Single-Chip WDM Switches and Cross Connect (CSWDM)

Researchers: Chao-Hsi (Josh) Chi

Funding Agency: DARPA

Figure 1: Schematic of the single-chip integrated 1×4 MEMS WSS. WDM signal is demultiplexed and distributed across the output waveguides

The goal of this project is to develop a single-chip integrated 1xN wavelength-selective switch (WSS) for
WDM networks. The Si-based planar lightwave circuits (PLC) and the MEMS micromirrors are monolithically fabricated
on a 1.4×2-cm 2 silicon-on-insulator ( SOI) chip. All optical paths are defined by photolithography and no optical
alignment is necessary. The WSS provides WDM functions including demultiplexing, multiplexing, space division
switching, wavelength blocking, and channel equalization. Multiple 1xN WSS’s can be further cascaded to form an NxN
wavelength-selective cross connect (WSXC).

The schematic of the integrated 1×4 WSS is shown in Fig. 1. The input waveguide carries the WDM signal of 8
wavelength channels, which are demultiplexed by the diffraction grating. Total internal reflection (TIL) is used for the
collimating and the focusing parabolic mirrors. An 8-element micromirror array is integrated at the focal plane of the
focusing mirror for independent switching of the 8 wavelength channels across the output waveguides.