Hybrid quantum-dot microring laser on silicon

Abstract

Future high-performance computers demand highly dynamic data rates, e.g., a few terabytes per second communication bandwidth between switch hubs, and hundreds of gigabytes per second bandwidth between nodes and hubs, in order to overcome the challenges to rapidly growing traffic. Integrated photonic interconnect on silicon is believed to be one of the best solutions for low-cost, energy efficient, and high-speed data communications because of its fundamental advantages in high-volume throughput and dense integration. Applied with signal multiplexing techniques, e.g., wavelength division multiplexing (WDM), large bandwidth data links have been proved to be achievable on silicon. In such a system, an on-chip, robust, low-power consumption laser source is the key component as well as one of the fundamental limits to the silicon platform. In this work, we report the first hybrid silicon microring lasers with quantum-dot (QD) gain material to show great potential for uncooled, highly energy efficient, and isolator-free operation. The hybrid silicon QD lasers have a microring cavity with a 50 μm diameter that incorporates InAs/GaAs QD gain material at a 1.3 μm emission wavelength. The threshold current is as low as 0.7 mA under continuous wave (CW) operation at room temperature, and the laser operates at stage temperatures of up to 70°C. We demonstrate, to the best of our knowledge, a hybrid QD laser with non-return-to-zero (NRZ) communication at a record-high direct modulation rate of 15 Gb/s with energy efficiency of 1.2 pJ/bit. We believe this work shows huge benefits from superior QD lasing material and hybrid photonic integration not only for data communications but also optical memory and many other emerging applications.