Hybrid integrated InP-Si₃N₄ diode laser with a 40-Hz intrinsic linewidth

Abstract

We demonstrate a hybrid integrated and widely tunable diode laser with an intrinsic linewidth as narrow as 40 Hz, achieved with a single roundtrip through a low-loss feedback circuit that extends the cavity length to 0.5 meter on a chip. Employing solely dielectrics for single-roundtrip, single-mode resolved feedback filtering enables linewidth narrowing with increasing laser power, without limitations through nonlinear loss. We achieve single-frequency oscillation with up to 23 mW fiber coupled output power, 70-nm wide spectral coverage in the 1.55 µm wavelength range with 3 mW output and obtain more than 60 dB side mode suppression. Such properties and options for further linewidth narrowing render the approach of high interest for direct integration in photonic circuits serving microwave photonics, coherent communications, sensing and metrology with highest resolution.

High-Power (>300 mW) On-Chip Laser With Passively Aligned Silicon-Nitride Waveguide DBR Cavity

“…Analysis of this spectrum reveals integrated and Lorentzian linewidths of 192 kHz and 8 kHz, respectively [19]. The fundamental line width of 8 kHz presented in this study is broader than that reported by others [5], [12], and is not fully understood, but may arise from mode competition within the cavity.…”

Thermally Tuned High-Performance III-V/Si3N4 External Cavity Laser

“…Moreover, the relatively low refractive index contrast of Si3N4 waveguides makes the waveguide propagation loss lower and coupling between the III-V gain chip and the Si3N4 PIC easier, thereby guaranteeing good laser performances. A Si3N4 hybrid laser has been demonstrated with a 40-Hz linewidth and 20-mW output power [32]. A 100-mW high power Si3N4 hybrid laser with a 320-Hz intrinsic linewidth has also been reported [36].…”

“…For the hybrid lasers, various external cavity structures including Fabry-Perot (FP) cavities [24], distributed feedback (DFB) gratings [25], Bragg gratings [26,27], sampled grating distributed Bragg reflectors (SG-DBR) [28], interferometric structures [29], and Vernier microring resonators (MRRs) have been demonstrated on the silicon or Si3N4 platforms [21,[30][31][32]. Among them, the Vernier MRRs-based hybrid external cavity lasers (ECLs) have attracted lots of attention due to the merits of narrow passband response with a large free spectral range (FSR) and a small footprint.…”

Design of an Integrated-Photonics RF Beamformer for Multi-Beam Satellite Synthetic Aperture Radar

“…The laser is built interfacing an InP gain section with a resonator in TriPleX: such structure demonstrated to provide an output power > 20 dBm, with a linewidth < 1 kHz [8]. The laser is first split into two paths.…”