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Energy efficient optical frequency combs based on photonic integrated resonators and temporally structured pump light

English title Energy efficient optical frequency combs based on photonic integrated resonators and temporally structured pump light
Applicant Kippenberg Tobias Jan
Number 176563
Funding scheme Bridge - Discovery
Research institution Laboratoire de photonique et mesures quantiques EPFL - STI - IEL - LPQM2
Institution of higher education EPF Lausanne - EPFL
Main discipline Other disciplines of Physics
Start/End 01.05.2018 - 30.04.2022
Approved amount 1'150'603.00
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All Disciplines (2)

Other disciplines of Physics
Microelectronics. Optoelectronics

Keywords (3)

Photonic Damascene fabrication process; Silicon Nitride microresonators; electro-optic comb

Lay Summary (French)

Ce projet vise à développer des sources de peignes de fréquences ultra-cohérents à meilleure efficacité énergétique en utilisant des microrésonateurs miniaturisés aux pertes réduites pompés par de la lumière structurée temporellement.
Lay summary

Il a été démontré qu’il est possible de générer de façon déterministe des solitons temporels à l’intérieur d’une micro-cavité optique en l’illuminant avec un laser continu. Ceci permet la génération de peignes de fréquences optiques de très grande cohérence sur un large domaine spectral. Bien que ce phénomène ait été démontré dans plusieurs types de micro-résonateurs, la faible efficacité énergétique de ces sources lasers limitent grandement leur développement dans des applications concrètes.

Ce projet vise donc à optimiser de façon significative l’efficacité énergétique des peignes de fréquences basés sur des micro-résonateurs miniaturisés au Nitrure de Silicium. Premièrement, il s’agit d’exploiter le nouveau procédé de fabrication inventé par l’EPFL pour réaliser des micro-résonateurs aux surfaces plus régulières, et présentant ainsi moins de pertes. L’autre objectif est d’employer la technique de pompage nouvellement démontrée par le CSEM qui consiste à utiliser une lumière de pompe impulsionnel permettant d’optimiser le recouvrement temporel avec le soliton pour augmenter l’efficacité générale du processus de génération du peigne.

Les peignes de fréquences miniaturisés basés sur des micro-résonateurs fournissent à la fois un grand nombre de porteuses optiques cohérentes, et un taux de répétition au-delà du GHz. Ceci est particulièrement attractif pour le domaine des télécommunications qui requiert la combinaison de multiples signaux sur différents canaux pour augmenter le débit de transfert des données. Cependant cela n’est jusqu’alors pas possible avec les peignes de fréquence commerciaux actuels.

Direct link to Lay Summary Last update: 11.04.2018

Responsible applicant and co-applicants


Associated projects

Number Title Start Funding scheme
165933 Microresonators based Frequency combs: exploring temporal solitons 01.03.2017 Project funding (Div. I-III)
161573 Photonic Damascene Fabrication Process for High Q integrated SiN Photonic Circuits 01.04.2016 precoR


Photonic integrated circuits (PIC), i.e. photonic waveguide technology fabricated via established semiconductor processing, have within a time frame of about 15 years, transitioned from research into commercial applications, such as optical data centers. Currently, a further PIC technology is at the crossroad of making this transition in the coming years: Specifically, Kerr-nonlinear silicon nitride (Si3N4) microresonator based frequency comb generators. Such compact, chip-scale combs are a disruptive technology to various fields with applications in broadband, coherent optical spectroscopy, optical coherence tomography, timekeeping, signal generation, optical sensing and laser ranging as well as high-bandwidth optical telecommunication. The present research consortium (EPFL & CSEM) have been at the forefront of these technological developments, which include the first demonstration of low noise ultra-short soliton pulse sources in PIC (EPFL, Science 2015 & Nature Photonics 2013), ultra-efficient pulsed optical pumping of microresonators (CSEM, Nature Photonics 2016, in revision) and most recently coherent optical communication over 70 km with data rates exceeding 30 Tb/s using EPFL’s chip based frequency comb generators 5 (Nature, 2017, in press). An important advance towards the commercial use of Si3N4 nonlinear photonic waveguides has been the development of novel fabrication method, the photonic damascene process, at EPFL that has overcome the materials processing issue related to the high stress. This process, developed and optimized in the precoR program, is now transitioning outside of the laboratory, and part of the process portfolio of LiGenTec SA, a spinoff from EPFL that is making Si3N4 widely available to academics and industry alike. EPFL’s photonic damascene process6, the generation of ultra-short soliton pulses, as well as CSEM’s pulsed optical pumping have been filed as EU and US patents. Yet to date, photonic chipscale frequency combs are not yet part of a commercial product or development. Indeed, the key challenges for the commercialization of chip-scale frequency combs are predominantly their low energy efficiency, which affects optical packaging, choice of availability of laser modules and determines long-term full photonic integration on a chip, and finally market potential for telecommunications. In this project, we aim to address these challenges via two routes that complement each other:First, EPFL will develop novel techniques to produce low loss dispersion engineered photonic integrated waveguides, both with regard to resonator geometry as well as material. Specifically, the resonator’s quality-factor and mode dispersion will be improved to enable broadband optical soliton spectra at significantly lower threshold power than presently the case. A key challenge, that of efficient input coupling to the PIC, will be solved via a novel 3D tapered waveguide. Second, CSEM will develop pulsed optical pumping for driving and controlling ultra-short soliton pulses in the PIC fabricated by EPFL. Pumping the PICs with temporally structured light will not only allow for substantial reduction of required pump laser power, but will also allow for control and stabilization of soliton pulse number, soliton repetition rate and carrier-envelope offset frequency.The outcome of the project will provide the technology for compact PIC based frequency combs with 2-4 orders of magnitude increased energy efficiency and intrinsic stabilization bridging the gap between academic research and commercialization of PIC based frequency comb generators.