We report a hollow-core photonic crystal fiber that is engineered so as to strongly suppress higher-order modes, i.e., provide robust LP01 single-mode guidance in all the wavelength ranges where guides with low loss. Encircling core single ring of nontouching glass elements whose modes are tailored ensure resonant phase-matched coupling modes. show resulting modal filtering effect depends on only one dimensionless shape parameter, akin well-known d/Λ parameter for endlessly solid-core PCF....

In attosecond and strong-field physics, the acquisition of data in an acceptable time demands combination high peak power with average power. We report a 21 W mid-IR optical parametric chirped pulse amplifier (OPCPA) that generates 131 μJ 97 fs (sub-9-cycle) pulses at 160 kHz repetition rate center wavelength 3.25 μm. Pulse-to-pulse stability carrier envelope phase (CEP)-stable output is excellent 0.33% rms over 288 million (30 min) compression close to single cycle was achieved through...

Improved analytical tools are urgently required to identify degradation and failure mechanisms in Li-ion batteries. However, understanding ultimately avoiding these detrimental requires continuous tracking of complex electrochemical processes different battery components. Here, we report an operando spectroscopy method that enables monitoring the chemistry a carbonate-based liquid electrolyte during cycling batteries with graphite anode LiNi0.8Mn0.1Co0.1O2 cathode. By embedding hollow-core...

We developed a new algorithm that fits optical coherence tomography (OCT) signals as function of depth to general theoretical OCT model which takes into account multiple scattering effects. With use this algorithm, it was possible extract both the coefficient and anisotropy factor from particular region interest in an image. The extraction evaluated against measurements integrating sphere on set tissue phantoms yielded valid results. Finally, preliminary ex vivo investigation human aortic...

In optical fiber telecommunications, there is much current work on the use of orbital angular momentum (OAM) modes for increasing channel capacity. Here we study properties a helically twisted photonic crystal (PCF) that preserves chirality OAM same order, i.e., it inhibits scattering between an order +1 mode to −1 mode. This achieved by thermally inducing helical twist in PCF with novel three-bladed Y-shaped core. The effect seen periods few millimeters or less. We develop scalar theory...

We report on the generation of a three-octave-wide supercontinuum extending from vacuum ultraviolet (VUV) to near-infrared, spanning at least 113 1000 nm (i.e., 11 1.2 eV), in He-filled hollow-core kagome-style photonic crystal fiber. Numerical simulations confirm that main mechanism is novel and previously undiscovered interaction between dispersive-wave emission plasma-induced blueshifted soliton recompression around fiber zero dispersion frequency. The VUV part supercontinuum, which...

Supercontinuum generation with femtosecond pulses in photonic crystal fibers two zero-dispersion wavelengths (ZDWs) is investigated numerically. The role of the higher ZDW examined for 5 fiber designs a nearly constant lower ZDW. It found that resulting spectrum mainly determined by self-phase modulation first few mm fiber, followed soliton self-frequency shift and amplification dispersive waves. demonstrated how can be generated any desired center wavelength 1020-1200 nm range adjusting...

A new model of pump noise in supercontinuum and rogue wave generation is presented.Simulations are compared with experiments show that the provides significantly better agreement than currently ubiquitously used one-photon-per-mode model.The also allows for a study influence spectral line width on broadening mechanisms.Specifically, it found four-wave mixing (FWM) narrow ( 0.1 nm) initially leads to build-up FWM from quantum noise, whereas broad 1 gradual spectrum.Since still simple...

We numerically investigate supercontinuum generation using continuous-wave pumping.It is found that energy transfer during collision of solitons plays an important role.The relative influence Raman gain on spectral broadening shown to depend the width calculation time window.Our results indicate increasing linewidth pump can decrease width.Using a fiber with smaller dispersion at wavelength reduces required length by decreasing temporal formed from modulation instability.This also...

Understanding bend loss in single-ring hollow-core photonic crystal fibers (PCFs) is becoming of increasing importance as the enter practical applications. While purely numerical approaches are useful, there a need for simpler analytical formalism that provides physical insight and can be directly used design PCFs with low loss. We show theoretically experimentally wavelength-dependent critical radius exists below which reaches maximum, this calculated from structural parameters fiber using...

A century ago, Einstein proposed that gravitational forces were the result of curvature space-time and predicted light rays would deflect when passing a massive celestial object. We report twisting periodically structured "space" within coreless photonic crystal fiber creates helical channel where guided modes can form despite absence any discernible core structure. Using Hamiltonian optics analysis, we show follow closed spiral or oscillatory paths channel, in close analogy with geodesics...

Compression of 250-fs, 1-μJ pulses from a KLM Yb:YAG thin-disk oscillator down to 9.1 fs is demonstrated. A kagomé-PCF with 36-μm core-diameter used pressure gradient 0 40 bar krypton. 22 achieved by 1200 fs2 group-delay-dispersion provided chirped mirrors. By coupling the output into second 25 argon, octave spanning spectral broadening via soliton-effect observed at 18-W average power. Self-compression measured, compressibility 5 predicted. Also strong emission in visible dispersive wave...

We demonstrate that a high-numerical-aperture photonic crystal fiber allows lensless focusing at an unparalleled resolution by complex wavefront shaping. This paves the way toward high-resolution imaging exceeding capabilities of with multi-core single-mode optical fibers. analyze beam waist and power in focal spot on output using different types fibers shaping approaches. show technique, together properly designed multimode fiber, enables us to create tightly focused desired position facet...

We present both experimental measurements and simulations for a simple fiber-optical liquid refractive index sensor, made using only commercially available components without advanced postprocessing of the fiber.Despite simplicity, we obtain highest sensitivity experimentally demonstrated to date aqueous solutions (refractive around 1.33), which is relevant extensions biosensing.The sensor based on measuring spectral shift peaks arising from four-wave mixing (FWM), when filling holes...

We demonstrate the use of a large-pitch Kagome-lattice hollow-core photonic crystal fiber probe for Raman spectroscopy. The large transmission bandwidth enables both excitation and beams to be transmitted through same fiber. As beam is mainly air inside hollow core, silica luminescence background reduced by over 2 orders magnitude as compared standard probes, removing need subtraction.

We report a series of experimental, analytical, and numerical studies demonstrating strong circular dichroism for the HE11-like core mode in helically twisted hollow-core single-ring photonic crystal fiber (SR-PCF), formed by spinning preform during drawing. In SR-PCFs studied, hollow is surrounded single ring nontouching capillaries. Coupling between these capillaries results formation helical Bloch modes carrying orbital angular momentum. When twisted, birefringence appears ring, so that...

Soliton dynamics can be used to temporally compress laser pulses few fs durations in many different spectral regions. Here we study analytically, numerically and experimentally the scaling of soliton noble gas-filled hollow-core fibers. We identify an optimal parameter region, taking account higher-order dispersion, photoionization, self-focusing, modulational instability. Although for single-shots effects photoionization reduced by using lighter gases, they become increasingly important as...

Stimulated Brillouin scattering (SBS) has many applications, for example, in sensing, microwave photonics and signal processing. Here we report the first experimental study of SBS chiral photonic crystal fiber (PCF), which displays optical activity robustly maintains circular polarization states against external perturbations. As a result, circularly polarized pump light is cleanly back-scattered into Stokes with orthogonal state, as required by angular momentum conservation. By comparison,...

We numerically study supercontinuum generation in photonic crystal fibers with two zero-dispersion wavelengths, weakly tapered to have normal dispersion at all wavelengths after a certain distance. pump 15 fs pulses milliwatt average power and show that distinct smooth spectral parts are generated, improved stability due the dispersion. characterize how 3 dB bandwidth, center wavelength, of depend on taper parameters power.

We demonstrate a nonlinear fiber-optic strain sensor, which uses the shifts of four-wave mixing Stokes and anti-Stokes peaks caused by strain-induced changes in structure refractive index microstructured optical fiber. The sensor thus inherent nonlinearity fiber does not require any advanced postprocessing Strain sensitivity -0.23 pm/με is achieved experimentally numerical simulations reveal that for present can be increased to -4.46 optimizing pump wavelength power.

We report generation of an ultrafast supercontinuum extending into the mid- infrared in gas-filled single-ring hollow-core photonic crystal fiber (SR-PCF) pumped by 1.7 µm light from optical parametric amplifier. The simple structure offers shallow dispersion and flat transmission near mid-infrared, enabling broadband spectra 270 nm to 3.1 µm, with a total energy few µJ. In addition, we demonstrate emission ultraviolet dispersive waves whose frequency can be tuned simply adjusting pump...

Continuously twisted solid-core photonic crystal fiber (PCF) exhibits pure circular birefringence (optical activity), making it ideal for current sensors based on the Faraday effect. By numerical analysis, we identify PCF geometry which (which scales linearly with twist rate) is a maximum. For silica-air PCF, this occurs at shape parameter (diameter-to-spacing ratio of hollow channels) 0.37 and scale (spacing-to-wavelength) 1.51. This result confirmed experimentally by testing range...

Optical nonreciprocity, which breaks the symmetry between forward and backward propagating optical waves, has become vital in photonic systems enables many key applications. So far, all existing nonreciprocal are implemented for linearly or randomly polarized fundamental modes. vortex modes, with wavefronts that spiral around central axis of propagation, have been extensively studied over past decades offer an additional degree freedom useful Here, we report a light-driven isolation system...