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Surface plasmon polaritons (SPPs) in plasmonic metal waveguides can excite a third-order nonlinear response [1] much akin the well-known self-phase modulation (SPM) and two-photon absorption seen in light propagating in dielectric waveguides. In metals, the nonlinearity mainly arises as a self-acting effect: after absorption of the incident light the nonlinearity arises due to hot-electron contributions...
Sources of spectrally broadband and coherent light are necessary for frequency metrology and ultrashort pulse generation. Near-infrared (NIR) wavelengths are practical for such devices because of the emergence of robust and reasonably priced femtosecond lasers operating in this part of spectrum. This further enabled pulse preserving and coherent, so called all-normal dispersion supercontinuum (ANDi...
Hollow-core anti-resonant (HC-AR) fibers where a symmetric distribution of cladding tubes compose a “negative-curvature” core boundary have extraordinary optical properties, such as low transmission loss, wide transmission bands and weak power overlap between the core modes and the silica parts [1], especially when smaller tubes are “nested” inside the larger tubes [2, 3]. Here we investigate the...
Hollow-core anti-resonant (HC-AR) fibers with a “negative-curvature” of the core-cladding boundary have been extensively studied over the past few years owing to their low loss and wide transmission bandwidths. The key unique feature of the HC-AR fiber is that the coupling between the core and cladding modes can be made anti-resonant (strongly inhibited) by suitably arranging the anti-resonant tubes...
The light confinement inside hollow-core (HC) fibers filled with noble gases constitutes an efficient route to study interesting soliton-plasma dynamics [1]. More recently, plasma-induced soliton splitting at the self-compression point was observed in a gas-filled fiber in the near-IR [2]. However, the role of the plasma is so far not investigated in the mid-IR. This range is interesting because the...
Hollow-core anti-resonant (HC-AR) fibers are perhaps the best platform for ultrafast nonlinear optics based on light-gas interactions because they offer broadband guidance and low-loss guidance. The main advantage of using gases inside HC fibers is that both the dispersion and nonlinearity can be tuned by simply changing the pressure of the gas [1]. The emission of efficient dispersive wave (DW) in...
Hollow-core fibers with node-free anisotropic anti-resonant elements give broadband low-loss fibers that are also single-moded. At 1.06 μm silica-based fiber designs show higher-order-mode extinction-ratio >1000 and losses below 10 dB/km over a broad wavelength range.
We generate supercontinuum (817–2250 nm at −30dB) in a dispersion-engineered silicon-rich nitride waveguide by pumping fs pulses with 82 pJ from an erbium-fiber oscillator. Spectral broadening mechanisms include soliton fission and dispersive wave generation.
We report an antiresonant hollow core fiber formed of 7 non-touching capillaries with inner tubes. The fiber has a core diameter of ∼33μm and a core wall of ∼780nm of thickness. We demonstrate robust single mode operation at 1064nm and broad transmission bandwidth.
In this paper, a node-free anisotropic hollow-core anti-resonant fiber has been proposed to give low transmission loss in the near-IR to mid-IR spectral regime. The proposed silica-based fiber design shows transmission loss below 10 dB/km at 2.94 μm with multiple low loss transmission bands. Transmission loss of 1 dB/m up to 4 μm is also predicted.
Experimental values of the third-order susceptibility of ultra-thin gold layers are obtained and compared to the values of the third-order susceptibility for bulk gold. The effective enhancement of the third-order nonlinearity depending on the thickness of the gold layers is observed. We discuss possible reason for such enhancement. The two-temperature model is applied to model the nonlinear response...
Hollow-core fibers with a single ring of circular anti-resonant tubes as the cladding provide a simple way of getting a negative-curvature hollow core, resulting in broadband low-loss transmission with little power overlap in the glass. These fibers show a significant improvement in loss performance if the anti-resonant tubes have nested tubes inside them, and here we investigate the role of the shape...
Self-defocusing soliton compression supported by the cascaded phase-mismatched second-harmonic generation process is numerically demonstrated in unpoled lithium niobate ridge waveguides where nano-joule pulses are operated and quasi-phase-matching is unnecessary. The soliton range is 1100–1800 nm.
An octave-spanning mid-IR supercontinuum is observed experimentally using ultrafast cascaded nonlinearities in an LiInS2 quadratic nonlinear crystal pumped with 70 fs energetic mid-IR pulses and cut for strongly phase-mismatched second-harmonic generation.
A new high-energy pulse compressor uses self-defocusing spectral broadening in anomalously dispersive quadratic nonlinear crystals, followed by positive group-delay-dispersion compensation. Compression to sub-50 fs is possible from Joule-class 1.03 µm femtosecond amplifiers in large-aperture KDP.
Experiments on cascaded quadratic soliton compression in unpoled phase-mismatched lithium niobate waveguides are presented. Pulse self-phasemodulation dominated by an overall self-defocusing nonlinearity is observed, with an variation of pump wavelength and waveguide core width.
A popular crystal for ultrafast cascading experiments is beta-barium-borate (β-BaB2O4, BBO). It has a decent quadratic nonlinear coefficient, and because the crystal is anisotropie it can be birefringence phase-matched for type I (oo → e) second-harmonic generation (SHG). For femtosecond experiments BBO is popular because of low dispersion and a high damage threshold. The main attractive property...
Dispersive waves (DW) are radiated when temporal solitons are perturbed by higher-order dispersion (HOD). This is also called optical Cherenkov radiation (OCR). Currently among much efforts of generating optical octave-spanning supercontinuum (SCG), OCR has become an efficient nonlinear frequency conversion in the blue edge of SCG and blue-shifting the edge with the soliton self-frequency shift(SSFS)...
Third-order nonlinear optical materials have gained special attention due to their unique role in all optical switching, optical limiting and optical communication applications. Composite materials based on nanoparticles (NP) in transparent matrix proved to be promising candidates whose χ(3) can be adequately tailored by tuning the material parameters such as size, shape, and filling factor of nanoparticles...
Effects based on the χ(3)-nonlinearity are arguably the most commonly discussed nonlinear interactions in photonics. In the description of pulse propagation, however, the generation of the third harmonic (TH) is commonly neglected, because it is strongly phase mismatched in most materials and waveguide geometries and thus of negligible influence to the overall dynamics. This mismatch is characterized...
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