Spatial light modulator, wavelength selective switch, and projection system

A wavelength selective switch, comprising:

• a polarization conversion prism;
• a diffraction grating plate;
• a reflective lens;
• a transmitting lens;
• and
• a spatial light modulator, comprising:
• a substrate layer;
• a first electrode layer;
• a second electrode layer;
• a first metasurface layer comprising at least two metasurface units that are sequentially arranged, and a resonance frequency of each of the at least two metasurface units corresponds to a preset incident optical wavelength of each metasurface unit;
• a phase change material layer configured to perform first phase modulation on incident light of a first wavelength based on a voltage provided by the first electrode layer and the second electrode layer to obtain a first optical wave, and send the first optical wave to a first metasurface unit in the at least two metasurface units, wherein a preset incident optical wavelength of the first metasurface unit is the first wavelength, wherein the first metasurface unit is configured to perform second phase modulation on the first optical wave to obtain and output a second optical wave;
• and
• a first flat layer, wherein the substrate layer and the first flat layer are parallel to each other, the first electrode layer and the second electrode layer are respectively disposed on opposite sides of the substrate layer and the first flat layer, and the first metasurface layer and the phase change material layer are disposed between the first electrode layer and the second electrode layer,
• wherein the polarization conversion prism, the diffraction grating plate, the reflective lens, and the transmitting lens are jointly configured to convert incident light of the wavelength selective switch into a plurality of third optical waves of different wavelengths, and send the plurality of third optical waves to the spatial light modulator configured to perform phase modulation on each of the plurality of third optical waves to obtain a plurality of fourth optical waves, and send the plurality of fourth optical waves to the transmitting lens at different deflection angles, wherein the plurality of fourth optical waves sequentially pass through the transmitting lens, the reflective lens, the diffraction grating plate, and the polarization conversion prism, and are propagated to an outside of the wavelength selective switch as emitted light of the wavelength selective switch.