DIRECTLY MODULATED DISTRIBUTED FEEDBACK-LASER DIODE OPTICAL TRANSMITTER APPLYING VESTIGIAL SIDEBAND MODULATION THERETO

摘要

PURPOSE: A directly modulated DFB-LD(Distributed Feedback-Laser Diode) optical transmitter applying a VSB(Vestigial Sideband Modulation) thereto is provided to apply an optical tunable filter having a VSB modulation system to the optical transmitter, thereby reducing bandwidths of an optical signal. CONSTITUTION: An electric signal generator(120) converts an inputted signal into an electric signal. A DFB-LD(140) converts the electric signal into an optical signal. An optical tunable filter(160) differently sets a central wavelength set for filtering the optical signal from a central wavelength of the inputted optical signal, performs a VSB modulation process for the optical signal to reduce bandwidths of the optical signal by degenerating a predetermined band of the optical signal, and improves an extinction ratio by reducing the bandwidths.