Intensity profile in a distributed feedback fibre laser characterised by a green fluorescence scanning technique

We report on an experimental technique for investigating the intensity profile in distributed feedback fibre lasers. By scanning along the laser length and monitoring the side green fluorescence, the intensity distribution in the laser can be inferred. With this approach, we experimentally verify the sharply peaked intensity distribution predicted for lambda/4 phase-shifted distributed feedback lasers

High power (60mW) single frequency erbium:ytterbium codoped fiber laser

The characteristics of a high power Er3+:Yb3+ single frequency fiber laser pumped at 980nm are reported. The device gives 60mW output power with RIN 10MHz and linewidth 500kHz. At low output powers (< 30mW) the slope efficiency is as high as 25%, falling to 12% at higher powers, the saturation behaviour is related to a bottleneck effect due to the finite Yb-Er transfer rate. Improved performance can be obtained using new fibers with an increased rare-earth concentration which show negligible signs of erbium clustering

Properties of dysprosium doped GaLaS fibre amplifiers operating at 1.3µm

In light of the recent progress on the fabrication of GaLaS fibres we have modelled the performance of dysprosium doped GaLaS fibre amplifiers operating at 1.3µm. Based on experimental data, we find the incorporation of a co-dopant (terbium) in the fibre core significantly shortens the optimum amplifier length from >30m to ~3m. Such a device may be practical given the fibre losses currently achieved in GaLaS fibres

1.2dB/cm gain in an erbium:lutecium co-doped Al/P silica fibre

We report a peak gain of 1.2dB/cm at 1535nm in an Erbium:Lutecium codoped Al/P/Si fibre fabricated using a standard MCVD and solution doping technique. This is the highest gain per unit length yet reported in an erbium doped fiber amplifier. The incorporation of lutetium into the glass is shown to reduce the erbium ion clustering within the fiber

Rare-earth doped chalcogenide glass fibre laser

We report on the first laser action in a rare-earth doped chalcogenide glass fibre. Laser action at 1080nm was obtained in a 22mm long gallium lanthanum sulphide glass fibre with a neodymium doped core, fabricated by the rod-in-tube technique. The laser was pumped continuous wave with a Ti:sapphire laser at 815nm and showed a self-pulsing behaviour

Spectral properties of Er³⁺-doped chalcogenide glasses

Lanthanum sulphides glasses formed with sufficient proportions of Ga2S3 constitute a very convenient matrix for rare earth sulphides, and Pr3+-doped Ga2S3:La2S3 (GLS) glasses have been recognized as one of the most promising candidates for fibre amplifiers operating at a wavelength of 1.3µm. In this report, the spectral properties of chalcogenide glass of the molar composition 0.7Ga2S3:0.3La2S3 doped with Er3+ are presented and discussed. Emission and absorption spectra and lifetimes of energy levels have been measured. The 2.7µm emission, as shown below, has been observed from chalcogenide glass for the first time. Radiative and non-radiative transition rates are calculated and compared with the measured lifetimes of interesting energy levels

Progress towards mid-infrared fibre lasers in rare-earth doped gallium lanthanum sulphide glass for gas sensing and remote sensing

Diode-pumped rare-earth doped fibre lasers in the mid-infrared wavelengths region would offer a compact and efficient alternative to the either relatively weak or very complex existing mid-infrared sources such as thermal emitters, gas lasers and OPOs. A prerequisite for the rare-earth host material is a low phonon energy leading to mid-infrared transparency and to low nonradiative decay rates and therefore higher quantum efficiencies of mid-infrared transitions. Conventional silica glass fibres cannot fulfill these requirements leading to a need for new glass materials with lower phonon energies which must also be suitable for fibre pulling. Our approach towards mid-infrared laser sources is based on the stable, non-toxic and non-hygroscopic chalcogenide glass gallium lanthanum sulphide (GLS) with the molar composition 70Ga2S3:30La2S3 which has been pulled into fibre form successfully [1]. It has a low phonon energy (425 cm) and a wide infrared transmission extending beyond 8µm. The characterization of undoped GLS glasses and fibres such as loss measurements and theoretical loss calculations will be presented in another paper at this conference [2]. In this paper we present the spectroscopy of rare-earth doped GLS glasses and fibres which show fluorescence at wavelengths which are interesting for gas sensing and remote sensing. Examples are the 3.4µm emission from praseodymium and the 4.3µm emission from dysprosium which overlap with the strong fundamental absorption bands of methane and carbon dioxide, respectively, and could therefore find application as gas sensors for these two important greenhouse gases. The emission of thulium at 3.8µm and holmium at 3.9µm fall into the atmospheric window with the highest transmission and could therefore be suitable for remote sensing applications. Laser action an the above transitions has not been achieved to date but the first laser action in a rare-earth doped chalcogenide glass fibre which has been demonstrated in a neodymium doped GLS fibre shows the potential for mid-infrared fibre lasers in this chalcogenide glass system [3]

Performance characteristics of single frequency Er³⁺:Yb³⁺ codoped fiber laser

The performance of Er3+:Yb3+ single frequency fiber lasers is reported. With lasing powers up to 60mW, they are shown to have excellent specifications in terms of optical linewidth, signal-to-noise ratio, RIN, SMSR and polarisation purity

Raman and excitation spectroscopy of semiconductor low dimensional structures

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Neodymium doped gallium lanthanum sulphide glass fibre laser

We report laser action in a neodymium doped gallium lanthanum sulphide glass fibre at 1.08µm. To our knowledge, this is the first demonstration of laser action in a rare-earth doped chalcogenide glass fibre