Phase shift modulation light transmitter

Abstract

Abstract PURPOSE:To obtain a prescribed value of phase modulation wave where the phase shift amount is decided by using a part of output light not modulated from a laser light source as reference light, synthesizing it with a part of the modulated signal light and applying optical self-homodyne detection. CONSTITUTION:Laser output light 2 from a semiconductor laser light source 1 oscillated in the single mode is subjected to 2-phase modulation by a waveguide path of optical modulator 4 via an optical isolator 3 and becomes signal light 5. The signal light 5 becomes transmission signal light 7 by an optical branching circuit 6 and given to an optical transmission line 8 and coupled to the 1st polalized wave face preserving fiber 11 and propagated as a branch light 9. After the monitor light 23 passes through the 2nd optical isolator 24, the result is propagated while being coupled with the 2nd fiber 12. The branched light 9 and the monitor light 23 are synthesized by the synthesis circuit 14, incident on a photodetector 15 and converted into a base band signal 16. The signal 16 is inputted to the peak level detector 17 and a minimum level detector 18 to measure a pulse peak value and the base value, they are processed by a microprocessor 19 to adjust the optical modulator 4.

Inventors

• 👤 Minoru Shikada
• 👤 鹿田　實

Bibliographic Details