Device and method for processing an optical signal

A reconfigurable optical add/drop multiplexer, ROADM, comprising a device for processing an optical signal, the device comprising:

• a photonic device arranged between a first input/output and a second input/output, the photonic device being in optical communication with the first and second inputs/outputs by a signal path, the signal path being selectively for transmission of a first optical signal in a first direction from the first input/output to the second input/output and for transmission of a second optical signal in a second direction from the second input/output to the first input/output;
• an optical gain element for receiving the first or second optical signal and outputting an amplified first or second optical signal respectively, the optical gain element being selectively configurable to optically amplify the first optical signal downstream of the photonic device in the first direction and the second optical signal downstream of the photonic device in the second direction;
• and
• a path switching circuit comprising:
• a first signal amplification path connectable between the first input/output and the photonic device for optically coupling the signal path to and from the optical gain element, the first optical signal being transmitted through the photonic device in the first direction;
• a second signal amplification path connectable between the photonic device and the second input/output for optically coupling the signal path to and from the optical gain element, the second optical signal being transmitted through the photonic device in the second direction;
• and
• the path switching circuit being configured to selectively connect the first signal amplification path or the second signal amplification path into the signal path.

A method for processing an optical signal, the method comprising:

• receiving an optical signal at a first input/output or a second input/output;
• transmitting the optical signal either from the first input/output in a first direction along a signal path to a photonic device and from the photonic device to the second input/output, or from the second input/output in a second direction along the signal path to the photonic device and from the photonic device to the first input/output;
• amplifying the optical signal at an optical gain element by selectively directing the optical signal to either a first signal amplification path or a second signal amplification path, the first signal amplification path optically coupling the signal path between the first input/output and the photonic device to and from the optical gain element, and the second signal amplification path optically coupling the signal path between the photonic device and the second input/output to and from the optical gain element;
• and
• the optical gain element being selectively configurable to optically amplify the optical signal downstream of the photonic device in the first direction and another optical signal downstream of the photonic device in the second direction.

A method of operating a reconfigurable optical add/drop multiplexer, ROADM, the method comprising:

• receiving an optical signal at a first input/output or a second input/output;
• transmitting the optical signal either from the first input/output in a first direction along a signal path to a photonic device and from the photonic device to the second input/output, or from the second input/output in a second direction along the signal path to the photonic device and from the photonic device to the first input/output;
• amplifying the optical signal at an optical gain element by selectively directing the optical signal to either a first signal amplification path or a second signal amplification path, the first signal amplification path optically coupling the signal path between the first input/output and the photonic device to and from the optical gain element, and the second signal amplification path optically coupling the signal path between the photonic device and the second input/output to and from the optical gain element;
• and
• the optical gain element being selectively configurable to optically amplify the optical signal downstream of the photonic device in the first direction and another optical signal downstream of the photonic device in the second direction.