Broadband on-chip SiN lasers

Abstract

Broadband active materials are pivotal for advancing emerging technologies spanning on-chip optical interconnects, artificial intelligence, quantum systems and precision metrology. Current semiconductor gain media face bandwidth limitations; and Ttitanium-doped sapphire (Ti:sapphire), the most widely used broadband light-emitting material, covering the red to short-wave near-infrared (SW-NIR) spectrum, lacking emission in the entire visible range. Here, a mechanism for generating ultra-broadband gain is revealed, which utilizes defect and band-tail states in the bandgap, and balances cavity enhanced reabsorption and radiation. By leveraging this mechanism, the gain of on-chip integrated silicon nitride (SiN) is greatly enhanced at longer wavelengths, thereby achieving broadband emission, from blue light to SW-NIR (approximately 450 nm to 1000 nm), and mode-hop-free tuning about 1.6 nm at about 738 nm and amplification at about 532.3 nm was achieved. By leveraging the maturity, cost-effectiveness, and CMOS compatibility of SiN photonics, this work transitions SiN from conventional passive photonic material to ultrawide-band active medium, establishing a disruptive foundation for next generation visible and SW-NIR integrated photonic platforms.