Directly modulated optical negative feedback lasers for long-range FMCW LiDAR

Area of Science:

• Photonics and Optical Engineering
• Laser Technology
• Sensing and Measurement

Background:

• Frequency-modulated continuous-wave (FMCW) light detection and ranging (LiDAR) requires lasers with stable frequency sweeps for high signal-to-noise ratio (SNR).
• Directly modulated lasers offer a compact solution but often suffer from high frequency (FM) noise, limiting their range performance.

Purpose of the Study:

• To investigate the frequency sweep operation of directly modulated optical negative feedback lasers.
• To enhance the SNR and enable long-range capabilities for FMCW LiDAR systems.

Main Methods:

• Numerical and experimental investigation of frequency sweep operation in directly modulated optical negative feedback lasers.
• Utilizing optical feedback from a Fabry-Perot etalon to suppress FM noise and reduce spectral linewidth.
• Testing with a 300-m delay fiber as a ranging sample to evaluate performance.

Main Results:

• Achieved sustained low FM noise with a spectral linewidth of approximately 2.0 kHz.
• Demonstrated a beat note spectrum with a high 30-dB SNR, even with a 300-m delay fiber.
• Confirmed the effectiveness of optical negative feedback in improving laser performance for FMCW LiDAR.

Conclusions:

• Directly modulated optical negative feedback lasers are a promising technology for high-SNR, long-range FMCW LiDAR.
• The proposed method effectively suppresses FM noise, paving the way for practical long-range LiDAR applications.