Solar-Pumped TEM_00 Mode Nd:YAG laser

Abstract

Here we show a significant advance in solar-pumped laser beam brightness by utilizing a 1.0 m diameter Fresnel lens and a 3 mm diameter Nd:YAG single-crystal rod. The incoming solar radiation is firstly focused by the Fresnel lens on a solar tracker. A large aspheric lens and a 2D-CPC concentrator are then combined to further compress the concentrated solar radiation along the thin laser rod within a V-shaped pumping cavity. 2.3 W cw TEM₀₀ (M² ≤ 1.1) solar laser power is finally produced, attaining 1.9 W laser beam brightness figure of merit, which is 6.6 times higher than the previous record. For multimode operation, 8.1 W cw laser power is produced, corresponding to 143% enhancement in collection efficiency.

Identification of Cr valence states in Cr and Nd co-doped Lu 3 Al 5 O 12 laser ceramics

“…However, it is difficult to prevent the valence state transformation of chromium ions in Cr 3þ and Nd 3þ co-doped laser materials, which is extremely detrimental to the laser oscillation [21,30,31]. And a strong and wide near-infrared (NIR) absorption band around 1100 nm were observed in the vacuum and HIPsintered Cr,Nd:LuAG ceramics in our previous work [10].…”

Photonic Engineering Technology for the Development of Terahertz Quantum Cascade Lasers

“…[117][118][119][120] Second-order concentric-circular DFB grating was also reported to impose a rotational symmetry to the farfield patterns. [121,122] In these proposals, robust single-mode operation and reduced beam divergence were reported. Nonetheless, the quasi-doughnut-shape www.advopticalmat.de or double-lobe farfield profiles are not satisfying due to the intrinsic structure symmetry and many other perturbation effects such as wire bonding, [123] contact-connecting bridge, and structure anisotropic.…”

“…Nonetheless, the quasi-doughnut-shape www.advopticalmat.de or double-lobe farfield profiles are not satisfying due to the intrinsic structure symmetry and many other perturbation effects such as wire bonding, [123] contact-connecting bridge, and structure anisotropic. [121,122] An alternative solution is to phase-lock an array of surface-emission THz QCLs. [91] This was realized by connecting one edge of each laser with a curved waveguide coupler.…”

“…However, the improvement is quite limited. For 1D-and 2D-PhC THz QCLs, it is possible to engineer the photonic parameters, such as the slit duty cycle of DFB gratings, [123] air hole sizes of PhCs, [65][66][67] and the periods across the structure [121,122] to enhance the power extraction/outcoupling efficiency of the resonators. Nevertheless, most of these designs output a comparable power level to their DM ridge equivalents.…”

Design of a solar-pumped semiconductor laser

“…Two figures of merit are used to characterize the performance of solar-powered lasers, the output power emitted per unit primary collection area which characterizes the laser efficiency, and the output power divided by the square of the M 2 beam quality factor, taken as a metric of the potential usefulness of the output. Current records for these factors are 20 W∕m 2 [28] and 1.1 W [29], achieved in different systems. On the basis of the conservative estimates above, an SP-VECSEL with 1 mm pump spot diameter would reach 49 W∕m 2 and 0.47 W (assuming a typical value of M 2 3 for a VECSEL with a 1 mm diameter pump spot).…”