1,720,992 research outputs found
Simple scheme for active mode selection in a multimode fibre oscillator
No full textOperation of fibre lasers on individual higher order transverse modes has many attractions from a power scaling perspective. These include a higher threshold for unwanted nonlinear loss processes, reduced sensitivity to mode skew [1], as well as the prospect of improved energy extraction in pulsed systems. Moreover, it has also been shown that in some laser processing applications the use of doughnut-shaped beams or beams with a dynamically adaptable transverse profile can yield substantially higher processing speeds. However techniques for selecting individual higher order modes in multimode fibre oscillators are often quite difficult to implement and lack the flexibility to switch between modes to suit the application
Bandwidth-controllable tunable Q-switched thulium fibre laser
No full textA tunable Q-switched thulium fibre laser source with continuously-adjustable linewidth is described. The laser yielded peak power above 1kW at 1960nm and the spectral width could be varied from 0.6nm to 15nm
Rapid, electronically controllable transverse mode selection in a multimode fiber laser
Full text linkA novel technique for the electronically-controllable generation and switching of transverse modes within a multi-mode fiber laser oscillator is presented. Preliminary results demonstrate individual transverse mode lasing and fast switching between modes with watt-level output powers. When applied to a core-pumped Tm-doped silica fiber laser with a multimode core the fundamental mode (LP01), the next higher order mode (LP11), or a donut-shaped LP11 superposition were selectively excited with power levels in excess of 5 W. Fast switching between LP01 and LP11 modes at up to 20kHz was also realized
Generation of pseudo-radially-polarized beams in a diode pumped solid-state laser
No full textA simple technique for directly generating pseudo-radially-polarised or donut-shaped beams in a diode-pumped solid-state laser is presented. Preliminary results for a Nd:YAG laser are described and the further potential of this technique is discussed
Controlling the handedness of directly excited Laguerre Gaussian modes in a solid-state laser
No full textA novel approach for directly exciting the lowest order Laguerre-Gaussian donut mode with controllable handedness of the helical phase front trajectory in an end-pumped solid-state laser is described
Power-scalable wavelength-agile fibre laser source at two-microns
No full textA simple wavelength-agile Tm-doped fibre laser source employing an acousto-optic tunable-filter to achieve narrow-band operation (~0.16 nm) with wide and rapid wavelength tunability in the two-micron spectral region at watt-level output power is described. The prospects for extended wavelength coverage using spectral beam-combination and scaling to much higher output powers are considered
Ultra-short wavelength operation of a thulium fibre laser in the 1660-1750nm wavelength band
No full textUltra-short wavelength operation of a thulium fibre laser is investigated. Through use of core pumping and high feedback efficiency wavelength selection, a continuously-tunable fibre laser source operating from 1660nm to 1720nm is demonstrated in a silica host. We discuss the range of applications within this important wavelength band such as polymer materials processing and medical applications targeting characteristic C-H bond resonance peaks. As a demonstration of the power scalability of thulium fibre lasers in this band, fixed wavelength operation at 1726nm with output power up 12.6W and with slope efficiency >60% is also shown
Single mode operation of a large mode area thulium fibre laser using a novel wavelength selective mode filter
No full textUltra-broadband wavelength swept Tm-doped fiber laser
No full textWavelength-swept laser sources with broad wavelength tunability and narrow instantaneous linewidth in the two-micron band have potential applications in a number of areas, including spectroscopic characterisation and optical coherence tomography (OCT). The use of OCT for non-invasive investigation of paintings to provide the information necessary for effective restoration and to aid conservation is one example of an emerging application where operation in two-micron band brings the advantage of increased penetration depth due to lower loss in commonly used pigments compared to the situation at near-infrared wavelengths. Tm-doped silica fibre lasers provide an efficient way to access the relevant wavelength region due to the wide emission line that extends from ~1700 nm to ~2100 nm. Unfortunately, wavelength tuning across the entire emission band with a single fibre gain stage is extremely difficult due to the combination of varying quasi-three-level character as a function of wavelength and gain saturation due to short wavelength amplified spontaneous emission. In order to access the full emission bandwidth potential of Tm-doped fibres, a different approach must be employed with two or more fibre gain stages and with each gain stage tailored to provide emission in complementary bands
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