Calibration and alignment of coherent lidar system

A method of assembling a lidar system, the method comprising:

• assembling a light source to generate a frequency modulated continuous wave (FMCW) signal;
• disposing a waveguide splitter to obtain and split the FMCW signal into an output signal and a local oscillator (LO) signal;
• arranging a transmit grating coupler to provide the output signal for transmission through a transmit lens;
• aligning a receive lens to obtain a received signal resulting from reflection of the output signal by a target and provide it to a receive grating coupler;
• disposing a waveguide coupler to obtain and combine the received signal and the LO signal and to split a result of combining into a first combined signal and a second combined signal;
• configuring a first phase modulator to adjust a phase of the first combined signal and provide a first phase modulated signal to a first photodetector;
• configuring a second phase modulator to adjust a phase of the second combined signal and provide a second phase modulated signal to a second photodetector;
• and
• configuring a processor to obtain a first electrical signal from the first photodetector and a second electrical signal from the second photodetector and to process the first electrical signal and the second electrical signal to obtain a lidar result that indicates information about the target.

A vehicle, comprising:

• a lidar system comprising:
• a light source configured to generate a frequency modulated continuous wave (FMCW) signal;
• a waveguide splitter configured to split the FMCW signal into an output signal and a local oscillator (LO) signal;
• a transmit coupler configured to provide the output signal for transmission through a transmit lens;
• a receive lens configured to obtain a received signal resulting from reflection of the output signal by a target and provide it to a receive coupler;
• a waveguide coupler configured to combine the received signal and the LO signal and to split a result of combining into a first combined signal and a second combined signal;
• a first phase modulator configured to adjust a phase of the first combined signal and provide a first phase modulated signal to a first photodetector;
• a second phase modulator configured to adjust a phase of the second combined signal and provide a second phase modulated signal to a second photodetector;
• and
• a processor configured to obtain a first electrical signal from the first photodetector and a second electrical signal from the second photodetector and to process the first electrical signal and the second electrical signal to obtain a lidar result that indicates information about the target;
• and
• a vehicle controller configured to augment or automate operation based on the information from the lidar system.