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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Tailorable Supercontinuumc Generation in Liquid-Composite-Core Fibers
摘要： Nonlinear light generation in optical fibers is an indispensable tool for generating light to access wavelengths away of the fundamental laser lines broadening the field of applications in biophotonics, metrology, and communications. However, most multi-wavelength sources rely on glass fibers which are static in their material properties after fabrication, thus post-tuning their properties is impossible. Complementary to the pressure-adjustable gas-filled hollow-core fibers in the high power laser regime, liquid-core fibers (LCF) offer a versatile platform for tunable nonlinear light generation and pulse control in the low- to medium-power regime. Recently, we demonstrated accurate control of the soliton fission process via temperature due to the large thermo-optical coefficient of the core liquid. However, those experiments were performed with rather cost-intensive thulium laser technology. Here, we present the composition of the liquid core as further degree of control to switch the operation regime of a simple step-index LCF from normal to anomalous dispersion, thus, opening the soliton regime for the inexpensive and technology-rich telecom SCL bands. We show the design and applicability limits (e.g., guidance and absorption limits) of multiple liquid-composite-core fibers with focus on broadband supercontinuum generation. Fig. 1b exemplarily shows the zero-dispersion at pump wavelength (ZDPW) and two isolines of the V-parameter over varying core diameter and amount of the admixture C2Cl4 in CCl4, clearly revealing a favorable parameter domain for soliton fission close to the zero-dispersion (colored in green). We confirm the design maps experimentally by investigating the nonlinear spectral broadening of a 30 fs pump pulse at 1.56 μm center wavelength launched into multiple LCFs with varying core composition and diameter (see Fig. 1a). The LCFs are fabricated by capillary force-assisted filling of capillaries safely mounted in sealed opto-fluidic mounts. The core diameter of each sample is chosen such that the V-parameter is well above the empirically found limit of V = 1.6 (see Fig. 1b). Output spectra are measured for increasing input power. The measured output spectra in Fig. 1e show clean soliton fission exemplarily for a LCF infiltrated with 20 vol% C2Cl4 in CCl4, indicated by efficient generation of non-solitonic radiation at around 1.3 μm and a soliton red-shifting towards 1.7 μm. This is in distinct contrast to the unaltered output spectrum of a normal dispersive CCl4-core fiber in Fig. 1c. Nonlinear pulse propagation simulations match the experiments well (see Fig. 1d,f). Similar experiments have been conducted using deuterated toluene and nitrobenzene as admixture to CCl4 significantly increasing the bandwidth of the output spectrum. In conclusion, we unambiguously show dispersion tuning of LCFs to a great extent by small changes in the core composition directly offering unexplored ways of online tailorable nonlinear light generation and control in the telecom regime.
关键词： liquid-composite-core fibers,soliton fission,nonlinear light generation,supercontinuum generation,telecom SCL bands
更新于2025-09-16 10:30:52
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Nonlinear light generation in topological nanostructures
摘要： Topological photonics has emerged as a route to robust optical circuitry protected against disorder and now includes demonstrations such as topologically protected lasing and single-photon transport. Recently, nonlinear optical topological structures have attracted special theoretical interest, as they enable tuning of topological properties by a change in the light intensity and can break optical reciprocity to realize full topological protection. However, so far, non-reciprocal topological states have only been realized using magneto-optical materials and macroscopic set-ups with external magnets, which is not feasible for nanoscale integration. Here we report the observation of a third-harmonic signal from a topologically non-trivial zigzag array of dielectric nanoparticles and the demonstration of strong enhancement of the nonlinear photon generation at the edge states of the array. The signal enhancement is due to the interaction between the Mie resonances of silicon nanoparticles and the topological localization of the electric field at the edges. The system is also robust against various perturbations and structural defects. Moreover, we show that the interplay between topology, bi-anisotropy and nonlinearity makes parametric photon generation tunable and non-reciprocal. Our study brings nonlinear topological photonics concepts to the realm of nanoscience.
关键词： Silicon nanoparticles,Nonlinear light generation,Third-harmonic signal,Mie resonances,Topological nanostructures
更新于2025-09-09 09:28:46