SWEEP LIGHT FREQUENCY GENERATOR

摘要

PROBLEM TO BE SOLVED: To provide a sweep light frequency generator in which its optical loop circuit is constituted of polarization dependent parts and is capable of outputting a light pulse signal train having stable light intensity while intersecting the linear polarization state of light pulses orthogonally at every circulation. SOLUTION: The polarization state of the light pulses circulating in the optical loop circuit 100 is that of linear polarization which intersects orthogonally at every circulation. Both of optical frequency shifters 5, 6 for shifting the optical frequencies have polarization dependent loss characteristics. The respective optical frequency shifters are connected to a polarization separating element 4 in compliance with the polarization plane of the input light pulses so as to minimize the input loss of the light pulse signal to be inputted. A polarization synthesizing element 8 multiplexes the outputs of the respective optical frequency shifters and returns the polarization state of the light pulses outputted therefrom to the same state as the state at the point of the time when the light pulses are inputted to the polarization separating element 4. As a result, polarization mode dispersion is canceled at every circulation and the ripples in the output light pulse signal train are suppressed.