Method and apparatus for monitoring wavelength multiplexed optical signals

An apparatus for monitoring the signal to noise ratio of optical signals comprising:

• an optical channeling device having a first, a second and a third port, wherein said optical channeling device couples optical signals from said first port to said second port and couples optical signals from said second port to said third port;
• a reflector array having an input port and an output port, said reflector array comprising at least one wavelength specific reflector coupled in series between said reflector array input port and said reflector array output port, said reflector array input port coupled to said optical channeling device second port;
• a tunable filter having an input port and an output port;
• an optical switch having a first, a second and a third port, said optical switch first port coupled to said optical channeling device third port, said optical switch second port coupled to said reflector array output port, said optical switch third port coupled to said tunable filter input port;
• a processing device, said processing device coupled to said tunable filter output port, wherein said processing device provides control signals, determines the amplitude of signals and computes a signal to noise ratio.

An apparatus for monitoring the signal to noise ratio of optical signals comprising:

• a tunable filter having an input port and an output port;
• a final photodetector having an input port and an output port, said final photodetector input port coupled to said tunable filter output port;
• a controller having a plurality of input ports;
• a plurality of wavelength reflection stages, each having an input port, a transmission port, and a reflection port, said wavelength reflection stages each comprising:
• an optical channeling device having a first, a second and a third port, wherein said optical channeling device couples optical signals from said first port to said second port and couples optical signals from said second port to said third port, said optical channeling device first port coupled to said wavelength reflection stage input port;
• a wavelength specific reflector, said wavelength specific reflector coupled in series between said optical channeling device second port and said wavelength reflection stage transmission port;
• and
• a photodetector having an input port and an output port, said photodetector input port coupled to said optical channeling device third port, said photodetector output port coupled to said wavelength reflection stage reflection port;
• wherein adjacent wavelength reflection stages are coupled such that said transmission port of a first wavelength reflection unit is coupled to said input port of a second wavelength reflection unit;
• said tunable filter input port coupled to said transmission port of the last wavelength reflection stage;
• each of said reflection ports of said plurality of wavelength reflection stages coupled to one of said controller input ports, said final photodetector output port coupled to one of said controller input ports.

A method of monitoring the signal to noise ratio for optical signals comprising the steps of:

• (a) calibrating a reflector array to determine the reflectivity of the reflector array for predetermined frequency signals;
• (b) receiving an optical signal at a reflector array;
• (c) measuring optical signals reflected from the reflector array;
• (d) computing the amplitude of a predetermined frequency optical signal received at the grating array using a measured reflected predetermined frequency signal and a calibration factor generated in said calibrating step;
• (e) measuring the noise floor by measuring peaks outside of a predetermined range of said predetermined frequency signals;
• (f) reconstructing the noise floor;
• (g) computing the signal to noise ratio using the computed signal amplitudes level and the reconstructed noise floor.

An apparatus for monitoring the signal to noise ratio of optical signals comprising:

• an optical channeling device, having a first, a second and a third port, wherein said optical channeling device couples optical signals from said first port to said second port and couples optical signals from said second port to said third port;
• a reflector array having a port, said reflector array comprising at least one wavelength specific reflector coupled to said reflector array port, said optical channeling device second port coupled to said reflector array port;
• a tunable filter having an input port and an output port, said tunable filter input port coupled to said optical channeling device third port;
• a processing device, said processing device coupled to said tunable filter output port, wherein said processing device provides a control signal, determines the amplitude of signals and computes a signal to noise ratio.