Photonic switching integrated circuits based on multi-mode interference couplers and semiconductor active devices

1.开发了基于多本征模展开法的多模干涉耦合器分析与设计仿真软件，并将其命名为MOSIMUL。利用它，我们研究了入射波导以大角度耦合的MMI耦合器，并表明这种耦合器可以用作光子集成电路中的紧凑弯曲器件。MMI半导体光子器件在WDM光子开关中的适用性我们讨论了本研究中的光子开关器件在多大程度上有利于WDM光子开关系统，并发现损耗将提高30dB以上。此外，温度控制设备可以由所有元件共享，不同设备之间的校准可以变得不必要。金属-有机气相扩散增强选择性区域外延作为单片光子集成电路中的一种有源/无源集成技术，我们提出了金属-有机气相扩散增强选择性区域外延（MOVE2）的进一步研究和发展。利用这一技术，我们可以实现1.55 μ m的有源区和无源区带隙差在块状材料中（由于成分变化）可达200nm，在量子阱中（由于成分和厚度变化）可达500nm。这些数字远远大于传统数字。因此，我们期望使无源波导的吸收损耗最小化。利用上述MOVE2工艺，我们首次成功地采用选择性面积外延技术制备了MMI耦合器。采用成分为1.25 μ m的InGaAsP作为芯层，在其顶部用MOVE2形成上层InP覆层。相对于光波传播方向，MMI耦合器在垂直方向上的厚度变化最小，为5%，在平行方向上的厚度变化最小，为10%。光输出不平衡可以忽略不计，30mm长的MMI耦合器的插入损耗为2dB。少

1.Development of software tool MOSIMULWe developed a simulation software for the analysis and design of multi-mode interference (MMI) couplers based on multiple eigen mode expansion method, and named it MOSIMUL.By utilizing it, we studied MMI couplers with their incident waveguides coupled at large angles, and showed that such couplers could be used as compact bending devices in photonic integrated circuits.2.Applicability of MMI semiconductor photonic devices to WDM photonic switchingWe discussed to what extent the photonic switching devices in this research benefit WDM photonic switching systems, and found that more than 30dB improvement in loss would be achieved. Furthermore, temperature control equipment could be shared by all the elements, and alignment between different devices could become unnecessary.3.Development of metal-organic vapor-phase-diffusion-enhanced selective-area epitaxyAs an active/passive integration technology in monolithic photonic integrated circuits, we propo … More sed and developed metal-organic vapor-phase-diffusion-enhanced selective-area epitaxy (MOVE2). By utilizing this technique, we could achieve band gap difference between active and passive regions at 1.55mum as large as 200nm in bulk material (due to composition variation), and as large as 500nm in quantum wells (due to composition and thickness variation). These numbers are by far larger than conventional ones. Therefore, we expect minimizing the absorption loss of passive waveguides.4.First fabrication of MMI couplers by MOVE2We succeeded in fabricating MMI couplers by selective-area epitaxy for the first time, making use of the above MOVE2 process. InGaAsP of 1.25mum composition was used as a core layr, and an upper InP cladding layr was formed by MOVE2 on its top. The thickness variation in the MMI coupler was as low as 5% in perpendicular direction and 10% in parallel direction with respect to the direction of lightwave propagation. Imbalance of light output was negligible, and insertion loss in a 30mum-long MMI coupler was 2dB. Less