Influence of acousto-optic frequency shifter's thermal-induced birefringence on laser frequency-shifted feedback system. (January 2023)

• Record Type: Journal Article
• Authors: Deng, Shiwei; Shen, Hua
• Is Part Of: Optics and lasers in engineering. Volume 160(2023)
• Publication Date: 2023-01
• Subjects: Laser feedback -- Heterodyne interference -- Acousto-optic frequency shifter; Lasers in engineering -- Periodicals; Optical measurements -- Periodicals; Optics -- Periodicals; Lasers en ingénierie -- Périodiques; Mesures optiques -- Périodiques; Optique -- Périodiques; 621.36605
• DOI: 10.1016/j.optlaseng.2022.107290
• Languages: English
• ISSNs: 0143-8166

Abstract

Highlights: The influence of the acousto-optic frequency shifter (AOFS)'s thermal-induced birefringence (TIB) on laser frequency-shifted feedback (LFSF) system is usually ignored by users but seriously affects the stability of the system especially startup stability. Analyze the phenomenon of amplitude and phase of frequency-shifted signal cause by AOFS's TIB, such as the amplitude variation, phase fluctuation, phase jump and phase temperature drift. The methods to eliminate or suppress these negative influences are proposed by principal axis alignment or quasi-common-path compensation. This study improves the startup stability and shorten startup preheating time of the LFSF system, which also has guiding significance to other heterodyne interference systems. Abstract: The acousto-optic frequency shifter (AOFS) is the key component of the laser frequency-shifted feedback (LFSF) system, and its thermal-induced birefringence (TIB) seriously affects the stability of the system. In this paper, the influence of the AOFS's TIB on LFSF system is analyzed, and the method of suppressing this influence is proposed. The theoretical model of LFSF considering the AOFS's TIB is established, and the influence on both amplitude and phase of frequency-shifted signal is analyzed. When the AOFS starts working, its TIB effect is obvious due to the accumulation of working heat, which makes the polarization state of its diffraction light change dynamically in most cases. The laser feedback imaging system and laser feedback displacement measurement system are built separately to evaluate the amplitude and phase stability. By principal axis alignment or quasi-common-path compensation, the amplitude variation, phase fluctuation, phase jump and phase temperature drift caused by the AOFS's TIB can be eliminated or suppressed. This study improves the startup stability and anti-ambient temperature interference ability of the LFSF system, which also has guiding significance to other heterodyne interference systems.