Abstract: An optical amplifier control circuit and method controls transients and avoids the problems associated with measuring gain. The input power level is detected and amplified by a transient control setting to provide a desired gain value against which is compared the output power level. This transient control error may be used in conjunction with a constant power error and/or a constant current error such that the lowest of the error values is used to drive the pump laser. Current and power feedback signals and settings are used to derive the error values. Multiple pump lasers per stage may also be controlled and a multi-stage amp having a cascaded structure may be realized using the inventive techniques.