Researchers from Samsung’s Advanced Sensor Laboratory have presented a prototype of a real-time imaging lidar using OPA (optical phased array) technology. The key element of the system is based on the prototype development of a single-chip solid-state beam scanner. The beam scanner is integrated with a fully functional 32-channel optical phased array; 36 optical amplifiers, and a tunable laser at central wavelength ~1310 nm, all on a 7.5 × 3 mm2 single chip fabricated with III-V on silicon processes.
All the optical components, such as wavelength-tunable laser (TLD), splitters, optical amplifiers, phase shifters, and grating antenna, were integrated on the chip.
The laser beam generated at the TLD is divided into 32 channels through cascaded beam splitters, and the phase shifter at each channel adjusts the 32 optical phases. The optical powers attenuated in the circuit are amplified through the 36 SOAs—four in the 1st stage and 32 in the 2nd stage—and finally the focused optical beam is emitted from the grating-based antenna array. The OPA is calibrated with self-evolving genetic algorithm to enable beam forming and steering in two dimensions.
Distance measurement is performed by measuring ToF (time of flight) of the emitted laser pulses. The prototype system as used by the team is schematically shown here.
According to the research team, a lidar module using this OPA solution can generate point cloud images with 120 × 20-degree resolution and 20-frame-per-second image acquisition. Currently the achievable range is about 20 metres, and improvements are on the roadmap.
This work presents a chip-scale OPA lidar scanner without any moving parts, and includes the laser light sources on a chip of less than 25 mm2. If realised in mass production, this technology can be an enabler for compact, affordable lidar sensors. With some increase in the detection range, application for short/mid-range lidar sensors will become feasible.