1,720,991 research outputs found
Control of material transport through pulse shape manipulation - a development toward designer pulses
No full textThe variety of laser systems available to industrial laser users is growing and the choice of the correct laser for a material target application is often based on an empirical assessment. Industrial master oscillator power amplifier systems with tuneable temporal pulse shapes have now entered the market, providing enormous pulse parameter flexibility in an already crowded parameter space. In this paper, an approach is developed to design interaction parameters based on observations of material responses. Energy and material transport mechanisms are studied using pulsed digital holography, post process analysis techniques and finite-difference modelling to understand the key response mechanisms for a variety of temporal pulse envelopes incident on a silicon (1|1|1) substrate. The temporal envelope is shown to be the primary control parameter of the source term that determines the subsequent material response and the resulting surface morphology. A double peak energy-bridged temporal pulse shape designed through direct application of holographic imaging data is shown to substantially improve surface quality
In-situ solution doping technique for novel geometry rare-earth doped fiber fabrication
No full textWe report on the fabrication and characterization of a YDFL with a pedestal geometry fabricated using an in-situ solution doping process. The fiber has a unique non-stressed inner-cladding and exhibits good efficiency
Large aperture PPMgLN based high-power optical parametric oscillator at 3.8 µm pumped by a nanosecond linearly polarized fiber MOPA
No full textWe report a large aperture PPMgLN based OPO generating 21W of average output power at a slope efficiency of 45%. The OPO is pumped with the output from a polarization maintaining Ytterbium doped fiber MOPA operating at 1060nm producing 20ns pulses at a repetition rate of 100kHz and an average output power of 58W (after the isolators). A maximum of 5.5W of optical power was recorded at the idler wavelength of 3.82µm without thermal roll-off. The pulse rise/fall time plays a significant role in the OPO conversion efficiency and that further enhancements in the efficiency should be possible using pulses with faster rise and fall times
An all-fibre PM MOPA pumped high-power OPO at 3.82 microns based on large aperture PPMgLN
No full textWe report a large aperture PPMgLN based OPO generating 21W of average output power at a slope efficiency of 45%, pumped by the output from a polarization maintaining Ytterbium doped fiber MOPA operating at 1060nm producing 58W of average output power and 20ns pulses at a repetition rate of 100kHz. A maximum of 5.5W of optical power was recorded at the idler wavelength of 3.82µm without thermal roll-off. We have experimentally verified that the pulse rise/fall time plays a significant role in the OPO conversion efficiency and that further enhancement in the OPO conversion efficiency will be possible using sub-nanosecond rise and fall times
A fiber based synchronously pumped tunable Raman laser in the NIR
No full textRaman lasers have attracted much interest since they allow a very wide range of wavelengths to be generated [1]. Operation in the pulsed regime is compromised by the power dependence of the gain - different parts of the pulse with different instantaneous power will undergo differing amounts of Raman scattering leading to major variations in spectral content across the pulse (varying amounts of light in different Raman orders). To address this issue active pulse shaping technique can be applied to obtain rectangular shaped output pulses so that constant Raman gain can be ensured across the pulse profile [2]. Here we demonstrate a new approach combining pulse shaping with a synchronously pumped scheme [3] to produce narrower linewidths as well as higher extinction ratios between neighboring Raman Stokes lines. Several tens of nanometer of tuning range for each Stokes order and a total tuning range of over 200 nm was achieved using resonant feedback from an external bulk grating
Synchronously pumped tunable Raman laser in the visible pumped by an all-fiber PM MOPA at 1060nm
No full textTunable synchronously-pumped fiber Raman laser in the visible and near-infrared exploiting MOPA-generated rectangular pump pulses
No full textWe report a tunable synchronously pumped fiber Raman laser (SPFRL) in the near-infrared (NIR) and visible wavebands pumped by a pulsed, all-fiber PM 1060 nm master oscillator power amplifier (MOPA) and its frequency-doubled output, respectively. The seed was adaptively shaped to deliver rectangular output pulses, thereby enabling selective excitation of individual Raman Stokes lines. Using filtered synchronous feedback of the desired Raman Stokes line, the linewidth of the SPFRL was reduced by a factor of 4 and the extinction ratio of the desired Raman Stokes was improved by more than 3 dB relative to a simple single-pass conversion scheme. A continuous tuning range of 2.2 THz was obtained for each of the Raman Stokes orders in the visible (spanning from green to orange - first to fifth Stokes lines). A larger 5.0 THz tunable range was achieved in the NIR spectral region
High power pulsed optical parametric oscillator at 3.5 micron pumped by a diode seeded Yb<sup>3+</sup>- doped fiber MOPA
No full textWe report a high power pulsed optical parametric oscillator (OPO) at 3.5µm using a MgO:PPLN as the gain medium pumped by 1062nm all-fiber MOPA. Output powers as high as 11W at an overall slope efficiency of 67% was achieved, with nearly 2.5W of power obtained at a wavelength of 3.5µm
Rapidly tunable, wavelength agile, visible fiber based light source exploiting Raman scattering of multi-step pulses
No full text100W fiberised linearly-polarized picosecond ytterbium doped fiber MOPA
Full text linkWe report a PM, fully-fiberised, picosecond fiber MOPA delivering 20 ps pulses at repetition rates up to 970 MHz and at average powers of up to 100 W
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