Advanced photonic functional materials based on quantum microstructures with atomic scale precision and their application to optical modulation / switching

1.耦合量子阱的电光性质：我们研究了由一对通过薄势垒耦合的量子阱组成的系统中的电吸收。在这种系统中发现了独特的偏振相关性，这似乎对光调制有用，从理论和实验上都得到了发现。制作了基于耦合量子阱的种子双稳光学器件。因此，我们获得了较宽的工作波长范围(-15 nm)和较低的偏置电压(2V)。2.抛物线量子井光调制的偏振不敏感问题：量子井光调制的问题之一是量子限制斯塔克效应(QCSE)的有效质量依赖。我们已经解决了这个问题，把量子势能分布变成了一个有效的悖论分布。首次将抛物量子阱引入光波导光调制器中，实现了准连续波结构的偏振不敏感调制。3.极化…提出了一种新的偏振不敏感的量子阱结构，该结构易于生长，具有较大的加工容限。它由一个插入两个或四个薄势垒的正方形量子阱组成，因此其有效势垒宽度依赖于有效质量。经过理论分析和设计，我们制作了一种具有优良特性的波导调制器，其工作波长范围宽至10 nm，在5V开关电压下的最大消光比高达-28d B。4.在GaAs衬底上生长张拉应变量子阱及其应用：我们发展了一种在GaAs衬底上生长InAlAs衬底(晶格常数大于GaAs)的技术。利用这一技术，首次在GaAs衬底上实现了张应变量子阱。它们已被应用于偏振不敏感的光调制器。其次，研究了将势控结构引入到张应变量子阱中。作为理论分析的结果，我们预测了TE/TM匹配不仅在激子吸收峰值波长上，而且在斯塔克位移上都是完全偏振不敏感的。5.利用量子阱的定向耦合光开关：提出并制作了一种新的横向结构耦合系数调制方案。因此，我们在一个138微米长的器件中实现了5V的开关电压。长度和开关电压的乘积是迄今为止报道过的最小的

1.Electro-optic properties of coupled quantum wells : We have studied electro-adsorption in a system comprising a pair of quantum wells coupled through a thin barrierin between. Unique polarization dependence in such a system which seems useful for optical modulation has been found theoretically and experimentally. SEED bistable optical devices based on the coupled quantum wells have been fabricated. As a result, we have achieved a wide operation wavelength range (-15nm) and a low bias voltage(2V)2.Polarization insensitive optical modulation using parabolic quantum wells : One of the problems in optical modulation with quantum wells is effective mass dependence of the quantum confined Stark effect (QCSE). We have solved the problem by making the potential profile of the quantum well into an effective paradolic profile. Polarization insensitive optical modulation by QCSE has been realized for the first time by introducing the parabolic quantum well to waveguide optical modulators3.Polar … More ization insensitive optical modulation using quantum wells with mass-dependent width : We have proposed a novel quantum well structure with polarization insensitivity which is easy to grow and has larger tabrication tolerance. It consists of a square quantum well with two or four thin barriers inserted, and thereby its effective well width becomes dependent on effective mass. After theoretical analysis and design, we have fabricated a waveguide modulator with excellent characteristics, such as polarization-independent operation wavelength range as wide as 10nm and maximum extinction ratio as large as -28dB at 5V switching voltage4.Growth of tensile strained quantum wells on GaAs substrates and its application : We have developed a technique to grow InAlAs substrates (having a larger lattice constant than GaAs) on GaAs substrates. By using this technique, tensile strained quantum wells are realized on GaAS substrates for the first time. They have been applied to a polarization insensitive optical modulator. Next, introduction of potential controlled structure to the tensile strained quantum wells has been investigated. As a result of theoretical analysis, we have predicted complete polarization insensitivity with TE/TM matching not only in exciton adsorption peak wavelengths but also in Stark shifts.5.Directional coupler optical switch utilizing quantum wells : A novel coupling-coefficient modulation scheme in a transverse structure is proposed and fabricated. Consequently, we have achieved a 5V switching voltage in a 138um-long device. Product of the length and the switching voltage is the smallest ever reported Less