The orbits of a photon in an axially symmetrical medium are treated by using the optical metric model. The behaviors of the photon near instable orbits is analyzed, and its stimulated emission in an active medium is discussed.

• 采用光学度规模型，研究了光子在轴对称介质中的运动轨道，分析了光子在不稳定轨道附近的行为，进而讨论了它在激活介质中的受激发射。