Examples of a three-dimensional (3D) optical sensing system for a vehicle include a modular architecture. Light can be transmitted to an optical signal processing module, which can include a photonic integrated circuit (PIC) that can create one or more signals with tailored amplitude, phase, and spectral characteristics. The plurality of optical signals processed by the optical signal processing module can be sent to beam steering units distributed around the vehicle. The steering units can direct a plurality of optical beams towards targets. The return optical signal can be detected by a receiver PIC including an array of sensors and using a direct intensity detection technique or a coherent detection technique. The return optical signal can be converted into an electrical signal by the array of sensors, which can then be processed by the electronic signal processing unit, and information about the location and speed of the targets can be quantified.