Optical properties and Raman visualization in KTP crystals waveguide by 2.4 MeV helium ion implantation and femtosecond laser ablation

Abstract

The Z-cut potassium titanium phosphate single crystals were implanted with 2.4 MeV helium ions at a fluence of 2.2 × 10¹⁶ ions/cm². The vacuum level duing ion implantation is approximately ∼10⁻⁴ Pa. The vacancy distribution was calculated using the SRIM code. Post-implantation, the samples underwent annealing at temperatures of 200 °C, 300 °C, 400 °C, and 500 °C for a duration of 1 h in an ambient atmosphere. To assess the waveguide's optical confinement capabilities, the dark mode spectra were measured using prism-coupling, while the end-face coupling method was employed to capture the near-field patterns of light propagation at a wavelength of 633 nm. The micro-Raman spectroscopy was utilized to investigate the structural properties across the entire implanted region. Additionally, combined with femtosecond ablation, the ridge waveguides with acceptable propagation loss were obtained. These results suggest that He-implanted KTP optical waveguide has prospects in appropriate optical devices for practical applications and warrant further exploration to unlock their full potential.