Silicon-based quantum dot lasers integrated with silicon waveguide monoliths
Silicon-based optoelectronic chips have a wide range of applications in artificial intelligence, hyperscale data centers, high-performance computing, light-emitting(LIDAR) and microwave photonics. Monolithically integrated silicon-based lasers have the advantages of low power consumption and high integration, which are the future development trend of optical interconnects and high-speed optical communication chips. In recent years, the direct epitaxial growth of group III-V quantum dot (QD) lasers on silicon substrates has made remarkable progress, laying a solid foundation for silicon-based optoelectronic integration, but the monolithic integration of silicon-based lasers and optoelectronic devices has not yet been realized.
Jianjun Zhang, Ting Wang, and Zihao Wang at the Institute of Physics, Chinese Academy of Sciences (IPS)/National Research Center for Condensed Matter Physics (NRCP) in Beijing have been focusing on silicon-based on-chip light sources for large-scale silicon-based optoelectronic integration in recent years, and have made significant progress in the direction of silicon-based integratable lasers, which is at the forefront of the relevant international research fields. His representative works in recent years include the realization of the widest flat-topped quantum dot frequency comb laser, with a transmission rate of 4.8 Tbit/s for a four-laser array (Photon. Res. 2022; 10, 1308), and the realization of epitaxial group III-V quantum dot lasers on silicon with narrow linewidth by phase-modulated self-injection locking (Photon. Res. 2022; 10, 1308), as well as the realization of epitaxial group III-V quantum dot lasers on silicon by phase-modulated self-injection locking ( Photon. Res. 2022; 10, 1840); and pioneered the realization of SOI-based monolithically integrated InAs quantum dot single transverse mode lasers (ACS Photon. 2023; 10, 1813). The team has recently collaborated with Yikai Su and Xuhan Guo of Shanghai Jiaotong University and Wenqi Wei of Songshan Lake Materials Laboratory, etc. On the basis of the team's previous high-quality silicon-based III-V materials, the team proposes a silicon-based embedded epitaxy method to integrate InAs/GaAs quantum dot lasers and silicon waveguides on the same SOI substrate (Fig. 1), which successfully passes the light from silicon-based lasers through the The researchers successfully coupled the light from a silicon-based laser to a silicon waveguide through the endface, realizing the monolithic integration of laser and waveguide for the first time, which was evaluated by the reviewer as "an excellent research work with great scientific and technological impacts, and this is a significant progress in the field of integrated photonics".
The researchers investigated the embedded laser's L-I curves at different temperatures and the output power after coupling. The laser excitation temperature in continuous-wave (CW) current operation mode can be up to 95°C or more, with a room-temperature threshold current of about 50 mA, and a maximum output power of 37 mW at an injection current of 250 mA. At an injection current of 210 mA, the embedded laser outputs an optical power of 6.8 mW coupled to a silicon waveguide (Fig. 2). In addition, it was found that edge couplers with multiple tapered tips have higher coupling efficiency and better alignment tolerance than the common reverse-tapered couplers with a single tip due to their spot size that is more similar to the mode profile of the laser.
The results of the study were recently published in Light: Science & Application (Light. Sci. Appl. 12, 84 (2023)), with first authors Wenqi Wei, a postdoctoral fellow at the Institute of Physics, CAS (now an associate researcher at the Songshan Lake Materials Laboratory), Majestic Yang, a doctoral student, Hao Zi, an associate researcher, and An He, a doctoral student at Shanghai Jiaotong University. Dr. Hao Wang, Associate Researcher, and An He, Ph. Corresponding authors are Research Fellow Jianjun Zhang, Associate Research Fellow Ting Wang, Prof. Yikai Su and Associate Prof. Xuhan Guo.
The above research work was supported by the National Key Research and Development Program of China, the National Natural Science Outstanding Youth Fund and the Top-level Fund, and the Youth Promotion Committee of the Chinese Academy of Sciences.
Monolithic Integration of Silicon Based Quantum Dot Lasers with Silicon Waveguides
Figure 1. Laser and waveguide monolithic integrated device
Figure 2. Operating characteristics of SOI-based integrated III-V quantum dot lasers
