Study on ultra-fast optical memories using semiconductor lasers

我们主要研究了以下四个主题，以通过使用激光二极管来创建超快光学存储器。(1)应变量子阱激光器中的偏振开关利用GaAsP/AlGaAs应变量子阱增强激光器的TM模增益，实现了激光器中的TE-TM模开关。电极分为两部分，主电极和控制电极。在固定的主电流下，改变控制电流，器件的光-电流曲线呈现S型偏振双稳态。(2)偏振双稳开关速度的理论估算：利用行波速率方程的数值分析表明，在垂直腔面发射激光器（VCSEL）中，利用音叉分叉偏振双稳可以实现比特率高于100 Gbit/s的触发器操作。(3)本文首次在VCSEL中观测到了音叉型分叉极化双稳现象。通过注入具有两个正交偏振的触发光输入，已经成功地证明了全光触发器操作。当注入一个0（90）触发脉冲时，VCSEL将其偏振从90（0）变为0（90）。当停止注入0 μ m（90 μ m）的触发脉冲时，仍能产生0 μ m（90 μ m）偏振态的激光振荡。(4)超快速全光触发器操作我们演示了高速全光触发器操作使用VCSEL注入具有两个正交偏振的光触发脉冲。在注入功率仅为-120 μ W的条件下，成功实现了5.3GHz全光触发器的工作，并利用锁模钛宝石激光器产生的-3.5ps超短光脉冲实现了双偏振开关。

We have investigated mainly the following four topics to create ultra-fast optical memories by using laser diodes.(1) Polarization switching in strained quantum well laser diodes.The TE-TM mode switching in laser diodes was achieved using GaAsP/AlGaAs tensely strained quantum well for TM mode gain enhancement. The electrodewas devid into two, i.e., a main electrode and a control electrode. The device showed S-shaped polarization bistability in the light vs. current curves, when the control current was changed at the fixed main current.(2) Theoretical estimation of switching speed of polarization bistability.We showed by the numerical analysis using traveling-wave rate equations that flip-flop operation with bit rates of higher than 100Gbit/s can be achieved by pitchfork bifurcation polarization bistability in vertical-cavity surface-emitting lasers (VCSELs).(3) Experimental demonstration of pitchfork bifurcation polarization bistability in VCSELsPitchfork bifurcation polarization bistability has been observed experimentally in a VCSEL for the first time. All-optical flip-flop operation has been successfully demonstrated by injecting the trigger light inputs having the two orthogonal polarizations. When a 0ﾟ (90ﾟ) trigger pulse is injected, the VCSEL changes its polarization from 90ﾟ (0ﾟ) to 0ﾟ (90ﾟ). The laser oscillation with 0ﾟ (90ﾟ) polarization continues even when the injection of the 0ﾟ (90ﾟ) tigger pulse was stoped.(4) Ultra-fast all-optical flip-flop operationWe demonstrated high-speed all-optical flip-flop operation using VCSELs by injecting optical trigger pulses having two orthogonal polarizations. We successfully obtained a 5.3GHz all-optical flip-flop operation with injection power of only - 120muW.We also obtained bistable polarization switching by injecting - 3.5ps ultra-short optical pulses generated from a mode-locked Ti : Sapphire laser.