OPTICAL FILTER

摘要

PROBLEM TO BE SOLVED: To decrease deterioration in communication quality caused by the modulation component of the light intensity superposed on the optical TDM signals which are optically multiplexed with time by removing the component, and to generate TL pulses in a desired waveform from a pulse light source which can not directly generate TL pulses. SOLUTION: The transmission frequency band is discretely and periodically determined according to the repetition frequency of the input optical pulse train so that only the vertical mode component present in the frequency spectrum caused by the repetition frequency of the light pulses is transmitted but other frequency components as noise except for the vertical mode are removed. Or, the transmission frequency band is discretely and periodically determined according to the repetition frequency of the input optical pulse train and specified transmissivity is determined for each transmission frequency band to generate TL pulses corresponding to the envelope line form of the transmission spectrum.