| Popis: |
In this paper we describe a new class of tunable interferometric MOEMS devices able to perform tunable wavelength selective beam steering. These GEMOEMS (Grating Enhanced Micro Opto Electro Mechanical Systems) devices comprise a diffraction grating etched on top of a selective and tunable vertical interferometric MOEMS filter. The underlying filter reflects the transmitted orders with controllable amplitude and phase so that they interfere with the reflected orders and modulate the diffraction efficiency distribution into these reflected orders. Our first demonstrator is a 1X2 optical switch designed for operation over the C-band (1530-1560 nm). The diffraction efficiency in the reflected orders is controlled by changing the distance from the grating to a Bragg mirror via an electrostatic actuation of the suspended grating membrane. The devices are fabricated using a multiple InP-air-gap MOEMS technology based on the sacrificial etching of an InP / InGaAs stack. The grating is realized using an electron-beam lithography step. The simulated performances on the C-band show low insertion loss (less than 0.3dB), low ripple (0.15dB), reasonable cross-talk (-15dB), and an estimated switching time around 10μs. These characteristics make such an optical switch a solid contender of a rotating mirror, with the advantage of a much faster response. In this presentation, we introduce the general physical principles of GEMOEMS and describe the design, simulation, fabrication and preliminary experimental results for a simplified 1x2 optical switch. We also propose other prospective devices such as add-drop filters. |
