A Highly Efficient Thermo-Optic Microring Modulator Assisted by Grapheme
Sheng Gan,a Chuantong Cheng,b Yaohui Zhan,c Beiju Huang,b Xuetao Gan,d Shaojuan Li,a Shenghuang Lin,a Xiaofeng Li,c Jianlin Zhao,d Hongda Chen*b and Qiaoliang Bao*a,e
aInstitute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215123, P. R. China.
bState Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China.
cCollege of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Nano Science and Technology, Soochow University, Suzhou 215006, China
dKey Laboratory of Space Applied Physics and Chemistry, Ministry of Education, and Shaanxi Key Laboratory of Optical Information Technology, School of Science, Northwestern Polytechnical University, Xi’an 710072, China
eDepartment of Materials Science and Engineering, Monash University, Clayton, Victoria 3800, Australia
Graphene’s remarkable electrical and optical properties afford great potential for constructing various optoelectronic devices, including modulators, photodetectors and pulse lasers. In particular, graphenebased optical modulators were demonstrated to be featured with a broadband response, small footprint, ultrafast speed and CMOS-compatibility, which may provide an alternative architecture for light-modulation in integrated photonic circuits. While on-chip graphene modulators have been studied in various structures, most of them are based on a capacitance-like configuration subjected to complicated fabrication processes and providing a low yield of working devices. Here, we experimentally demonstrate a new type of graphene modulator by employing graphene’s electrical and thermal properties, which can be achieved with a simple fabrication flow. On a graphene-coated microring resonator with a small active area of 10 μm2, we have obtained an effective optical modulation via thermal energy electrically generated in a graphene layer. The resonant wavelength of the ring resonator shifts by 2.9 nm under an electrical power of 28 mW, which enables a large modulation depth of 7 dB and a broad operating wavelength range of 6.2 nm with 3 dB modulation. Due to the extremely high electrical and thermal conductivity in graphene, the graphene thermo-optical modulator operates at a very fast switching rate compared with the conventional silicon thermo-optic modulator, i.e. 10%–90% rise (90%–10% fall) time of 750 ns (800 ns). The results promise a novel architecture for massive on-chip modulation of optical interconnects compatible with CMOS technology.