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Optics Virtual 2020

Ligang Huang

Ligang Huang, Speaker at Ligang Huang: Speaker for Optics Conference
Chongqing University, China
Title : Dynamic parameter measurement of Ultra-Narrow-Linewidth lasers


With excellent properties of the high purity spectrum and long coherent length, narrow-linewidth lasers can be applied in many fields, such as optical quantum information, low-noise microwave generation, high-resolution spectroscopy, precise sensing, high-speed optical coherent communication and so on. We propose the fundamental route to achieve the deep compression of the laser linewidth and demonstrate that the Rayleigh Backscattering (RBS) as weak feedback is an efficient linewidth-compression mechanism to realize the route. In theory, the dynamic characteristics of the spectrum evolution of Rayleigh scattering in a one-dimensional waveguide (ODW) is investigated based on the quantum theory and a spectrum evolution model of RBS source is established. In the experiment, to verify the linewidth compression mechanism, we construct dynamic laser parameter measurement method based on short delayed fiber self-heterodyne interferometer (SDSHI), and analyze the corresponding optical frequency evolution process from quantum theory. Based on the SDSHI method, we demonstrate and observe the Rayleigh-scattering-based linewidth compression process of fiber lasers and semiconductor lasers. The linewidths of fiber lasers are dynamically compressed to sub-100 Hz from the conventional value of >1 kHz. Meanwhile, the linewidths of DFB semiconductor lasers are compressed to 200 Hz from the conventional value of >1 MHz within 1 ms. We also explore the measurement of dynamic parameters of tunable lasers. With all-optical tunable narrow-band fiber Bragg gratings and RBS linewidth compression, we obtain tunable fiber lasers with a precise tuning step of less than 0.02 nm and linewidth of about 200 Hz. With all-fiber acousto-optical tunable filters, we obtain fast tunable narrow-linewidth fiber lasers with a tuning band of 20 nm and switching time of less than 1 ms.


Ligang Huang is a Chinese Physicist. He received Ph.D. in Physics from Nankai University (China) in 2016. Since September 2020, he works as an associate professor at the College of Optoelectronic Engineering in Chongqing University, China. His research interests include narrow-linewidth lasers, laser parameter measurement, all-fiber acousto-optic tunable filters and whispering-gallery-mode tunable filters. He is author or co-author of more than 50 peer-reviewed journal papers in the field of narrow-linewidth lasers and tunable filters, which have been cited by more than 500 times.