Study of ultrafast all-optical flip-flop operation with vertical-cavity surface-emitting lasers

基于垂直腔面发射激光器(VCSEL)的干叉分叉双稳工作，我们主要研究了以下四个方面的内容：(1)在垂直腔面发射激光器(VCSEL)中观察到了干叉分叉偏振双稳现象，并成功地演示了VCSEL的全光触发器工作。利用皮秒光触发脉冲实现了开关时间为7ps的超快偏振双稳开关。(2)数值分析了偏振双稳VCSEL的全光触发器工作，利用速率方程，考虑了VCSEL的增益饱和和入射光束频率与VCSEL腔内谐振频率的失谐，阐明了最适合超快触发器工作的条件。可获得高达3…的全光触发器(3)自饱和系数和交叉饱和系数的相对大小是决定偏振开关特性的关键。为了得到非线性增益的详细性质，我们数值研究了平行偏振和正交偏振光场的非线性增益系数。数值计算证实了自饱和系数和交叉饱和系数之间的关系满足偏振双稳条件。(4)提出了一种解复用(DEMUX)器件。当输入信号和选通脉冲同时注入偏振双稳激光二极管(BLD)时，利用其与门功能将BLD的偏振设置为TE偏振。然后，TE偏振中的激光振荡继续，直到注入具有TM偏振的重置脉冲。因此，在TE偏振输出信号中实现了具有信号位宽转换功能的光解复用。结果表明，可以实现从50Gbit/S信号到5Gbit/S RZ信号的超快全光解复用。较少

We have investigated mainly the following four topics to create new nonlinear optical functional devices based on the pitchfork bifurcation bistable operation of vertical-cavity surface-emitting lasers (VCSEL).(1) We observed the pitchfork bifurcation polarization bistability and successfully demonstrated all-optical flip-flop operation in a VCSEL.Switching between the two polarization states was accomplished by injecting trigger optical input, We also achieved the ultrafast polarization bistable switching with a switching time of 7ps by using picosecond optical trigger pulses.(2) We numerically analyzed an all-optical flip-flop operation using a polarization bistable VCSEL.We used rate equations taking into account gain saturation in the VCSEL and detuning of the incident optical beam frequency from the cavity resonant frequency of the VCSEL.We have clarified the most suitable operation conditions for the ultrafast flip-flop operation. The all-optical flip-flop can be obtained up to 3 … More 00 Gbit/s.(3) The relative magnitude of self- and cross-saturation coefficients are crucial to determine the characteristics of polarization switching. In order to obtain the detailed properties of nonlinear gain, we studied numerically the nonlinear gain coefficient for the optical fields in parallel and orthogonal polarization. The numerical calculation confirmed that the relation between self-and cross-saturation coefficients satisfies the condition for polarization bistability.(4) We newly proposed a demultiplexing (DEMUX) device. When the input signal and the gate pulse are injected simultaneously into the polarization bistable laser diode (BLD) with TE polarization, the polarization of the BLD is set to TE polarization using its AND gate function. Then, laser oscillation in TE polarization continues until the reset pulse with TM polarization is injected. Thus, the optical demultiplexing with a signal-bit width conversion function is achieved in the TE polarization output signal. Our results show that the ultrafast all-optical demultiplexing from a 50 Gbit/s signal to a 5 Gbit/s RZ signal can be obtained. Less