Multistate Latching MEMS Variable Optical Attenuator

Abstract

Abstract-A multistate latching variable optical attenuator (VOA) is demonstrated using microelectromechanical systems (MEMS) technology. The mechanism is used to fix the position of a shutter inserted into the optical path between two single-mode fibers. The mechanism and fiber mounts are fabricated in 85 m thick silicon using bonded silicon-on-insulator material, by deep reactive ion etching. The device can be continuously adjusted or latched into a discrete set of attenuation states using a rack-and-tooth mechanism driven by electrothermal shape bimorph actuators. Electromechanical and optical characterization is performed to demonstrate a latching VOA function, with a maximum attenuation of 30 dB. Index Terms-Microelectromechanical systems (MEMS), microoptoelectromechanical systems (MOEMS), variable optical attenuator (VOA).

Modeling and Characterization of a Vernier Latching MEMS Variable Optical Attenuator

“…Such latched microactuator systems have been implemented in chevronlatch [24] and chevron-peg [25] mechanisms. A shutter-based latched VOA driven by electrothermal shape bimorph actuators was described by Syms et al [5] and used an optical lever format in conjunction with a conventional rack-andtooth mechanism yielding a discrete set of attenuation states over a 30 dB range through 1 μm incremental steps of the shutter.…”

Mechanical stability of a latching MEMS variable optical attenuator

“…A shutter insertion MEMS VOA with elastic clamps to allow fixing of the attenuation has also been described [10]. Recently, we have demonstrated a latching MEMS VOA with a rack-andtooth mechanism [11]. This approach has the advantage of very stable fixing, but the disadvantage of limited tooth resolution.…”

“…This approach has the advantage of very stable fixing, but the disadvantage of limited tooth resolution. In [11], a mechanical amplifier was used to improve the resolution. A similar principle was used in a two-stage VOA, which had a compound mechanism for coarse and fine control of the fixed attenuation state [12].…”

“…In this paper, we explore these issues by performing a range of electrical, mechanical and optical tests on the latching VOA described previously in [11] to determine its sensitivity to vibration. Since this device contains a mechanical lever to magnify resolution, considerable sensitivity to inertial loading might be expected.…”

“…Fig. 1 shows the latching VOA in [11]. Here, an elastic mechanism is used to insert an angled shutter into a gap between two coaxial single-mode optical fibers, located on the substrate by alignment springs.…”