Semiconductor Optical Switches Utilizing Thickness Modulation in Depletion Layer

本课题旨在研制半导体光开关/调制器，为光通信系统和光信息处理技术的进一步发展奠定基础。我们的开关的工作机制是基于作者新提出的p-n结周围的耗尽吸收变化。制作了两种不同类型的开关。一种是波导型，另一种是面板型。随着光波导型开关的发展，在外加电压为8V的情况下获得了3%的透过率变化，达到了1990年透过率变化的99.97%(35dB)，这可能是所有电子机械工作的光开关中的最高纪录。我们取得进展的原因来自于对晶体生长过程中杂质原子扩散效应的诚实研究和对…设计方法的改进更多的设备。通过多次测试，验证了基于上述机理制作的器件的工作状态。该器件的调制带宽为10 MHz，具有很好的电容特性。通过制作多层结构和窄条纹结构来减小电容，未来调制带宽可能会更宽。我们还制作了取代波导型的面板型结构。由于用液相外延生长晶体的技术困难，我们制作了由两组p-n结组成的初步结构，尽管面板的最终结构应该包括大量的p-n结。连接三个器件，即由6组结点组成，当外加电压为18V时，观察到10%的入射光变化。我们将通过改变电压施加方式和制作多层结构来改进器件。我们将我们的器件命名为EDAC(电子耗尽吸收控制)光开关/调制器。较少

This research project was to fabricate semiconductor optical switches/modulators for further development of optical communication system and optical information processing. The operating mechanism of our switches is based on the absorption change by depleting around the p-n junction, which is newly proposed by the authors. Two different types of the switch were fabricated. One is the wave-guide type and another is the panel type. Both types were made of AlGaAs/GaAs alloy system grown with the liquid phase epitaxy.As the progress of the wave-guide type switches, 3% change of the transmission was obtained with 8V variation of the applied voltage in 1989, and reached to 99.97% (35dB) of the change in 1990, which may be the top record in world among all optical switches operating with any electronic mechanism. The reason of our progress comes from honest investigation on the diffusion effect of the impurity atom caused under the crystal growth and improvement of the designing method of the … More device. We confirmed the operation of the fabricated device based on the above mentioned mechanism through several measurements. The modulation band width of the device was several 10MHz, which was well characterized with the electric capacitance. By reducing of the capacitance by makiing multi-layer structure as well as narrow stripe structure, the modulation band width may be more widened in future.We also fabricated the panel type structure in succeeding to the wave-guide type. We fabricated preliminary structure consisting with two sets of the p-n junctions because of technical difficulty on crystal growth with liquid phase epitaxy, although the final structure of the panel should consist with large number of the p-n junctions. Connecting three pieces of the device, that is, consisting of 6 sets of the junctions, 10% change of the incident light was observed with 18V variation of the applied voltage. We will improve the device by changing the voltage applying method and making the multi-layer structure in future.We named our device as EDAC (Electron Depleting Absorption Control) Optical Switch/Modulator. Less