Investigation of Planar Optical Waveguide Formed by MeV $He^{+}$ Ion-Implantation into NaEr(WO$_4$)$_2$ Crystal

NaEr(WO$_4$)$_2$ is a new laser material. The planar optical waveguide was formed in NaEr(WO$_4$)$_2$ crystal by 2.6 MeV He$^{+}$ ion implantation at doses of 1.0-1.5 $\times$ 10$^{16}$ ions/cm$^2$ at room temperature. The effective refractive indices of the dark modes were measured using the prism coupling method. foul n modes and five TM modes were observed in the waveguide. The refractive index profiles were analyzed using the reflectivity calculation method (RCM). The influence of heat treatment at moderate temperature on the refractive index profiles of the waveguide was also investigated. We used the TRIM'98 (Transport of ton in Matter) code to simulate the damage profile in the NaEr(WO$_4$) crystal by 2.6 MeV He$^{+}$ion implantation which is helpful for a better understanding of the waveguide formation.ion.