In this paper we report a two octave spanning supercontinuum generation in a bandwidth of 700-3000 nm in a single-mode photonic crystal fiber made of lead-bismuth-gallate glass. To our knowledge this ...is the broadest supercontinuum reported in heavy metal oxide glass based fibers. The fiber was fabricated using an in-house synthesized glass with optimized nonlinear, rheological and transmission properties in the range of 500-4800 nm. The photonic cladding consists of 8 rings of air holes. The fiber has a zero dispersion wavelength (ZDW) at 1460 nm. Its dispersion is determined mainly by the first ring of holes in the cladding with a relative hole size of 0.73. Relative hole size of the remaining seven rings is 0.54, which allows single mode performance of the fiber in the infrared range and reduces attenuation of the fundamental mode. The fiber is pumped into anomalous dispersion with 150 fs pulses at 1540 nm. Observed spectrum of 700-3000 nm was generated in 2 cm of fiber with pulse energy below 4 nJ. A flatness of 5 dB was observed in 950-2500 nm range.
Dispersion Management in Hybrid Optical Fibers Michalik, Damian; Stefaniuk, Tomasz; Buczynski, Ryszard
Journal of lightwave technology,
03/2020, Letnik:
38, Številka:
6
Journal Article
Recenzirano
We report a new fiber concept, which is a hybrid design between classical step-index and photonic crystal fibers (PFCs). The proposed structure has a centrally located Ge doped core surrounded by a ...set of smaller microinclusions distributed in the cladding. In numerical investigations, we demonstrate that such a combination allows to arbitrarily shape the dispersion profile in a 1 μm wide spectral range while reducing the confinement losses with respect to air-hole PCFs exhibiting similar dispersion characteristics. We present simple guidelines for optimizing the structure. Finally, as a proof of concept, we show an adequately designed fiber which, even though is based on fused silica glasses and is an all-solid construction, is still capable of providing flat and all-normal dispersion characteristics (-37 ± 2.5 ps/nm/km) in broadband range from 1.3-2.15 μm and ultra-flat (-37 ± 0.2 ps/nm/km) for wavelength values from 1.5-1.9 μm.
We report on the multidimensional characterization of femtosecond pulse nonlinear dynamics in a tellurite glass graded-index multimode fiber. We observed novel multimode dynamics of a quasi-periodic ...pulse breathing which manifests as a recurrent spectral and temporal compression and elongation enabled by an input power change. This effect can be assigned to the power dependent modification of the distribution of excited modes, which in turn modifies the efficiency of involved nonlinear effects. Our results provide indirect evidence of periodic nonlinear mode coupling occurring in graded-index multimode fibers thanks to the modal four-wave-mixing phase-matched via Kerr-induced dynamic index grating.
Introduction of subwavelength inclusions in the core opens up an additional degree of freedom in shaping of dispersion characteristic in photonic crystal fibers (PCFs). We have developed a PCF with a ...nanostructured inclusion in the core to verify this concept. To suppress higher order modes, the photonic cladding structure of the developed fiber is composed of a first ring with linear filling factor of 0.95 and the remaining 5 rings with a lower linear filling factor of 0.4 with a lattice constant of
2.6
μ
m
. Diameter of the nano-inclusion in the core is 410 nm. For the fiber development, we used a pair of thermally matched soft glasses: Schott SF6 lead glass and an in-house synthesized NC21 borosilicate glass. In this paper, we report on dispersion measurements using a spectral interferomeric technique. A dispersion unbalanced Mach–Zehnder interferometer, combined with a supercontinuum source is used. Dispersion characteristics in wide range of wavelengths extending from 0.65 to
1.6
μ
m
, are measured and verified against calculated results.
The objective of the study is to optimize the optical fiber structure for mode-division multiplexing systems using nanostructurization. The nanostructuring technique allows to fabricate fibers with ...arbitrarily designed (free-form) refractive index distribution based on two glasses. Three optimization schemes have been proposed. The nanostructuring method allows for designing fibers with optical properties similar and even better parameters impossible to produce by other methods. In this proposal, we examined four linearly polarized (
LP
) few-mode fibers. We report a high effective refractive index difference between modes while maintaining other important parameters for the weakly coupled approach.
We demonstrate the development of anti-resonant hollow core fibers functionalized with nanodiamonds and their application to ODMR-based and microwave-free magnetic field gradiometry. The diamond ...particles were uniformly deposited from a solvent suspension on the inner surfaces of two 50 cm long hollow-core fiber sensors. This enabled efficient excitation of the diamond fluorescence using 532 nm light, as well as collecting the nitrogen vacancy color center red fluorescence to the hollow fiber guided modes, which facilitated fully guided mode operation of each sensor with 400 nT/sqrt(Hz) sensitivity. Two fiber probes in a differential arrangement provided magnetic field gradient measurement with a 35 mT dynamic range without the presence of microwaves. Specific applications, like the control of magnetic switching in spintronics computing, could benefit from accurate and microwave-free readout modalities for mT-scale magnetic fields. The demonstrated hollow core fiber probes fulfill these requirements. They combine the robustness and the possibility of macroscopic separation between the scanned target and the readout location due to the guiding of the NV fluorescence, while maintaining a dynamic range that matches state-of-the-art single-crystal diamond-based sensors.
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•Demonstration of a 50 cm-long magnetically sensitive silica hollow core fibers with fluorescent diamonds in the air core.•Demonstration of 400 nT/sqrt(Hz) field sensitivity when the NV light is excited and collected from the fiber’s far ends.•35 mT dynamic range magnetic field gradiometry by employing a differential measurement with or without microwaves.•Room temperature diamond introduction into fiber compatible with concentration scaling or bio-functionalized diamonds.
Nanodiamond integration with optical fibers has proved a compelling methodology for magneto-optics. We reveal that the applicability of nanodiamonds in nonlinear optics goes beyond the previous ...demonstrations of frequency converters. Instead, we exploit the recently reported volumetric integration of nanodiamonds along the optical fiber core and show that the nonlinear response of glasses can be manipulated by nanodiamonds. By taking the mature z-scan approach we measure the nonlinear absorption and nonlinear refraction of three dielectric materials containing nanodiamonds in different concentrations and sizes. The work begins with nanodiamond-water suspensions, which offer the advantage of rapidly assessing the dependence of the nonlinear refractive index on the nano-particle concentration and size. Subsequently we investigate two fiber preforms based on silica and soft glass doped with nanodiamonds to evaluate the feasibility of nonlinearity shaping. We achieve a nearly 20% reduction of the nonlinear refractive index of fused silica containing trace amounts of nanodiamonds relative to a pristine reference. The demonstration of such a noticeable impact on the nonlinear response of the key optical material widely accepted by ultrafast optics practitioners provides a guideline for future work on the novel concept of negative nonlinearity fibers, which could disrupt the established chromatic dispersion-nonlinearity landscape.
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In this work a photonic crystal fiber made of a heavy metal oxide glass with optimized dispersion profile is proposed for supercontinuum generation in a broad range of wavelengths in the ...near-infrared, when pumped by a mode-locked fiber-based laser. The fiber is modelled and optimal geometrical parameters are selected to achieve flat and low dispersion in the anomalous regime. Supercontinuum generation in the range of 0.76⁻2.40 µm, within the dynamics of 30 dB, when pumped at 1.56 µm with 400 fs⁻long pulses and an average power 660 mW is possible. The applicability of such fibers is also discussed.
We test the development of a silica all-glass optical fiber with a highly birefringent large mode area (HB-LMA). In the fiber, the birefringence and single mode operation are independent of bending ...and results from the internal nanostructuring of the core, which makes the glass anisotropic. Taking into account technological limitations of the doped silica glasses, we optimized the HB-LMA fiber properties by appropriate selection of germanium and fluorine doping level of silica used in the fiber core and cladding. We demonstrated that the anisotropic glass can be successfully used as a core material in large core area fibres in C-band for polarization components of the fundamental mode. We obtained phase birefringence of 1.92 × 10
−4
in the fiber with the core diameter of 30 µm and the effective mode area equal to 573 µm
2
and 804 µm
2
, for
x-
and
y-
polarization, respectively. The same approach was applied to designing a single mode fiber with 40 µm core diameter and effective mode area over 1000 µm
2
, which supports only single polarization.
All-normal dispersion supercontinuum (ANDi SC) generation in a lead-bismuth-gallate glass solid-core photonic crystal fiber (PCF) with cladding air-holes infiltrated with carbon tetrachloride (CCl
4
...) is experimentally investigated and numerically verified. The liquid infiltration results in additional degrees of freedom that are complimentary to conventional dispersion engineering techniques and that allow the design of soft-glass ANDi fibers with an exceptionally flat near-zero dispersion profile. The unique combination of high nonlinearity and low normal dispersion enables the generation of a coherent, low-noise SC covering 0.93–2.5 µm requiring only 12.5 kW of pump peak power delivered by a standard ultrafast erbium-fiber laser with 100 MHz pulse repetition rate (PRR). This is a much lower peak power level than has been previously required for the generation of ANDi SC with bandwidths exceeding one octave in silica- or soft-glass fibers. Our results show that liquid-composite fibers are a promising pathway for scaling the PRR of ANDi SC sources by making the concept accessible to pump lasers with hundreds of megahertz of gigahertz PRR that have limited peak power per pulse but are often required in applications such as high-speed nonlinear imaging, optical communications, or frequency metrology. Furthermore, due to the overlap of the SC with the major gain bands of many rare-earth fiber amplifiers, our source could serve as a coherent seed for low-noise ultrafast lasers operating in the short-wave infrared spectral region.
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