Hollow-core Photonic Bandgap Fiber Research Articles

High Capacity Mode-Division Multiplexed Optical Transmission in a Novel 37-cell Hollow-Core Photonic Bandgap Fiber

We present the first demonstration of combined wavelength-division multiplexed (WDM) and mode-division multiplexed (MDM) optical transmission in a hollow-core photonic bandgap fiber (HC-PBGF). For this purpose a novel low loss, broadband 310 m long HC-PBGF with a 37 cell (37c) core geometry is used. The modal properties of the HC-PBGF are characterized in detail, showing an absence of surface modes and low modal crosstalk, which enable WDM and MDM transmission with record high capacity (73.7 Tb/s) for a HC-PBGF. Several modulation formats have been tested, showing very good and stable performance. The transmission properties are assessed by looking into both single-mode transmission and MDM transmission, showing good agreement with the modal characterization of the 37c HC-PGBF.

Impact of structural distortions on the performance of hollow-core photonic bandgap fibers

We present a generic model for studying numerically the performance of hollow-core photonic bandgap fibers (HC-PBGFs) with arbitrary cross-sectional distortions. Fully vectorial finite element simulations reveal that distortions beyond the second ring of air holes have an impact on the leakage loss and bandwidth of the fiber, but do not significantly alter its surface scattering loss which remains the dominant contribution to the overall fiber loss (providing that a sufficient number of rings of air holes (≥ 5) are used). We have found that while most types of distortions in the first two rings are generally detrimental, enlarging the core defect while keeping equidistant and on a circular boundary the glass nodes surrounding the core may produce losses half those compared to "idealized" fiber designs and with no penalty in terms of the transmission bandwidth.

Fast and broadband fiber dispersion measurement with dense wavelength sampling

We report on a method to obtain dispersion measurements from spectral-domain low-coherence interferograms which enables high accuracy (≈ ps/(nm · km)), broadband measurements and the determination of very dense (up to 20 points/nm over 500 nm) data sets for both dispersion and dispersion slope. The method exploits a novel phase extraction algorithm which allows the phase associated with each sampling point of the interferogram to be calculated and provides for very accurate results as well as a fast measurement capability, enabling close to real time measurements. The important issue of mitigating the measurement errors due to any residual dispersion of optical elements and to environmental fluctuations was also addressed. We performed systematic measurements on standard fibers which illustrate the accuracy and precision of the technique, and we demonstrated its general applicability to challenging problems by measuring a carefully selected set of microstructured fibers: a lead silicate W-type fiber with a flat, near-zero dispersion profile; a hollow core photonic bandgap fiber with strongly wavelength dependent dispersion and dispersion slope; a small core, highly birefringent index guiding microstructured fiber, for which polarization resolved measurements over an exceptionally wide (≈ 1000 nm) wavelength interval were obtained.

Low-loss and low-bend-sensitivity mid-infrared guidance in a hollow-core–photonic-bandgap fiber

Hollow-core-photonic-bandgap fiber, fabricated from high-purity synthetic silica, with a wide operating bandwidth between 3.1 and 3.7 μm, is reported. A minimum attenuation of 0.13 dB/m is achieved through a 19-cell core design with a thin core wall surround. The loss is reduced further to 0.05 dB/m following a purging process to remove hydrogen chloride gas from the fiber-representing more than an order of magnitude loss reduction as compared to previously reported bandgap-guiding fibers operating in the mid-infrared. The fiber also offers a low bend sensitivity of <0.25 dB per 5 cm diameter turn over a 300 nm bandwidth. Simulations are in good agreement with the achieved losses and indicate that a further loss reduction of more than a factor of 2 should be possible by enlarging the core using a 37-cell design.

The Optimization Research on Hollow-Core Photonic BandgapFiber CoreTransversal Radius

In hollow-core optical fibers, surface mode is one most important reasons causes fiber loss. In order to suppress surface mode loss, simulations of the designed hollow-core optical fibers have been made numerically using full vector finite element method, and the light intensity distributions are in the different core transversal radius is obtained. Analysis results show that both the enlargement of core radius and using fusing transversal method lead into the core holeare more helpful to suppress surface mode loss. This conclusion may provide a basis for small duty cycle (f&lt; 85%) hollow-core optical fibers fabrication the theoretically. Keywords:hollow-corephotonic band-gap fiber (HC-PBF),finite element method (FEM), surface mode loss, core transversal radius, core intersected method

Gamma irradiation of minimal latency Hollow-Core Photonic Bandgap Fibres

Hollow-Core Photonic-Bandgap Fibres (HC-PBGFs) offer several distinct advantages over conventional fibres, such as low latency and radiation hardness; properties that make HC-PBGFs interesting for the high energy physics community. This contribution presents the results from a gamma irradiation test carried out using a new type of HC-PBGF that combines sufficiently low attenuation over distances that are compatible with high energy physics applications together with a transmission bandwidth that covers the 1550 nm region. The radiation induced attenuation of the HC-PBGF was two orders of magnitude lower than that of a conventional fibre during a 67.5 h exposure to gamma-rays, resulting in a radiation-induced attenuation of only 2.1 dB/km at an accumulated dose of 940 kGy.

Hollow-core photonic bandgap fibers: technology and applications

Abstract Since the early conceptual and practical demonstrations in the late 1990s, Hollow-Core Photonic Band Gap Fibres (HC-PBGFs) have attracted huge interest by virtue of their promise to deliver a unique range of optical properties that are simply not possible in conventional fibre types. HC-PBGFs have the potential to overcome some of the fundamental limitations of solid fibres promising, for example, reduced transmission loss, lower nonlinearity, higher damage thresholds and lower latency, amongst others. They also provide a unique medium for a range of light: matter interactions of various forms, particularly for gaseous media. In this paper we review the current status of the field, including the latest developments in the understanding of the basic guidance mechanisms in these fibres and the unique properties they can exhibit. We also review the latest advances in terms of fibre fabrication and characterisation, before describing some of the most important applications of the technology, focusing in particular on their use in gas-based fibre optics and in optical communications.

Demonstration of amplified data transmission at 2 µm in a low-loss wide bandwidth hollow core photonic bandgap fiber

The first demonstration of a hollow core photonic bandgap fiber (HC-PBGF) suitable for high-rate data transmission in the 2 µm waveband is presented. The fiber has a record low loss for this wavelength region (4.5 dB/km at 1980 nm) and a >150 nm wide surface-mode-free transmission window at the center of the bandgap. Detailed analysis of the optical modes and their propagation along the fiber, carried out using a time-of-flight technique in conjunction with spatially and spectrally resolved (S2) imaging, provides clear evidence that the HC-PBGF can be operated as quasi-single mode even though it supports up to four mode groups. Through the use of a custom built Thulium doped fiber amplifier with gain bandwidth closely matched to the fiber's low loss window, error-free 8 Gbit/s transmission in an optically amplified data channel at 2008 nm over 290 m of 19 cell HC-PBGF is reported.

Gas detection with micro- and nano-engineered optical fibers

This paper overviews recent development in gas detection with micro- and nano-engineered optical fibers, including hollow-core fibers, suspended-core fibers, tapered optical micro/nano fibers, and fiber-tip micro-cavities. Both direct absorption and photoacoustic spectroscopy based detection schemes are discussed. Emphasis is placed on post-processing stock optical fibers to achieve better system performance. Our recent demonstration of distributed methane detection with a ∼75-m long of hollow-core photonic bandgap fiber is also reported.

Sensitivity Characteristics of Fabry-Perot Pressure Sensors Based on Hollow-Core Microstructured Fibers

In this paper, the sensitivity characteristics of Fabry-Perot (F-P) hydrostatic pressure sensor based on two different hollow-core (HC) microstructured optical fibers are experimentally and theoretically investigated. The sensors are fabricated by simply splicing a length of HC fiber to singlemode fibers. Hydrostatic pressure is measured by monitoring the wavelength shifts of the interferometric fringes as a result of the two reflection beams at the splicing points. The measured pressure sensitivities of F-P sensors fabricated on the simplified HC microstructured fiber and hollow-core photonic bandgap fiber (HC-PBGF) are - 17.3 and - 23.4 pm/MPa, respectively. Theoretical investigation is then carried out based on the analysis of elastic properties for the individual fibers. The calculated result suggests that the pressure sensitivities are dominantly determined by the induced changes in cavity length. In comparison, the contribution of mode-index change is slight. The mechanisms behind the mode-index changes for the two fibers are clarified by analyzing the deformation of the fiber structure under pressure. The holey microstructure is highly deformable compared to the solid fiber, which provide another dimension for the implementation of tunable photonic devices.

Enhancement of acoustic sensitivity of hollow-core photonic bandgap fibers

The acoustic pressure sensitivities of hollow-core photonic bandgap fibers (HC-PBFs) with different thicknesses of silica outer-cladding and polymer jacket were experimentally investigated. Experiment with a HC-PBF with 7 μm-thick silica outer cladding and 100 μm-thick Parylene C jacket demonstrated a pressure sensitivity 10 dB higher than the commercial HC-1550-02 fiber and 25 dB higher than a standard single mode fiber. The significant enhancement in sensitivity would simplify the design of fiber hydrophone arrays and increase the number of sensors that could be multiplexed in a single fiber.

Supercritical xenon-filled hollow-core photonic bandgap fiber

We demonstrate that filling a hollow-core photonic-bandgap fiber with supercritical xenon creates a medium with a controllable density up to several hundred times that at STP, while working at room temperature. The high compressibility of the supercritical fluid allows rapid tuning of the spectral guidance window by making small changes of gas pressure near the critical point. We discuss potential applications of this system in linear and nonlinear optics.

Real-time prediction of structural and optical properties of hollow-core photonic bandgap fibers during fabrication

We formulate a simple model based on mass conservation to accurately predict the structural parameters of hollow-core photonic bandgap fibers from knowledge of the second stage preforms from which they are drawn. We show that combining this model with precalculated property maps can allow real-time prediction of the optical properties of manufactured fibers.

Pulse quality analysis on soliton pulse compression and soliton self-frequency shift in a hollow-core photonic bandgap fiber

A numerical investigation of low-order soliton evolution in a proposed seven-cell hollow-core photonic bandgap fiber is reported. In the numerical simulation, we analyze the pulse quality evolution in soliton pulse compression and soliton self-frequency shift in three fiber structures with different cross-section sizes. In the simulation, we consider unchirped soliton pulses (of 400 fs) at the wavelength of 1060 nm. Our numerical results show that the seven-cell hollow-core photonic crystal fiber, with a cross-section size reduction of 2%, promotes the pulse quality on the soliton pulse compression and soliton self-frequency shift. For an input soliton pulse of order 3 (which corresponds to an energy of 1.69 μJ), the pulse gets compressed with a factor of up to 5.5 and a quality factor of 0.73, in a distance of 12 cm. It also experiences a soliton-self frequency shift of up to 28 nm, in a propagation length of 6 m, with a pulse shape quality of ≈ 0.80.

Towards high-capacity fibre-optic communications at the speed of light in vacuum

Wide-bandwidth signal transmission with low latency is emerging as a key requirement in a number of applications, including the development of future exaflop-scale supercomputers, financial algorithmic trading and cloud computing. Optical fibres provide unsurpassed transmission bandwidth, but light propagates 31% slower in a silica glass fibre than in vacuum, thus compromising latency. Air guidance in hollow-core fibres can reduce fibre latency very significantly. However, state-of-the-art technology cannot achieve the combined values of loss, bandwidth and mode-coupling characteristics required for high-capacity data transmission. Here, we report a fundamentally improved hollow-core photonic-bandgap fibre that provides a record combination of low loss (3.5 dB km-1) and wide bandwidth (160 nm), and use it to transmit 373 x 40 Gbit s-1 channels at a 1.54 ms km-1 faster speed than in a conventional fibre. This represents the first experimental demonstration of fibre-based wavelength division multiplexed data transmission at close to (99.7%) the speed of light in vacuum

空芯光子带隙光纤成栅机理及特性研究

空芯光子带隙光纤成栅机理及特性研究

Phase modulation at the few-photon level for weak-nonlinearity-based quantum computing

Researchers demonstrate large cross-phase shifts of 0.3 mrad per photon in a single pass through room-temperature Rb atoms confined to a hollow-core photonic bandgap fibre. The response time of less than 5 ns indicates that phase modulation bandwidths greater than 50 MHz are possible with a highly sensitive atomic-vapour-based scheme.

Selectable infiltrating large hollow core photonic band-gap fiber

A selectable infiltrating large hollow core photonic band-gap fiber is fabricated with simple arc discharge technique. The offset, discharge duration, arc current and discharge times are optimized for selected sealing side air-holes but leave the central large air-hole partially open. The collapse length of the PCF is shortened by increasing the number of discharges and offset with discharge duration and arc current kept at a relatively low level. Light with the wavelength located at the photonic band-gap can still propagate while the central hollow air-hole is infiltrated with a kind of oil with refractive index of 1.30. The selectable infiltrating large hollow core photonic band-gap fiber has potential application for implementing novel lasers, sensors and tunable optoelectronic devices.

Analysis of light scattering from surface roughness in hollow-core photonic bandgap fibers

We present a theoretical method for analyzing radiation loss from surface roughness scattering in hollow-core photonic bandgap fibers (HC-PBGFs). We treat the scattering process as induced dipole radiation and combine statistical information about surface roughness, mode field distribution and fibre geometry to accurately describe the far-field scattering distribution and loss in fibers with an arbitrary cross-sectional distribution of air holes of any shape. The predicted angular scattering distribution, total scattering loss and the loss wavelength dependence are all shown to agree well with reported experimental data. Our method yields a simpler result than that obtained by more complex approaches and is to the best of our knowledge the first successful attempt to accurately describe roughness scattering in HC-PBGFs.

Analysis of a hollow core photonic bandgap fiber ring resonator based on micro-optical structure

The fiber ring resonator (FRR) is the key component of resonator fiber optic gyros (R-FOGs). The configuration of a novel hollow core photonic bandgap fiber (HC-PBF) ring resonator is proposed based on the usage of micro-optical structure. The normalized transfer function of such kind of FRR is derived, and the effects of different FRR parameters' on the resonant depth, resonant finesse and sensitivity limited by the shot noise of the detector are simulated. The laboratory sample of integrated HC-PBF ring resonator is fabricated and tested experimentally and the optimal scheme is proposed based on the acquired test data. The experimental setup and results verify the feasibility of the micro-optical coupling structure used in the HC-PBF ring resonator and also support the integration and miniaturization of R-FOGs composed of HC-PBFs.