Nd:BaYF Laser Produces 2.4 W

Daniel S. Burgess

Lasers based on BaY₂F₈ (BaYF) have the potential to compete with other neodymium-doped solid-state devices for moderate-power, near-IR applications, a team of scientists in Italy has reported. In recent experiments, the group, which included members from the Universitàs di Pavia and Pisa and from Bright Solutions Srl of Cura Carpignano, obtained 2.4 W of nearly diffraction-limited 1.05-µm radiation from Nd:BaYF pumped with 6.2 W of 804-nm radiation from a fiber-coupled diode array.

Researchers in Italy are exploring the potential of Nd:BaY₂F₈ to be used in moderate-power, near-IR laser applications. The complexity and costs of growing the laser crystal, such as this 20-mm-diameter, 70-mm-long boule, are comparable to that of Nd:YLF, they say. Courtesy of Antonio Agnesi.

The researchers suggest that Nd:BaYF is an interesting alternative to crystals such as Nd:YLF because its 2.6-nm fluorescence bandwidth makes it better suited for use in the generation and amplification of subpicosecond pulses. Moreover, they claim, its 470-µs fluorescence lifetime and 1.35-J/cm² saturation fluence enable its use for the production of high-energy Q-switched pulses. The ability to dope the host crystal with up to 3.75 percent Nd³⁺ without compromising its lasing efficiency also may make it an appropriate choice for microchip lasers.

In their work, they compared the performance of homegrown Nd:BaYF with an Nd:YVO₄ crystal from Fujian JDSU Casix Inc. of Fuzhou, China, with the same 12-W diode array pumping each crystal. The Nd:BaYF displayed lower thermal lensing and diffractive loss than the Nd:YVO₄. Tests to confirm Nd:BaYF's susceptibility to thermal fracture were inconclusive but suggested a lower thermal fracture parameter than Nd:YLF.

Antonio Agnesi, a member of the team from Università di Pavia, noted that the wide bandwidth and the thermal properties of Nd:BaYF suggest applications in master oscillator power amplifier setups and in the development of compact diode-pumped Q-switched lasers with energies in the millijoule range. Future research will focus on such real-world uses, he said. "We need to investigate the performance of Nd:BaYF in such specific applications, as the laser material has already reached a quality standard sufficient for commercial laser sources."

The scientists next plan to explore power scaling with lightly doped Nd:BaYF, the generation of ultrafast pulses with mode-locked oscillators and the crystal's Q-switching performance at 1.05 µm in diode-pumped oscillators, he said.