3D chaos lidar system with a pulsed master oscillator power amplifier scheme

Abstract

We investigated the characteristics of chaos-modulated pulses amplified by a pulsed master oscillator power amplifier (MOPA) for application in a new chaos lidar system in this study. Compared with the loss modulation applied in a continuous-wave (CW) time-gating scheme, the pulsed MOPA scheme could generate chaos-modulated pulses with much higher peak power, resulting in an improved peak-to-standard deviation of sidelobe level (PSLstd) in correlation-based lidar detection. When the pulsed MOPA scheme was applied at a duty cycle of 0.1% and pulse repetition frequency of 20 kHz, which correspond to specifications compliant with eye safety regulations, it outperformed the CW time-gating scheme with respect to PSLstd by 15 dB. For the first time, we applied the chaos lidar system with the pulsed MOPA scheme to execute high-resolution, high-precision three-dimensional (3D) face profiling from a distance of 5 m. We also added the corresponding PSLstd value to each pixel in the point clouds to generate false-color images; thus, we obtained 3D images of a scene with multiple objects at a range of up to 20 m.

Parallel random LiDAR with spatial multiplexing of a many-mode laser

“…It is defined as the ratio between the maximal peak height and three times the standard deviation of the background. In our experiment, the peak-sidelobe ratio is 5.4 dB, well above the 3 dB limit for successful detection [33].…”

“…Compared to pseudo-random sequences created by optical modulators, intensity fluctuations of chaotic lasers [26][27][28] and thermal emitters [29], as well as stochastic spontaneous emission events [30,31], can provide true random waveforms with higher modulation speed. In particular, a chaotic semiconductor laser with radio-frequency (RF) bandwidth ∼10 GHz provides centimeter resolution for long-distance ranging [27,[32][33][34][35]. * *hui.cao@yale.edu However, it is technically challenging to make a large array of chaotic lasers with distinct dynamics for parallel LiDAR.…”

3-D Multi-Input Multi-Output (MIMO) Pulsed Chaos Lidar Based on Time-Division Multiplexing

“…By adjusting the relative onset delay times between the two pulse drivers (AeroDIODE, CCS-std) with the function generator (FG; Agilent 81150 A), we generated uncorrelated chaos-modulated pulses with the modulations time-gated from different parts of the CW chaos waveform. We then sent these pulses into the band-pass filters (BPF; Fiber Optic M-AD-1) to reduce the amplified spontaneous emissions from the BOAs and use two erbium-doped fiber amplifiers (EDFAs) (Channel 1: GIP CGBC1E3128001 A; Channel 2: GIP EFAS1EB128002 A) to amplify them in a pulsed MOPA configuration [28]. To record the waveforms of these two input pulses with channel 1 and channel 2 as the references, we used fiber couplers before the EDFAs to split the lights and detect them with two identical avalanche photodetectors (APD; Thorlabs APD430 C, 400 MHz).…”

“…From the obtained results, we know that by time-gating the pulses with a relative channel delay time of τ ch ≥ PW, interference between the channels can be minimized. For the following assessment and demonstration, we generate pulses with PW of 100 ns for a better range precision [28] and τ ch of 200 ns (100 ns time separation between pulses) between channel 1 and channel 2 for minimal interference.…”

“…To take advantage of both the pulsed and modulated CW lidars, we proposed and studied a 3D pulsed chaos lidar system that utilizes chaos-modulated pulses to improve the SNR [24]- [27]. By employing a pulsed master oscillation power amplifier (MOPA) scheme and quadrant avalanche photodetectors (APDs) [28], [29], high-speed 3D imaging at a throughput of 100 kHz, a frame rate of 10 Hz, and a field-of-view (FOV) of 24.5 × 11.5 degrees have been demonstrated. While the detection performance of the single-input single-output (SISO) chaos lidar system keeps being improved, its FOV is still limited by the mechanical turning angle of the micro-electro-mechanical system (MEMS) mirror and the physical parameters of the receiving optics.…”