Compact 1x2 MEMS optical switches with low-actuation voltage

Abstract

In this paper, we report a compact 1x2 MEMS optical switch actuated by less than one voltage. Over past few years, micro-electro-mechanical systems (MEMS) have emerged as a leading candidate for achieving true all-optical multiwavelength network. Due to the inheritance of mechanical vibration in the under damping condition, most MEMS switches might need external control circuit or mechanical stoppers to suppress the undesired jittering of optical signal. To overcome this difficulty, we redesigned a MEMS optical switch monolithically integrated with a vertical micromirror with large surface area. The micromirror is made by the low-cost anisotropic wet etching technique. The size of the micromirror is 500 µm x 1200 µm, which is large enough to accommodate the optical beam diameter of 62 µm from a ball lens fiber. Because the moving direction of the MEMS optical switch is perpendicular to the surface normal of the micromirror, the effect of the mechanical vibration is compensated by the large surface area of the micromirror. In addition, a capacitor of 100 µF is connected in parallel with the MEMS switch to serve as a low pass filter. The switching time can be improved in the 5 ms range. Finally, a calculated driving waveform derived from the square wave is used as the triggering signal, after analyzing the switching performance by Fourier transform function. Our experimental results show the rising time and fall time of the MEMS switch is 3 ms and 3.1 ms, respectively. The optical insertion loss caused by the micromirror is 0.45 dB. The actuation voltage is around 0.3 volt and the switch is actuated by electromagnetic force. The footprint of the packaged device is 18 mm x 12 mm. A low cost, small size and high performance optical switch is experimentally demonstrated.