双环、三纤互耦全光纤熔锥滤波器用正常色散的双折射光纤所作的暗孤子开关的开关条件

通过将熔锥结构中强、弱耦合段的总幅度耦合系数与滤波网络方程中的幅度耦合系数等效的方法,定量分析了双环、三纤互耦滤波器的频谱特性。实验滤波器通带特性的测试结果与理论分析基本吻合。所测滤波器的中心波长、抑制度、半功率带宽及插入损耗分别为1.27 μm,>13 dB、72 μm及3.9 dB。在正常色散的双折射光纤中传输的暗孤子对之间由于耦合周期性交换能量,一个暗孤子可把能量完全转给另一暗孤子,因此双折射光纤可作光开关。本文讨论了椭圆角为35°的双折射光纤的开关条件,发现脉冲只有以特定的极化角入射才有开关现象产生,而且建立了光纤长度与孤子对相差、初始能量差的解释关系。

An All-Fiber Fused Biconical Filter with Two Ring-Three Fiber Mutually CouplingsSwitching Condition for Dark Soliton Switching Made by Birefringent Fiber with Normal Dispersion

In this paper, a spectral characteristic of two ring-three fiber mutually coupling filter has quantitatively analysed by assuming a total-amplitude coupling coefficient in the weakly and strongly coup0ling sections of the fused biconical structure to be equal to the amplitude coupling coefficient in the filtering network equations. The measured passband profile of the experimehntal filter is basically in agreement with the theoretical one. The measured center wavelength, regraction, half-power bandwidth and insertion loss of the investigated filter are 1.27 μm, >1.3 dB, 72 μm and 3.9 dB, respectively.Dark soliton pairs propagating in the birefringent fiber with the normal dispersion exchange the energy periodically by coupling between them. The energy of one dark soliton may be transformed to another, so the birefringent fiber can be used to make the optical switching. The switching condition for the birefringent fiber with the ellipticity angle 35° is discussed, and switching phenomenon only appears when the pulse is input with a special polarization angle. The formula related to the length of fiber, difference of phase and initial relative energy difference between the soliton paris are presented.