1,720,990 research outputs found
Highly efficient Ho:YLF and Ho:YAG lasers pumped by Tm-doped silica fibre laser
No full textEfficient operation Ho:YLF and Ho:YAG lasers end-pumped by a tunable cladding-pumped Tm-doped silica fibre laser is reported. Output powers of 4.8W at 2066nm and 6.4W at 2097nm were obtained from the Ho:YLF and Ho:YAG lasers for < 9.6W of incident pump at 1940nm and 1905nm respectively
Efficient single-mode operation of a cladding-pumped ytterbium-doped helical-core fiber laser
No full textA novel approach to achieving robust single-spatial-mode operation of cladding-pumped fiber lasers with multimode cores is reported. The approach is based on the use of a fiber geometry in which the core has a helical trajectory within the inner cladding to suppress laser oscillation on higher-order modes. In a preliminary proof-of-principle study, efficient single-mode operation of a cladding-pumped ytterbium-doped helical-core fiber laser with a 30µm diameter core and a numerical aperture of 0.087 has been demonstrated.The laser yielded 60.4 W of output at 1043 nm in a beam with M2<1.4 for 92.6 W launched pump power from a diode stack at 976 nm. The slope efficiency at pump powers well above threshold was 84%, which compares favorably with the slope efficiencies achievable with conventional straight-core Yb-doped double-clad fiber lasers
Cladding-pumped Yb-doped helical-core fibre lasers and amplifiers
No full textOver the last few years there has been very rapid progress in scaling output power from cladding-pumped fibre lasers and amplifiers [1]. One of the key issues to address for further power-scaling of single-mode operation will be to increase the core area in order to avoid the need for excessively long fibres for efficient pump absorption, and to raise the threshold for unwanted nonlinear processes and optical damage, whilst maintaining robust single-mode operation. At the moment, this is generally achieved by employing a multimode large-mode-area core design with a low numerical aperture in combination with bend loss suppression of higher-order modes [2] to promote single-mode operation. However, scaling to higher power levels will require an even larger core diameter and a larger inner-cladding diameter to accommodate more pump power, making it increasingly difficult to coil the fibre with a small enough diameter to use bend-induced loss as an effective means for suppressing higher-order modes. An alternative approach for achieving single-mode operation in a large-core fibre laser/amplifier is to employ a fibre with a helical core trajectory within the inner-cladding. In a preliminary demonstration of this approach, we recently reported a core-pumped Yb-doped helical-core fibre laser with 350mW of single-mode output at 1047nm [3]. Here, we report a highly efficient cladding-pumped Yb-doped helical-core fibre laser at 1043nm with a much higher single-mode output power of ~60.4W and preliminary results for a cladding-pumped Yb-doped helical-core fibre amplifier seeded by a single-mode Yb:YAG laser at 1050nm. --
Geometrical factor modification of helical-core fiber radiation loss formula
No full textA strict consideration of the geometry of helical-core fibers leads to a modification of a previously published formula for radiation loss in such fibers. We derive an expression for the radiation loss of the fundamental mode, and find that it differs from the previous expression by a simple modification factor, which depends on the geometric parameters of the helix (pitch and offset). The derived expression predicts a loss which is of the order of 40% lower for typical helix parameters
Efficient Tm:silica fiber laser pumped Ho:YAG lasers
No full textHo:YAG lasers employing standing-wave and ring cavity configurations have yielded 6.4W of multi-axial-mode output and 3.7W of single-axial-mode output at 2.1 µm respectively for <9.6W of incident pump power at ~1.9 µm from a cladding-pumped Tm:silica fiber laser
Efficient single-axial-mode operation of a Ho:YAG ring laser pumped by a Tm-doped silica fiber laser
No full textEfficient single-frequency operation of a Ho:YAG ring laser at room temperature with a traveling-wave TeO2 acousto-optic modulator to enforce unidirectional operation is reported. By use of a 2-at.% Ho3+-doped 10-mm-long Ho:YAG rod, end pumped by a cladding-pumped tunable Tm-doped silica fiber operating at 1.9 µm, the Ho:YAG ring laser yielded 3.7 W of single-frequency output at 2.1 µm in a diffraction-limited TEM_00 beam with M2 < 1.1 for an incident pump power of 8.8 W. The rf power required for unidirectional operation was 0.3 W and corresponded to an increase in cavity loss for the lasing direction (due to diffraction) of only 0.5%. The prospects for further improvement in efficiency are discussed
Helical-core ytterbium-doped fibre laser
No full textAn Yb-doped fibre laser with a helical core trajectory in the cladding material has been demonstrated for the first time. The laser yields 350mW of linearly-polarised, single-spatial-mode output at 1047nm from a multimode core of diameter 26 micron, and numerical aperture 0.14, when core-pumped by an Yb:YAG laser at 1030nm
Efficient Ho:YAG laser pumped by a cladding-pumped tunable Tm:silica-fibre laser
No full textHighly efficient room-temperature operation of a Ho:YAG laser end pumped by a cladding-pumped tunable Tm-doped silica-fibre laser operating at 1905 nm is reported. Using a simple two-mirror resonator configuration, we obtained 6.4 W of unpolarized output at 2097 nm in a diffraction-limited TEM00 beam (with M2 ~ 1.1) for 9.6 W of incident pump power, corresponding to a slope efficiency with respect to incident pump power of 80% and an optical-to-optical efficiency of 67%. Using a folded-resonator configuration incorporating a Brewster-angled glass plate, we obtained 5.8 W of linearly polarized TEM00 output, corresponding to an optical-to-optical efficiency of ~60%. Due to low quantum defect heating, the depolarization loss due to thermally induced birefringence in the Ho:YAG crystal was <0.14% at the maximum available pump power, indicating that there is scope for further power scaling
3.7-Watt single-frequency cw Ho:YAG ring laser end-pumped by cladding-pumped Tm-doped silica fibre laser
No full textAcousto-optically induced unidirectional operation of a Ho:YAG ring laser pumped by a Tm-doped silica fibre laser has been demonstrated. 3.7W of single-frequency output at 2114nm for 8.8W of incident pump power at 1905nm was obtained
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