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

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 <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.

Micro-Transfer Printing for Heterogeneous Si Photonic Integrated Circuits

“…The lines are equally spaced by 3 GHz, corresponding to the repetition rate of the laser. More details about heterogeneous III/V-on-SiN mode-locked lasers can be found in the references [25], [26].…”

A Review of Capabilities and Scope for Hybrid Integration Offered by Silicon-Nitride-Based Photonic Integrated Circuits

“…Recent advances in telecom-wavelength lasing based on high-gain GaAs QDs heteroepitaxially grown on Si and SOI substrates with low thresholds and high temperature stability [282], indicate that it is a promising gain material for III-V/SiN monolithic integration and there is a strong possibility that 100 mW level heterogeneous/monolithic III-V/SiN lasers are achievable in the near future. [239,, (c) schematic layout of a heterogeneous III-V/SiN laser and its optical taper between SiN and III-V gain sections [245] and (d) development of linewidth of III-V/SiN lasers [244,246,248,249,252,254,[256][257][258][261][262][263][264]266,267,270,[272][273][274][275][276]279,280,[283][284][285].…”

“…Benefiting from the fast-developing SiN devices, especially resonators with Q up to >200 M [294], a highly precise phase (factor A) and spectral (factor B) feedback [295,296] is achievable in addition to an extended cavity length (thereby reducing ∆ω 0 ), likely to generate ultranarrow linewidth. Figure 11d displays the state-of-the-art linewidth of III-V/SiN-coupled lasers in terms of integration method [244,246,248,249,252,254,[256][257][258][261][262][263][264]266,267,270,[272][273][274][275][276]279,280,[283][284][285]]. It appears that significant progress has been made with hybrid integration when compared to heterogenous/monolithic integration, though the latter started its development at a later stage.…”

“…Figure 11. Development of (a) threshold current and (b) maximum output power of III-V/SiNcoupled lasers[239,, (c) schematic layout of a heterogeneous III-V/SiN laser and its optical taper between SiN and III-V gain sections[245] and (d) development of linewidth of III-V/SiN lasers[244,246,248,249,252,254,[256][257][258][261][262][263][264]266,267,270,[272][273][274][275][276]279,280,[283][284][285].…”

The sound of light: photoacoustics for biomedical applications

“…group at Ghent University, recently created a mode-locked laser-the most popular light source to generate a dual comb-that can be integrated on chip (Figure 5). 2 On-chip integration opens the possibility of miniaturised, stable and low-cost laser sources. Current demonstrations on a silicon platform have shown a limited performance regarding pulse energy, noise and stability due to relatively high waveguide losses and temperature sensitivity of the platform.…”