Semiclassical Approach in the Analysis of Ring Laser : II.Mode Coupling due to Backscattering and Interference

概要

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In the research on ring lasers, the relationship between the lock-in phenomenon and backscattering was usually analyzed by treating the backscattered waves as phenomenological coupling terms. However, with these approaches, it is difficult to quantitatively estimate the relationship between lock-in phenomena and reflection due to backscattering. Also, the dependence of the coupling constant for a two-mode operation on backscattering reflection has not been described. To overcome these problems, rate equations, in which spatial distributions of the fields are expressed as superpositions of traveling wave and its backscattered wave, have been derived in our previous paper[Jpn.J.Appl.Phys.39(2000)3983]. Based on these newly derived rate equations, this paper introduces a modified coupling constant, which includes backscattering reflectivity, the Doppler effect, linear mode pulling, and the interference between two modes. As a result, it is found that the Doppler effect plays an important role in the modified coupling constant which is related to lock-in phenomena. It is also shown that a weak coupling for all relative phase angles which leads to stable two-mode operations can be observed when the Doppler effect is significant. Moreover, an upper limit of reflectivity of backscattered waves to achieve stable two-mode operations is revealed quantitatively.
社団法人応用物理学会の論文
2000-07-15