P2O5-doped Silica Research Articles

Synchronously pumped picosecond all-fibre Raman laser based on phosphorus-doped silica fibre.

Reported for the first time is picosecond-range pulse generation in an all-fibre Raman laser based on P₂O₅-doped silica fibre. Employment of phosphor-silicate fibre made possible single-cascade spectral transformation of pumping pulses at 1084 nm into 270-ps long Raman laser pulses at 1270 nm. The highest observed fraction of the Stokes component radiation at 1270 nm in the total output of the Raman laser amounted to 30%. The identified optimal duration of the input pulses at which the amount of Stokes component radiation in a ~16-m long phosphorus-based Raman fibre converter reaches its maximum was 140-180 ps.

Cascaded SRS of single- and double-scale fiber laser pulses in long extra-cavity fiber.

This work presents, for the first time, the results of studies of stimulated Raman scattering (SRS) in 1.2-km P2O5-doped silica fiber of radiation of single- and double-scale picosecond pulses generated in a fiber master oscillator and amplified in a one-stage fiber amplifier. Shown are differences in supercontinuum spectra composed of several Stokes components when pumped with pulses of different structure. More efficient Raman transformation of double-scale pulses was identified, leading to broader supercontinuum spectra.

Characterization of an Intra-Cavity Pumped P2O5-Doped Silica Raman Fiber Laser

We examine the characteristics of a P2O5-doped Raman fiber laser pumped by a double-clad ytterbium-doped fiber laser in an intra-cavity configuration. The double-clad fiber laser consists of two high reflection fiber Bragg gratings at 1092 nm, with an active length of 17 m, where the output grating is located at the end of the 400m P2O5-doped fiber. The Raman cavity is formed by a 1278-nm-high reflection fiber Bragg grating spliced to the double-clad fiber, and a 50% output coupler. The maximum conversion efficiency at 1278 nm with respect to the input pump power at 915 nm was 26.9%.

Effect of the spectral broadening of the first Stokes component on the efficiency of a two-stage Raman converter

A two-stage Raman fibre converter (1.089/1.273/1.533 μm) based on a P2O5-doped silica fibre is fabricated and studied. The spectral broadening of the first Stokes component is investigated. The Raman converter is simulated numerically. By using the experimental data, the method of Raman converter simulation is improved by taking into account the additional power loss of the first Stokes component. The results of calculations by the improved method are in good agreement with the experiment. It is shown that the additional power loss of the first Stokes component results in a change in the region of the optimal resonator length from 300–600 m to 600–800 m.

Peculiarities of the photosensitivity of low-loss phosphosilica fibres

The peculiarities of the refractive-index change in low-loss heavily P2O5-doped silica fibres fabricated by the MCVD method caused by irradiation with UV light are studied. The pre-exposure effect is found in these fibres. The mechanisms of the refractive-index change in phosphosilica and germanosilica fibres are considered and compared in the presence of this effect.

Output characteristics of a fibre Raman laser with a composite GeO2 and P2O5-doped silica fibre

A new type of fibre Raman laser composed of a GeO2- and P2O5-doped silica fibre was investigated experimentally and theoretically. The output of the laser displays two difference characteristics depending on the type of fibre being used as the input end. Using the P2O5-doped fibre as the input end, the Raman Stokes line of 1320cm−1 shift was enhanced by the latter GeO2-doped fibre. While the GeO2-doped fibre used as the input end, a wideband continuous spectrum was obtained. A model including effects of bandwidth of the Raman gain, four-wave mixing and the mutual influence of the GeO2- and P2O5-doped silica fibre was constructed to illustrate the experimental observation.

Dopant effect on transmission loss increase due to hydrogen permeation

The transmission loss increase due to hydrogen permeation in a GeO2-doped silica fibre and a P2O5-doped silica fibre are investigated. As a result, the difference of the loss increase between them is observed, and is considered to be due to the difference of the electronegativity between silica, germanium and phosphorus.

Very low OH content P 2 O 5 -doped silica fibres

Very low OH content optical fibres consisting of P2O5-doped silica core and GeO2-P2O5-B2O3-doped silica cladding were fabricated by the m.c.v.d. technique. The relation between the OH absorption loss and the deposition temperature was clarified. The OH content in this fibre could be reduced to about seven parts per billion (∼ 7 × 10−9) by using a low deposition temperature.

Pulse delay measurements in the zero-material-dispersion region for germanium- and phosphorus-doped silica fibres

Wavelength-dependent pulse dispersion in germanium- and phosphorus-doped silica fibres of different concentrations was measured using mode-locked subnanosecond pulses in the 1.064–1.55 μm wavelength range. Zero dispersion for GeO2-SiO2 fibres was observed in the 1.3–1.33 μm region depending on the concentration. P2O5-doped silica fibres showed zero dispersion near 1.28 μm, independent of doping concentration.