Can 2D materials enable passively $Q$-switched lasers in the nanoscale?

TL;DR

This paper investigates the potential of 2D materials to enable compact, passively Q-switched nanophotonic lasers on-chip, demonstrating high repetition rates, short pulses, and tunability through a theoretical framework.

Contribution

It develops a comprehensive theoretical model to analyze 2D materials as gain and saturable absorbers in nanolasers, revealing their capability to achieve high-performance pulsed laser operation.

Findings

Repetition rates up to 50 GHz are achievable.

Pulse durations can be as short as a few picoseconds.

Peak power can exceed several milliwatts.

Abstract

Achieving compact on-chip pulsed lasers with attractive performance metrics and compatibility with the silicon photonics platform is an important, yet elusive, goal in contemporary nanophotonics. Here, the fundamental question of whether 2D materials can be utilized as both gain and saturable absorption media to enable compact integrated passively Q-switched nanophotonic lasers is posed and addressed by examining a broad range of 2D material families. The study is conducted by developing a temporal coupled-mode theory framework involving semi-classical rate equations that is capable of rigorously handling gain and saturable absorption by 2D materials, allowing to perform stability and bifurcation analysis covering broad parameter spaces. The range of pulse-train metrics (repetition rate, pulse width, peak power) that can be obtained via different 2D materials is thoroughly assessed. Our work illustrates that nanophotonic cavities enhanced with 2D materials can enable passive Q-switching with repetition rates ranging up to 50~GHz, short pulse duration down to few picoseconds, and peak power exceeding several milliwatts. Such attractive metrics, along with the ultrathin nature of 2D materials and the ability to electrically tune their properties, demonstrate the potential of the proposed platform for compact and flexible integrated laser sources.