1,720,968 research outputs found
Efficient operation of a Yb-sensitised Er fibre laser pumped in the 0.8 µm region
No full textThe dependence of threshold and slope efficiency on pump wavelength around 0.8µm has been investigated for an Yb-sensitised fibre laser. Results confirm a wider choice of pump wavelength compared with unsensitised Er fibre. A 5mW threshold and slope efficiency of 8.5% were observed for 820-830nm pumping
Continuous-wave oscillation of a holmium-doped silica fibre laser
No full textLaser emission at 2.04µm has been observed in a silica fibre doped with Ho3+. When pumped with an argon laser at 457.9 nm an absorbed threshold power of 46mW and a slope efficiency of 1.7% were measured
Efficient and tunable operation of a Tm-doped fibre laser
No full textWe report on improved performance from a silica based thulium doped fibre laser. Under excitation at 810nm this system has demonstrated a near theoretical maximum slope efficiency of 36% (84% photon conversion efficiency), corresponding to 44mW of laser output power at 1900 nm for 167mW of absorbed power. In addition we have used a birefringent filter to continuously tune the laser over a range of 276nm, from 1780 to 2056nm
Characterisation of spontaneous and stimulated emission from Praseodymium (Pr<sup>3+</sup>) ions doped into a silica based monomode optical fibre
No full textThe fluorescence spectrum of praseodymium in a silica host has been investigated through the direct excitation of the 3P0, 1D2, and 1G4 absorption bands, which occur at around 488, 590, and 974 nm, respectively. The observed spontaneous emission consists of four main bands with peaks at 633, 707, 888, and 1080 nm. In each case the level principally responsible for these emissions was found to be 1D2. Stimulated emission has been seen for the first time at 888 nm for a threshold of 10 mW absorbed power. In addition, the lasing characteristics at 1080 nm have been investigated
Continuous-wave oscillation of a monomode ytterbium doped fibre laser
No full textThe last few years have seen intense interest and activity in the field of rare earth doped monomode fibre lasers and amplifiers [1,2],since these components could be used in fields as diverse as medicine and communications. Furthermore their small active volume offers a number of important advantages over conventional bulk glass lasers. We have chosen to investigate ytterbium doped fibre as it provides a very "clean" system (ie free from excited state absorption. Apart from the energy levels around 11,000cm-1 there are no other levels until the ultra-violet). The ytterbium fibre laser should therefore offer a good system on which to test some of the basic physics of fibre lasers. In addition it offers 3-level, 4-level and quasi 3-level laser transitions. Published work on ytterbium doped glass lasers in bulk form has been sparse with the main publication being that of Snitzer [3]. In this paper we describe the characteristics of an ytterbium-doped, silica based, monomode fibre laser operating at discrete wavelengths in the range 1035nm to 1076nm
A diode-pumped, first-window optical fibre amplifier providing up to +12dBm of output
No full textThe thulium ion is one of great interest when it is doped within fluorozirconate glass due to the number of transitions available for stimulated emission. One such transition is the 3F4 to 3H6 transition at 0.8 µm. This is of interest as it lies within the first window for optical communication. There is growing interest in the use of this window for local area networks, passive optical networks, or supervisory systems. Small signal amplification of up to 23 dB has been reported for this transition in a thulium-doped fluoride fibre using a Ti:sapphire laser as the pump source. We report here the first diode pumped operation of this optical amplifier. An intrinsic small signal gain in excess of 30 dB was achieved. With a launched 807-nm signal power of -10 dBm, intrinsic gain of 21 dB was observed, producing amplified output powers of +11 dBm. An intrinsic gain of greater than 20 dB was observed for signals over the spectral range of 802 nm to 810 nm. The greatest amplified output power obtained for this system was 12.8 dBm for 30 mW of launched diode pump power
Thulium-doped monomode silica fibre as a laser medium
No full textTm3+ is an interesting activator ion for a glass fiber laser because it emits in regions of the spectrum where such lasers have not previously operated. The fiber waveguide geometry confers a low threshold for laser action. Therefore, semiconductor diode laser pumping is a possibility since Tm3+ has an absorption band at ~800 nm
Frequency upconversion in Tm- and Yb:Tm-doped silica fibers
No full textFrequency upconversion has been observed and studied in Tm3+-doped and Yb3+-sensitized Tm3+-doped silica fibers. In the singly singly doped fiber upconversion to the blue and UV has been observed under excitation in the red (660 nm) and infra-red (1.064µm). In the co-doped fiber upconversion has also been observed under excitation at around 800-900 nm
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