Advanced progress on χ(3) nonlinearity in chip-scale photonic platforms

χ(3) nonlinearity enables ultrafast femtosecond scale light-to-light coupling and manipulation of intensity, phase, and frequency. χ(3) nonlinear functionality in micro-and nano-scale photonic waveguides can potentially replace bulky fiber platforms for many applications. In this Review, we summarize and comment on the progress on χ(3) nonlinearity in chip-scale photonic platforms, including several focused hot topics such as broadband and coherent sources in the new bands, nonlinear pulse shaping, and all-optical signal processing. An outlook of challenges and prospects on this hot research field is given at the end

Frequency- and amplitude- modulated semiconductor laser frequency combs

Chip-scale coherent semiconductor light sources generating optical frequency combs currently revolutionize mid-infrared on-chip spectroscopy, near-infrared optical communications and nonlinear microscopy. Their key advantages is the efficient generation of narrow and equidistant spectral lines or laser modes with a fixed phase relationship across a broadband spectral region. An attractive realization of such combs is based on nanostructured semiconductor lasers with semiconductor quantum dots forming their active region. In this thesis, frst, the formation of two types of optical frequency combs in a semiconductor quantum dot laser is presented: in-phase synchronization of the intermode beatings, leading to optical pulses, and the splay-phase synchronization, leading to quasi continuous wave optical output. Both states can be generated on demand in a single semiconductor laser. By varying the laser design and the biasing conditions, frequency- and amplitude-modulated combs can be generated on demand. Second, based on their identifed particular temporal characteristics, a novel technique to determine the sensitivity of semiconductor laser frequency combs to optical feedback, is presented. Results suggest, that amplitude-modulated semiconductor laser frequency combs are less sensitive to optical feedback than frequency-modulated semiconductor laser frequency combs. The developed insights are expected to elevate semiconductor laser frequency combs in current and future integrated photonic circuits in optical communications, where unavoidable optical feedback from downstream active and passive components deteriorates comb stability

Conception de laser et capteur distribué de température par cascade d'ondes Stokes Brillouin stimulées

La diffusion Brillouin fut prédite au début des années vingt par Léon Brillouin. Cette dernière décrit le comportement émanant de l’interaction lumière matière où une partie de l’énergie de la lumière est transférée au matériau sous la forme d’une onde acoustique thermique (phonon). Cet effet non linéaire d’ordre 3 est l’un des plus faciles à générer dans les fibres optiques où à saturation, la majorité de la puissance incidente est transférée vers l’onde Stokes rétrodiffusée, ce qui par le fait même limite la puissance de transmission maximale pouvant être envoyée. Vue initialement comme un problème majeur pour le réseau de télécommunication mondial, de nos jours, la diffusion Brillouin, ainsi que son homologue stimulé (SBS), sont employées dans une foule d’applications. Entre autres, la SBS sert de source laser monomode à faible largeur spectrale ou encore comme laser multicanal par un effet en cascade des ondes Stokes, comme amplificateur optique et filtre radiofréquence, ainsi que comme capteur distribué de température ou contraintes et bien plus encore. Le sujet de cette thèse porte sur la conception, la fabrication, la modélisation ainsi que l’utilisation de lasers Brillouin multi-Stokes (MWBEFL) et se divise en deux sections. Dans la première section, une analyse complète appuyée par une modélisation mathématique décrit le comportement fréquentiel et principalement temporel des lasers MWBEFL. Bien que ce type de génération en cascade existe depuis deux décennies et de nombreuses configurations aient été proposées par le passé, une analyse temporelle exhaustive est manquante dans la littérature, ce qui est par ailleurs présenté à l’article 1. La grande conclusion de cet article 1 est que bien qu’attrayant tant comme source WDM ou comme horloge optique pour les télécommunications, les lasers MWBEFLs à longue cavité sont loin d’être simple à opérer de façon stable temporellement. Ceci est dû à la trop grande présence de modes de cavité sous chaque onde Stokes influençant aléatoirement le transfert d’énergie, la fréquence centrale des ondes Stokes ainsi que leur phase relative. La compétition de modes, les sauts de modes ainsi que l’opération multimode et les fluctuations thermiques sont toutes responsables de l’instabilité temporelle de ce type de laser. Des pistes de solutions employant un MWBEFL à courte cavité n’allouant qu’un seul mode de cavité par onde Stokes est proposé en conclusion de cette section. Lors des articles 2 et 3 présentés dans le cadre de cette thèse et composant la seconde section du travail, une attention est portée à l’intégration des sources MWBEFLs comme senseur de température.----------Abstract Brillouin scattering was predicted at the beginning of the twenty-first century by Leon Brillouin. It describes the behaviour emanating from light-matter interaction where part of the energy of the light is transferred to the material in the form of an acoustic thermal wave (phonon). This nonlinear effect of 3rd order is one of the easiest to be generated in optical fibers where at saturation, the majority of the incident power is transferred to the backscattered Stokes wave. This drastically limits the maximum power transmitted through this media. Originally seen as a major problem for global telecommunication networks, nowadays Brillouin scattering (BS), as well as its stimulated counterpart (SBS), are employed in a number of applications. Among other things, SBS serves as a single-mode laser source with a narrow spectral width or as a multichannel laser by a cascade process of Stokes waves, or as an optical amplifier and a radio frequency filter, as well as a distributed temperature or strain sensor and much more. The subject of this thesis is the design, fabrication, modelling and use of multi-Stokes Brillouin lasers (MWBEFL) and is divided into two sections. In the first section, a complete analysis supported by a mathematical model describes the frequency and mainly temporal behaviour of the MWBEFL lasers. Although this cascading process has been investigated for over two decades and many configurations have been proposed in the past, an exhaustive temporal analysis is missing from the literature, which is also presented in the 1st article. The general conclusion of article 1 is that while attractive as both, a WDM source or as an optical clock for telecommunications, MWBEFLs long cavity lasers are far from simple to operate in a temporally stable manner. This is due to the excessive presence of cavity modes under each Stokes wave randomly influencing the energy transfer, the central frequency of each Stokes waves as well as their relative phases. Mode competition, mode hops, as well as multimode operation and thermal fluctuations are all responsible for the temporal instability of this type of laser. Solutions using a short cavity MWBEFL that allows only one cavity mode per Stokes wave are proposed at the end of this section. In articles 2 and 3 presented as part of this thesis and composing the second section of this work, attention is paid to the integration of an MWBEFL source as a temperature sensor. A new method in the already rich universe of Brillouin based sensors is proposed with a completely new approach by using higher order Stokes waves to improve the sensitivity of the detector compared to the literature and to commercially available products