Tom Ryan

All-fibre photonic crystal distributed Bragg reflector (PC-DBR) fibre laser

We describe an Er3+-doped aluminosilicate core photonic crystal fibre laser incorporating distributed Bragg reflectors written by two-photon 193nm irradiation through an optical phase mask as the feedback elements. The laser is diode pumped at 980nm and evidence of dual linewidth laser operation close to threshold is observed. However, at higher pumping levels gain competition preferentially selects one laser line.

Distributed feedback photonic crystal fibre (DFB-PCF) laser

A distributed feedback laser is fabricated in Er3+-doped photonic crystal fibre. Preferential single-mode lasing is obtained with no special consideration of polarisation issues. The results demonstrate practical implementation of a multi-photon writing process for complex structures in these optical fibres. No hydrogen loading and no germanium are involved.

Wavelength dependent leakage in a Fresnel-based air–silica structured optical fibre

An air-silica structured fibre is designed with air holes placed in circular rings marking the effective Fresnel zones of the waveguide. By educing the holes to six in each ring and pulling the fibre to appropriate dimensions, light at 633nm leaks out between the holes and is unable to propagate along the fibre. On the other hand confinement and propagation is achieved at 1550nm despite a large hole separation.

Modification of thermal poling evolution using novel twin-hole fibers

Thermal poling current and electrooptic evolution were studied for a standard twin-hole fiber and two novel design twin-hole fibers. The poling characteristics were modified in the novel fibers, which had a trap or donor region inside the anode hole. Modifications of the poling characteristics were observed in both the current evolution and the electrooptic evolution. The novel fiber designs can facilitate the tailoring of poled fiber device characteristics.

Complex mode coupling within air-silica structured optical fibres and applications

Abstract Novel twin-core coupling at shorter wavelengths (∼633 nm) but not at longer wavelengths (∼1.5 μm) is achieved within an air–silica structured optical fibre. This is the opposite of a conventional twin-core fibre coupler. The implications for a new class of all-optical devices are discussed.

High power Tm3+-doped silica fibre laser fabricated using chelate delivery deposition

Abstract We present the results from experiments relating to the characterisation of a high power Tm 3+ -doped silica fibre laser that has the Tm 3+ -dopant incorporated into the fibre using chelate delivery deposition. We achieve an output power of >1.5 W at a slope efficiency of 13% with respect to launched pump power for a fibre length of 54 m. These results indicate that the scattering, absorption and clustering-induced losses that are present with this fibre are small.

Bending-induced colouring in a photonic crystal fibre

A photonic crystal fibre has been fabricated with a photonic crystal that is surrounded by a number of silica cores. Bending of the fibre induces an interaction between the core and photonic crystal areas, resulting in a highly wavelength-dependent loss of the core modes. White-light transmission experiments are presented which show that the colour of the transmitted light changes as a function of the fibre-bending radius. We compare the results to a simple model and find agreement.

Eliptically polarizing optical fiber

Elliptically polarizing optical fiber has been fabricated. Measurements show an extinction of the lossy mode relative to the transmitted mode of around 10 dB/m. The preform is spun during drawing and the ellipticity of the transmitted polarization state is as expected from the measured beat length of the unspun fiber and the pitch length of the spun fiber. This fiber is expected to be useful for interferometric or laser-based electric-current sensing, and perhaps in other applications for an in-line polarizer.

Effective resource multiplexing for scientific workflows

Scientific workflows feature complex precedence constraints that are mostly dictated by data dependencies between tasks. The inter-task communication (data staging) in these complex workflow applications incurs significant overheads resulting in a major hindering factor of high performance and effective resource utilization. As the scale of these applications becomes increasingly large due primarily to the recent explosive growth of data, addressing this hindrance is of great practical importance. In this paper, we present a resource multiplexing (RM) technique, which leverages data staging aiming to minimize idle times between execution of tasks due to inter-task communication overheads. In particular, we incorporate RM into our DEWE framework 1 with making a set of extensions to the framework. The rationale behind RM is each slot or core pairs up the actual workflow task and the RM-enabled file loading DEWE extension (File Client) in the way that their resource usage is complementary. We demonstrate the efficacy of our multiplexing technique in a data-intensive computing environment using an astronomy application. Our results from experiments conducted in Amazon EC2 demonstrate that our multiplexing technique is effective with the reduction in resource idle time between jobs by 57% on average and up to 91%.

DFB photonic crystal fiber (DFB-PCF) laser in Er3+ doped air-silica structured optical fibre

The construction and operation of a DFB photonic crystal fibre laser produced in Er3+ core doped air-silica structured optical fibre is presented. Its potential in sensing generally is elaborated.