Chalcogenide fibers are known for their large transparency window and their high nonlinear optical properties. Indeed, they can be transparent from the visible region up to the mid-infrared (mid-IR) until 12 µm..For these reasons, chalcogenide glass fibers are well suited for generating mid-IR supercontinuum source. The management of dispersion profile is of fundamental importance for supercontinuum generation. In order to address this problem, we have developed for the first-time chalcogenide graded index fibers with a nanostructured core composed by two different glass compositions
Fiber-based supercontinuum (SC) generation has been a subject of intense interest over the last decade, with a significant impact on both basic science and industry. New uses for SC fiber sources are constantly emerging due to their unique properties that combine high brightness, visible to mid-infrared (MIR) wavelength coverage, fiber delivery, and single-mode output. Recent years have seen significant progress in overcoming the current shortcomings of SC sources in terms of wavelength coverage towards the 2 to 20 mu molecular fingerprint mid-infrared (MIR) region and in the ultraviolet (UV) down to 100 nm, while also improving stability, noise, coherence, power density, and robustness. In this talk, we will review all the recent advances in supercontinuum generation in a range of specialty optical fibers including: fluoride, chalcogenide, telluride, and silicon-core fibers for the MIR; UV-grade silica fibers and gas-filled hollow-core fibers for the UV range; and all-normal dispersion fibers for ultra-low noise coherent SC generation. Significant developments have been made in reaching target UV and MIR wavelength ranges, and the fiber SC has matured considerably to become a truly disruptive technology able to meet a range of societal and industrial challenges.
We report for the first time the generation of a two-octave spanning supercontinuum (SC) from 700 nm to 2800 nm in a 20 cm non-silica graded-index multimode fiber. We study the SC generation and associated nonlinear instabilities in different dispersion regimes and characterize the SC stability. Significantly, under particular injection conditions, we observe clear signatures of self-cleaning dynamics with a near single-mode spatial intensity distribution at the fiber output. Our results are confirmed by numerical simulations of the 3D+1 generalized nonlinear Schrodinger equation
Anti-resonant hollow-core silica fiber is used to demonstrate near- and mid-infrared laser absorption spectroscopy of methane. Molecular transitions near 6057 cm-1 (~1651 nm) and at 3057.7 cm-1 (~3270 nm) are targeted. Distributed feedback laser diode and interband cascade lasers are used as tunable laser sources. Detection of methane in ambient air is demonstrated using this mid-infrared system.
Hollow core, anti-resonant fiber with 65 μm core diameter is used for transmission of ultrashort laser pulses under 100 fs at a central wavelength of 1560 nm from a mode-locked laser. Meter-scale lengths of the fiber (up to 3 m) and bend radii down to 6 cm are considered. Cross-correlation frequency-resolved optical gating is used for investigation of performance of the fiber in this application. Achieved results on dispersive stretching of the pulse up to around 200 fs are compared with nonlinear propagation simulations, performed using the generalized nonlinear Schrödinger equation parametrized with measured characteristics of the fiber. Dechirping of the pulse to its original shape in the fiber under bending is observed and related to suppression of higher-order modes. As shown, the proposed fiber can be used to transmit sub-100 fs long laser pulses without spectral or temporal distortions providing a 6 cm radius loop.
We present laser-based spectroscopy in the mid-infrared spectral region inside novel anti-resonant (AR) hollow core fiber (HCF). AR-HCF used in this work has small (few dB/m) attenuation near 4 µm and exceptionally small bending losses. This gives perspective for compact all-fiber-based mid-infrared chemical sensors with optical path lengths of several meters. For gas sensing demonstration, a distributed feed-back (DFB) quantum cascade laser (QCL) operating near 4.54 μm and a 3.2-m-long fiber were used to detect nitrous oxide (N2O) and carbon monoxide (CO) using direct laser absorption spectroscopy (DLAS) and wavelength modulation spectroscopy (WMS).
ABSTRACT In this paper we investigate supercontinuum (SC) generation in several suspended-core soft-glass photonic crystal fibers (PCFs) pumped by an optical parametric oscillator (OPO) tunable around 1550 nm. The fibers were drawn from leadbismuth- gallium-cadmium-oxide glass (PBG81) featuring a wide transmission window from 0.5 μm till 2.7 μm and a high nonlinear refractive index up to 43×10-20 m2/W. They have been specifically designed with a microscale suspended hexagonal core for efficient pumping around 1550 nm. This microstructure geometry also prevents from glass recrystallization and provides higher mechanical durability. We experimentally demonstrate two SC spectra spanning from 1.07 μm to 2.31 μm and 0.89 μm to 2.46 μm by pumping two PCFs in both normal and anomalous dispersion regimes at 1550 nm and 1580 nm, respectively. We further show a number of nonlinear phenomena such as spectral broadening due to self-phase modulation, soliton generation, and Raman soliton self-frequency shift in the fiber at the pumping wavelengths. We also numerically simulate the group velocity dispersion curves for these fibers from their scanning electron microscope (SEM) images.
In this paper we present a numerical study on the optimization of dispersion of a photonic crystal fiber infiltrated with water-ethanol mixtures. The advantage of such an approach stems from the fact that the dependence of the refractive index on temperature is larger in liquids than in solid materials. Here, we examine photonic crystal fibers with a regular, hexagonal lattice and with various geometrical and material parameters, such as different number of rings of holes, various lattice constants and the size of core and air-holes. Additionally, for the optimized structure with flat dispersion characteristics, we analyze the influence of temperature and concentration of the ethanol solution on the dispersion characteristic and the zero dispersion wavelength shift of the fundamental mode.
Most of the research work related to photonic crystal fibres has to date been focused on silica based fibres. Only in the recent years has there been a fraction of research devoted to fibres based on soft glasses, since some of them offer interesting properties as significantly higher nonlinearity than silica glass and wide transparency in the infrared range. On the other hand, attenuation in those glasses is usually one or more orders of magnitude higher that in silica glass, which limits their application area due to limited length of the fibres, which can be practically used. We report on the development of single-mode photonic crystal fibres made of highly nonlinear lead-bismuth-gallate glass with a zero dispersion wavelength at 1460 nm and flat anomalous dispersion. A two-octave spanning supercontinuum in the range 700–3000 nm was generated in 2 cm of the fibre. In contrast to the silica glass, various oxide based soft glasses with large refractive index difference can jointly undergo multiple thermal processing steps without degradation. The use of two soft glasses gives additional degrees of freedom in the design of photonic crystal fibres. As a result, highly nonlinear fibres with unique dispersion characteristics can be obtained. Soft glass allow also development of fibres with complex subwavelength refractive index distribution inside core of the fibre. A highly birefringent fibre with anisotropic core composed of subwavelength glass layers ordered in a rectangular structure was developed and is demonstrated
Supercontinuum (SC) generation contained in the normal dispersion range of an optical fiber has been shown to be limited primarily by the available peak power and length of the pump pulse. In this work, we numerically investigate the SC spectral width and flatness for various pump pulse conditions in a nonlinear, all-solid, soft-glass, photonic crystal fiber (PCF) with a flattened dispersion profile. We assume a range of pump pulse parameters with pulse lengths between 250 and 100 fs (60 to 150 kW of peak power), and input pulse energies between 10 and 30 nJ, numerically reaching a maximum SC width of 800 to 2600 nm. The presented theoretical study provides a guideline for the selection of a fiber laser pump source, or in other words, it enables one to expect the extent of spectral broadening in the developed, all-normal dispersion PCF, when presently available fiber laser pump pulse parameters are assumed.
Tellurite glass photonic crystal fibers (PCF) offer a large potential for broadband supercontinuum generation with bandwidths of 4000 nm demonstrated in suspended-core tellurite PCFs under pumping at 1500-1600 nm. We fabricated a hexagonal-lattice, tellurite PCF with lattice constant Λ = 2 μm, linear filling factor d/Λ=0.75 μm, and a solid core with 2.7 μm diameter. Dispersion, calculated from SEM image of drawn fiber, has ZDW at 1500 nm and 4350 nm with a maximum of 193 ps/nm/km at 2900 nm. Under pumping with 150 fs / 36 nJ / 1580 nm pulses, supercontinuum in a bandwidth from 800 nm to over 2500 nm was measured in a 2 cm long PCF sample. Measured coupling efficiency was 8%. Dispersive and nonlinear length scales are 52 cm and 0.2 mm respectively, yielding nonlinearity-dominant propagation regime in the fiber. Numerical analysis of measured supercontinuum spectrum using NLSE, enabled identification of soliton fission and their subsequent red-shifting, dispersive wave generation across first ZDW, as well as FWM among the red-shifted spectral components. FWM phase-matching condition in the fiber is satisfied in a broad range from 1500 nm to 4000 nm with roughly 900 nm bandwidth around the signal wavelength. Developed model is in good agreement with experimental results. Model is used to estimate supercontinuum bandwidth for other experimental conditions with pump pulse lengths up to 1 ps and PCF lengths up to 10 cm.
Supercontinuum generation (SG) in photonic crystal fibers (PCFs) usually takes advantage of soliton dynamics, when pump wavelength is located in the anomalous dispersion region near the zero-dispersion wavelength of the fiber. This results in broader bandwidth than pumping in the normal dispersion region (NDR). SG in NDR is of interest, because of its potential for high degree of coherence and low intensity fluctuations. It was experimentally demonstrated in silica fibers and PCFs pumped around 1000 nm, covering the visible and near-infrared. We developed an all-solid PCF with hexagonal lattice made from N-F2 capillaries, with lattice constant Λ=2.275 μm, filling factor d/Λ=0.9, and a solid N-F2 core with 2,5μm diameter. The capillaries were filled with thermally matched borosilicate glass rods with lower refractive index. The PCF has all-normal dispersion, flattened within 1400- 2750 nm (-35 to -29 ps/nm/km) and a local maximum of -29 ps/nm/km at 1550 nm. Measured attenuation in 1500-1600 nm is around 3.2 dB/m. Nonlinear coefficient calculated at 1550 nm is 17/W/m. We numerically investigate the evolution of supercontinuum formation with a maximum bandwidth of 900-2400 nm. Considered pump pulse lengths were between 1 ps and 50 fs, with corresponding peak powers from 20 kW to 200 kW. Measured coupling efficiency using 20× microscope objective was 50%. One-photon-per-mode noise was used to simulate pump noise and multi-shot SG spectra were calculated. Preliminary experimental results are in good agreement with developed model.
In this work we present our results on supercontinuum (SC) generation using a photonic crystal fiber (PCF) fabricated from lead-bismuth-gallium-oxide glass (PBG-08). Due to high refractive index, high nonlinearity and high transmittance, the PBG-08 glass-based fibers seem to be excellent media for broad supercontinuum generation in the infrared spectral region. In our experiment, a short-length piece of PCF (6 cm) is pumped by a femtosecond fiber laser system, delivering 540 fs pulses at 60 MHz repetition rate and 2.75 W of maximum average power. This compact and cost-effective system allows to generate supercontinuum spanning from 900 to 2400 nm.
Thermally stable tellurite, lead-bismuth-gallium oxides based boron-silicate and lead-silicate glasses dedicated for multiple thermal processing are presented. The glasses are successfully used for the development of photonic crystal fibers, nanostructured gradient index lenses, all-solid microstructured fibers as well as refractive or diffractive micro-optical elements with ultra-broadband transmission.
Supercontinuum generation spanning an octave from 900 nm to 2400 nm was obtained in all-solid glass, photonic crystal
fiber, designed with flattened, all-normal dispersion and optimized for pumping in the 1500-1560 nm range. The report
includes designing of microstructure of all-solid glass photonic crystal fiber and relation of dispersion profile to fiber
filling factor d/Λ, numerical and experimental characteristic of fabricated fiber dispersion profile, supercontinuum
generation experiment under 1530 nm pumping with 70 fs pulses, concluded with numerical analysis based on solution
to nonlinear Schrödinger equation. Interplay among self-phase modulation, optical wave breaking and four-wave mixing
is discussed in context of observed pump pulse broadening.
The main goal of this work was to examine the possibility of fabrication of glassy diffractive optical elements for application in the near-infrared and mid-infrared spectral ranges. In the paper we focused on fabrication of Fresnel lenses with use of the hot embossing process. Lead-bismuth-gallium oxide and tellurite glasses were used in the experiment. Both types of glasses possess high transmittance from the visible up to mid-infrared (0.4÷6.5μm). Fused silica element was used as the mold, which was fabricated with standard ion etching method. The elements presented in this work were fabricated in a static process with the use of low pressure. The quality of the fabricated elements was examined with white light interferometer.
This paper is a continuation of our earlier works on remote measurement tools for supporting the research on novel photonic materials. The scope of this particular work encompasses especially a brief review of present exemplary implementations of remote access methods to measurement equipment, followed by proposing a design for a system management web-based application and related databases, selection of optimal software technologies and their implementation. Case-study for a real-time working system has been developed and proposed, which utilizes apparatus available at three collaborating laboratories located at Warsaw University of Technology and dedicated to photonics research.
Proof-of-concept, rate-equation based model is present to asses feasibility of population inversion build-up for novel
optical transitions in Ho3+ doped ZBLAN fibres. Measured, fundamental spectroscopic parameters, as well as fibre cross-section
geometry are taken into account, yielding preliminary conditions of population inversion for optical transitions
from 3D3 state under direct and up-conversion excitation.
In this work we present analysis and comparison of two basic operating schemes for praseodymium-doped up-conversion
fiber laser. Single and double wavelength pumped systems were considered, taking into account pumping efficiency and
pump power required for population inversion build-up. Time-dependent rate equation models have been developed for
single and double doped systems, which allow detailed discussion and optimization of pumping parameters. Performed
initial numerical simulations confirm usefulness of model for purposes of up-conversion fiber lasers analysis and design.
The scope of this work encompasses an introduction to the design, set-up and internet commissioning of a virtual laboratory dedicated to photonics research support. General fundaments, as well as technically oriented details are discussed in the perspective of establishing an international measurements platform, in framework of European Research Area in the field of optoelectronics and photonics.
The paper is focused on numerical analysis of lasing in blue and yellow spectral range of a Dy:ZBLAN fiber laser system, working in a Fabry-Perot configuration. A mathematical model based on measured spectroscopic data, as well as fiber structural parameters is implemented and yielded results are confronted with available experimental data. A reasonable agreement is found despite relative simplicity of the proposed solution.
In this paper we analyze the threshold violet and ultra-violet laser operation in Nd3+ doped ZBLAN fibers, using
relatively fast and accurate method, based on measured spectroscopic parameters like fluorescence lifetimes and
emissiod/absorption cross-sections spectra. Our approach, which is based on energy theorem and threshold field
approximation, extends the model presented in [1] by taking into account the longitudinal and transverse field
distribution of the fiber laser mode.
Specifically, in this work we compare the efficiency of two possible laser pumping schemes: direct and two-photon
excitation. The problem of laser resonator optimization is discussed by providing the analytical formulas for small signal
gain in active fiber medium as a function of structure parameters i.e. the cavity geometry, distributed losses of the active
medium, output power level and the mirror reflectivity. As the result of the carried-out optimizations we can determine
the conditions for obtaining short-wavelength lasing in Nd:ZBLAN fiber laser with minimal threshold and maximal
output power level.
In this work we focus on an analysis and a comparison of different, both multi-photon and multi-ion excitation mechanisms which can be used for pumping of a short wavelength neodymium doped ZBLAN fiber laser. Spectroscopic properties of Nd:ZBLAN examined under various excitation conditions enabled identification of the involved processes. Rate equation based models have been developed and employed to compare the efficiency of main excitation schemes, giving a good starting point for further optimization and development of Nd:ZBLAN up-conversion fiber laser.
In this work we present our theoretical investigations on optimization of double doped up-conversion fiber laser, operating in the visible part of spectrum. The developed mathematical model, based on measured spectroscopic parameters, enables analysis of influences of the active fiber and resonator parameters on the threshold and above-threshold laser characteristics. In particular, we discuss the behavior of output power versus the pumping power and mirror reflectances for the basic optical transitions in praseodymium ion, corresponding to the lasing in red, green and blue range.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.