Optical transmitter for reducing impulse noise in a fiber optic link

摘要

The bias current of the semiconductor laser is adjusted in relation to the amplitude of modulation. A signal for transmission is presented at the input (1) then amplified by an amplifier (2) and transmitted to the laser by a coupling capacitor (3). A control photodiode (5) is optically coupled to the laser and an assembly of four resistors (6-9) forming a bridge. A differential amplifier (10) supplied the bias current via an inductance (11) prevents the passage of the modulation signal. A peak detector (12) measures the amplitude of the signal applied to the laser, in order to ultimately control the balance of the bridge and hence the transmission power of the laser.