Cavity-dumping of a semiconductor disk laser for the generation of wavelength-tunable micro-Joule nanosecond pulses

We report on cavity-dumping of a semiconductor disk laser as a method to generate energetic wavelength-tunable nanosecond pulses with repetition rates ranging from 0.1 to 4MHz. Experimentally, emission of 24ns pulses with peak output power of 41W in a single beam output (and of 30 ns with peak power of 57W in a combined beam output) with wavelength tuning from 1045 to 1080nm was obtained. Numerical modeling is also introduced to provide more insight into the most important parameters controlling this mode of operation and to define optimization avenues

Optically pumped saturable Bragg reflectors : nonlinear spectroscopy and application in ultrafast lasers

A detailed study of the changes in the nonlinear optical response of a saturable Bragg reflector (SBR) in the presence of continuous-wave (CW) optical pumping was performed. A model of the heating dynamics within the device under such nonresonant external optical pumping was also configured. In this way, it was shown that fast optically induced heating could be used to externally control the behavior of the SBR. This external optical pumping of the SBR is shown to be an effective method for rapid (~75 μs) switching between CW and femtosecond pulse operation of a passively mode-locked Ti:sapphire laser

Passive mode-locking of a Ti:sapphire laser by InGaP quantum-dot saturable absorber

We demonstrate the use of a novel InGaP quantum-dot (QD) saturable absorber (SA) to induce passively mode-locked (ML) operation of a Ti : sapphire laser. Pulses as short as 518 fs are obtained at 752 nm with an average output power of up to 190 mW for 2.3 W of absorbed pump power at 532 nm. The absorption recovery of the SA is characterized by two decay coefficients: a fast and a slow component having time constants of 0.4 and 300 ps, respectively. The saturation fluence of the InGaP QDs was measured to be 28 J/cm2, the initial low-signal absorption was 1.5%, where 1.15% was nonsaturable loss

Temperature-dependent spectroscopy and microchip laser operation of Nd:KGd(WO₄)₂

High-resolution absorption and stimulated-emission cross-section spectra are presented for monoclinic Nd:KGd(WO4)2 (Nd:KGW) laser crystals in the temperature range 77–450 K. At room-temperature, the maximum stimulated emission cross-section is sigma(SE) = 21.4 × 10-20 cm2 at 1067.3 nm, for light polarization E || Nm. The lifetime of the 4F3/2 state of Nd3+ in KGW is practically temperature independent at 115 ± 5 µs. Measurement of the energy transfer upconversion parameter for a 3 at.% Nd:KGW crystal proved that this was significantly smaller than for alternative hosts, ~2.5 × 10-17 cm3/s. When cut along the Ng optical indicatrix axis, the Nd:KGW crystal was configured as a microchip laser, generating ~4 W of continuous-wave output at 1067 nm with a slope efficiency of 61% under diode-pumping. Using a highly-doped (10 at.%) Nd:KGW crystal, the slope efficiency reached 71% and 74% when pumped with a laser diode and a Ti:Sapphire laser, respectively. The concept of an ultrathin (250 µm) Nd:KGW microchip laser sandwiched between two synthetic diamond heat-spreaders is demonstrated

Laser performance of Ng-cut flash-lamp pumped Nd : KGW at high repetition rates

A comparative study of the flash-lamp pumped laser performance of standard b-grown Nd:KGW and Nd:KGW grown for propagation along the optical axis N-g is presented. The results show that, in comparison with b-grown crystal, the N-g-grown Nd:KGW is very promising for use at high repetition flash-lamp pumping rates. With the same laser cavity configuration, the N-g-grown Nd:KGW can operate at an average flash-lamp input power of at least 1.4 kW, while the b-cut one ceases lasing at average flash-lamp input power of similar to 0.5 kW. The reason for this is that the thermal lens induced in the N-g-oriented Nd:KGW rod under pump radiation is relatively weak, nearly spherical and positive, whereas the b-grown Nd:KGW rod acts as a quite weak positive lens for radiation with radial polarization, and as a much stronger negative lens for tangentially polarized radiation