Gilbert Reyne

Self-aligned vertical mirror and V-grooves applied to an optical-switch: modeling and optimization of bi-stable operation by electromagnetic actuation

Abstract High performance silicon-based, micro-optical switches are being developed for application to optical networks. The mechanical part was fabricated in a one-level mask step by bulk micromachining of (1xa00xa00) monocrystalline silicon with KOH. The resulting structure was assembled with a 100xa0μm-thick Permalloy piece and then, it was associated to a small magnetic circuit for its electromagnetic actuation. In order to avoid power consumption while holding ON and OFF states, a bi-stable operation principle is proposed. The bi-stable behavior is obtained by using a stable mechanical position due to the cantilever stiffness and a second magnetic stable position due to a permanent magnet. Switching operation is provided by electrical currents in windings. The aim of this paper is to present a study on modeling and optimization of this system by means of Finite Element Modelling (FEM) simulations, using ANSYS software. Iterative magneto-mechanical simulations are performed. Optimization of dimensions and material properties is presented.

Self-aligned micromachining process for large-scale, free-space optical cross-connects

A new micromachining process for large-scale optical cross-connects is presented. It satisfies the high-accuracy optical alignment required for free-space optics. A self-aligned batch-process allowing the simultaneous fabrication of vertical mirrors and fiber guides is performed with only one-mask. This process is based on bulk micromachining of [100] silicon. A first demonstration is performed on a 2/spl times/2 elementary cell then, it is extended to the fabrication of larger mirror arrays. Promising performances such as insertion loss lower than 0.5 dB, sub-millisecond switching time (0.3 ms) and reliable operation (more than 20 million cycles) are demonstrated on a bypass switch. An improved fabrication process, leading to an increase of integration density is also presented. It is based on the combination of deep dry-etching and anisotropic wet-etching.

Integration of two degree-of-freedom magnetostrictive actuation and piezoresistive detection: application to a two-dimensional optical scanner

A novel two-dimensional (2-D) optical-scanner device is presented. This device incorporates a highly magnetostrictive thin film with anisotropic properties, so that it can produce 2-D-actuation corresponding to bending and torsion vibrations. The magnetostrictive material is a TbFe-CoFe multilayer film, which has optimized properties for micro-actuators operating at low excitation magnetic fields. The new scanner also integrates an original 2-D piezoresistive detector realized in an easy fabrication process using integrated circuit (IC)-compatible technology. The detectors are able to selectively measure bending and torsional vibrations. This new device enables the synchronization of actuation and sensing for 2-D position control.

Electromagnetic actuation for MOEMS, examples, advantages and drawbacks of MAGMAS

Abstract Electromagnetic actuation is applied to optical electro-mechanical systems (MOEMS) for industrial applications requiring large and long-range forces. Advantages and drawbacks are outlined while downscaling laws are discussed. Technological improvements and new available materials bring the limit between electromagnetism and electrostatic to much smaller dimensions. Remote control and bi-stability are unique characteristics of electromagnetic actuation. The importance of remote control is stressed so as to allow easy tests and optimisation with no technological compatibility problem. These advantages are illustrated on three different optical magnetic micro-actuator and system or electromagnetic MOEMS, developed in LIMMS, a Franco-Japanese research Laboratory based in Tokyo. The first is a resonant 1D magnetic scanner, the second is a magnetic bi-stable matrix array of optical micro-switches and the last is a remarkable application of the properties of thick magnetostrictive thin layers to a 2D scanner.

Application of a multilayered magnetostrictive film to a micromachined 2-D optical scanner

A novel two-dimensional (2-D) optical scanner has been designed, manufactured and characterized. This scanner features a large mirror (8/spl times/6 mm) and is therefore suitable for industrial applications where cheap optical sources and lenses are requested. This scanner uses a multilayer film for its actuation. This film is well known for its high magnetostriction. The mechanical design has been optimized using conventional mechanical considerations as well as finite-element simulations. The device has been characterized in two configurations. Depending on the direction of the applied magnetic field, the magnetostrictive properties of the active film or the electromagnetic force are selectively used. Using this last, total optical deflection angles of 32/spl deg/ and 11/spl deg/ for an applied magnetic field of 0.3 mT are obtained. The ratio of the corresponding resonant frequencies is around 4.5, allowing a nice scanning pattern. Compared to our previous prototype on the same project , the mechanical-magnetic sensitivity has been improved by about a factor 24 when the magnetostriction is used, and by about a factor 75 when the electromagnetic force is used.

Copper microcoil arrays for the actuation of optical matrix microswitches

Copper micro-coil arrays have been designed and realized by electroplating for the actuation of arrays of optical matrix micro-switches. The good operation of the micro-switches needs large force that is well fulfilled by the electromagnetic actuation of copper micro-coils. The electromagnetic behavior of the actuator has been examined using the simulator FLUX2DTM and an optimized configuration of ferromagnetic materials was determined. Arrays of micro-coils with high aspect ratio have been achieved with the use of SU8 resin mould. The diameters of micro-coils range from 0.5 millimeters to 4 millimeters with thickness of about 30 micrometers and few tens of turns. Electric measurements have been done in order to characterize the micro-coils.

A Novel Optical Scanner with Integrated Two-Dimensional Magnetostrictive Actuation and Two-Dimensional Piezoresistive Detection

A novel two-dimensional (2D) optical-scanner device is presented. This device incorporates a highly magnetostrictive thin film with anisotropic properties so that it can produce 2D-actuation corresponding to bending and torsion vibrations [1–2]. The magnetostrictive material is a TbFe/CoFe multilayer film [3–4], which has optimized properties for micro-actuators operating at low excitation magnetic fields. The new scanner also integrates an original 2D piezoresistive detector realized in an easy fabrication process using IC-compatible technology. The detectors are able to selectively measure bending and torsional vibrations. This new device enables the synchronization of actuation and sensing for 2D position control. It could be used in a laser-radar system for obstacle detection in automobiles.

New self-aligned micromachining process for large free-space optical cross-connects

An improved self-aligned micromachining process for large-scale free-space optical cross-connect is presented. It satisfies the high accuracy optical alignment required for such application. This self-aligned batch process allows the simultaneous fabrication of vertical mirrors and fiber guides. It is performed in one level of mask lithography and combines deep RIE and KOH silicon etching.

Electromagnetic remote control and downscaling advantages and examples for MOEMS

Electromagnetic actuation is applied to MOEMS for industrial applications requiring large and long-range forces. Advantages and drawbacks are outlined while down scaling laws are discussed. Technological improvements and new available materials bring to much smaller dimensions, the limit between Electromagnetism and Electrostatics. Remote control and bi-stability are unique characteristics of electromagnetic actuation. The importance of remote control is stressed so as to allow easy tests and optimization with no technological compatibility problem. These advantages are illustrated on three different electromagnetic MOEMS, developed in LIMMS, a Franco-Japanese research Laboratory based in Tokyo. The first is a resonant 1D magnetic scanner, the second is a magnetic bi-stable matrix array of optical micro-switches and the last is a remarkable application of the properties of thick Magnetostrictive thin layers to a 2D scanner.