Abstract
Recently, the delivery of frequency standards using optical combs through optical fiber networks has become an important subject. When we transmit optical combs through an optical fiber network, it is very important to investigate the distortion in the power spectrum of the longitudinal modes that occurs during the transmission. In this paper, we describe the spectrum deformation of the longitudinal mode that occurs during long-haul transmission through a dispersion-shifted fiber, when we use a 10 GHz mode-locked fiber laser with a linewidth as narrow as 1 kHz as the signal source. We found that the deformation of the longitudinal mode power spectrum occurs mainly at the tail of the spectrum, and the linewidth broadening increases in proportion to the transmission distance. The main reason for the linewidth broadening was the phase fluctuation of the optical fiber caused by temperature fluctuation.
