Development of fiber-optic depolarizer and its application to measurement systems for polarization-insensitive operation of silica-waveguide matrix switches

This paper describes an automatic system that measures the bias and switching currents of all the switch elements in the polarization-insensitive operation of silica-waveguide 8×8 matrix switches. A new type of depolarizer that can be used for coherent laser sources was compactly packaged with an excess loss of 6 dB. The packaged depolarizer was coupled to an automatic measurement system that was achieved mainly by using two 64-channel power supplies that drive all the heaters of a matrix switch via a computer. By using a DFB laser source at 1305 nm, whose output was unpolarized with the depolarizer, all the switch elements could be adjusted so that they were polarization insensitive within 0.3 dB to any polarization state. About 2 hours were required to complete the measurement for one matrix switch