體積布拉格光柵為近代雷射系統中極為重要的元件，其對於雷射的波長選擇及光譜窄化有很大的改善，因此對體積布拉格光柵的研究就顯得十分重要，然而在雷射系統裡，共振腔長是一極為重要的要素，而當使用體積布拉格光柵作為雷射系統之輸出耦合鏡時，該如何計算此雷射系統的有效共振腔長以及其輸出之縱向模態即是此論文探討的重點。本論文使用將體積布拉格光柵等效為一有效反射面的概念，配合週期性結構的耦合波理論，推導出體積布拉格光柵有效反射面與光柵表面的距離的表示式，並求得當平面波入射時有效反射面距離隨著入射角度及入射波長改變的變化情形，以及當高斯光束入射時有效反射面距離隨著入射波長改變的變化情形，並將此有效反射面距離納入雷射共振腔之有效共振腔長，計算出雷射輸出之縱向模態行為。Volume Bragg grating is an important optical element for laser spectral narrowing and wavelength selection. Therefore, the research of volume Bragg grating is important. The cavity length is a essential factor in a laser system. This paper will mainly talk about how to get the effective cavity length and the longitudinal mode of lasers using volume Bragg grating as the cavity mirror.In this paper, the concept of effective reflection surface is used. The effective reflecting surface distance can be derived from the coupled-mode theory. The formulas of the effective reflection surface distance when incident wave are plane wave or Gaussian wave are derived. The longitudinal mode of lasers using volume Bragg grating as the cavity mirror is discussed.
