Ultra-large bandwidth hollow-core guiding in all-silica Bragg fibers with nano-supports
G. Vienne, Y. Xu, C. Jakobsen, H. -J. Deyerl, J. B. Jensen, T. Sorensen, T. P. Hansen, Y. Huang, M. Terrel, R. K. Lee, N. A. Mortensen, J. Broeng, H. Simonsen, … 展开作者
G. Vienne, Y. Xu, C. Jakobsen, H. -J. Deyerl, J. B. Jensen, T. Sorensen, T. P. Hansen, Y. Huang, M. Terrel, R. K. Lee, N. A. Mortensen, J. Broeng, H. Simonsen, A. Bjarklev, A. Yariv
We demonstrate a new class of hollow-core Bragg fibers that are composed of concentric cylindrical silica rings separated by nanoscale support bridges. We theoretically predict and experimentally observe hollow-core confinement over an octave frequency range. The bandwidth of bandgap guiding in this new class of Bragg fibers exceeds that of other hollow-core fibers reported in the literature. With only three rings of silica cladding layers, these Bragg fibers achieve propagation loss of the order of 1 dB/m.
The ultimate limit on fiber loss is set by the intrinsic Rayleigh scattering of silica glass material. Here, we challenge this limit in the visible region by using a hollow-core fiber approach. Two visible-guiding hollow-core conjoined-tube negative-curvature fibers are successfully fabricated and exhibit the overall losses of 3.8 dB/km at 680 nm and 4.9 dB/km at 558 nm respectively. The loss of the latter fiber surpasses the Rayleigh scattering limit of silica glass fiber in the green spectral region by 2 dB. Numerical simulation indicates that this loss level is still much higher than the fu…
In this paper we consider mid-infrared Raman lasers based on gas-filled hollow-core silica fibers and provide theoretical and experimental analysis of factors that limit the efficiency and output power of these lasers. As a result, we realized an efficient ns-pulsed 4.42 μm Raman laser based on an 1H2-filled revolver silica fiber. Quantum efficiency as high as 36 % is achieved, and output average power as high as 250 mW is demonstrated. The possibilities of further improving the laser efficiency are discussed.
By means of the transfer matrix method, the optical properties of fibers with a distinct intermediate layer between a hol-low core and periodic cladding are calculated. The periodic cladding consists of two types of the alternating layers. The intermediate layer has distinct thickness and refractive index. Depending on these parameters, the fiber can work in the single-mode or multi-mode regimes. In the multi-mode regime, the optical loss of the smallest loss mode can be de-creased by increasing the thickness of the layer. In the single-mode regime, the optical loss falls with a rise in the re…
The authors report on observation of Bragg confined mode in a hollow cylindrical dielectric cavity. A resonance was observed at 13.4 $GHz$ with an unloaded Q-factor of order $2\times10^5$, which is more than a factor of 6 above the dielectric loss limit. Previously such modes have only been realized from pure Transverse Electric modes with no azimuthal variations and only the $E_ϕ$ component. From rigorous numeric simulations it is shown that the mode is a hybrid mode with non-zero azimuthal variations and with dominant $E_r$ and $E_ϕ$ electric field components and $H_z$ magnetic field compone…
A hollow bottle-like microresonator (BLMR) with ultra-high quality factor is fabricated from a microcapillary with nearly parabolic profile. At 1.55 $μm$ pumping, degenerate four-wave mixing can be observed for a BLMR of diameter 102 $μ$m. The parabolic profile of the BLMR guarantees a nearly zero waveguide dispersion, which is theoretically discussed in detail. From the simulation, at 1.55 $μ$m wavelength in such a BLMR, the fundamental bottle mode is in the anomalous dispersion regime, whilst the ordinary whispering gallery mode (WGM) confined at the center of the BLMR is in the normal dispe…
Optical properties of hollow-core revolver fibers are numerically investigated depending on various parameters: the hollow-core diameter, the capillary wall thickness, the values of the minimum gap between the capillaries, the number of capillaries in the cladding and the type of glass (silica and chalcogenide). Preliminary, similar calculations are made for simple models of hollow-core fibers. Based on the obtained results, the optimal design of the revolver fiber for Raman laser frequency conversion (1560 nm to 4420 nm in H2) was determined. As a result, efficient ns-pulsed 4420 nm Raman las…
A blazed chirped Bragg grating in a planar silica waveguide device was used to create an integrated diffractive element for a spectrometer. The grating diffracts light from a waveguide and creates a wavelength dependent focus in a manner similar to a bulk diffraction grating spectrometer. An external imaging system is used to analyse the light, later device iterations plan to integrate detectors to make a fully integrated spectrometer. Devices were fabricated with grating period chirp rates in excess of 100nm/mm, achieving a focal length of 5.5mm. Correction of coma aberrations resulted in a d…
We present two novel hybrid photonic structures made of silica that possess two well-separated frequency bandgaps. The addition of interstitial air holes in a precise location and size allows these bandgaps to open up with a ratio of ${\sim3}$ between their central frequencies at the air line ${ck_z/w=1}$, thus fulfilling the basic guidance condition for third harmonic generation in hollow-core fibers. In addition, these designs may serve as high-power laser delivery of two well-separated wavelengths, such as visible and near infrared.
We propose and experimentally demonstrate a low-refractive-index-contrast hollow-core Bragg fiber sensor for liquid analyte refractive index detection. The sensor operates using a resonant sensing principle- when the refractive index of a liquid analyte in the fiber core changes, the resonant confinement of the fiber guided mode will also change, leading to both the spectral shifts and intensity changes in fiber transmission. As a demonstration, we characterize the Bragg fiber sensor using a set of NaCl solutions with different concentrations. Strong spectral shifts are obtained with the senso…
Hollow core fibers are considered as promising candidates to deliver intense temporally overlapping picosecond pulses in applications such as stimulated Raman scattering (SRS) microscopy and endoscopy because of their inherent low nonlinearity compared to solid-core silica fibers. Here we demonstrate that, contrary to prior assumptions, parasitic signals are generated in Kagomé lattice hollow core fibers. We identify the origin of the parasitic signals as an interplay between the Kerr nonlinearity of air and frequency-dependent fiber losses. Importantly, we identify the special cases of experi…
Using the finite element method we investigate plasmon-mediated transmission in a periodically modulated metal-insulator-metal (MIM) grating. We compute the eigenmodes of a silver-silica-silver conformal coating atop an array of close-packed silica rods, and correlate them with extinction and transmission characteristics of the structure. We observe efficient coupling of impinging plane-waves to gap plasmon modes, allowing control of both bandwidth and intensity of the transmitted radiation.
A polymer/liquid crystal-based fiber Bragg grating (PLC-FBG) is fabricated with visible two-beam holography by photo-induced modulation of a pre-polymer/LC solution infiltrated into the hollow channels of a solid core photonic crystal fiber (PCF). The fabrication process and effects related to the photonic bandgap guidance into the infiltrated PCF, and characterization of the PLC-FBG are discussed. Experimental data here presented, demonstrate that the liquid crystal inclusions of the PLC-FBG lead to high thermal and bending sensitivities. The microscopic behavior of the polymer/liquid crystal…
Supercritical Xe at 293 K offers a Kerr nonlinearity that can exceed that of fused silica while being free of Raman scattering. It also has a much higher optical damage threshold and a transparency window that extends from the UV to the infrared. We report the observation of nonlinear phenomena, such as self-phase modulation, in hollow-core photonic crystal fiber filled with supercritical Xe. In the subcritical regime, intermodal four-wave-mixing resulted in the generation of UV light in the HE12 mode. The normal dispersion of the fiber at high pressures means that spectral broadening can clea…
We propose supercritical xenon in a hollow-core photonic bandgap fiber as a highly nonlinear medium, and demonstrate 200 nm control over the guidance window of the fiber as the xenon goes through its supercritical phase transition. The large optical polarizability and monoatomic nature of xenon are predicted to allow large optical nonlinearity, on the same order as that of fused silica, while maintaining greatly reduced Raman scattering, offering benefits for nonlinear and quantum optics.
We propose an efficient method to determine the effective refractive index of step-index optical fibers from the visible to the mid-IR and thus allowing to infer their dispersive properties over a broad spectral range. The validity of the method, based on the writing of an array of fiber Bragg gratings (FBGs) with known periods using the fs scanning phase mask technique, is first confirmed with a standard silica fiber, then applied to various fluoride glass fibers to determine their effective refractive index and dispersion over more than three octaves, i.e. from 550 to 4800 nm.
In this letter, to the best of our knowledge, a new type of hollow-core anti-resonant fiber (HC-ARF) design using hybrid silica/chalcogenide cladding is presented for single-polarization, high-birefringence, and endlessly single-mode operation at 2 $μ$m wavelength. We show that the inclusion of a chalcogenide layer in the cladding allows strong suppression of $x$-polarization, while maintaining low propagation loss and single-mode propagation for $y$-polarization. The optimized HC-ARF design includes a combination of low propagation loss, high-birefringence, and polarization-extinction ratio (…
We build ring resonators to assess the potentialities of Kagome Hollow-Core Photonic Crystal Fibers for future applications to resonant rotation sensing. The large mode diameter of Kagome fibers permits to reduce the free space fiber-to-fiber coupling losses, leading to cavities with finesses of about 30 for a diameter equal to 15 cm. Resonance linewidths of 3.2~MHz with contrasts as large as 89\% are obtained. Comparison with 7-cell photonic band gap (PBG) fiber leads to better finesse and contrast with Kagome fiber. Resonators based on such fibers are compatible with the angular random walk …
We investigate numerically soliton-plasma interaction in a noble-gas-filled silica hollow-core anti-resonant fiber pumped in the mid-IR at 3.0 μm. We observe multiple soliton self-compression stages due to distinct stages where either the self-focusing or the self-defocusing nonlinearity dominates. Specifically, the parameters may be tuned so the competing plasma self-defocusing nonlinearity only dominates over the Kerr self-focusing nonlinearity around the soliton self-compression stage, where the increasing peak intensity on the leading pulse edge initiates a competing self-defocusing plasma…
We report a novel technique for launching broadband laser light into liquid-filled hollow-core photonic crystal fiber (HC-PCF). It uniquely offers self-alignment and self-stabilization via optomechanical trapping of a fused silica nanospike, fabricated by thermally tapering and chemically etching a single mode fiber into a tip diameter of 350 nm. We show that a trapping laser, delivering ~300 mW at 1064 nm, can be used to optically align and stably maintain the nanospike at the core center. Once this is done, a broadband supercontinuum beam (~575 to 1064 nm) can be efficiently and close to ach…
The effective Kerr nonlinearity of hollow-core kagome-style photonic crystal fiber (PCF) filled with argon gas increases over 100 times when the pressure is increased from 1 to 150 bar, reaching 15 % of that of bulk silica glass, while the zero dispersion wavelength shifts from 300 to 900 nm. The group velocity dispersion of the system is uniquely pressure-tunable over a wide range while avoiding Raman scattering : absent in noble gases and having an extremely high optical damage threshold. As a result, detailed and well controlled studies of nonlinear effects can be performed, in both normal …
The advent of photonic bandgap (PBG) guiding hollow- core photonic crystal fiber (HC-PCF) sparked the hope of guiding light with attenuation below the fundamental silica Rayleigh scattering limit (SRSL) of conventional step-index fibers. Unfortunately, the combination of the strong core-cladding optical-overlap, the surface roughness at the silica cladding struts and the presence of interface-modes limited the lowest reported transmission-loss to 1.2 dB/km at 1550 nm. This hope is recently revived by the introduction of hypocycloid core- contour (i.e. negative curvature) in inhibited-coupling …
Transmission of UV light with high beam quality and pointing stability is desirable for many experiments in atomic, molecular and optical physics. In particular, laser cooling and coherent manipulation of trapped ions with transitions in the UV require stable, single-mode light delivery. Transmitting even ~2 mW CW light at 280 nm through silica solid-core fibers has previously been found to cause transmission degradation after just a few hours due to optical damage. We show that photonic crystal fiber of the kagomé type can be used for effectively single-mode transmission with acceptable loss …
Four-wave mixing in the form of Bragg scattering (BS) has been predicted to enable quantum noise less frequency conversion by analytic quantum approaches. Using a semi-classical description of quantum noise that accounts for loss and stimulated and spontaneous Raman scattering, which are not currently described in existing quantum approaches, we quantify the impacts of these effects on the conversion efficiency and on the quantum noise properties of BS in terms of an induced noise figure (NF). We give an approximate closed-form expression for the BS conversion efficiency that includes loss and…
We report a silica glass nested capillary anti-resonant nodeless fiber with transmission and low bending sensitivity in the mid-infrared around 4000 nm. The fiber is characterized in terms of transmission over 1700-4200 nm wavelengths, revealing a mid-infrared 3500-4200 nm transmission window, clearly observable for a 12 m long fiber. Bending loss around 4000 nm is 0.5 dB/m measured over 3 full turns with 40 mm radius, going up to 5 dB/m for full turns with 15 mm radius. Our results provide experimental evidence of hollow-core silica fibers in which nested, anti-resonant capillaries provide hi…
The emergence of optical micro/nano-fiber (MNF) with a subwavelength diameter, which has ultra-light mass and an intense light field, brings an opportunity for develop fiber based optomechanical systems. In this study, we theoretically show an optomechanical effect in silica MNF Bragg gratings (MNFBGs). The light-induced mechanical effect results in continuously distributed strain along the grating. It is shown that the power-related strain introduces an optically reconfigurable chirp in the grating period. We develop new optomechanical coupled-mode equations and theoretically analyze the infl…
We introduce a new simple design of hollow-core microstructured fiber targeted to guide mid-infrared light at a wavelength 2.94 $ μ$m. The fiber has a triangular-core supported via silica-glass webs enclosed by a large hollow capillary tube. The fiber specific dimensions are determined based on the guiding technique, which is based on the anti-resonant mechanism. For a triangular-core with side length $100$ $ μ$m, the fiber has a minimum transmission loss $0.08\pm0.005$ dB/m and dispersion 2.3 ps/km/nm at the operational wavelength 2.94 $ μ$m.
In this work, we numerically investigate an experimentally feasible design of a tapered Ne-filled hollow-core anti-resonant fiber and we report the generation of multiple dispersive waves (DWs) in the range 90-120 nm, well into the extreme ultraviolet (UV) region. The simulations assume an 800 nm pump pulse with 30 fs 10 $μ$J pulse energy, launched into a 9 bar Ne-filled fiber with $34~μ$m initial core diameter that is then tapered to a $10~μ$m core diameter. The simulations were performed using a new model that provides a realistic description of both loss and dispersion of the resonant and a…
Stimulated Brillouin scattering (SBS) offers among the highest nonlinear gains in solid materials and has demonstrated advanced photonics functionalities in waveguides. The large compressibility of gases suggests that SBS may gain in efficiency with respect to condensed materials. Here, by using a gas-filled hollow-core fibre at high pressure, we achieve a strong Brillouin amplification per unit length, exceeding by 6 times the gain observed in fibres with a solid silica core. This large amplification benefits from a higher molecular density and a lower acoustic attenuation at higher pressure,…
Backward stimulated Raman scattering in gases provides a promising route to compression and amplification of a Stokes seed-pulse by counter-propagating against a pump-pulse, as has been already demonstrated in various platforms, mainly in free-space. However, the dynamics governing this process when seeded by noise has not yet been investigated in a fully controllable collinear environment. Here we report the first unambiguous observation of efficient noise-seeded backward stimulated Raman scattering in a hydrogen-filled hollow-core photonic crystal fiber. At high gas pressures, when the backw…
While optical fibers display excellent performances in the infrared, visible and ultraviolet ranges remain poorly addressed by them. Obtaining better fibers for the short-wavelength range has been restricted, in all fiber optics, by scattering processes. In hollow-core fibers, the scattering loss arises from the core roughness and represents the limiting factor in reducing their loss regardless of the fiber cladding confinement power. To attain fibers performing at short wavelengths, it is paramount developing means to minimize the height variations on the fiber microstructure boundaries. Here…
Design of Angular-offset Interstitial-Tube- Assisted Hollow-Core Fibers with Ultrahigh Mode Purity and Ultralow Loss
Guangdong Provincial Key Laboratory of Optical Fibre Sensing and Communication, Institute of Photonics Technology, Jinan University（广东光纤传感与通信重点实验室，光子技术研究所，暨南大学）；College of Physics & Optoelectronic Engineering, Jinan University（暨南大学物理与光电工程学院）；Department of Fundamental Network Technology, China Mobile Research Institute（中国移动研究院基础网络技术部）；Linfiber Technology (Nantong) Co., Ltd.（林菲科技（南通）有限公司）
The field energy distributions and effective mode areas of silica-based photonic bandgap fibers with a honeycomb airhole structure in the cladding and an extra airhole defining the core are investigated. We present a generalization of the common effective area definition, suitable for the problem at hand, and compare the results for the photonic bandgap fibers with those of index-guiding microstructured fibers. While the majority of the field energy in the honeycomb photonic bandgap fibers is found to reside in the silica, a substantial fraction (up to ~30%) can be located in the airholes. Thi…
The performances of optical fibre-based quantum information systems are limited by the intrinsic properties of silica glass materials, e.g. high latency, Rayleigh-scattering loss wavelength scaling law, and cross-coupling induced modal impurity. Hollow-core optical fibre (HCF) promises to unify air-borne light propagation and non-line-of-sight transmission, thus holding great potentials for versatile photonics-based quantum infor-mation applications. The early version of HCF based on photonic-bandgap guidance has not proven itself as a reliable quantum channel because of the poor modal purity …
Internal physical structure can drastically modify the properties of waveguides: photonic crystal fibers are able to confine light inside a hollow air core by Bragg scattering from a periodic array of holes, while metamaterial loaded waveguides for microwaves can support propagation at frequencies well below cutoff. Anisotropic metamaterials assembled into cylindrically symmetric geometries constitute light-guiding structures that support new kinds of exotic modes. A microtube of anodized nanoporous alumina, with nanopores radially emanating from the inner wall to the outer surface, is a manif…
Polarization Purity and Dispersion Characteristics of Nested Antiresonant Nodeless Hollow-Core Optical Fiber at Near- and Short-wave-IR Wavelengths for Quantum Communications
Light storage in an optical fiber is an attractive component in quantum optical delay line technologies. Although silica-core optical fibers are excellent in transmitting broadband optical signals, it is challenging to tailor their dispersive property to slow down a light pulse or store it in the silica-core for a long delay time. Coupling a dispersive and coherent medium with an optical fiber is promising in supporting long optical delay. Here, we load cold Rb atomic vapor into an optical trap inside a hollow-core photonic crystal fiber, and store the phase of the light in a long-lived spin-w…
