Patent ID: 8897657

Claim:
An apparatus for stabilizing power to an optical multimode receiver comprising: a first multimode variable optical attenuator operatively connected to the receiver; a second multimode variable optical attenuator operatively connected in series to the first multimode variable optical attenuator; an output detector for receiving an output of the second multimode variable optical attenuator; an optical switch operatively connected between the second multimode variable optical attenuator and the receiver, and a controller operatively connected to the first and second multimode variable optical attenuators, the output detector and the optical switch, wherein the controller is configured to: characterize a curve of attenuation versus voltage in at least one of the first and second multimode variable optical attenuators over a range of temperatures; curve fit the attenuation versus voltage to temperature; process the curve fitted attenuation versus voltage to temperature; output a value using a proportional-integrate-differential algorithm; scale a plurality of parameters to allow only integer operations; calculate a desired attenuator voltage using the outputted value to control at least one of the first and second multimode variable optical attenuators; and control the attenuator voltage based on the desired attenuator voltage and to control the optical switch to isolate the receiver from received optical power responsive to the received optical power being below a threshold value.