Patent ID: 8068736

Claim:
A tunable dispersion compensator comprising: a plurality of Mach-Zehnder interferometers cascaded on a planar lightwave circuit (PLC); a tunable coupler connected to between any pair of a plurality of the Mach-Zehnder interferometers; and a waveguide loop mirror connected to a final stage Mach-Zehnder interferometer among a plurality of the Mach-Zehnder interferometers through which an incident light is propagated, wherein a tunable dispersion property is obtained by changing a coupling efficiency of the tunable coupler, the PLC is a silica-based PLC in which a silica-glass optical waveguide is formed on a silicon substrate, the waveguide loop mirror is formed on a same substrate as that of the plurality of the Mach-Zehnder interferometers, the plurality of the Mach-Zehnder interferometers includes five Mach-Zehnder interferometers, each of a plurality of the Mach-Zehnder interferometers includes two waveguides having a predetermined optical path difference, and the optical path difference of the Mach-Zehnder interferometers at a first stage and the final stage is ΔL, and the optical path difference of the other three Mach-Zehnder interferometers is 2ΔL.