Justin Digweed

Temperature independent highly birefringent photonic crystal fibre

A highly birefringent photonic crystal fibre has been characterised as a function of temperature. The modal birefringence has been found to be independent of temperature from -25 to 800 degrees C.

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.

Spun elliptically birefringent photonic crystal fibre

Elliptically birefringent fibre has been fabricated by spinning the preform of a highly linearly birefringent photonic crystal fibre (PCF) during the drawing process. The resulting Spun Highly Birefringent (SHi-Bi) PCF offers intrinsic sensitivity to magnetic fields through the Faraday effect without the high inherent temperature sensitivities suffered by conventional spun stress birefringence fibres. The ellipticity of the birefringence has been measured and temperature independence has been demonstrated.

Spun elliptically birefringent photonic crystal fibre for current sensing

Spun elliptically birefringent fibre has been fabricated by spinning the preform of a highly linearly birefringent photonic crystal fibre (PCF) during the drawing process. The resulting spun highly birefringent (SHi-Bi) PCF offers sensitivity to magnetic fields for current measurements with greatly reduced temperature dependence in comparison with conventional spun stress birefringence fibres. The ellipticity of the birefringence has been measured and temperature independence has been demonstrated.

Geometry control of air-silica structured optical fibres using pressurisation

The use of pressurisation can allow substantial and fine control of the geometrical dimensions of air-material structured optical fibres. A comparison is made between three air-silica structured optical fibres drawn from thin and thick capillary stacks. The effect of temperature on pressurisation is also discussed.

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.

Temperature independent polarisation maintaining fibre for sensing and interferometry

Polarisation maintaining fibres used for sensing and interferometry typically have high birefringence [1-3] and are known as HiBi fibres. Since photonic crystal fibre (PCF) was first reported [4,5], HiBi PCFs with birefringence comparable to and greater than conventional highly stressed bow-tie and PANDA fibre have been demonstrated [6-10]. Very high levels of form birefringence in PCFs have been possible due to the flexibility in geometry and the high refractive index contrast offered by making a fibre with an air silica structure (ASS). In this paper we present experimental results that show effective temperature independent, or athermal, birefringence in a HiBi-PCF [11-14]. This is expected to be beneficial for a number of sensing and interferometric applications. For example, fibre optic gyroscopes (FOG) generally use very long lengths of coiled HiBi fibre in a Sagnac configuration to attain suitable sensitivity. FOG cost is, however, a significant driving factor in limiting the expansion of FOGs into new lower cost applications. FOG performance has been primarily limited by environmental temperature sensitivity [15,16] and stabilisation routes, using temperature-stabilised packaging, add too much to their cost. The use of a passive, temperature insensitive HiBi-PCF is a much lower cost alternative that does not require active stabilisation, thereby potentially overcoming these limitations and potentially opening up a new low cost market for FOG technology whilst retaining high performance.

Spun highly birefringent (SHi-Bi) photonic crystal fibre

We report on the fabrication of a spun hi-birefringence photonic crystal fibre. The measured elliptical birefringence of 1.6times10-3 which is an order of magnitude larger than conventional stress spun hi-birefringence optical fibres.

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.