ARROW's in KTiOPO4

Antiresonant reflecting optical waveguides (ARROW's) have been designed and fabricated in z-cut KTiOPO
₄
(KTP) by e-beam direct writing and double Rb/spl rlhar2/K ion exchange. Strong diffusion anisotropy allows the realization of ARROW's in this electrooptical crystal. It was found, that argon-ion dry etching of the crystal surface prevents the ion exchange process totally. Using this as a new masking technique, antiresonant reflectors with lateral tolerances of less than 0.1 μm could be realized. Typical quasi-single-mode waveguiding and attenuation of about 1.0 dB/cm were observed at /spl lambda/=860 mm, which are in good agreement with our simulations made by the vectorial finite element method and effective index approach.