OPTICAL AMPLIFIER CONTROLLER HAVING ADJUSTABLE SLEW-RATE LIMITER

A method and apparatus is provided for controlling the optical output power from an optical amplifier arrangement. The arrangement includes a rare-earth doped fiber (1) for imparting gain to an optical input signal (4) propagating therethrough, a pump source (2) for supplying pump power to the rare-earth doped fiber (1), and a tap (5) for receiving a portion of the output power generated by the rare-earth doped fiber (1) and converting it to a control signal. A controller (10) is also provided for receiving the control signal and generating a bias current in response thereto for driving the pump source (2). The method begins by receiving an optical input signal that is being amplitude modulated at a prescribed frequency. The slew-rate of the controller (10) is adjusted so that the bias current drives the pump source to generate pump (2) power that cannot vary at a rate greater than a slew-rate limit established by the controller (10). In this way resonance between the input signal and the frequency of the feedback control loop can be avoided. © KIPO & WIPO 2007