High-extinction ratio and low-loss silica-based 8/spl times/8 strictly nonblocking thermooptic matrix switch

This paper describes a silica-based 8/spl times/8 strictly nonblocking thermooptic matrix switch with a high-extinction ratio and low loss. We realized this matrix switch by using a configuration which combines a double Mach-Zehnder interferometer (MZI) switching unit and an N/spl times/N matrix arrangement thus reducing the total waveguide length. The 8/spl times/8 matrix switch was fabricated on a 4-in wafer using planar lightwave circuit technology. We obtained an average extinction ratio of 60.3 dB and an average insertion loss of 5.1 dB. The operating wavelength bandwidth completely covers the gain band of practical erbium-doped fiber amplifiers (EDFAs).