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Lithium niobate whispering-gallery resonators (WGRs) show high intensity enhancement due to small mode volumes and high Q-factors. With bulk WGRs, shaped by diamond-blade-cutting tools followed by surface polishing, Q-factors in the range of 1011 have been demonstrated, which make them of significant interest for e.g. nonlinear-optical frequency conversion [1]. However, WGRs are still rare in commercial...
Optically confined structure is a fundamental topic in both basic and applied physics including potential application in information engineering, biological and medical sciences, sensing. In this scenario one-dimensional photonic crystals have been widely investigated and still remain an outstanding tool for new photonics, being the simplest system to exhibit a so-called photonic bandgap and therefore...
The main limitation of second-order nonlinear optical materials is the requirement of non-centrosymmetry within the electric-dipole approximation. However, higher multipole effects (such as magnetic-dipole and electric-quadrupole) do not suffer from such restriction. Thus, multipole effects can provide an interesting path towards novel second-order materials. Although multipole effects have been already...
Microresonator Kerr frequency combs have the potential to revolutionize many aspects of modem technology (e.g. in precision metrology, spectroscopy, as well as telecommunications). In Kerr cavities, stable, low-noise, optical frequency combs often take the form of temporal cavity solitons (CSs): ultra-short optical pulses that persist in driven nonlinear resonators [1]. Recently, studies of CSs under...
Bounded-phase dynamics, also called phase-trapping or frequency-locking without phase-locking, is a synchronization regime found when a phase-locked state bifurcates via a Hopf bifurcation to self-sustained phase and amplitude oscillations. After the instability, the coupled oscillators are not phase-locked anymore, yet they maintain frequency-locking and synchronization [1]. This phenomenon is rather...
Shock waves have been thoroughly investigated during the last century in many different branches of physics. In conservative (Hamiltonian) systems the shock singularity is regularized by weak wave dispersion, thus leading to the formation of a rapidly and regular oscillating structure, usually termed in the literature dispersive shock wave (DSW), see e.g. [1]. Here, we show that this fundamental singular...
We present a numerical study of the nonlinear dynamics of a population of coupled semiconductor lasers with saturable absorber operating in the excitable regime [1] and described by a set of coupled Yamada models [2]. In particular we have investigated the self-organized synchronization process taking place spontaneously among the lasers, showing significant correlations between the spike-like pulses...
In the last few years several experimental and numerical results have been reported on the emergence of extreme events and instabilities in different laser configurations such as Raman fiber lasers, optically injected semiconductor lasers, laser diodes with optical feedback and mode-locked lasers [1-4]. Rogue events can however be expected in some of these systems due to the complex noise-driven processes...
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...
There are materials which their nonlinear refractive index (n2) have contributions from fast isotropic and slow reorientational effects. Due to the presence of the slow noninstantaneous effect, the magnitude of the effective nonlinear refractive index (n2, eff) depends of the pulse width (τ). Here, we propose to measured the n2eff of several organic solvents as a function of pulse width and from these...
Nonlinear wavelength generations by using the optical waveguides are more compact, low cost, and efficient than using the traditional solid state systems [1], and the generated broadband light sources can be utilized in optical coherence tomography, frequency metrology, optical communications, and many other. In this work, the high quality of tantalum pentoxide (Ta2O5) micro-ring resonator has been...
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...
Microwave photonics is the study of the interaction between microwave and optical waves and their applications. One area of significant interest is the photonic generation of a microwave signal. Several techniques have been developed to generate such photonic microwave sources [1]. In particular, one popular method for generating photonic microwave uses Period-one (P1) oscillations from optically...
We investigate the possibility of slowing down terahertz light via intersubband transitions in quantum well heterostructures. The slow-down effect is achieved via tunneling induced transparency [1] in a three level Λ-system by careful engineering of the wave functions [2]. The inherently short coherence times in such solid state media inevitably leads to strong absorption of the signal, which we propose...
Label-free optical microscopy plays an important role in biological research. Coherent Raman microscopy combines three-dimensional resolution and fast image acquisition with molecular selectivity based on the vibrational spectrum of the sample. During the last years stimulated Raman scattering (SRS) microscopy has become an important technique in this framework since it does not display an electronic...
Upconversion detection is a promising technology for measurement of IR signals in the 1.5 μm–2 μm region used for lidar remote sensing [1-2]. In comparison to conventional InGaAs detector, the upconversion detector can achieve IR detection with better signal-to-noise ratio (SNR), not only due to lower dark noise directly, but also because of its limited field-of-view and acceptance bandwidth that...
Lithium niobate (LN) is a key material in electronic and photonic technology and, besides this, can be considered as a prototype system among polar oxides characterized by a strong spontaneous polarization and pronounced couplings between the different thermodynamic fields that describe its macroscopic state. In particular the illumination of LN containing some Fe impurities triggers the onset of...
Stimulated Raman scattering presents one of important trends in nonlinear optics enabling to generate Stokes-shifted radiation at frequencies that are not readily available from solid state lasers. This method is suitable also because the phase matching fulfilment isn't required. To get stable and efficient Raman generation of picosecond and even femtosecond ultra-short Stokes pulses, the method of...
Photonic implementations of novel information processing schemes based on machine learning approaches like reservoir computing (RC) [1] have raised strong interest in the last years due to their speed and performance. A reservoir computer, conceptionally as simple as a semiconductor laser with delayed optical feedback already proved excellent performance at 5 GSamples/s rates thanks to its nonlinear...
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