Photonic integrated distance measuring pixel and method of distance measurement

A distance-measuring pixel apparatus, comprising:

• I.) a photonic integrated circuit disposed on a common substrate, comprising:
• a photonic integrated circuit substrate having disposed thereon,
• a first 3 dB directional coupler having first and second output ports and first and second input ports;
• a second 3 dB directional coupler having first and second output ports and first and second input ports,
• wherein the second input port of the first 3 dB directional coupler is directly optically coupled to the first input port of the second 3 dB directional coupler;
• a GRIN lens having a first side that is optomechanically coupled to the first output port of the first 3 dB directional coupler;
• a partially reflecting Faraday mirror having a first side that is optomechanically coupled to a second side of the GRIN lens and configured to reflect between 0.1%, to 50% of light emitted from the first output port of the first 3 dB directional coupler;
• II.) a source laser having an output that is optically coupled to the first input port of the first 3 dB directional coupler;
• III.) a first photodetector optomechanically coupled to the first output port of the second 3 dB directional coupler;
• and
• IV.) a second photodetector optomechanically coupled to the second output port of the second 3 dB directional coupler.