Waveguides in LTB (Li2B4O7) by He+ implantation

Planar optical waveguides are formed in Y-cut LTB materials by He+ ion implantation. The profiles of the ordinary and the extraordinary refractive indices are determined from m-line spectroscopy and by using an IWKB method. The positions of the optical barriers are in good agreement with the calculated average penetration depth of the ions. The best coupling efficiency and light confinement are obtained with TM (n(o)) modes, but this could be due to the used crystal cut (Y-cut) with respect to the propagation direction.