Novel microstructured fibres for optical sensing of gases

Air/Silica Microstructured Optical Fibres (MOFs) provide a novel and enabling platform for absorption-based optical sensing of gases [1]. These fibres have arrays of wavelength-scale holes in their cross section, which run along the full length and define their waveguiding properties by way of their geometry and size. Awider variety of gUidance mechanisms and optical properties is possible in MOFs, as compared to conventional fibres, due to the high index contrast between air and glass, and the almost endless variety of structures that can be realised with this technology

Microstructured optical fibres for gas sensing: design fabrication and post-fab processing

Air/silica Microstructured Optical Fibers (MOFs) offer new prospects for fiber based sensor devices. In this paper, two topics of particular significance for gas sensing using air guiding Photonic Bandgap Fibers (PBGFs) are discussed. First, we address the issue of controlling the modal properties of PBGFs and demonstrate a single mode, polarization maintaining air guiding PBGF. Secondly, we present recent improvements of a femtosecond laser machining technique for fabricating fluidic channels in PBGFs, which allowed us to achieve cells with multiple side access channels and low additional loss

Mid-infrared transmission properties of step index and large mode area ZnSe microstructured optical fibers

ZnSe microstructured fibers have been designed and fabricated using silica capillaries and an air-silica photonic band-gap optical fiber as high-pressure microfluidic templates for semiconductor growth via chemical fluid deposition. We examine their transmission properties over a wide spectral range

Robust low loss splicing of hollow core photonic bandgap fiber to itself

Robust, low loss (0.16dB) splicing of hollow core photonic band gap fiber to itself is presented. Modal content is negligibly affected by splicing, enabling penalty-free 40Gbit/s data transmission over > 200m of spliced PBGF

Predicting Structural and Optical Properties of Hollow-Core Photonic Bandgap Fibers from Second Stage Preforms

We propose a simple theory based on mass conservation that allows accurate prediction of guidance properties in hollow-core photonic bandgap fibers (HC-PBGF) from knowledge of the second stage preforms from which the fibers are drawn

Modelling applications of photonic bandgap fibres

Photonic crystal fibres (PCFs)[1] are one of the most exciting developments in the field of photonics that has emerged in recent years. Not only have they already led to cheap all-fibre high brightness white light sources and have sparked a renaissance in the field of nonlinear optics but they also have the potential to dramatically change the next generation of telecommunication systems. PCFs can be split into two categories, the first have a solid core and guide light by modified total internal reflection, while the second photonic bandgap fibres (PBF) guide light by photonic bandgap effects and typically have a low index core compared to the cladding. Also of interest are "arrow" fibres which have a solid core and guide light due to the arrangement of high index defects in the cladding. In this paper we will be concentrating on designing and manipulating the properties of PBFs. etc..

RGB generation by four-wave mixing in small-core holey fibers

We report the generation of white light comprising red, green, and blue spectral bands from a frequency-doubled fiber laser by an efficient four-wave mixing process in submicron-sized cores of microstructured holey fibers. A master-oscillator power amplifier (MOPA) source based on Yb-doped fiber is employed to generate 80 ps pulses at 1060 nm wavelength with 32 MHz repetition rate, which are then frequency-doubled in an LBO crystal to generate up to 2 W average power of green light. The green pump is then carefully launched into secondary cores of the cladding of photonic bandgap fibers. These secondary cores with diameters of about 400 to 800 nm act as highly nonlinear waveguides. At the output, we observe strong red and blue sidebands which, together with the remaining green pump light, form a visible white light source of about 360 mW. The generating process is identified as four-wave mixing where phase matching is achieved by birefringence in the secondary cores which arises from non-symmetric deformation during the fiber fabrication. Numerical models of the fiber structure and of the nonlinear processes confirm our interpretation. Finally, we discuss power scaling and limitations of the white light source due to the damage threshold of silica fibers

Manufacturing of high performance hollow core microstructured optical fibres

Although fabrication technologies of Microstructured Optical Fibres (MOFs) fibres have matured at an impressive rate over the past ten years, these fibres are widely perceived as "challenging" and some key issues are still outstanding in order to improve their manufacturability. One such issue revolves around methods to improve structural control during the fibre draw. Structural control is of particular importance for certain types of microstructured fibres, such as hollow core Photonic Bandgap Fibres (PBGFs) and Anti-resonant (AR) fibres (also known as Kagome fibres). These fibres exploit resonant and/or anti-resonant guidance mechanisms and thus their transmission properties depend on the structure to a much greater extent as compared to conventional fibres. Hollow core MOFs have been identified as promising media for applications such as low latency (speed-of-light-in-air) communications, fibre sensing (chemical sensing, gyroscopes, sensors based on distributed scattering), laser power delivery (both high-peak and high average). However the successful implementation of these fibres in advanced demonstrators leading to commercial devices has been hindered by high cost, poor consistency and, in some instances, by lack of fibres with sufficiently good properties. We are actively investigating methods to improve structural control during the fibre draw and methods for scaling up the current manufacturing yields. Here we present recent progress in the fabrication hollow core MOFs at the Optoelectronics Research Centre; in particular, we report the fabrication of ultra-low loss (~few dB/km), wide bandwidth (>150nm) Photonic Bandgap Fibres and anti-resonant Hexagram Fibres with broadband low loss transmission suitable for the delivery of extremely high peak optical powers

A single-mode, high index-contrast, lead silicate glass fibre with high nonlinearity, broadband near-zero dispersion at telecommunication wavelengths

We report on the design, fabrication and characterization of a single-mode W-type lead silicate glass fibre with flattened and near-zero dispersion profile at telecom wavelengths and high nonlinearity of 820 W-1km-1 at 1.55 µm

Understanding wavelength scaling in 19-cell core hollow-core photonic bandgap fibers

First experimental wavelength scaling in 19-cell core HC-PBGF indicates that the minimum loss waveband occurs at longer wavelengths than previously predicted. Record low loss (2.5dB/km) fibers operating around 2µm and gas-purging experiments are also reported