Exploring Structure-Sensitive Factors Relevant to Cryogenic Laser Operation in Oxide Crystals Doped with Er3+ Ions

Crystals of Gd₃Al_2.5Ga_2.5O₁₂:Er³⁺, (Lu_0.3Gd_0.7)₂SiO₅:Er³⁺ and LiNbO₃:Er³⁺ compounds differing in origin and the nature of their inherent structural disorder were crystalized. Optical absorption and luminescence spectra for transitions between the ⁴I_15/2 and the ⁴I_13/2 multiplets of Er³⁺ ions for the crystal samples were recorded versus temperatures in the region of 80-300 K. Gathered data were analyzed thoroughly providing the in-depth knowledge of the effects of temperature on intensities, wavelengths and bandwidths of Er³⁺ transitions. The information acquired together with the knowledge of significant structural dissimilarities of the host crystals chosen made it possible to propose an interpretation of the impact of a structural disorder in Er³⁺-doped crystals on their spectroscopic properties, and to determine their lasing ability at cryogenic temperatures upon resonant (in-band) optical pumping.

Efficient Nd:Ti:LiNbO3 ridge waveguide lasers emitting around 1085 nm

In this work, we report on efficient neodymium-doped titanium in-diffused ridge waveguide lasers in x-cut congruent LiNbO₃ under excitation at 814 nm. For the sample fabrication we used our novel technique of three-side evaporation and in-diffusion for Nd and Ti incorporation into pre-defined ridges. Due to improved photorefractive damage resistance by indium tin oxide (ITO) coating we achieved stable laser operation at 1084.7 nm with a maximum output power of 108 mW and a slope efficiency of 34% exceeding the best literature values for Nd:Ti:LiNbO₃ ridge waveguide lasers.

MeV Ion Implantation of Er into LiNbO3

The incorporation of Er into LiNbO3 is of great interest for fabricating waveguide lasers and amplifiers. We compare Er diffusion data with the results of Er implantation, performed at 3.6 MeV energy. Even after annealing for 4h at 1060°C, the resulting Er profiles display very good matching to the optical modes. The results of a theoretical gain estimate are presented.

Theoretical studies of EPR spectra and defect structure for Er3+ center in lithium niobate

The optical and EPR spectra of octahedral Er(3+) center in LiNbO(3) have been studied by diagonalizing 364 x 364 complete energy matrices. The new set of crystal-field parameters that can well account for the Stark levels and EPR parameters have been obtained for Er(3+) ions in LiNbO(3). Simultaneously, by simulating the most reliable six-order parameter B(60) obtained, we have presented the evidence that the Er(3+) ions do not occupy the actual Li(+) site, but have a displacement along the C(3)-axis away from the Li(+) center by about 0.0454 nm. The conclusion is well in accord with that drawn by earlier workers.

900-nm Nd:Ti:LiNbO(3) waveguide laser

We report what is to our knowledge the first laser operation of Nd(3+) -doped LiNbO(3) near 900 nm. An absorbed power threshold of 26 mW was obtained when the device was pumped at 814 nm. The design of the waveguide geometry to favor laser operation at this wavelength is demonstrated.