OPTICAL MODULATOR

摘要

PURPOSE:To provide an optical modulator capable of maintaining the always highest state of modulation efficiency by maintaining the specified polarization direction of the light inputted to an external optical modulator having optical modulation efficiency depending on the polarization direction of the light inputted thereto. CONSTITUTION:The input light is separated to two light waves of the polarization directions intersecting orthogonally with each other in a polarized light separating section 102. One thereof is the polarized light (hereafter described as the TM wave) which maximizes the modulation efficiency in the external optical modulator 109 and the other is the polarized light (described as the TE wave) having the polarization direction orthogonal with the TM wave. The polarization direction of the TE wave is rotated 90 deg. in the polarized light rotating section 104 and is then multiplexed with the TM wave in a multiplexing section 107. The multiplexed waves are inputted to the external optical modulator 109. The input light is optically modulated by a modulation signal 111 in the external optical modulator 109 and is outputted.