Techniques for processing a target return signal using free-space optics

A light detection and ranging (LIDAR) apparatus, comprising:

• an optical source to emit an optical beam;
• and
• free-space optics coupled with the optical source, comprising:
• a first photodetector (PD);
• a second PD
• a polarizing beam-splitter (PBS) to direct the optical beam in a first direction toward a target environment;
• a polarization wave plate (PWP) to direct the optical beam toward the target environment and to reflect a portion of the optical beam to the PBS for receipt by the PD, and wherein the reflected portion of the optical beam comprises a local oscillator signal (LO) to mix with a target return signal to generate target information;
• a wavelength demultiplexer coupled between the PBS and the first and second PDs, the wavelength demultiplexer to separate a portion of the target return signal comprising light of a first wavelength to the first PD or the second PD;
• and
• a lens system coupled between the PBS and the PWP to magnify the optical beam.

A method for light detection and ranging (LIDAR) with free-space optics, comprising:

• generating an optical beam from an optical source having a first polarization;
• directing the optical beam in a first direction, toward a polarizing beam splitter (PBS);
• propagating a first portion of the optical beam with the first polarization from the PBS as a local oscillator (LO) signal;
• separating a portion of the LO signal comprising light of a first wavelength utilizing a wavelength demultiplexer;
• and
• directing the portion of the LO signal comprising the light of the first wavelength to a first photodetector (PD) or a second PD;
• directing a second portion of the optical beam from the PBS through a lens system to a polarization wave plate (PWP) to convert the second portion of the optical beam from the first polarization to a second polarization;
• receiving a target return signal from a target environment at the PWP to convert the target return signal from a third polarization to a fourth polarization;
• receiving, at the PBS through the lens system, the target return signal having the fourth polarization;
• receiving, at the first PD or the second PD, the portion of the LO signal and a portion of the target return signal;
• and
• mixing the portion of the target return signal with the portion of the LO signal to generate target information.