X. Feng

Nonsilica glasses for holey fibers

The authors of this paper investigated the thermal properties and optical properties of typical nonsilica glasses, including viscosity, surface tension, thermal conductivity, transmission, linear and nonlinear refractive index, and fiber attenuation in order to judge the feasibility of using nonsilica glasses as the background material of holey fibers (HFs). Novel techniques were presented to fabricate the nonsilica glass microstructured fiber preforms. Examples of fabricated nonsilica glass HFs with various promising optical applications were finally exhibited.

High-nonlinearity dispersion-shifted lead-silicate holey fibers for efficient 1-/spl mu/m pumped supercontinuum generation

This paper reports on the recent progress in the design and fabrication of high-nonlinearity lead-silicate holey fibers (HFs). First, the fabrication of a fiber designed to offer close to the maximum possible nonlinearity per unit length in this glass type is described. A value of /spl gamma/=1860 W/sup -1//spl middot/km/sup -1/ at a wavelength of 1.55 /spl mu/m is achieved, which is believed to be a record for any fiber at this wavelength. Second, the design and fabrication of a fiber with a slightly reduced nonlinearity but with dispersion-shifted characteristics tailored to enhance broadband supercontinuum (SC) generation when pumped at a wavelength of 1.06 /spl mu/m-a wavelength readily generated using Yb-doped fiber lasers-are described. SC generation spanning more than 1000 nm is observed for modest pulse energies of /spl sim/ 100 pJ using a short length of this fiber. Finally, the results of numerical simulations of the SC process in the proposed fibers are presented, which are in good agreement with the experimental observations and highlight the importance of accurate control of the zero-dispersion wavelength (ZDW) when optimizing such fibers for SC performance.

Towards efficient and broadband four-wave-mixing using short-length dispersion tailored lead silicate holey fibers

We demonstrate four-wave-mixing based wavelength conversion at 1.55 mum in a 2.2 m-long dispersion-shifted lead-silicate holey fiber. For a pump peak power of ~6 W, a conversion efficiency of -6 dB is achieved over a 3-dB bandwidth of ~30 nm. Numerical simulations are used to predict the performance of the fiber for different experimental conditions and to address the potential of dispersion-tailored lead silicate holey fibers in wavelength conversion applications utilizing four-wave-mixing. It is shown that highly efficient and broadband wavelength conversion, covering the entire C-band, can be achieved for such fibers at reasonable optical pump powers and for fiber lengths as short as ~2 m.

Mid-infrared supercontinuum generation in suspended core tellurite microstructured optical fibers

We report the fabrication of a tellurite optical fiber with a suspended core design, formed on a 220-nm-wide filament of glass. The fiber was pumped at two different wavelengths (1500 and 2400 nm) using femtosecond pulses generated from an optical parametric oscillator (OPO) in order to produce mid-infrared supercontinuum (SC). We observed that SC spectra extending to 3 μm were readily generated. To further optimize the design, detailed numerical study was performed, which revealed how the fiber structural characteristics dramatically influence the spectral broadening because of the changes in the dispersion profile and in turn, the interplay of nonlinear effects that give rise to SC generation. We found that an accurate control of the core shape can be employed to contain the generated SC spectra within well-defined spectral regions or to provide a broad extension of the continuum to beyond 4 μm.

Advances in microstructured fiber technology

We review our recent progress in the area of microstructured fiber design, fabrication and applications with particular emphasis on the control of both the nonlinearity and dispersion.

Recent advances in highly nonlinear fibres

We review recent progress in the areas of silica and compound glass based highly nonlinear fibres, highlighting and contrasting the current start-of-the-art, merits, drawbacks and future potential of both approaches.

Low Walk-Off Kerr-Shutter Using a Dispersion-Shifted Lead Silicate Holey Fiber

We present, for the first time to our knowledge, the use of a dispersion-shifted soft-glass holey fiber (HF) in a Kerr-shutter configuration. Wavelength conversion of 10-Gb/s data pulses is achieved in the C-band using just 2.1 m of a lead-silicate HF with a nonlinear parameter ¿ of 164 W-1 · km-1. The low dispersion and the short length of the fiber enable short switching windows to be realized.

Single-mode high-index-core one-dimensional microstructured fiber with high nonlinearity

We report the first fabrication of a high-index-core one-dimensional microstructured optical fiber with high index-contrast layers. Extrusion is utilized to fabricate the microstructured preform. Single mode guidance and high nonlinearity were observed in the fiber.

High Nonlinearity Holey Fibers: Design, Fabrication and Applications

We describe our recent progress in the development of next-generation small-core holey fibers (HFs) with unique dispersive and nonlinear properties. We report the use of Genetic Algorithms to optimize the dispersion characteristics of silica-based HFs, and report progress in soft-glass HF fabrication which has resulted in fibers with record values of nonlinearity.

PbSe quantum dots grown in a high-index low-melting-temperature glass for infrared laser applications

PbSe quantum dots (QDs) were grown in high-refractive-index low-melting-temperature leadphosphate glass. QDs with various sizes ranging from 2 nm to 5.3 nm were grown by controlling the growth parameters, heat-treatment temperature and time. The corresponding room-temperature exciton absorption was tuned within the infrared region from 0.93 μm to 2.75 μm. Photoluminescence was measured for samples with absorption peaks above 0.95eV. Real time quantum dot growth was demonstrated by monitoring the evolution of exciton absorption with temperature and time duration. As a demonstration of the use of QDs in laser applications, the saturation fluence (Fsat) of one of the QDs was evaluated and found to be ~2.1 μJ/cm2 at 1.2 μm.