OPTICAL EXTERNAL MODULATOR FOR OPTICAL TELECOMMUNICATIONS

摘要

There is provided an optical external modulator that can modulate the polarization of incident light without regulating the state of polarization of the light entering the modulator. Such a modulator can be suitably incorporated into an optical telecommunications system. An optical external modulator according to the invention comprises a substrate 1, an optical transmission line 7, a polarization modulating section 11 and a phase changing section 8 for changing the state of polarization of the light passing through the optical transmission line by applying stress to the optical transmission line 7 as a function of a modulation signal given to the modulator such that the phase difference between the X-component and the Y-component of the light being propagated through the optical transmission line 7 is shifted by (2m-1)*.pi./2 (m is a positive integer).