Wavelength selective switching apparatus and related method

A reconfigurable optical add drop module (ROADM), comprising one or more wavelength selective switching apparatuses, wherein each of the one or more wavelength selective switching apparatuses comprises:

• at least one input port and a plurality of output ports, wherein the at least one input port is configured to receive a first-band optical signal and a second-band optical signal, each of the plurality of output ports is configured to output an optical signal within a predetermined band range;
• a dispersion assembly, configured to respectively disperse the first-band optical signal and the second-band optical signal that are received from the at least one input port into a plurality of first optical sub-signals and a plurality of second optical sub-signals in a dispersion plane, wherein the plurality of first optical sub-signals respectively correspond to a plurality of first sub-bands in a first band, the plurality of second optical sub-signals respectively correspond to a plurality of second sub-bands in a second band, and the dispersion plane is a plane in which a light propagation direction and a dispersion direction are located;
• a first-band filter, configured to reflect the plurality of first optical sub-signals and transmit the plurality of second optical sub-signals;
• and
• a light redirection device, configured to:
• receive the plurality of first optical sub-signals and the plurality of second optical sub-signals in a forward propagation direction from the first-band filter, and make, in a port plane in which a predetermined arrangement direction of the plurality of output ports and the light propagation direction are located, the plurality of first optical sub-signals and the plurality of second optical sub-signals be respectively incident to the first-band filter at a first backward incidence angle and a second backward incidence angle in a backward propagation direction in a redirected manner, to propagate the plurality of redirected first optical sub-signals and the plurality of redirected second optical sub-signals to a predetermined output port in the plurality of output ports through the first-band filter, wherein the forward propagation direction is an optical propagation direction from the input port to the light redirection device, and the backward propagation direction is an optical propagation direction from the light redirection device to the output port;
• and
• wherein both the first backward incidence angle and the second backward incidence angle are within a first predetermined angle range.

A wavelength selective switching method, comprising:

• using at least one input port to input a first-band optical signal and a second-band optical signal;
• using a dispersion assembly to respectively disperse the input first-band optical signal and the input second-band optical signal into a plurality of first optical sub-signals and a plurality of second optical sub-signals in a dispersion plane, wherein the plurality of first optical sub-signals respectively correspond to a plurality of first sub-bands in a first band, the plurality of second optical sub-signals respectively correspond to a plurality of second sub-bands in a second band, and the dispersion plane is a plane in which a light propagation direction and a dispersion direction are located;
• using a first-band filter to reflect the plurality of first optical sub-signals and transmit the plurality of second optical sub-signals;
• and
• using a light redirection device to receive the plurality of first optical sub-signals and the plurality of second optical sub-signals in a forward propagation direction from the first-band filter, and make, in a port plane, the plurality of first optical sub-signals and the plurality of second optical sub-signals be respectively incident to the first-band filter at a first backward incidence angle and a second backward incidence angle in a backward propagation direction in a redirected manner, to propagate the plurality of redirected first optical sub-signals and the plurality of redirected second optical sub-signals to a predetermined output port in the plurality of output ports through the first-band filter, wherein the port plane is a plane in which a predetermined arrangement direction of the plurality of output ports and the light propagation direction are located, the forward propagation direction is an optical propagation direction from the input port to the light redirection device, and the backward propagation direction is an optical propagation direction from the light redirection device to the output port;
• and
• both the first backward incidence angle and the second backward incidence angle are within a first predetermined angle range.