Q-switched neodymium-doped phosphate glass fibre lasers

The operation of a short-pulse, Q-switched, neodymium-doped fiber laser operating at 1.054µm is described experimentally and theoretically. The laser is efficiently pumped with a single-stripe AlGaAs laser diode and emits &gt;1kW pulses. It is seen that due to high gain, short pulses with high energy extraction efficiency can be obtained. The feature of broad emission lines associated with rare-earth-doped glasses is exploited to demonstrate tunable, Q-switched operation over a 40 nm tuning range. <br/

Cavity dumping of neodymium-doped fibre lasers using acousto-optic modulator

We report high-repetition-rate pulses obtained by cavity dumping of a neodymium-doped phosphate glass fibre laser operating at 1053 nm using a specially constructed acoustooptic modulator. With 27 mW absorbed pump power at 812 nm we obtained stable trains of output pulses with repetition rate in the range 0.5 to 8MHz having corresponding pulse widths in the range 127 to 19 ns without significant sacrifice in the average output power of 8 mW

Tapered fibre LPG device as a sensing element for refractive index

The fabrication and characterisation of Long Period Gratings in fibre tapers is presented alongside supporting theory. The devices possess a high sensitivity to the index of aqueous solutions due to an observed spectral bifurcation effect

Acousto-optically Q-switched fibre laser source of high peak power and short duration pulses for fibre sensor applications

We report on a fibre laser source which emits high peak power (&gt;0.7 kW) and short (2.8 ns) Q-switched pulses at 1.06 µm suitable for distributed fibre sensor applications using an absorbed pump power of 13 mW and miniature acousto-optic modulator

Regenerative Nd-glass amplifier seeded with a Nd fibre laser

Wavelength tuning and broad-bandwidth operation of a passively mode-locked Nd:fiber laser is demonstrated at 1060 nm. The oscillator pulses are used to seed a bulk regenerative Nd:glass amplifier, and 300-fs transform-limited pulses with an energy of 10µJ are obtained after 31 round trips at a repetition rate of 500 Hz

High power diode-pumped Nd³⁺ fibre laser

In the medical field high power fibre-coupled AlGaAs diode lasers operating around 800nm are already making an impact in surgery but for more specialised applications high powers at other wavelengths are required. It is an attractive idea to develop active fibres as add-ons to such fibre coupled diode systems increasing the range of applications of such devices at little extra cost and minimal additional complexity. Rare-earth-doped optical fibres exhibit the traditional advantages of a glass laser host of broad emission and absorption spectra but without the usual associated thermal problems. With fibre lasers wavelength selection and temperature stabilisation of the pump diode is unnecessary, and the emission spectra allows for broad tuning. Double-clad fibres comprising a doped core, usually single-moded located within a large multimode waveguide enable efficient pumping of fibre lasers with diode ways or diode bars. Fibre lasers can thus be considered as simple wavelength convertors and brightness enhancers for the high power but poorly specified output of diode sources. In the this paper we describe a multiwatt Nd3+ fibre laser pumped via a second cladding by the DIOMED 25 laser diode unit. This multi diode array source is designed for coupling up to 25 Watts of diode power into a plastic-clad silica fibre of 400µm diameter. The laser fibre which is a double-clad structure fabricated from lead-silicate glasses is interchangeable with the normal PCS delivery fibre. The device operates at 1.058µm with a slope efficiency &gt;50% and a 150 times brightness enhancement. This laser though useful in itself is also a key intermediate laser for generation of high powers at other wavelengths. Tandem pumping of Tm3+ and Er3+/Yb3+ fibre lasers at 1.058µm enables efficient generation of 2.0µm and 1.55µm radiation respectively. In addition the Nd3+ laser can be operated close to 1.3µm and there are prospects for in-fibre frequency doubling of the 1.06µm line to generate a high power source in the green

+21dBm erbium power amplifier pumped by a diode-pumped Nd:YAG laser

Efficient energy transfer has been demonstrated in an Er/Yb co-doped phosphorus doped silica fiber for the first time. This has indirectly allowed the use of reliable, high-power AlGaAs diode laser arrays as the semiconductor pump source through the use of a diode-pumped Nd:YAG (DPL) laser operating at 1064 nm. Small signal gains of 42 dB and output powers of 71 mW (+18.5 dBm) have been observed with a single DPL. Bidirectional pumping with two DPLs has yielded an output power of 130 mW (+21 dBm)

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Q-switching of fibre lasers is an attractive means of converting the relatively low CW power of pump laser diodes into short, high intensity pulses for use in time-resolved sensor systems. Peak powers of 100W at 1.06µm with 15ms duration have previously been reported based on the use of Nd-doped alumino-silicate fibre as the gain medium. We report here the attainment of much higher powers in short pulses in a module specifically designed for high-resolution distributed sensor applications

High-gain superfluorescent neodymium-doped single-mode fibre source

High brightness, low coherence sources are required in a number of optical sensor applications, particularly the fibre-optic gyro. An efficient superfluorescent, neodymium-doped phosphate glass fibre source has been developed which fulfils this requirement. The fibre shows a high gain efficiency at 1.053µm of 1dB/mW pump power and this permits pumping with an 810nm single-stripe AlGaAs laser diode to obtain &gt; 5mW CW output power at a wavelength of 1.053µm for only 45mW of pump power

Yb³⁺ sensitised Er³⁺-doped silica optical fibre with ultrahigh transfer efficiency and gain

Efficient 1.54µm emission under 1064nm excitation of Er3+:Yb3+ codoped silica fibre is reported. The energy transfer efficiency from Yb3+ to Er3+, ~95% even under high inversion, is comparable to that in multicomponent glass fibres. The small signal gain of ~45dB is measured and power amplifiers with 145mW output power demonstrated