1,721,009 research outputs found
Multi-watt high efficiency diffraction limited Nd: YAG planar waveguide laser
No full textAn efficient, longitudinally diode-pumped, diffraction-limited, Nd:YAG double-clad planar waveguide laser was operated on four transitions of the Nd3+ ion. Optimised output powers of 4.3W, 3.5W, and 2.7W, were obtained for absorbed pump powers of ~7W, for the transitions at the lasing wavelengths of 1.064µm, 946nm, and 1.3µm, respectively. Operation of the weak 4F3/2 to 4I15/2 transition, lasing at 1.833µm, was demonstrated at an absorbed pump power threshold of 300mW and an output power of 400mW, with a non-optimised output coupling. Diffraction-limited performance was obtained in both the guided and non-guided axes
Growth of PbSe quantum dots within high-index lead-phosphate glass for infrared saturable absorbers
No full textPbSe quantum dots (QDs) were grown in high-refractive-index low-melting-temperature lead-phosphate glass. The lowest energy exciton transition of the QDs was tuned over a wide range within the infrared spectral region (0.93-2.75µm) by a controlled heat treatment. The measured QD radius ranged between 2 and 5.3nm, with a time (t) dependence of t0.29 for long dwelling times during the heat treatment, indicating that the QD growth mechanism tends to follow Lifshitz-Slyozov-Wagner theory. The QD saturable absorber behavior at 1.2µm had a measured saturation fluence of ~2.1µJ/cm2
Graphene Q-switched mode-locked and Q-switched ion-exchanged waveguide lasers
Full text linkIn this paper, we present the use of mono-layer graphene saturable absorbers to produce Q-switched and Q-switched mode-locked operation of Yb and Yb:Er-doped phosphate glass waveguide lasers, respectively. For the 1535-nm wavelength Yb:Er laser, the Q-switched pulses have repetition rates up to 526 kHz and contain mode-locked pulses at a repetition frequency of 6.8 GHz. The measured 0.44 nm bandwidth should allow pulses as short as ~6ps to be generated. Maximum average output powers of 27 mW are obtained at a slope efficiency of 5% in this mode of operation. For the 1057-nm-wavelength Yb laser, Q-switched pulses are obtained with a repetition rate of up to 833 kHz and a maximum average output power of 21 mW. The pulse duration is found to decrease from 292 ns to 140 ns and the pulse energy increase from 17 nJ to 27 nJ as the incident pump power increases from 220 to 652 mW
Fiber-laser-pumped, high-energy, mid-IR, picosecond optical parametric oscillator with a high-harmonic cavity
No full textWe demonstrate the generation of high-energy, mid-IR, picosecond pulses in a high-harmonic-cavity optical parametric oscillator (OPO) that has a relatively compact cavity with a length that is a small fraction of that required to match the pump repetition rate. The OPO, based on an MgO-doped periodically poled LiNbO3 crystal, is pumped by a fiber master-oscillator-power-amplifier system employing direct amplification and delivering 11µJ, 150ps pulses at 1035nm. For a 1.554-m long OPO cavity, resonating near-infrared signal pulses with a repetition rate that is the 193rd harmonic of the 1MHz pump are demonstrated. The mid-infrared idler output pulses, tunable from 2300nm to 3500nm, are generated at a 1 MHz repetition rate and have energies as high as 1.5µJ
Nd: glass tapered planar waveguide laser
No full textWe have demonstrated the first use of a tapered waveguide in a planar dielectric geometry. The Nd/sup 3+/-doped BK7 glass laser had a threshold of 15mW, and a slope efficiency of 42% for a 20% output coupler when end-pumped by a Ti:sapphire laser
Spatial dopant profiles for transverse-mode selection in multi-mode waveguides
No full textWe theoretically investigated the effect of the spatial distribution of the active-ion concentration in multimode step-index waveguides on transverse-mode selection for continuous-wave laser operation. We found that uniform doping of a central portion of as much as 60% of the full waveguide core width is highly effective for the selection of fundamental-mode operation, even under highly saturated, high-power conditions. Profiling the dopant distribution to match that of the particular mode desired was also found to be effective, especially if it is the saturated inversion profile that is matched to the shape of the mode
Generation of mode-locked optical pulses at 1035 nm from a fiber Bragg grating stabilized semiconductor laser diode
No full textWe report the generation of transform-limited, ~18 ps optical pulses from a fiber Bragg grating (FBG) stabilized semiconductor laser diode. Up to 7.2 pJ of pulse energy and a peak power of 400mW were achieved when operating at a repetition frequency of 832.6 MHz, a multiple of the cavity (diode + FBG) free spectral range (FSR). A small detuning in the repetition frequency resulted in broader optical pulses. We have shown experimentally the transition from a gain-switched regime of operation to mode-locked operation once the injection current modulation frequency is set to match a harmonic of the cavity FSR. The transition also results in a reduction in the timing jitter of the optical pulses
- …
