A Linear Frequency-Swept Laser With Negative Voltage Tuning for Long-Range FMCW LiDAR Applications

We present a linear frequency-swept laser for long-range frequency-modulated continuous-wave (FMCW) light detection and ranging (LiDAR), utilizing negative voltage tuning with a high output power distributed-Bragg-reflector (DBR) laser integrated with a spot size converter (SSC) and semiconductor optical amplifier (SOA). Compared to positive voltage tuning, negative voltage tuning offers key advantages including a linear tuning response and reduced spectral broadening. To enhance the coupling efficiency to the lensed fiber, an SSC with a buried waveguide structure is introduced at the output port. The laser features a free spectral range of 0.3 nm and a Lorentzian linewidth of 140 kHz. Negative voltage tuning in the phase region enables linear frequency sweeping, while phase noise compensation allows for long-range measurements.