Efficient generation of orange light by frequency-doubling of a quantum-dot laser radiation in a PPKTP waveguide

Orange light with maximum conversion efficiency exceeding 10% and CW output power of 12.04 mW, 10.45 mW and 6.24 mW has been generated at 606, 608, and 611 nm, respectively, from a frequency-doubled InAs/GaAs quantum-dot external-cavity diode laser by use of a periodically-poled KTP waveguides with different cross-sectional areas. The wider waveguide with the cross-sectional area of 4×4 μm demonstrated better results in comparison with the narrower waveguides (3×5 μm and 2×6 μm) which corresponded to lower coupling efficiency. Additional tuning of second harmonic light (between 606 and 614 nm) with similar conversion efficiency was possible by changing the crystal temperature

In-band pumped conical refraction Nd:KGW laser

We have demonstrated an in-band pumped conical refraction (CR) Nd: KGW laser. The CR laser was diode-pumped at 910 nm and produced an output power of 1.15 W at 1069 nm

Conical refraction output from a Nd:YVO4 laser with an intracavity conerefringent element

A conical refraction (CR) laser based on an a-cut Nd:YVO4 laser was demonstrated. By using a KGW crystal as a CR element, a typical laser with a Gaussian intensity output profile was transformed into a laser with conically refracted output. The CR laser delivered 220 mW of output power for 500 mW of pump power. The separation of the laser gain medium and the CR element reduced the complexity of the pumping scheme, and resulted in the generation of well-behaved CR laser beams with outstanding quality. The presented approach is power scalable and offers a unique possibility of studying the transformation of a Gaussian laser mode into a conically refracted one in a laser cavity

Conical refraction of a high-M2 laser beam

We report on experiments with conical refraction of laser beams possessing a high beam propagation parameter M2. With beam propagation parameter values M2=3 and M2=5, unusual Lloyd's distributions with correspondingly three and five dark rings were observed. In order to explain this phenomenon, we extend the dual-cone model of the conical refraction that describes it as a product of interference of two cones that converge and diverge behind the exit facet of the crystal. In the extended model, these converging/diverging cones are represented as the cone-shaped quasi-Gaussian beams possessing the M2 parameter of an original beam. In this formalism, a beam-waist of these cone-shaped beams is proportional to the M2 value and defines the area of their interference which is a width of the Lloyd's ring. Therefore, the number of dark rings in the Lloyd distribution is defined by the M2 value and can be much greater than unity. The results of the numerical simulations within the extended dual-cone model are in excellent agreement with the experiment

Diode-pumped Yb:CALGO laser with conical refraction output

A high power conical refraction (CR) laser was demonstrated based on Yb:CALGO laser crystal with a separate intracavity CR element. The CR laser delivered the maximum output power of 6.25 W at 25 W of incident pump power which is the highest output power for the CR lasers to date. The separation of the CR element from the laser gain medium reduced the complexity of laser pumping. The generated CR laser beam exhibited excellent quality with well-resolved concentric rings and the Poggendorff dark ring

Generation of tunable visible picosecond pulses by frequency-doubling of a quantum-dot laser in a PPKTP waveguide

We demonstrate a compact all-room-temperature picosecond laser source broadly tunable in the visible spectral region between 600 nm and 627 nm. The tunable radiation is obtained by frequency-doubling of a tunable quantum-dot external-cavity mode-locked laser in a periodically-poled KTP multimode waveguide. In this case, utilization of a significant difference in the effective refractive indices of the high- and low-order modes enables to match the period of poling in a very broad wavelength range. The maximum achieved second harmonic output peak power is 3.25 mW at 613 nm for 71.43 mW of launched pump peak power at 1226 nm, resulting in conversion efficiency of 4.55%

QCL active region overheat in pulsed mode: effects of non-equilibrium heat dissipation on laser performance

Quantum cascade lasers are of high interest in the scientific community due to unique applications utilizing the emission in mid-IR range. The possible designs of QCL are quite limited and require careful engineering to overcome some crucial disadvantages. One of them is an active region (ARn) overheat, that significantly affects the laser characteristics in the pulsed operation mode. In this work we consider the effects related to the non-equilibrium temperature distribution, when thermal resistance formalism is irrelevant. We employ the heat equation and discuss the possible limitations and structural features stemming from the chemical composition of the AR. We show that the presence of alloys in the ARn structure fundamentally limits the heat dissipation in pulsed and CW regimes due to their low thermal conductivity. Also the QCL post-growths affects the thermal properties of a device only in (near)CW mode while it is absolutely invaluable in the pulsed mod