Optical loopback in a wavelength division multiplexing system

An optical communication comprising:

• a transmitter having a transmitter port and transmitting a first multiplexed signal in a first optical spectrum from the transmitter port;
• a receiver having a loopback port and a receiver port, the receiver receiving the first multiplexed signal in the loopback port and a second multiplexed signal in the receiver port, the second multiplexed signal in a second optical spectrum different from the first optical spectrum, the receiver comprising a demultiplexer in optical communication with the loopback port and the receiver port, the demultiplexer demultiplexing the first and second multiplexed signals received by the loopback and receiver ports;
• an optical switch in optical communication with the transmitter port and the loopback port, the optical switch routing the first multiplexed signal to the loopback port;
• a combiner in optical communication with the optical switch and the loopback port and
• a controller connected to and controlling the optical switch, the controller allowing the demultiplexer to receive the first multiplexed signal while the demultiplexer fails to receive the second multiplexed signal.

An optical communication device comprising:

• a transmitter having a transmitter port and transmitting a first multiplexed signal in a first optical spectrum from the transmitter port;
• and
• a receiver having a loopback port and a receiver port, the receiver receiving the first multiplexed signal in the loopback port and a second multiplexed signal in the receiver port, the second multiplexed signal in a second optical spectrum different from the first optical spectrum, the receiver comprising a demultiplexer in optical communication with the loopback port and the receiver port, the demultiplexer demultiplexing the first and second multiplexed signals received by the loopback and receiver ports,
• wherein, for each multiplexed signal, the demultiplexer separates the multiplexed signal into demultiplexed signals and outputs the demultiplexed signals to respective mapped output ports, and
• wherein the demultiplexer comprises an arrayed waveguide grating having first and second input ports and N output ports, the first input port receiving the first multiplexed signal from the loopback port, and the second input port receiving the second multiplexed signal from the receiving port.

A method of processing optical signals in a wavelength division multiplexing passive optical network, the method comprising:

• transmitting a first multiplexed signal in a first optical spectrum from a transmitter port;
• splitting the first multiplexed signal, the split first multiplexed signal having a threshold percentage of power;
• receiving the split first multiplexed signal in a loopback port;
• receiving a second multiplexed signal in a receiver port, the second multiplexed signal in a second optical spectrum different from the first optical spectrum;
• and
• demultiplexing the first and second multiplexed signals.