Beam steering optical switches using LCOS: The 'ROSES' demonstrator

Abstract

The design, assembly and performance of a prototype 1/spl times/8 reconfigurable holographic free-space switch is described. Central to the switch fabric is a ferroelectric liquid crystal (FLC) on silicon spatial light modulator (SLM) deposited with a 540/spl times/1 array of planar mirror strips. The input and output ports to the switch are fabricated as a linear array of silica planar waveguides connected to single-mode fibres. The waveguide array and the single Fourier transform lens for the holographic replay system are housed in an optomechanical mount to provide stability. The switch operates at 1.55 /spl mu/m wavelength and has a designed optical bandwidth of >60 nm. The primary aim of the ROSES project was to develop the technology required to implement a large scale N/spl times/N holographic routing switch. As a first step towards this goal, a prototype polarisation independent linear 1/spl times/8 fibre optic routing switch was developed. The switch was designed to take a signal beam from a single mode fibre, and dynamically route it to one of eight single-mode output fibres. The switch consists of four main components: a waveguide array providing spatial fan-in to and from the input and output fibres, a Fourier lens, a reflective binary-phase FLC silicon backplane SLM that acts as a beam steering element, and a custom interface board.