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Fibre lasers display complex dynamical regimes which involve nonlinear interactions of millions of cavity modes. Recently, the transition to “optical turbulence” [1] (in analogy with the laminar-turbulence transition in hydrodynamic) was experimentally studied and was shown to be a phase transition which is accompanied by the occurrence of temporal correlations in the laser intensity with specific...
Photoacoustic microscopy (PAM) is a promising imaging modality that combines optical and ultrasound imaging. It combines the advantages of high ultrasonic spatial resolution and high optical contrast. When a short laser pulse illuminates the tissue, absorbed light leads to an acoustic emission via thermoelastic expansion [1]. The laser system needs to generate short enough pulses, i.e., several nanoseconds,...
Ring-type and whispering-gallery mode microresonators combine strong light confinement with high optical non-linearity to give rise to and enable efficient nonlinear optical parametric frequency conversion processes [1], stimulated Brillouin and Raman scattering.
Mid-infrared coherent sources at 3–4 μm have a wide variety of applications that include, but are not limited to gas sensing, material processing and production control. The MgO-doped periodically poled lithium niobate (MgO:PPLN) crystal is a well-known nonlinear element for quasi-phase-matched optical parametric oscillators (OPOs) typically pumped by 1-μm laser radiation [1]. However, strong multi-phonon...
Spectral compression (SC) by self-phase modulation in optical fibre has been known for a long time and has since been reported for various parameters [1]. In this paper, we analyse the impact of amplitude fluctuations and a degraded optical signal-to-noise ratio (OSNR) of the seed pulses on the SC process by means of extensive nonlinear Schrödinger equation numerical simulation. Remarkably, our results...
Nonlinear image up-conversion is an alternative for the acquisition of real-time and full unscanned 2D images at different spectral ranges of the infrared [1, 2] where sensors are not fully developed, as compared to existing imaging sensors in the visible in terms of noise, speed, resolution, or uncooled operation. Wavelength shift is accomplished through a sum-frequency mixing (SFM) process in a...
The Optical Frequency Comb (OFC) represents a cornerstone of precision metrology, because it provides a clockwork to down-convert hundreds of THz of optical frequency standards to the countable and traceable radio frequency (RF) domain. In particular, for a future redefinition of the Coordinated Universal Time by an optical atomic transition [1], it will be an essential ingredient. Nowadays, narrowband...
Phase-sensitive amplification (PSA) is a nonlinear optical interaction providing attractive functionalities for all-optical classical and quantum signal processing with a wide range of promising applications, such as regeneration of high modulation formats [1] and amplification of entangled single-photon sources [2]. To exploit PSA in a scalable and compact implementation, this technique has been...
Nonlinear optical microresonators driven by continuous-wave (CW) lasers have enabled a variety of novel applications and phenomena including the generation of optical frequency combs [1], [2]. Particularly the formation of femtosecond temporal dissipative Kerr-cavity soliton pulses [3], [4] has recently attracted significant attention as it enables the generation of ultra-short optical pulse as well...
Recent developments in single-ring hollow-core photonic crystal fibre (SR-PCF) have made possible robust single-mode guidance over a broad bandwidth [1]—an important attribute in many applications, for example high power delivery of laser light and ultrafast gas-based nonlinear optics. Here we report for the first time that these fibres can be designed to transmit just one circular polarisation state...
Ultrashort pulse fiber lasers are very versatile for laser applications due to their robustness, compact foot print and maintenance-free operation. Attractive systems to further extend the wavelength range accessible with rare-earth doped fiber lasers are fiber-based optical parametric oscillators (FOPO), working with the technique of dispersion filtering. In this technique, a highly dispersive resonator...
Induced broadband supercontinua via long pulses in solid-core optical fibres has been the subject of huge research in the recent years, after the evidence presented by Solli et al. that the output spectra contain statistically rare rogue events with large intensities and enhanced redshift [1]. In this work, we report new missing details on the dynamics that proceed the rogue-soliton generation [2]...
In order to deliberately control the flow of optically encoded information, optical storage is an indispensable tool, but it must maintain all the advantages of optics, such as i.e. the coherence, the bandwidth and capacity. An elegant approach to this problem is to coherently transfer the information from optical to acoustic waves via an opto-mechanical nonlinearity, such as stimulated Brillouin...
The remarkable progress in nonlinear materials and laser pump sources continues to advance optical parametric oscillators (OPOs) to new frontiers in spectral and temporal coverage and performance capability, with no end in sight. The advent of a new class of mid-infrared (mid-IR) birefringent nonlinear materials such as CdSiP2 (CSP) and quasi-phase-matched (QPM) crystals such as orientation-patterned...
Among non-linear optical processes, Four Wave Mixing (FWM) can be exploited for the generation of tunable light pulses in several spectral regions. Usually this process is driven in bulk materials [1], which are prone to optical damage at high pump laser intensities. Here we report on the implementation of a FWM experiment based on a two-colour ultrafast field interaction inside a gas-filled Hollow...
The generation of ultrashort wavepackets with optical angular momentum (OAM) enables to combine the extreme intensity, temporal localization and spectral bandwidth of pulsed light fields with topological charges. Because of additional rotational degrees of freedom, such potential applications in optical communication, optical tweezing, microscopy, or material modification, pulses with are currently...
Nonlinear interactions occurring in the framework of so-called optical event horizons attract attention from the scientific community as the propagation of waves in nonlinear dispersive media has been proven to be a useful testbed for the study of artificial event horizons [1, 2]. Analogue of optical event horizons occurs when an intense soliton pulse prevents a weak probe wave propagating at a different...
Ultrafast laser sources emitting in the spectral range 1600–1800 nm are very attractive for many biomedical applications such as multi-photon microscopy [1] and laser surgery [2]. Taking into account tissue scattering and absorption, it has indeed been shown that the optimum wavelength window in terms of penetration lies around 1700 nm [3]. The development of fiber-based ultrafast lasers to address...
Low-cost biocompatible nanomaterials with opto-electronic properties are highly desirable as they may open avenue onto new biomedical imaging or sensing technologies. It was recently unveiled that short peptides self-assemble into various micro- and nano-structures including tubes, tapes and fibrils. These structures were found to possess striking mechanical, electrical and optical properties, which...
Parametric light generation has been utilized very successfully in the past as a means of generating wavelength-tunable light pulses in a variety of systems. Especially fiber optical parametric oscillators (FOPO) based on four-wave mixing in a photonic crystal fiber [1, 2] have the potential to benefit from the inherent mechanical stability and robustness of a fiber-based setup. However, the presented...
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