Method, system, and apparatus for a lidar sensor with a large grating
A method for steering a beam is disclosed. According to the method, a scene is scanned with a surface emitting grating optically coupled to a free propagation region. The free propagation region is optically coupled to waveguides. The waveguides are disposed at different angles to the surface emitting grating. The scanning includes scanning in a first dimension by cycling through a cross connect to illuminate each waveguide of the waveguides. Scanning in a second dimension is performed by tuning a wavelength of light used to illuminate the waveguides.
1. A method for steering a beam comprising:
scanning a scene with a surface emitting grating optically coupled to a free propagation region; wherein the free propagation region is optically coupled to a plurality of waveguides; wherein each waveguide of the plurality of waveguides is disposed at a different angle to the surface emitting grating; wherein the scanning includes scanning in a first dimension by cycling through a cross connect to illuminate each waveguide of the plurality of waveguides; and wherein scanning in a second dimension is performed by tuning a wavelength of light used to illuminate each waveguide of the plurality of waveguides.
2. The method of claim 1 wherein the cross connect is a M×N cross connect; wherein M represents a number of light sources or receivers to be connected to the surface emitting grating; and wherein N represents a number of scan angles in the first dimension.
3. The method of claim 2 wherein the cross connect has a tree structure of Mach-Zehnder switches.
4. The method of claim 2 wherein cycling through each waveguide of the plurality of waveguides is performed by switching which cross connect is emitting light to the surface emitting grating.
5. The method of claim 1 wherein the scanning includes fine scanning; wherein the fine scanning is performed by rotating the surface emitting grating around an axis defining the second dimension.