MODULATOR IN OPTICAL TRANSMISSION SYSTEM

摘要

PURPOSE: To raise the total power density of an optical signal which can be charged to an optical fiber by simultaneously performing amplitude modulation and phase modulation of a light beam by a means, which generates a modulation signal for amplitude modulation of the light beam, and a means which generates a modulation signal for phase modulation of the light beam. CONSTITUTION: An external modulator 16 receives an optical signal 12 from a laser 10 through an input fiber 15. The eternal modulator 16 has two separate waveguides which can be independently controlled by a controller 24. The optical signal from the laser 10 is connected to two waveguides at the entrance of the modulator 16. The controller 24 receives an information signal from a data source 22. A modulation signal from the controller 24 and the a phase modulation signal from a signal source 25 control characteristics of waveguides A and B of the external modulator 16 through input ports 17 and 18 respectively. Thus, a data signal is simultaneously subjected to amplitude modulation and phase modulation.