We demonstrate experimentally and theoretically that the core-guided mode in helically twisted photonic crystal fiber exhibits resonantly enhanced optical activity and circular dichroism in the vicinity of anti-crossings with leaky orbital angular momentum (OAM) modes in the cladding. This arises because the anti-crossings for left and right circularly polarized core modes occur at slightly different wavelengths. (C) 2015 Optical Society of America
Deep-ultraviolet to mid-infrared supercontinuum generated in solid-core ZBLAN photonic crystal fibre
Xin Jiang,
Nicolas Y. Joly,
Martin A. Finger,
Fehim Babic,
Gordon K. L. Wong,
John C. Travers,
Philip St J. Russell
Silica-based photonic crystal fibre has proven highly successful for supercontinuum generation, with smooth and flat spectral power densities. However, fused silica glass suffers from strong material absorption in the mid-infrared (>2,500 nm), as well as ultraviolet-related optical damage (solarization), which limits performance and lifetime in the ultraviolet (<380 nm). Supercontinuum generation in silica photonic crystal fibre is therefore only possible between these limits. A number of alternative glasses have been used to extend the mid-infrared performance, including chalcogenides, fluorides and heavy-metal oxides, but none has extended the ultraviolet performance. Here, we describe the successful fabrication (using the stack-and-draw technique) of a ZBLAN photonic crystal fibre with a high air-filling fraction, a small solid core, nanoscale features and near-perfect structure. We also report its use in the generation of ultrabroadband, long-term stable, supercontinua spanning more than three octaves in the spectral range 200-2,500 nm.
Compressing mu J-level pulses from 250 fs to sub-10 fs at 38-MHz
repetition rate using two gas-filled hollow-core photonic crystal fiber
stages
K. F. Mak,
M. Seidel,
O. Pronin,
M. H. Frosz,
A. Abdolvand,
V. Pervak,
A. Apolonski,
F. Krausz,
J. C. Travers, et al.
Compression of 250-fs, 1-mu J pulses from a KLM Yb:YAG thin-disk oscillator down to 9.1 fs is demonstrated. A kagome-PCF with a 36-mu m core-diameter is used with a pressure gradient from 0 to 40 bar of krypton. Compression to 22 fs is achieved by 1200 fs(2) group-delay-dispersion provided by chirped mirrors. By coupling the output into a second kagome-PCF with a pressure gradient from 0 to 25 bar of argon, octave spanning spectral broadening via the soliton-effect is observed at 18-W average output power. Self-compression to 9.1 fs is measured, with compressibility to 5 fs predicted. Also observed is strong emission in the visible via dispersive wave generation, amounting to 4% of the total output power. (C) 2015 Optical Society of America
Supercontinuum generation in the vacuum ultraviolet through dispersive-wave and soliton-plasma interaction in a noble-gas-filled hollow-core photonic crystal fiber
A. Ermolov,
K. F. Mak,
M. H. Frosz,
J. C. Travers,
P. St. J. Russell
We report on the generation of a three-octave-wide supercontinuum extending from the vacuum ultraviolet (VUV) to the near infrared, spanning at least 113-1000 nm (i.e., 11-1.2eV), in He-filled hollow-core kagome-style photonic crystal fiber. Numerical simulations confirm that the main mechanism is an interaction between dispersive-wave emission and plasma-induced blue-shifted soliton recompression around the fiber zero dispersion frequency. The VUV part of the supercontinuum, the modeling of which proves to be coherent and possesses a simple phase structure, has sufficient bandwidth to support single-cycle pulses of 500 asec duration. We also demonstrate, in the same system, the generation of narrower-band VUV pulses through dispersive-wave emission, tunable from 120 to 200 nm with efficiencies exceeding 1% and VUV pulse energies in excess of 50 nJ.
Engineering of a Ge-Te-Se glass fibre evanescent wave spectroscopic (FEWS) mid-IR chemical sensor for the analysis of food and pharmaceutical products
Xin Jiang,
Animesh Jha
SENSORS AND ACTUATORS B-CHEMICAL
206
159-169
(2015)
| Journal
Using an unclad multimode Ge-Te-Se based chalcogenide glass fibre, simple design robust fibre evanescent wave spectroscopic (FEWS) sensor is demonstrated. Methodologies adopted for material development and fibre drawing are discussed in the following steps: purification of raw materials for high spectral purity, fabrication of glass and fibre preform leading to fibre drawing. The fabricated fibre has a minimum loss of 1.4 dB/m at 4.2 mu m, and less than 3 dB/m between 1.5 and 6.3 mu m. The feasibility of using such a fibre for evanescent wave spectroscopic sensing has been verified by using the finite-element (FE) computation technique. Supported optical modes as well as corresponding penetration depths of evanescent fields from different modes are discussed. Based on the FE computation, a FEWS sensor consisting of a 40 cm Ge-Te-Se fibre, coupled with a Fourier transform infrared (FTIR) spectrometer and a liquid nitrogen cooled mercury-cadmium-tellurium (MCT) detector, is demonstrated. The active length along this fibre employed for sensing is 3 cm. Based on FEWS design, the fabricated fibre sensor was used for the analysis of chemicals, namely the acetone, ethanol, methanol, tocopherol (vitamin E), ascorbic acid (vitamin C), fresh orange and lemon juice. (C) 2014 Elsevier B.V. All rights reserved.
Stable subpicosecond soliton fiber laser passively mode-locked by gigahertz acoustic resonance in photonic crystal fiber core
M. Pang,
X. Jiang,
W. He,
G. K. L. Wong,
G. Onishchukov,
N. Y. Joly,
G. Ahmed,
C. R. Menyuk,
P. St J. Russell
Ultrafast lasers with high repetition rates are of considerable interest in applications such as optical fiber telecommunications, frequency metrology, high-speed optical sampling, and arbitrary waveform generation. For fiber lasers mode-locked at the cavity round-trip frequency, the pulse repetition rate is limited to tens or hundreds of megahertz by the meter-order cavity lengths. Here we report a soliton fiber laser passively mode-locked at a high harmonic (similar to 2 GHz) of its fundamental frequency by means of optoacoustic interactions in the small solid glass core of a short length ( 60 cm) of photonic crystal fiber. Due to tight confinement of both light and vibrations, the optomechanical interaction is strongly enhanced. The long-lived acoustic vibration provides strong modulation of the refractive index in the photonic crystal fiber core, fixing the soliton spacing in the laser cavity and allowing stable mode-locking, with low pulse timing jitter, at gigahertz repetition rates. (C) 2015 Optical Society of America
Contact
TDSU Fibre Fabrication & Glass Studio Michael Frosz
Max Planck Institute for the Science of Light Staudtstr. 2 91058 Erlangen, Germany
