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Study of all optical switch using quantum dots structure

利用量子点结构的全光开关的研究

基本信息

批准号：
15560304
负责人：
SHIMOMURA Kazuhiko
金额：
$ 2.37万
依托单位：
Sophia University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15560304/
关键词：
Quantum dots InAs InP substrate MOVPE Self-assembled Stranski-Krastanow All optical switch Mach-Zehnder 二モード干渉型

项目摘要

In the study of quantum dots (QDs), QDs growth condition which includes previous conditions were investigated at first. To make uniform QDs, we use the phenomenon called Self Size Limiting (SSL), which is effective to arrange QDs size due to appearance of facet on the QDs. To enhance the effect of SSL, we grew QDs at low growth rate and low V/III ratio then we improve uniformity of the QDs on which (631) facet appeared. Next, growth condition for flat surface InP capping layer were investigated Reduction of growth rate and increase of V/III ratio were effective for surface flatness of InP capping layer. We improve surface flatness with the RMS value of 0.4nm. After then, optical property of the uniform QDs were investigated by PL spectra compared with conventional QDs. As the results, great improvement of FWHM as 40meV due to SSL was observed However, red shift of peak wavelength due to increase volume of the QDs was observed. We attempted to fabricate 2, 3, 5 stacking structure with InP spacing layer to investigate the dependence of stacking number and GaInAs under layer to QDs. At first, by inserting GaInAs under layer, In migration from under layer were prevented resulted in suppression of increase of QDs size. When we increase stacking number, QDs became large and low density with blue shift according to PL spectra It would be attributed to strain effect. In the study of all optical switch, we measured the nonlinear absorption and refractive index change in the waveguide grown by selective MOVPE growth. In the measurement of absorption loss by using the Fabry-Perot method, the absorption coefficient was more than 90cm^<-1> in the active region and less than 40cm^<-1> in the passive region. In the measurement of nonlinear refractive index change, we measured 0.025% refractive index change by using Mach-Zehnder interferometer And we have successfully obtained the all optical switching characteristics in the Mach-Zehnder type optical switch.

在量子点的研究中，首先考察了量子点的生长条件，包括前面的条件。为了制备均匀的量子点，我们使用了称为自尺寸限制（SSL）的现象，由于量子点上的刻面的出现，该现象有效地排列量子点的尺寸。为了增强SSL的效果，我们在低生长速率和低V/III比下生长量子点，然后提高量子点的均匀性，在量子点上出现（631）面。接着，研究了平坦表面InP覆盖层的生长条件。生长速率的降低和V/III比的增加对于InP覆盖层的表面平坦性是有效的。我们改善了表面平整度，RMS值为0.4nm。然后，通过光致发光谱研究了均匀量子点的光学性质，并与常规量子点进行了比较。结果表明，由于SSL的存在，半高宽得到了很大的提高，达到了40 meV，但是由于量子点体积的增加，峰值波长发生了红移。我们尝试以InP为间隔层制作2、3、5层堆叠结构，研究量子点的堆叠数和GaInAs底层对量子点的依赖性。首先，通过插入GaInAs底层，阻止了In从底层的迁移，从而抑制了量子点尺寸的增加。随着量子点堆积数的增加，量子点体积变大，密度变低，PL谱发生蓝移，这可能是由于应变效应的影响。在全光开关的研究中，我们测量了选择性MOVPE生长的波导的非线性吸收和折射率变化。在利用法布里-珀罗法测量吸收损耗时，吸收系数在有源区大于90 cm-3<-1>，在无源区小于40 cm-3<-1>。在非线性折射率变化的测量中，我们用马赫-曾德尔干涉仪测量了0.025%的折射率变化，成功地获得了马赫-曾德尔型光开关的全光开关特性。