GRATING DEVICE, LIGHT-EMITTING UNIT and LIGHT DETECTION METHOD

A light-emitting unit, comprising:

• a polarization controller configured to generate a first input beam of a TE mode and a second input beam of a TM mode;
• and
• one or more grating devices which are coupled to the polarization controller to receive the first and second input beams,
• wherein each of the one or more grating devices comprises:
• a substrate;
• a blocking layer on the substrate;
• a first waveguide on a first region of the blocking layer, through which the first input beam of the TE mode propagates;
• and
• a second waveguide on a second region of the blocking layer, through which the second input beam of the TM mode propagates;
• wherein the grating devices generates output beams by steering the first and second input beams by diffraction, with different steering angles, at least, at one wavelength.

A light detection method, comprising:

• generating first and second input beams, which have different polarization modes, from a source beam;
• generating output beams by steering the first and second input beams using first and second waveguides, with steering angles corresponding to wavelengths of the first and second input beams;
• illuminating the output beams onto an object;
• obtaining reflected beams from the object to generate a detection signal;
• and
• processing the detection signal to represent a distance of the object,
• wherein the first and second input beams have different steering angles, at least, at one wavelength.