An optical channel monitoring system using time-division multiplexed tone-frequency modulation for optical wavelength division multiplexing systems

摘要

PURPOSE: An optical channel monitor system using a time-division tone frequency modulating method in an optical wave-length division system is provided to monitor a channel without an interference or distortion between tone frequencies even though channels are increased in number by assigning only one tone frequency to one node, and recognize a source of a channel by using different tone frequencies between nodes. CONSTITUTION: Laser diode(3.2) of each block(3.1) is modulated as a signal sum of a 2.5Gbps data(3.3) and a tone signal(3.4) of a frequency f1. The tone signal is applied to the laser diode(3.2) for a certain time period(3.6) by a gate(3.5). A gate control signal(3.6) applied to a block-2 is different from that of a block-1. Each of channels having a modulated tone-frequency for only a certain time period is multiplexed by an optical multiplexer(3.7) and amplified by an optical amplifier(3.8) to be transferred to a destination. If a channel is desired to be monitored, a portion of the multiplexed light is extracted by using a tap coupler(3.9) and transferred to a photodetector(3.10). A monitor circuit(3.11) processes an output of the photodetector(3.10) to obtain information on the channel.