InP-based optical waveguide MEMS switches with evanescent coupling mechanism

Abstract

An optical waveguide MEMS switch fabricated on an indium phosphide (InP) substrate for operation at 1550 nm wavelength is presented. Compared to other MEMS optical switches, which typically use relatively large mirrors or long end-coupled waveguides, our device uses a parallel switching mechanism. The device utilizes evanescent coupling between two closely-spaced waveguides fabricated side by side. Coupling is controlled by changing the gap and the coupling length between the two waveguides via electrostatic pull-in. This enables both optical switching and variable optical coupling at voltages below 10 V. Channel isolation as high as 47 dB and coupling efficiencies of up to 66% were obtained with switching losses of less than 0.5 dB. We also demonstrate voltage-controlled variable optical coupling over a 17.4 dB dynamic range. The devices are compact with 2 m 2 m core cross section and active area as small as 500 m 5 m. Due to the small travel range of the waveguides, fast operation is obtained with switching times as short as 4 s. Future devices can be scaled down to less than 1 m 1 m waveguide cross-sectional area and device length less than 100 m without significant change in device design.[1372]Index Terms-Directional coupler, indium phosphide (InP), integrated waveguides, optical MEMS switches.

Design of dual-core optical fibers with NEMS functionality

“…Our system is thus the fiber equivalent of chip-based optical MEMS switches based on two evanescently coupled waveguides as demonstrated recently for example in silicon [12] and InP [13]. Comb actuators are usually used for moving sub-micron sized guiding beams and waveguides on chips [14].…”

“…Comb actuators are usually used for moving sub-micron sized guiding beams and waveguides on chips [14]. However, other methods have been recently introduced, including electrostatic actuation by means of a voltage applied directly to the waveguides [13] or by placing them in a non-uniform electric field created by nearby electrodes [15]. We demonstrate that the latter method gives a direct way to control light propagation in the dual-core fiber, leading to NEMS-type functionality in the system.…”

Single and multiple optical switches that use freestanding silicon nanowire waveguide couplers

“…13,15 A coupler switch using InP waveguides was operated by applying electrostatic forces between the freestanding waveguides. 13 In the case of a parallel-electrode actuator, a coupler gap smaller than two-thirds of the initial gap is not consistently controllable due to force instability. Using an in-plane comb-drive actuator, stable low-voltage operation has been realized for silicon waveguides.…”

“…7 Due to the very low power consumption associated with capacitive operation, this technology suits the large-scale integration and reduced energy consumption requirements of telecommunication systems. [8][9][10][11][12][13][14][15][16] Among these waveguide circuits, coupler switches have attracted interest due to the use of non-contact low-loss mechanisms.13,15 A coupler switch using InP waveguides was operated by applying electrostatic forces between the freestanding waveguides. 13 In the case of a parallel-electrode actuator, a coupler gap smaller than two-thirds of the initial gap is not consistently controllable due to force instability.…”

Detection of nanomechanical motion by evanescent light wave coupling

“…If the interaction length is sufficient, total and coherent energy transfer can be achieved; therefore this principle can be exploited in the design of optical directional couplers. 13 In Fig. 1͑a͒, the proposed sensing scheme is outlined.…”