High contrast grating for highly reflective mems surface for lidar

A method for manufacturing a mirror for use in an autonomous vehicle using Light Detection and Ranging (LiDAR), the method comprising:

• obtaining a semiconductor wafer, the semiconductor wafer comprising a device layer, a handle layer, and an insulting layer between the device layer and the handle layer;
• applying a mask to define a pattern, wherein the pattern is configured to form a grating to reflect an optical beam defined by a center wavelength;
• etching the device layer through the mask to form a plurality of ridges, wherein:
• the plurality of ridges have walls defining a plurality of trenches between the plurality of ridges;
• the plurality of ridges are defined by a period such that a width of one ridge plus a width of one trench is equal to a width of the period;
• and
• the width of the period is less than the center wavelength;
• removing a portion of the handle layer to form an opening in the handle layer;
• and
• removing a portion of the insulating layer through the opening in the handle layer.