Patent ID: 8660425

Claim:
An optical transmitting device comprising: a detector to detect a transmission rate of a received transmission signal; a transmission method selector to select, from among a plurality of transmission methods, a transmission method for the received transmission signal, based on the transmission rate detected by the detector; a modulation signal generator circuit to generate a modulation signal from the received transmission signal, based on the transmission method selected by the transmission method selector; and an optical modulator to generate a modulated optical signal from the modulation signal generated by the modulation signal generator circuit, wherein when the transmission rate of the received transmission signal is less than or equal to a client accommodation rate of a first transmission method, from among the plurality of transmission methods, to which a first modulation method and a single polarization are applied and when the transmission rate of the received transmission signal is less than or equal to a client accommodation rate of a second transmission method, from among the plurality of transmission methods, to which a second modulation method and a dual polarization are applied, the transmission method selector selects the first transmission method.