基于Add-drop型微环谐振腔的硅基高速电光调制器设计

Design of a high-speed silicon electro-optical modulator based on an add-drop micro-ring resonator

相比于传统的All-pass型微环谐振腔硅基电光调制器,Add-drop型微环谐振腔可提供更多的设计自由度,使调制器在不改变杂质掺杂浓度的情况下就能在调制带宽和消光比性能上获得均衡考虑.本文设计了基于Add-drop型微环谐振腔的高速、且在低调制电压下实现大消光比的硅基电光调制器,所用微环谐振腔的半径仅仅为20μm.重点分析了直波导与微环谐振腔的耦合对调制器性能的影响,发现较小的Drop端耦合系数有利于消光比的提高,但是不能同时达到最佳的调制带宽,因此设计上存在一个带宽和消光比性能上的折中考虑.根据优化设计的结果进行了实际器件的制作和测试.静态光谱测试表明,在3 V反向偏置电压的作用下,调制器的消光比最大可达12 dB.动态电光响应测试中,在仅仅1.2 V的信号幅值电压下测得了8 Gbps数据传输速率的清晰眼图.

Silicon electro-optical modulators based on add-drop micro-ring resonators have the advantage of more freedom in designing high-extinction-ratio and large-bandwidth modulators without changing the ion doping processes of the chip. Here we design a high-speed silicon modulator based on an add-drop micro-ring resonator with a radius of 20 μm; it demonstrates high extinction ratio with low reverse bias. How the coupling between the straight waveguide and the ring resonator affects the performances is studied theoretically and it is found that a lower coupling coefficient at drop port leads to a higher extinction ratio but not the best bandwidth. Therefore, a balance should be considered between extinction ratio and bandwidth. According to the optimized result of the parameters the device is fabricated and tested. The spectrum testing indicates that the device can have 12 dB extinction ratio when it is operated at 3 V reverse bias. Furthermore, we have observed 8 Gbps open-eye diagram with only 1.2 V peak-to-peak signal voltage.