Refractive index profile and attenuation measurement in KTiOPO4 waveguide by megaelectronvolt He ions

An optically polished x-cut KTiOPO4 crystal of size 22 x 6 x 1.5 mm(3) was implanted with 2.8-MeV He ions to a dose of 1.5 x 10(16) ions/cm(2) at room temperature to form a waveguide. The prism coupling method was used to mea sure the modes and the fiber probe technique was used to measure the attenu ation in the KTiOPO4 waveguide. The refractive index profile, n(z), in the KTiOPO4 waveguide was given based on the procedure by Chandler and Lama [P. J, Chandler and F.L. Lama, Optica Acta 33, 123 (1986)]. The waveguide atten uation measured was 2.57 dB/cm for m = 1 mode, After annealing at 260 degre esC for 30 min, there was no obvious change in the KTiOPO4 waveguide attenu ation.