 4x4 optical matrix switch for telecom application. It consists of a 4x4 array of vertical mirrors that have the same pitch as the fibers of commercially available fiber ribbons (250 μm). This compact design enables a parallel assembly to optical components, which simplifies the time consuming and costly process for switches with larger pitch. Additionally, a small pitch leads to a short optical coupling length, which facilitates the integration of a suitable collimation system. However there are physical limitations for optical MEMS in conjunction with assembled micro-optics. The optical beam exiting a collimator diverges, the divergence angle is indirectly proportional to the beam waist and the coupling length increases quadratically. Our calculations show that for a pitch of 250 µm a mirror height of 100 μm is optimal. The mirrors are monolithically etched onto a platform etched during a previous step. No assembly of the mirrors to the actuators is needed. Alignment structures for the optical components are etched during the same step as the mirrors, which lead to self aligned structures. The platform is supported by 150 μm long torsion beams with sub-micron diameter. The electrostatic actuation voltage is given by a separate chip. The mirror moves out of the optical path when the platform is actuated and goes to the switching state if no voltage is applied. The first prototypes have been actuated at 200 V, which agrees with a CoventorWare simulation used for designing the device. Light was successfully switched with a 4x4 OXC. An 8x8 OXC is shown and electrostatically characterized.

We have designed a bi-stable micro electro mechanical switch for an implantable lead electrode multiplexer application. It is easy to fabricate using only one mask. Applying an 18 V pulse to the actuators induces state changes. Total size of the structure is approximately 1.5 mm/spl times/1.5 mm. The contact resistance stays consistently below 30 Ohm for the first 40000 cycles.

A novel design of a process-insensitive latchable 2 /spl times/ 2 optical cross connector for single- and multimode optical MEMS fiber switches is proposed. This design utilizes suspension beams with integrated springs to provide stable positioning and process independence. The ANSYS simulation of the required force versus the displacement shows that the latching force is only 27 /spl mu/N, and the return force is only 6 /spl mu/N.

Micro-optical and micro-electro-mechanical technologies are merging to create a new and broader class of micro-opto-electro-mechanical (MOEM) devices. The goal of this paper is to study the functionality of a micro-mirror in a switchable opto-mechanical system. For that purpose, we have built a compact pulsed fiber laser with a torsional micro-mirror as switching element. The fiber laser is based on a 120 mm long Nd/sup 3+/ doped fiber. The cavity consists of a micro-mirror and a Bragg grating. The torsional micro-mirrors (50 /spl mu/m/spl times/70 /spl mu/m) are fabricated by polysilicon surface micro-machining. The fiber laser is spliced on a wavelength division multiplexing (WDM) coupler, allowing one to use the Bragg grating as output reflector, while pumping through it. With this configuration, we measured the laser threshold (3 mW) and the slope efficiency (19 %).

We present a fully packaged duplexer implementing a reflective Fabry-Perot modulator realised by silicon surface micromachining. The device demonstrates excellent performance for bit rates up to 2.8 Mbit/s. Relaxed positioning tolerances, a fiber to fiber loss below 3 dB, an extinction ratio better than 12 dB, and the potential for low cost fabrication make this device very attractive for use in economical optical links.

We discuss three MEMS based components for fiber optic communication: a reflective modulator, a 2/spl times/2 switch and a 4 channel variable attenuator. All devices take advantage of the silicon micromachining technology not only for their functionality but also to allow self aligned positioning of the single mode fibers.

We have reported on two MEMS based components for fiber optic communication: a reflective modulator and a fiber optic switch. Both devices take advantage of the silicon micromechanics technology not only for their functionality but also to allow self-aligned positioning of the single mode fibers. Therefore they have the potential of low fabrication costs and can be produced in large quantities.

We report on vertical mirrors fabricated by deep reactive ion etching of silicon. In view of their application in fiber optical switches the mirror height is 75 /spl mu/m. So the mirror covers well the fiber core of a single mode fiber, when the fiber is placed in a groove of the same depth and etched at the same time as the mirror. A minimal mirror thickness of 2.3 /spl mu/m was achieved, resulting in an aspect ratio over thirty. The verticality was better than 89.3/spl deg/. The surface roughness of the etched surface is 36 nm rms. For an increased reflectivity the silicon mirrors are coated with aluminium. Their reflectivity was measured to be 76%. To obtain an uniform etch depth, etching is stopped on a buried oxide layer. This allows to integrate at the same time mirrors with suspension and actuation structures as well as fiber-alignment grooves in one processing step. Using this technology we have fabricated a fiber optical switch with promising performance: The coupling loss in the OFF position is 2.5 dB and 4 dB in the ON position. The switching time is below 0.2 ms.

We propose a variety of miniaturized microelectromechanical (MEMS) spectrometers. Emphasis is put on the development of a Fourier transform spectrometer based on a Michelson interferometer. A new design of the existing chip has been realized in order to integrate an input fiber, a collimating system as well as a beam splitting plate. This new design allows to carry out spectroscopy with white light. In fact, since white light has a smaller length of coherence, the phase difference zero is extremely important to be well set, i.e. the optical path in each branch of the interferometer has to be equal. Finally, we present two other designs of spectrometers: a lamellar grating spectrometer and a Hadamard transform spectrometer.

We present the development of a 4×4 matrix of optical switches based on silicon microfabricated switches and integrated waveguides. The device consists of two chips connected together by flip-chip bonding. The first chip has 16 latched silicon switches with micro-mirrors, while the second one contains the integrated waveguides and ensures the electrical connection of the 16 switches. The incorporation of integrated waveguides, patterned using a SU-8 mask and deep reactive ion etching, in our switch devices allows both the size and the packaging complexity to be reduced, and a technology for higher order matrices to be developed.

We present the design and characterization of a new 4 X 4 switch based on the previously developed 2 X 2 fiber switch. The switching principle uses plasma etched vertical mirrors that can be moved in and out of two pairs of optical fibers with the integrated electrostatic actuator. The 4 X 4 switch is built by connecting 16 individual 2 X 2 switches in a common package (100 X 50 X 35 mm). Instead of integrating the 16 switch elements on the same chip, we preferred assembling the switches by fusion splicing. The insertion loss is less than 1.8 dB for each state.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Optical MEMS is a challenging new field that combines micro- optics with micro-mechanics in order to build compact systems. In this paper we present a miniaturized Fourier transform spectrometer (FTS) fabricated on silicon. The FTS is a Michelson interferometer with one scanning mirror. The motion of the mirror is carried out by a new type of electrostatic comb drive actuator. The mirror is designed to be linear with respect to the applied voltage. Experimentally, we have measured a mirror displacement of 38.5 micrometer corresponding to a maximum optical path difference of 77 micrometer. The applied voltage was plus or minus 10 V and the non-linearity of the driving system is plus or minus 0.25 micrometer. A method is presented to correct the spectrum in order to get rid of the non-linearity. The measured resolution of the spectrometer after the phase correction is 16 nm at a wavelength of 633 nm.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In this paper we present a miniaturized Fourier Transform spectrometer based on a Michelson interferometer with a scanning mirror. The motion of the mirror is carried out by a new type of electrostatic comb drive actuator. The displacement of the mirror is linear with the applied voltage. Experimental results are presented.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Two different types of micromirrors are integrated with a fiber laser to modulate the cavity Q-factor. Both systems operate at frequencies up to 60 kHz and generate a pulse peak power 100 times higher than the continuous emission. We simulate the emitted pulses and find a good agreement with the measured value for the period of relaxation oscillations. The simulations also show the necessity of a shorter rise time of the Q-factor modulation to achieve one single giant and narrow Q-switched pulse.

This paper reports on the fabrication and experimental results of a reed relay for end-course detection application. The end-course is detected by approaching an external magnet near the device. Nickel material has been chosen for the realisation of the device because of its good magnetic properties and its ability to be electrodeposited. The fabrication process requires a single photolithography step. The relay has been fabricated using a 55 /spl mu/m thick positive resist photopatterning process developed in our laboratory. Electrical, static and dynamic characterisations have been performed. The final chip dimensions are 3 mm long, 1 mm wide and 0.4 mm thick.

In this letter, we describe a variable optical attenuator for single mode fibers. As for its counterparts based on conventional mechanics the micromechanical attenuator operates by moving an obstructing element in the optical beam in order to adjust the light damping. The device is fabricated using the silicon micromachining technology. This allows one to integrate the electrostatic actuator together with the fiber alignment grooves and the obstructing element. With this design, an insertion loss below 1.5 dB was achieved. The response time was below 5 ms and no hysteresis was measured. The maximum attenuation was -57 dB. Backreflection attenuation was below -37 dB.

Future space exploration will emphasize on cost effectiveness and highly focused mission objectives. Missions costs are directly proportional to its total weight, thus, the trend will be to replace bulky and heavy components of space carriers, communication and navigation platforms and of scientific payloads. MEMS devices are ideally suited to replace several of these components in the future, first by substituting larger and heavier components (e.g. a gyroscope), then by replacing entire subsystems (e.g., inertial measurement unit), and finally by enabling the microfabrication of highly integrated picosats. This progressive approach will also enable new mission scenarios and more detailed investigations of the space environment and of planetary surfaces. Very small satellites (1 to 100 kg) stand to benefit the most from MEMS technologies because reaching the desired performance levels is only possible using a highly integrated approach. The small satellites are typically used for science or technology demonstration missions, with much higher risk tolerance than multi-ton telecommunication satellites. In addition, the ability to mass produce MEMS components opens a new approach to space exploration in the future by sending constellations of nano and picosatellites into space. Examples of such miniaturization and successful use of MEMS for space and planetary missions are described in this paper.

The continuous progress in micro- and nano-system technologies has allowed the successful development of many innovative products in process control, environmental monitoring, healthcare, automotive and aerospace as well as information processing systems. In this paper on overview will be given of current progress in micro- and nanofabrication process technologies, such as deep reactive ion etching, micro-electro discharge machining, thick photoresistant processing and plating. The availibility of these micro- and nanofabrication processes will be illustrated with examples of new generations of silicon-based sensors, actuators and Microsystems with a particular emphasis on real applications of these components and systems.

After microelectromechanical systems (MEMS) devices have been well established, components of higher complexity are now developed. Particularly, the combination with optical components has been very successful and have led to optical MEMS. The technology of choice for us is the silicon-on-insulator (SOI) technology, which has also been successfully used by other groups. The applications presented here give an overview over what is possible with this technology. In particular, we demonstrate four completely different devices: (a) a 2 /spl times/ 2 optical cross connector (OXC)with an insertion loss of about 0.4 dB at a switching time of 500 /spl mu/s and its extension to a 4 /spl times/ 4 OXC, (b) a variable optical attenuators (VOA), which has an attenuation range of more than 50 dB (c) a Fourier transform spectrometer (FTS) with a spectral resolution of 6 nm in the visible, and (d) an accelerometer with optical readout that achieves a linear dynamic range of 40 dB over /spl plusmn/6 g. Except for the FTS, all the applications utilized optical fibers, which are held and self-aligned within the MEMS component by U-grooves and small leaf springs. All devices show high reliability and a very low power consumption.

Microelectromechanical systems (MEMS) combined with optical components add optical functionality to the devices and lead to the terms OMEMS and MOEMS. The underlying technology of the presented devices is the silicon-on-insulator (SOI) based batch fabrication, which delivers small, reliable and lasting devices for commercial applications. Another different microfabrication process yields optical near-field sensors with an optical resolution of 32 nm.