Optical Switching

3Thermo‐Optical Switches

Fulong Yan¹, Xuwei Xue², and Chongjin Xie³

¹ Alibaba Cloud, Alibaba Group, Beijing, China

² State Key Laboratory of Information Photonics and Optical Communications (IPOC), Beijing University of Posts and Telecommunications, Beijing, China

³ Alibaba Cloud, Alibaba Group, Sunnyvale, CA, USA

3.1 History of Thermal Optical Switching

The electro‐optical effect has been used to design and implement fast optical switching from 1970s [1]. Although people noticed the thermo‐optical effect almost at the same time, the thermal effect was regarded as undesirable and is generally considered to cause a deterioration in operation performance. In addition, due to the slow switching speed of the thermo‐optic effect, it was not until the 1980s that people began to study the area of thermo‐optic switching [2].

In 1981, lithium niobate (LiNb03) [2] and ion‐exchanged glass [3] were used to fabricate thermo‐optical devices. However, the thermo‐optical effects of these two materials were relatively weak, resulting in inefficient devices. Benefiting from its strong thermo‐optical effect and low thermal conductivity, polymer was regarded a suitable material for fabricating thermo‐optical devices [4, 5], and many researchers focused on the manufacturing of polymer‐based and silica‐based thermo‐optical switches [6, 7].

Recently, a compact (15 μm × 15 μm) and a highly‐optimized 2 × 2 silicon thermo‐optic switch device was proposed. It achieved power consumption of <3 mW and a ...