Yb:Lu₂O₃ single-crystal fiber: spectroscopy, amplification, and lasing.

Area of Science:

• Materials Science
• Optics and Photonics
• Laser Technology

Background:

• Lutetium oxide (Lu2O3) is a promising material for optical applications due to its intrinsic properties.
• Single-crystal fibers (SCFs) offer advantages for laser development, including high surface area to volume ratio and efficient heat dissipation.
• Previous research has identified Lu2O3 as a potential platform for high-power lasers, but experimental demonstration was lacking.

Purpose of the Study:

• To demonstrate the first single-crystal fiber (SCF) laser based on lutetium oxide (Lu2O3) doped with ytterbium (Yb).
• To characterize the spectroscopic properties of Yb-doped Lu2O3 SCFs.
• To investigate the lasing performance of Yb:Lu2O3 SCFs and assess their potential for power scaling.

Main Methods:

• Yb-doped Lu2O3 SCFs were fabricated using the laser heated pedestal growth (LHPG) technique, with lengths ranging from 10 to 50 mm and diameters from 150 to 225 μm.
• Spectroscopic properties of the SCFs were analyzed, considering the two-site nature of the Lu2O3 host.
• A 50 mm long, 0.1% Yb:Lu2O3 SCF was configured as a laser by butt-coupling mirrors and pumping at 976 nm.

Main Results:

• The Yb:Lu2O3 SCF laser successfully operated at the 1033 nm peak emission wavelength of Yb.
• A maximum output power of approximately 300 mW was achieved.
• Spectroscopic characterization highlighted the importance of the two-site nature of the Lu2O3 host.

Conclusions:

• The successful demonstration of the Yb:Lu2O3 SCF laser confirms the viability of Lu2O3 as a platform for SCF lasers.
• The results suggest no obvious fundamental limitations hindering future interest in Lu2O3 SCFs for power-scaling applications.
• Further research is warranted to fully explore the potential of Lu2O3 SCFs in laser technology.