A photonic integrated circuit–based erbium-doped amplifier

TLDR

Erbium‑doped fiber amplifiers have transformed long‑haul optical communications and laser technology, yet integrating erbium ions into photonic circuits remains impractical due to insufficient output power. The study aims to demonstrate a photonic integrated circuit–based erbium amplifier that overcomes this output‑power limitation. The authors use ion implantation of erbium into ultralow‑loss silicon nitride photonic integrated circuits, boosting soliton microcomb output power by 100× to meet low‑noise microwave generation and wavelength‑division multiplexing needs. The integrated erbium amplifier delivers 145 mW output power and >30 dB small‑signal gain, matching commercial fiber amplifiers and exceeding III‑V semiconductor amplifiers, and its gain enables miniaturization of fiber‑based devices such as high‑pulse‑energy femtosecond lasers.

Abstract

Erbium-doped fiber amplifiers revolutionized long-haul optical communications and laser technology. Erbium ions could provide a basis for efficient optical amplification in photonic integrated circuits but their use remains impractical as a result of insufficient output power. We demonstrate a photonic integrated circuit-based erbium amplifier reaching 145 milliwatts of output power and more than 30 decibels of small-signal gain-on par with commercial fiber amplifiers and surpassing state-of-the-art III-V heterogeneously integrated semiconductor amplifiers. We apply ion implantation to ultralow-loss silicon nitride (Si3N4) photonic integrated circuits, which are able to increase the soliton microcomb output power by 100 times, achieving power requirements for low-noise photonic microwave generation and wavelength-division multiplexing optical communications. Endowing Si3N4 photonic integrated circuits with gain enables the miniaturization of various fiber-based devices such as high-pulse-energy femtosecond mode-locked lasers.