Monolithic MEMS-based wavelength-selective switches and cross connects

Wavelength-selective switches (WSSs) and wavelength-selective cross connects (WSXCs) enable flexible, intelligent wavelength-division-multiplexed (WDM) networks as well as reduce the operating cost. In a 1xN WSS, the wavelengths from the input port can be independently switched to any of the N output ports. WSXC allows switching of optical signals at wavelength level between N input ports and N output ports. Most of the WSSs and WSXCs reported to date are realized by free-space optical systems with either micro-electro-mechanical-systems (MEMS) or liquid crystal (LC) beamsteering array, or by silica-based planar lightwave circuits with cascaded 2x2 thermal optical switches.;In this dissertation, I present a new approach to monolithically integrate WSS and WSXC on a single chip. Using silicon-on-insulator (SOI) planar lightwave circuits (PLC), optical waveguides, microgratings, curved reflectors, as well as MEMS active switching micromirrors are monolithically fabricated on the same substrate using a one-step etching process. The micromirror array is integrated at the focal plane of the focusing mirror for independent switching of the wavelength channels to the desired output waveguides. We have successfully fabricated a 1x4 WSS for coarse WDM (CWDM) on a 2x1.4-cm2 chip, and achieved a fiber-to-fiber insertion loss of 11.7 dB, and a switching time of 0.5 msec.;The monolithic 4x4 WSXC is realized by integrating four 4x1 WSSs and four 1x4 multi-mode interference (MMI) splitters on the same wafer. No fiber connections or external splitters are required. The 90° waveguide bend and 90° waveguide crossing are employed to minimize insertion loss and crosstalk. The fabricated 4x4 WSXC has a chip area of 3.2x4.6 cm2 and an insertion loss of 24 dB, including a 6-dB splitting loss. The WSXC supports unicast, multicast, and broadcast functions.;The monolithic WSSs can also be realized by integrating the micromirror with arrayed-waveguide gratings (AWGs) on SOI platform. We have demonstrated the key element, a 1x8 optical switch, on hybrid PLC-MEMS platform. The switch is integrated with a microfabricated cylindrical lens, eliminating the need for external bulk lenses. The fabricated 1x8 switch has an insertion loss of 3.9 +/- 0.2 dB, and an extinction ratio greater than 27 dB.