Optical switch, an optical switching apparatus, an optical communications network node and an optical communications network

An optical switch, comprising:

• a first optical waveguide;
• a first optical drop path;
• a second optical drop path;
• and
• a micro-ring resonator operable to drop a first optical signal at a preselected wavelength travelling in a first direction through the first optical waveguide to the first optical drop path and to drop a second optical signal at the preselected wavelength travelling in a second direction through the first optical waveguide opposite to the first direction to the second optical drop path and
• an optical coupling apparatus having a first input coupled to the first optical drop path, a second input coupled to the second optical drop path and an output configured to output an optical signal, wherein the optical coupling apparatus comprises an optical switch element having a first state in which the optical switch element is configured to selectively output an optical signal received at the first input from the output and a second state in which the optical switch element is configured to selectively output an optical signal received at the second input from the output.

An optical switching apparatus comprising:

• a first plurality of optical switches each comprising
• a first optical waveguide;
• a first optical add path;
• a second optical add path;
• and
• a micro-ring resonator operable to add a first optical signal at a preselected wavelength received from the first optical add path to the first optical waveguide to travel in a first direction through the first optical waveguide, and to add a second optical signal at the preselected wavelength received from the second optical add path to the first optical waveguide to travel in a second direction through the first optical waveguide opposite to the first direction, and
• an optical coupling apparatus having an input configured to receive an optical signal, a first output coupled to the first optical add path and a second output coupled to the second optical add path;
• wherein the optical coupling apparatus comprises an optical switch element having a first state in which the optical switch element is configured to selectively output the received optical signal from the first output and a second state in which the optical switch element is configured to selectively output the received optical signal from the second output;
• and
• a second plurality of optical switches each comprising:
• a first optical waveguide;
• a first optical drop path;
• a second optical drop path;
• a micro-ring resonator operable to drop a first optical signal at a preselected wavelength travelling in a first direction through the first optical waveguide to the first optical drop path and to drop a second optical signal at the preselected wavelength travelling in a second direction through the first optical waveguide opposite to the first direction to the second optical drop path and
• an optical coupling apparatus having a first input coupled to the first optical drop path, a second input coupled to the second optical drop path and an output configured to output an optical signal, wherein the optical coupling apparatus comprises an optical switch element having a first state in which the optical switch element is configured to selectively output an optical signal received at the first input from the output and a second state in which the optical switch element is configured to selectively output an optical signal received at the second input from the output.