A method for sweeping frequency ranges of over 130GHz within a tuning range of 30nm, without mode hopping, has been realized. The optical frequency is swept with a fine translation-rotation grating drive which uses a new, simplified operation method and a thermally controlled semiconductor laser system.

Jitter accumulation is examined in a 122 optical regenerator line of a 4758 km submarine cable. Accumulated jitter at the 122nd regenerator is less than 3.6rms at a line bit rate 445.837 Mb/s using a 2231 pseudorandom signal. With a 2151 PN signal, obtained jitter saturates at about the 60th regenerator. These results agree with theoretical jitter accumulation estimations for PN pattern signals.