With the explosion of Internet and multi-service traffic, telecommunication transport networks today are turning to Wavelength Division Multiplexing. Optical cross-connects (OXCs) allow flexible rerouting of wavelength channels. It has been shown that 2-D free-space beam deflection by nematic liquid crystal gratings provide a good solution for the realization of optical switches in OXCs. Operating in the telecom 1.5 micrometers wavelength region they serve as an active holographic element. Liquid Crystal on Silicon (LCOS) combined with VLSI technologies allow the fabrication of large capacity, low cost and low consumption compact free-space switches. An N X N optical switch can be built by cascading two LCOS-based spatial light modulators (SLMs). The first part of the paper describes a circuit that provides the physical support as well as piloting circuitry for such SLMs. It is capable of piloting beams from a linear array of 8 incoming fibers towards a similar array of 8 outgoing fibers. The electrode command voltages are analog while the external interface as well as on-chip memory is digital. The chip has been implemented in a CMOS 0.5 (mu) process with 600,000 transistors while die size is 320 mm² (80 mm² active area).

Date Published: 26 December 2001
PDF: 11 pages
Proc. SPIE 4435, Wave Optics and VLSI Photonic Devices for Information Processing, (26 December 2001); doi: 10.1117/12.451145

Published in SPIE Proceedings Vol. 4435:
Wave Optics and VLSI Photonic Devices for Information Processing
Pierre Ambs; Fred Richard Beyette Jr.; Fred Richard Beyette Jr., Editor(s)