The polarization dynamics of laser subjected to weak optical feedback from birefringence external cavity are studied theoretically and experimentally. It is found that polarization flipping with hysteresis is induced by birefringence feedback, and the intensities of two eigenstates are both modulated by external cavity length. The variations of hysteresis loop and duty ratios of two eigenstates in one period of intensity modulation with phase differences of birefringence element in external cavity are observed. When the phase difference is ?/2, the two eigenstates will equally alternatively oscillate, and the width of hysteresis loop is the smallest.
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[Show abstract][Hide abstract]ABSTRACT: Optical-phase-retardation elements are widely used in many fields. Accurate measurement of their phase retardation is crucial to the practical effect of the element’s processing and application. The development and present situation of the methods for optical phase retardation measurement are reviewed, with the wave plate, the most typical phase-retardation element, as an example. The latest research progress in this field is introduced; the principles and characteristics of individual measurement method are summarized and discussed. Three new methods based on laser frequency splitting or laser feedback are presented in detail, in which the laser is not only regarded as a light source but also plays a role of sensor. Moreover, no standard wave plates are needed and arbitrary phase retardation can be measured. Traceability, high precision and high repeatability are achieved as well.
Full-text · Article · May 2013 · Science China Technological Sciences
[Show abstract][Hide abstract]ABSTRACT: This paper investigates the intensity tuning characteristics of a double longitudinal modes He-Ne laser subjected to optical feedback. The intensity undulations of the total light and the two modes are observed for different external cavity length. Two modulations of the internal cavity length are performed. One is only for the internal cavity length being modulated and the other is for both the internal and the external cavity length being modulated. The undulation frequency of the total light is found to be determined by the ratio of external cavity length to internal cavity length in both modulations. When the external cavity length is integral times of the internal cavity length, the fringe frequency of the total light could be seven or even more times of that in conventional optical feedback. A simple theoretical analysis is presented, which is in good agreement with the experimental results. The potential use of the experimental results is also discussed.
[Show abstract][Hide abstract]ABSTRACT: A review of the authors' work on orthogonal polarization of optical feedback in He-Ne and microchip Nd:YAG lasers is presented. Orthogonally polarized optical feedback has been applied to dual-frequency lasers and to monomode lasers with birefringent external cavity. The greatest advantage of the technique is that two modulated beams can be obtained with only one optical feedback path, so more information can be obtained than with conventional optical feedback. Polarization flipping with hysteresis and intensity transfer between the two eigenstates of the laser, the characteristics of intensity tuning, subdivision of the laser emission bandwidth, the phase relationship of the two orthogonally polarized intensity modulation curves, mode competition, signal frequency doubling through optical feedback, measurement of the small intracavity phase anisotropy in lasers, and antiphase intensity modulation of orthogonal polarization are experimentally and theoretically demonstrated. Possible applications are also discussed. (c) 2006 Society of Photo-Optical Instrumentation Engineers.
No preview · Article · Nov 2006 · Optical Engineering