Optical and fluorescent properties in Er, Yb:YAG double-line waveguide by femtosecond laser direct writing.

This paper reports the double-line waveguides in Er,Yb:YAG prepared by femtosecond laser (fs-laser) writing at 1030 nm, 450 fs pulse and 100 kHz repetition rate. When light propagates at 632.8 nm along transverse electric (TE) and transverse magnetic (TM) polarization, efficient single-mode guidance is demonstrated in the double-line structures. The minimum transmission loss is as low as 0.98 dB/cm in waveguide with space of 18 μm. The structural modifications in damaged tracks and strain-affected regions were characterized by confocal micro-Raman spectroscopy, and the refractive index variations were analyzed. The corresponding fluorescence emissions of Er3+ and Yb3+ are investigated in the Er,Yb:YAG double-line structure. [ABSTRACT FROM AUTHOR]