| 摘要 |
PROBLEM TO BE SOLVED: To time division multiplex two signals without using polarization multiplexing. SOLUTION: Pre-coders 20a, 20b preliminarily encode pieces of data #1, #2 from data input terminals 18a, 18b in accordance with characteristics of Mach-Zehnder type optical intensity modulators 12, 14. A phase adjusting circuit 22 adjusts a phase of output of the pre-coder 20b for time axis multiplexing. Bands of output of the pre-coder 20a and output of the circuit 22 are restricted by LPFs 24a, 24b respectively and impressed in amplifiers 26a, 26b. The amplifiers 26a, 26b amplify inputted signals respectively so that the maximum and minimum values of output voltage of the amplifiers 26a, 26b become equal to driving voltage values to give the adjacent maximum transmissivity to driving voltage of the modulators 12, 14 respectively. The outputs of the amplifiers 26a, 26b are impressed on the optical modulators 12, 14 respectively as driving signals. |
