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Publication . Article . Preprint . 2021 . Embargo end date: 01 Jan 2021

Ultralow-noise frequency-agile photonic integrated lasers

Lihachev, Grigory; Riemensberger, Johann; Weng, Wenle; Liu, Junqiu; Tian, Hao; Siddharth, Anat; Snigirev, Viacheslav; +4 Authors
Open Access
Published: 07 Apr 2021
Publisher: arXiv

Low-noise lasers are of central importance in a wide variety of applications, including high spectral-efficiency coherent communication protocols, distributed fibre sensing, and long distance coherent LiDAR. In addition to low phase noise, frequency agility, that is, the ability to achieve high-bandwidth actuation of the laser frequency, is imperative for triangular chirping in frequency-modulated continuous-wave (FMCW) based ranging or any optical phase locking as routinely used in metrology. While integrated silicon-based lasers have experienced major advances and are now employed on a commercial scale in data centers, integrated lasers with sub-100 Hz-level intrinsic linewidth are based on optical feedback from photonic circuits that lack frequency agility. Here, we demonstrate a wafer-scale-manufacturing-compatible hybrid photonic integrated laser that exhibits ultralow intrinsic linewidth of 25 Hz while offering unsurpassed megahertz actuation bandwidth, with a tuning range larger than 1 GHz. Our approach uses ultralow-loss (1 dB/m) Si$_3$N$_4$ photonic microresonators, combined with aluminium nitride (AlN) or lead zirconium titanate (PZT) microelectromechanical systems (MEMS) based stress-optic actuation. Electrically driven low-phase noise lasing is attained by self-injection locking of an Indium Phosphide (InP) laser chip and only limited by fundamental thermo-refractive noise. By utilizing difference drive and apodization of the photonic chip, a flat actuation response up to 10 MHz is achieved. We leverage this capability to demonstrate a compact coherent LiDAR engine that can generate up to 800 kHz FMCW triangular optical chirp signals, requiring neither any active linearization nor predistortion compensation, and perform a 10 m optical ranging experiment, with a resolution of 12.5 cm.


Optics (physics.optics), Applied Physics (, FOS: Physical sciences, Physics - Optics, Physics - Applied Physics

Funded by
Developement of compact single-cycle light sources
  • Funder: European Commission (EC)
  • Project Code: 846737
  • Funding stream: H2020 | MSCA-IF-EF-ST
EC| TeraSlice
Terahertz Analogue-to-Digital Conversion Using Photonic Chipscale Soliton Frequency Combs and Massively Parallel Spectrally Sliced Detection
  • Funder: European Commission (EC)
  • Project Code: 863322
  • Funding stream: H2020 | RIA