High-pulse-energy III-V-on-silicon-nitride mode-locked laser

Artur Hermans,Kazuya Hisada,Bart Kuyken,Xavier Rottenberg,Jon Ø Kjellman,Philippe Soussan,Yasuhisa Inada,Sulakshna Kumari,Günther Roelkens,Aleksandrs Marinins,Roelof Jansen,Taku Hirasawa,Stijn Cuyvers,Charles Caër,Kasper Van Gasse,Tasuku Nakamura

doi:10.1063/5.0058022

Abstract

Mode-locked lasers find their use in a large number of applications, for instance, in spectroscopic sensing, distance measurements, and optical communication. To enable widespread use of mode-locked lasers, their on-chip integration is desired. In recent years, there have been multiple demonstrations of monolithic III-V and heterogeneous III-V-on-silicon mode-locked lasers. However, the pulse energy, noise performance, and stability of these mode-locked lasers are limited by the relatively high linear and nonlinear waveguide loss, and the high temperature sensitivity of said platforms. Here, we demonstrate a heterogeneous III-V-on-silicon-nitride (III-V-on-SiN) electrically pumped mode-locked laser. SiN’s low waveguide loss, negligible two-photon absorption at telecom wavelengths, and small thermo-optic coefficient enable low-noise mode-locked lasers with high pulse energies and excellent temperature stability. Our mode-locked laser emits at a wavelength of 1.6 μm, has a pulse repetition rate of 3 GHz, a high on-chip pulse energy of ≈2 pJ, a narrow RF linewidth of 400 Hz, and an optical linewidth &lt;1 MHz. The SiN photonic circuits are fabricated on 200 mm silicon wafers in a CMOS pilot line and include an amorphous silicon waveguide layer for efficient coupling from the SiN to the III-V waveguide. The III-V integration is done by micro-transfer-printing, a technique that enables the transfer of thin-film devices in a massively parallel manner on a wafer scale.

Highlights

Mode-locked lasers are extremely versatile tools that can be used for distance measurements, spectroscopy, telecommunication, and astronomical spectrograph calibration, among others.1–6 In many of these applications, bulky and expensive solid-state or fiber lasers are still the go-to solutions
Pumped, on-chip mode-locked lasers have been demonstrated in heterogeneous III-V-on-silicon and monolithic III-V technology
The III-V integration is done by micro-transfer-printing, a technique that enables the transfer of thin-film devices in a massively parallel manner on a wafer scale

Summary

INTRODUCTION

Mode-locked lasers are extremely versatile tools that can be used for distance measurements, spectroscopy, telecommunication, and astronomical spectrograph calibration, among others. In many of these applications, bulky and expensive solid-state or fiber lasers are still the go-to solutions. The use of long extended cavities allows for the realization of on-chip mode-locked lasers with relatively low pulse repetition rates (repetition rates down to 1 GHz have been demonstrated10), a desirable feature for high-resolution spectroscopy and distance metrology with a large non-ambiguity range.. The use of long extended cavities allows for the realization of on-chip mode-locked lasers with relatively low pulse repetition rates (repetition rates down to 1 GHz have been demonstrated10), a desirable feature for high-resolution spectroscopy and distance metrology with a large non-ambiguity range.11 These on-chip extended-cavity mode-locked lasers typically have pulse energies limited to several 100 fJ and RF linewidths >1 kHz.. Our results represent first steps toward high-pulse-energy, low-noise, mass-manufacturable on-chip mode-locked lasers, which we envision to be used for ranging and remote sensing These mode-locked lasers may serve as on-chip sources for resonant supercontinuum generation in low-loss SiN cavities.

DESIGN

FABRICATION

CHARACTERIZATION AND DISCUSSION

Findings

CONCLUSION