Optical fiber communication 32021/2/19 受激辐射跃迁几率截面σ2=%2 受激辐受激吸收跃迁几率截面12=2/④ 辐射 1400145015001550160016501 - 3 Copyright Wang Yan 2021/2/19 Optical fiber communications 受激辐射跃迁几率 // 1 2 1 2 2 1 2 1     受激吸收跃迁几率截面 ＝ 受激辐射跃迁几率截面 ＝