Study on ultra-fast optical memories using semiconductor lasers

主要研究了以下四个方面的内容：(1)应变量子阱激光器中的偏振开关，利用GaAsP/AlGaAs张拉应变量子阱实现了半导体激光器中TE-TM模的转换，提高了TM模的增益。电极分为两部分，即主电极和控制电极。(2)偏振双稳开关速度的理论估计。通过行波速率方程的数值分析表明，垂直腔面发射激光器(VCSEL)中可以通过干叉分叉偏振双稳实现码率高于100Gbit/S的触发操作。(3)实验证明了垂直腔面发射激光器中的叉叉偏振双稳现象。通过注入具有两个正交偏振的触发光输入，成功地演示了全光触发器的工作。当注入0ﾟ(90ﾟ)触发脉冲时，垂直腔面发射激光器的偏振从90ﾟ(0ﾟ)变为0ﾟ(90ﾟ)。即使在停止注入0ﾟ(90ﾟ)触发脉冲的情况下，0ﾟ(90ﾟ)偏振的激光振荡仍在继续。(4)超快全光触发器操作我们通过注入具有两个正交偏振的光触发脉冲，展示了使用VCSEL的高速全光触发器操作。我们成功地获得了5.3 GHz的全光触发器运转，注入功率仅为-120微瓦，并通过注入锁模钛宝石激光器产生的-3.5ps超短光脉冲获得了双稳态偏振开关。

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.