New Functional Optical Cross Connect using Quantum Dots Structure

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In WDM networks, key components are the wavelength multi-/demultiplexers, which combine/separate wavelength channels. Various kind of demultiplexing principles have been proposed and already commercially available, such as arrayed-waveguide gratings (AWG). In the latest paper, we have proposed a novel wavelength demultiplexer using a GaInAs/InP multiple quantum well (MQW) arrayed waveguide in which refractive index varies linearly across the array. The conventional AWGs are designed so that phase differences between adjacent waveguides are obtained by gradually varying waveguide length. In the proposed design, however, phase differences between adjacent waveguides are achieved by varying the waveguide thickness which is the refractive indices of the waveguides. Therefore, it is possible to be realized a straight waveguide type wavelength demultiplexer. Furthermore, the device could be applied to wavelength switching since the refractive indices of the waveguides in the array can be con … More trolled dynamically by QCSE or TO effect. On the other hand, self-assembled semiconductor quantum dots (QDs) grown via the Stranski-Krastanov (S-K) growth mode have attracted much attention for the monolithic integration of QD devices. To realize wide wavelength range QDs in a single integrated optical device, a technique to control self-assembled QDs size in the same plane is important. In this project, we have studied the wavelength switch with refractive index varied arrayed waveguide using quantum dots in the waveguide core. In the wavelength switch using MQW structure, we have successfully demonstrated the wavelength switching in the straight arrayed waveguide with linearly varying refractive index distribution by changing the refractive index using thermo-optic effect. We have obtained the wavelength demultiplexing and its changing of the output ports by refractive index change in the waveguide. In the study of quantum dots, we have obtained the 140 nm wavelength emission range from the self-assembled InAs QDs array waveguides on the InP substrate by employing the selective MOVPE growth using asymmetrical mask and the double-cap procedure of QDs. These results are very effective for the realization of optical cross connects in the optical communication system. Less