METHOD FOR ADJUSTING CHARACTERISTIC OF MULTISTAGE MACH-ZEHNDER OPTICAL CIRCUIT AND MULTISTAGE MACH-ZEHNDER OPTICAL CIRCUIT

摘要

PROBLEM TO BE SOLVED: To provide a method for exactly and simply adjusting the characteristic of multistage Mach-Zehnder optical circuit.

SOLUTION: Low coherent light is made incident and the relation between the drive amount and the real phase shift amount of a phase control part of each symmetric Mach-Zehnder interferometer is successively measured with respect to all symmetric Mach-Zehnder interferometers (S1). Wavelength-variable coherent light is made incident and the intensity coupling ratio of the two symmetric Mach-Zehnder interferometers which are arranged adjacently to an asymmetric Mach-Zehnder interferometer as the object to be measured is set to be 50%, the intensity coupling ratio of the symmetric Mach-Zehnder interferometers other than described above is set to be 0% or 100% and, thereafter, the relation between the drive amount and the real phase shift amount of a phase control part in asymmetric Mach-Zehnder interferometer is successively measured with respect to all asymmetric Mach-Zehnder interferometers (S2). The optical characteristic desired for the whole optical circuit can be obtained in such a manner that the phase control amount of each interferometer coincides with the phase shift amount of the desirable optical output (S3).

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