J.E. Townsend

Diode-array pumping of Er/sup 3+//Yb/sup 3+/ Co-doped fiber lasers and amplifiers

Single-mode double-clad Er/sup 3+//Yb/sup 3+/ co-doped fibers are shown to be suitable for diode array pumping at around 960 nm. A fiber laser with 96-W output power at 1.53 mu m and a power amplifier exhibiting a small signal gain of 24 dB and a saturated output power of +17 dBm are reported.<<ETX>>

Frequency upconversion in Tm- and Yb:Tm-doped silica fibers

Frequency 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.

Er/sup 3+/-Yb/sup 3+/ and Er/sup 3+/ doped fiber lasers

Single-mode fiber lasers operating at approximately 1.57 mu m are described. Output powers of >2 mW are reported for laser diode pumped operation. Direct comparison is made between fiber lasers using sensitized erbium (Er/sup 3+/ and Yb/sup 3+/) and erbium on its own. The performance of Er/sup 3+/-Yb/sup 3+/ fiber lasers is analyzed in more detail as a function of fiber length. Both CW and Q-switched operations are studied and the results obtained demonstrate that practical sources at 1.5 mu m are available from diode pumped Er/sup 3+/-Yb/sup 3+/ systems. >

A 1-Watt thulium-doped cw fibre laser operating at 2 μm

Abstract We report efficient high power (>62; 1 W) single transverse mode continuous-wave laser action at 2 μm in a thulium-doped silica-based fibre laser pumped by a Nd : YAG laser at 1.064 μm. The highest measured output power was 1.35 W. A threshold of 600 mW absorbed and slope efficiency of 37% with respect to absorbed power were observed.

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

Efficient energy transfer has been demonstrated in an Er/Yb codoped 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 laser (DPL) 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).<<ETX>>

Single-mode tunable erbium:ytterbium fiber Fabry–Perot microlaser

A compact tunable single-mode fiber laser at 1535 nm is developed by use of a novel combination of high-gain erbium:ytterbium (Er:Yb) phosphate-glass fiber within a fiber Fabry-Perot cavity. We demonstrate what we believe to be the shortest Er:Yb phosphate-glass fiber Fabry-Perot laser ever reported, having a 100-microm cavity length and a continuous wavelength tuning range over 4.52 nm (limited by the sharp fiber gain peak). An alternative three-mirror laser design has also demonstrated single-mode lasing operation.

Cooperative energy transfer in silica fibres doped with ytterbium and terbium

Resonant excitation Yb3+ at 974 nm (10267 /cm) in codoped Yb3+-Tb3+ silica based fibres has lead to luminescence clearly being visible from the Tb3+ 5D4 level (20661 /cm). Through time resolved fluorescence measurements we have been able to directly assign the process responsible for the fluorescence to cooperative sensitisation of the Tb3+ 5D4 level by two excited Yb3+ ions. Energy transfer times for the cooperative process have been directly measured, enabling the effects of glass structure on the cooperative process to be explored. Numerical simulations based on the experimental findings have been conducted, enabling both the mechanism for the luminescence to be confirmed and the properties associated with the luminescence to be interpreted

Efficient superfluorescent emission at 974 nm and 1040 nm from an Yb-doped fiber

Abstract End-pumping of an Yb-doped single-mode fiber has yielded > 10mW and 30 mW of broadband superflourescence at 974 nm and 1040 nm, respectively. Slope efficiencies > 40% have been obtained. Pump wavelength dependent linewidths between 2 nm and 19 nm have been observed.

Characterization of special fibers and fiber devices

Methods for characterizing birefringent fibers (both those with high circular or linear birefringence and those with negligible intrinsic birefringence) are presented, and their relative merits are discussed. Fibers with high nonlinear coefficients exhibit interesting optical phenomena, and methods are developed to determine second harmonic, Pockels and Kerr effects, parametric phenomena, and the Verdet constant of silica and higher-loss, nonsilica fibers. Fibers containing rare-earth ions are of interest both as active (laser and amplifiers) and passive systems. Techniques are developed to characterize these devices, and conventional methods are modified to quantify dopant parameters within the fiber. Techniques for the measurement of the diverse properties of all these different fibers are presented with results, and, where appropriate, the problems with their characterization are discussed. >

Detailed characterization of Nd3+ doped SiO2-GeO2 glass fibre lasers

Several basic parameters of Nd3+ in a SiO2-GeO2 glass fibre have been determined. The stimulated emission cross-section for the 4F32→4I112 transition has been evaluated experimentally both by a laser technique and spectroscopically. Comparison is made between the two methods and a nonradiative decay process inferred. Theefficiency of the 800 nm pump band was determined from measurements of laser slope efficiencies. Branching ratios for the different fluorescent bands have been measured and cavity losses determined.