Optical coherent transmitting method

Abstract

Abstract PURPOSE:To perform optical transmission which requires no light carrier extraction, by distributing the light output of a light source which generates a single continuous polarized wave into two, and imposing signal modulation on one component, and, synthesizing with the other so that their planes of polarization are crossed each other at right angles. CONSTITUTION:The output light of the light source 21 is branched in two directions by an optical demoultiplexer 24 and they are inputted to a semiconductor laser 22 and a polarization plane control element 25. The output of the semiconductor laser 22 is modulated by a modulating circuit 23 and polarized on single linear polarization basis in single longitudinal mode. The control element 25 converts the input light so that the plane of polarization crosses that of the output light of the semiconductor laser 22 at right angle 22, and a multiplexer 26 multiplexes the resulting light with the output light of the laser 22. The light signal transmitted through an optical fiber 27 is demultiplexed by a polarized-wave demultiplexer 28 to send the modulated component to an optical multiplexer 29 and the unmodulated component to an optical amplifier 30. The output of the optical amplifier 30 is applied to the optical multiplexer 29 through a polarization control element 33 by energizing a semiconductor laser 31 for local oscillation in single longitudinal mode. Consequently, a photodetecting element 34 performs photodetection and an optical transmission line is constituted without using a carrier extracting circuit.

Inventors

• 👤 Yasutaka Ichihashi
• 👤 市橋　保孝
• 👤 Makoto Washio
• 👤 鷲尾　誠
• 👤 Kazuo Aida
• 👤 一夫 相田
• 👤 Kenji Takemoto
• 👤 竹本　憲治

Bibliographic Details