Mode-Locked Lasers Research Papers
Ultrafast mode-locked laser in nanophotonic lithium niobate
Authors: Qiushi Guo, Benjamin K. Gutierrez, Ryoto Sekine, Robert M. Gray, James A. Williams, Luis Ledezma, Luis Costa, Arkadev Roy , Selina Zhou, Mingchen Liu, and Alireza Marandi
Publisher: Science
Executive Summary
Mode-locked lasers are foundational technologies for modern photonics, generating ultrashort pulses and highly coherent optical frequency combs that enable applications ranging from precision metrology and spectroscopy to optical communications, nonlinear optics, and photonic computing. While these systems have traditionally relied on bulky laboratory-scale equipment, integrating high-performance mode-locked lasers onto a photonic chip has remained a significant challenge due to limitations in output power, pulse quality, and tunability.
This research demonstrates a high-performance, electrically pumped mode-locked laser integrated on a thin-film lithium niobate photonic platform through hybrid integration with a III-V semiconductor optical amplifier. By combining the high optical gain of III-V materials with the efficient electro-optic modulation capabilities of lithium niobate, the device generates stable picosecond optical pulses with energies exceeding 2.6 picojoules and peak powers greater than 0.5 watts at a repetition rate of approximately 10 GHz. These performance metrics represent one of the highest-output integrated mode-locked laser demonstrations on a nanophotonic platform.
A key innovation of this architecture is the separation of optical gain and mode-locking into two optimized components. Rather than relying on conventional semiconductor laser designs that tightly couple these functions, the hybrid approach enables significantly greater output power, broader operating flexibility, and precise electrical control of both the repetition rate and optical carrier frequency. This level of tunability provides a practical path toward fully stabilized chip-scale frequency combs, an essential capability for precision timing, sensing, and scientific measurement systems.
Beyond demonstrating a compact integrated laser source, this work establishes thin-film lithium niobate as a powerful platform for ultrafast photonic systems. The generated pulses provide sufficient peak power to directly drive a wide range of nonlinear optical processes that previously required much larger laboratory lasers. As a result, the mode-locked laser can serve as an integrated light source for advanced photonic circuits while remaining compatible with scalable semiconductor manufacturing.
This breakthrough significantly advances the development of fully integrated ultrafast photonic systems by combining high peak power, electrical tunability, and chip-scale integration within a single platform. The demonstrated architecture opens new opportunities for on-chip frequency combs, precision spectroscopy, optical atomic clocks, supercontinuum generation, nonlinear photonics, and photonic computing. By bringing laboratory-class ultrafast laser performance onto an integrated chip, this research represents an important step toward scalable, high-performance photonic systems for scientific, industrial, and commercial applications.