Design and characterization of a 3D MEMS VOA driven by hybrid electromagnetic and electrothermal actuation mechanisms

Abstract

By using a CMOS compatible process technology, a MEMS variable optical attenuator (VOA) is characterized in terms of actuation mechanisms. A dual-fiber collimator is aligned perpendicularly to the micromirror in a three-dimensional (3D) free space configuration, where the micromirror is mechanically connected with an electromagnetic actuator and two sets of electrothermal actuators. Three types of attenuation schemes based on electromagnetic, electrothermal and hybrid, i.e. combination of electrothermal and electromagnetic, actuations have been explored and studied. Dynamic attenuation ranges of 40 dB have been achieved at 4 V dc , 26 mW and 3 V dc, 20 mW by electromagnetic and electrothermal attenuation schemes respectively. Wavelength-dependent loss has been demonstrated to be less than 0.6 dB at all attenuation states for both attenuation schemes. In the hybrid attenuation scheme, various voltage combinations are made to the electromagnetic and electrothermal actuators. An optical attenuation of approximately 40 dB can be obtained when two volts are applied to both the electromagnetic and electrothermal actuators simultaneously, while the electrical power consumption of the actuators is 17 mW in total. Our unique design of using both electrothermal and electromagnetic actuators simultaneously to achieve attenuation is the first demonstration of such a hybrid-driven CMOS compatible MEMS VOA device.

Modeling and Characterization of an Electrowetting-Based Single-Mode Fiber Variable Optical Attenuator

“…13 = − 2 −1 ( ) (8) where = 0 √ 2 2 − 2 , = 0 √ 2 − 1 2 , = 0 √ 3 2 − 2 , n1, n2, n3 are the refractive indices of the fiber cladding, fiber core, and the external medium respectively, ne is the effective index of the guided mode and 0 = 2 . The effective index of the mode is described by = 0…”

“…Through the 1990s researchers took advantage of microelectro-mechanical systems (MEMS) technologies and applied these to create miniaturized optical fiber VOAs such as moving fiber [1,2], shutter [3,4,5] and mirror types [6,7,8]. Although MEMS VOAs are well-known, these devices can have reliability issues associated with the usage of moving micromechanical mechanisms [9].…”

In-line single-mode fiber variable optical attenuator based on electrically addressable microdroplets

“…Progress towards miniaturisation of VOAs has been facilitated by micro-electro-mechanical system (MEMS) implementations of fiber VOAs, such as moving fibers 2,3 , shutters 4,5,6 and mirror types 7,8,9 , but these devices can have reliability issues associated with the movable micromechanical parts…”

Dielectrically actuated attenuator at 1.55 μm

“…In a fiber-optic switch, the level of input optical power should be controlled so that the output power will not damage or saturate the receiver. To reduce output power, various VOAs based on MEMS [1][2][3][4], liquid crystal (LC) or polymer dispersed liquid crystal (PDLC) [5][6][7][8][9][10][11], electrowetting [12][13][14], dielectrophoretic effect [15], optofluidic [16][17][18][19][20], and other types [21] have been developed. Most of these VOAs work by reflection, deflection, refraction or interference.…”