Influences of Thermal Effect on the Performance of FMCW Signal Generated by Current-Modulated DFB-LDs

• Published in: IEEE journal of quantum electronics p. 1
• Main Authors: Wang, Qiupin, Xia, Guangqiong, Xie, Yingke, Ou, Pu, He, Chaotao, Hu, Shan, Zhang, Fengling, Zhao, Maorong, Wu, Zhengmao
• Format: Journal Article
• Language: English
• Published: IEEE 18.10.2024
• Subjects: Current-modulated distributed feedback laser diodes (CM-DFB-LDs); Distance measurement; Distributed feedback devices; frequency-modulated continuous-wave (FMCW); Gratings; Laser radar; Mathematical models; nonlinearity; Propagation; Substrates; Temperature; thermal effect; Time-domain analysis; Vectors
• ISSN: 0018-9197; 1558-1713
• DOI: 10.1109/JQE.2024.3484250

A cost-effective linear chirp source is urgently needed in various commercial scenarios. Based on typical coupled mode theory (CMT) and a highly effective split-step time-domain model (SS-TDM) method, the influence of thermal effect on the performance of frequency-modulated continuous-wave (FMCW) signal generated by current-modulated distributed feedback laser diodes (CM-DFB-LDs) is numerically simulated. The results show that the thermal effect in DFB-LDs has a significant impact on the nonlinearity of the FMCW signal, and the increasing thermal effect leads to an enhancement in the nonlinearity of the FMCW signal. For a given thermal diffusion coefficient D = 2.0×10 -5 m 2 /s, with the increase of the thickness H between the active region and the substrate from 1.5 μm to 6 μm, both the bandwidth and the nonlinearity increase gradually at first and then tend towards saturation. For H fixed at 4.5 μm, with the increase of D from 1.5×10 -5 m 2 /s to 6×10 -5 m 2 /s, both the bandwidth and the nonlinearity show a downward trend. For D = 6.0×10 -5 m²/s and H = 4.5 μm, a high-quality FMCW signal with a nonlinearity of 3.852×10 -5 and an root mean square (RMS) of 19.3 MHz under a bandwidth of 19.1 GHz can be obtained. Taking such FMCW signal as a transmitted signal, a 2 m distance ranging has been demonstrated, and the relative error is 0.340 %.