BER IMPROVEMENT CIRCUIT FOR OPTICAL IN-LINE AMPLIFIER IN OPTICAL TRANSMISSION APPARATUS

摘要

PURPOSE: A circuit for improving a bit error rate is provided to increase an optical receive sensitivity by mounting an external photo diode at a front stage and connecting an APC(Auto Power Control) circuit which is the same APC circuit as mounted at a back stage. CONSTITUTION: A tap coupler is connected to an optical part of a photo diode(PD2) in order to connect an APC(Auto Power Control) circuit to a main path of an optical part of an optical fiber amplifier, and an electric part of the photo diode(PD2) is connected to an optical module control part(101). The APC circuit operates through this connection. At this time, because the APC circuit is the same APC circuit as mounted at a back stage, a circuit for improving a bit error rate removes a drop of a receive sensitivity by SPM(Self Phase Modulation).