Patent ID: 8032020

Claim:
A self-calibrating optical spectrum monitor comprising: a) a tunable optical detector comprising a tunable filter and an optical detector having a signal input that receives optical channel monitoring signals from an optical channel and a control input that receives a control signal that selects a frequency of an optical channel monitoring signal for detection, the tunable optical detector detecting the optical channel monitoring signal selected by the control signal and generating an electrical signal related to a power of the detected optical channel monitoring signal; and b) a processor having an input that is electrically connected to an output of the tunable optical detector and an output that is coupled to the control input of the tunable optical detector, the processor measuring a plurality of differences between selected optical channel monitoring frequencies and their corresponding ITU center frequencies and then generating the control signal at the output in response to the measured differences in frequencies, the control signal correcting for at least one of systematic band offset and systematic band tilt in the optical channel monitoring frequencies at a time that is faster than a rate of frequency drift in the optical spectrum monitor caused by changes in at least one of electrical characteristics of the optical spectrum monitor and filter characteristics of the tunable optical detector resulting from aging effects.