Educação matemática pela arte
Gusmão, Lucimar Donizete
2013-08-28
Search results
46 records were found.
Efficient 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.
An Yb-doped fibre laser with a helical core trajectory in the cladding material has been demonstrated for the first time. The laser yields 350 mW of linearly-polarised, single-spatial-mode output at 1047 nm from a multimode core of diameter 26 micron, and numerical aperture 0.14, when core-pumped by an Yb:YAG laser at 1030 nm.
We report a Ho:YAG laser with 5.2W of TEM output at 2097nm at room temperature and with a slope efficiency with respect to incident pump power of 80%, pumped by a Tm-doped silica fibre laser.
Acousto-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.
Ho: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 ~1.9μm from a cladding-pumped Tm:silica fiber laser.
Direct UV-writing is a planar lightwave circuit fabrication technique ideal for rapid prototyping and small batch fabrication. The technique is based on the refractive index increase of a glass through exposure to a tightly focused UV beam. The translation of this beam relative to a suitable substrate allows the definition of 2-d waveguide structures such as s-bends and power couplers without the need for photolithographic or subsequent processing. Traditionally, Bragg grating structures are superimposed through UV exposure onto existing waveguides, increasing the fabrication complexity (therefore time and cost) and modifying the original properties of the channel. As an alternative to traditional techniques we have developed a Direct Grating Writing technique (DGW) retaining the advantages of Direct UV writing for channel definition b...
We demonstrate single-step writing of waveguide circuits with Bragg gratings between 1227nm and 1687nm and for the first time show that the grating bandwidth can be normalised over this large wavelength range.
Efficient operation of a Ho:YAG laser at 2.1μm, pumped by a tunable cladding-pumped Tm-doped silica fiber laser operating at 1.905μm is reported. A maximum output power of >5W was obtained for 9.1W of incident pump.
Direct UV writing is a dynamic planar lightwave circuit fabrication technique offering great potential as a means of rapid prototyping and small/medium batch fabrication. The technique is based on the refractive index increase of photosensitive glasses through exposure to ultraviolet light. In this case, a beam is tightly focused to create a writing spot in the order of microns and is translated relative to the sample. It is this translation over a 2-d plane that defines the channel waveguide structures; there is no need for a photolithographic mask or subsequent processing. This process has previously been shown to be a versatile system producing good quality, low loss waveguides compatible with existing silica based telecom fibres.
The use of a two-mirror beam shaper to re-format the output from a diode-stack to allow efficient cladding-pumping of fiber lasers is described. In addition, the use of a helical-core geometry to suppress oscillation on higher-order modes in large-core double-clad fiber lasers is discussed. In preliminary experiments we have obtained ~90W of output in a beam with M2 ~ 5 from a conventional straight-core Yb-doped double-clad fiber with V=11 for ~150W of launched pump power at ~938nm from a beam-shaped diode-stack, and ~ 24.3W of output in a beam with M2 ~ 3 from a Yb-doped helical-core fiber for ~50W of launched pump power. The prospects for further improvement in performance and beam quality are considered.
