| 摘要 |
An in-band tone is superimposed upon a data stream for monitoring purposes, particularly for controlling the biasing of an injection laser (1). The tone is generated using a phase-locked oscillator (4) so that it shall be in phase quadrature with any spectral component of the data stream at that frequency. For injection laser bias control purposes a proportion of the light of the laser is intercepted by a monitor photodiode (5) and fed to a phase sensitive detector (11) supplied with a reference signal from the phase-locked oscillator, to provide a bias current feedback control signal. <IMAGE> |
