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

本文主要研究了基于垂直腔面发射激光器干草叉分岔双稳态工作的非线性光学功能器件。(1)我们观察到了干草叉分叉偏振双稳性，并成功地在VCSEL中实现了全光触发器操作。通过注入触发光输入实现了两种偏振态之间的切换，并利用皮秒光触发脉冲实现了切换时间为7ps的超快偏振双稳态切换。(2)利用偏振双稳态VCSEL对全光触发器操作进行了数值分析。我们使用的速率方程考虑了VCSEL中的增益饱和和入射光束频率与VCSEL腔谐振频率的失谐。我们明确了超快触发器运行的最合适运行条件。全光触发器可以获得高达3…00 Gbit/s以上的速率。(3)自饱和系数和交叉饱和系数的相对大小是决定极化开关特性的关键。为了得到非线性增益的详细性质，我们对平行偏振和正交偏振光场的非线性增益系数进行了数值研究。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极化双稳定条件。(4)我们新提出了一种解复用（DEMUX）装置。将输入信号和栅极脉冲同时注入具有TE偏振的偏振双稳态激光二极管（BLD）中，利用其与门功能将BLD的偏振设置为TE偏振。然后，激光在TE偏振中继续振荡，直到注入具有TM偏振的复位脉冲。这样，在TE偏振输出信号中实现了具有信号位宽转换函数的光解复用。我们的研究结果表明，可以实现从50 Gbit/s信号到5 Gbit/s RZ信号的超快全光解复用。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