Efficient second-harmonic generation at 384 nm in periodically poled lithium tantalate by use of a visible Yb–Er-seeded fiber source

Abstract

We generated 56 mW of average power at 384 nm in periodically poled lithium tantalate by use of a visible fiber source based on a variable-pulse format seeded Yb-Er amplifier and frequency upconversion in periodically poled KTP. The feasibility of high-average-power, wide ultraviolet wavelength-range fiber-based sources is evaluated.

High-power 780-nm single-frequency linearly polarized laser

“…Various nonlinear effects such as Raman scattering and for-wave mixing for pulsed fiber lasers and stimulated Brilluin scattering for single-frequency CW operation restrict availability of these parameters. With the advent of periodically poled crystals that demonstrate high efficiencies at moderate levels of pump powers their tandem with fiber-based pump was intensively investigated [1][2]. Significant photorefraction (PPLN, PPLT) [3], visible-induced infrared absorption and thermal loading (PPLN, PPKTP) [4] and grey tracking (PPKTP) [5] restricts generating of high average and peak powers in these crystals.…”

Efficient second, third, fourth, and fifth harmonic generation of a Yb-doped fiber amplifier

“…In many cases, continuous tunability, broad wavelength coverage, narrow linewidth, high peak or average power, and high beam quality are also needed. Frequency conversion of pulsed, rare-earth-doped fiber lasers and amplifiers offers the possibility of a practical source that meets all of these requirements [1][2][3][4][5][6]. Fiber-based systems have not been widely used for visible and UV generation, however, because of their relatively low pulse energies and peak powers (in comparison to bulk lasers) and consequent low nonlinear conversion efficiency.…”

Multi-watt average power 388 nm UV generation through frequency quadrupling of Yb/Er fiber laser sources

“…With the dramatic break through in the development of high power fiber laser and amplifier sources [1], new approaches to high average and peak power uv generation have been realized, that will revolutionize the size, efficiency and ease of operation of sources that are set to impact on applications. The possibility of a dual stage, single-pass SHG has been demonstrated with quasi-CW Yb/Er fiber pump operating around 1550nm [2], although the average powers generated in UV were limited due to the relatively low fundamental peak powers associated with a single-mode format fibre pumping and because of the optical-damage susceptibility of periodically poled crystal used in second stage SHG. Despite the demonstrated possibility of growth of new materials potentially suitable for damage-free high power UV generation, like stoichiometric LiTaO3, the questions about s-PPLT's photorefraction and optical damage susceptibility in UY remain open.…”

“…At 22W average and 4.6kW peak powers, nearly 80%-efficient, first stage SHG was obtained by employing a periodically poled KTP in the configuration similar to that described elsewhere [2]. The resulting 775nm radiation of 17W average and 3.6kW peak power (beam quality M2<1.1) was confocally focused in a 15mm long LBO cut for Type-I SHG at 388nm.…”