Patent ID: 7254327

Claim:
An apparatus to monitor performance of an optical network, comprising: at least one probe signal generator configured to generate a probe signal, wherein said at least one probe signal generator is a tunable laser such that a frequency of the probe signal is tunable; at least one modulation signal generator optically or electrically connected to said at least one probe signal generator, said at least one modulation signal generator configured generate a modulation signal at a predetermined modulation frequency, wherein the probe signal generated by said probe signal generator is modulated based on the modulation signal; an ingress switch including at least one input and a plurality of outputs, wherein said at least one input of said ingress switch is optically connected to said at least one probe signal generator and said plurality of outputs are optically connected to a plurality of inputs of the optical network, said ingress switch being configured to selectively direct the probe signal to at least one of the plurality of inputs of the optical network; an egress switch including a plurality of inputs and at least one output, wherein said plurality of inputs of said egress switch are optically connected to a plurality of outputs of the optical network, said egress switch being configured to selectively direct an output signal from at least one of said plurality of outputs of said optical network to said at least one output of said egress switch; and at least one probe signal detector optically connected to said at least one output of said egress switch, said at least one probe signal detector configured to detect a presence of the probe signal in the output signal, wherein said at least one probe signal detector comprises a resonant photo detector configured to receive the output signal and to detect the probe signal within the output signal and a lock-in amplifier optically or electrically connected to said at least one modulation signal generator, said lock-in amplifier configured to amplify the probe signal detected by said at least one resonant photo detector based on the modulation signal.