Journal of Crystal Growth 251 (2003) 794–799 Template design and fabrication for low-loss orientation-patterned nonlinear AlGaAs waveguides pumped at 1.55 mm X. Yu*, L. Scaccabarozzi, O. Levi, T.J. Pinguet, M.M. Fejer, J.S. Harris Jr. Solid-State and Photonics Laboratory, Stanford University, CISX 126, Via Ortega, Stanford, CA 94305-4075, USA Abstract Orientation-patterned GaAs templates and Al x Ga 1x As waveguides were grown using molecular beam epitaxy technique for nonlinear optical wavelength converters applications and tested by second harmonic generation of 1.56 mm input beam. Current template design leads to waveguide core corrugation, and high transmission loss. An improved template fabrication process is proposed to eliminate template-induced corrugation. Initial growth and processing results show that high-quality template surfaces can be obtained, essential for the waveguide re-growth over the GaAs template. r 2003 Elsevier Science B.V. All rights reserved. PACS: 42.70.Mp Keywords: A3. Molecular beam epitaxy; B1. Gallium compound; B2. Nonlinear optical materials; B3. Nonlinear optical devices 1. Introduction Current optical communication networks are using more and more channels in a WDM scheme, and increasing the data rate of individual channels. These networks use many costly and sometimes unnecessary optical-to-electrical and electrical- to-optical conversions, as part of data routing. A more flexible, economic and scalable network design will enable a ‘‘transparent’’ network connectivity, by allowing all-optical signals to propagate un-touched through the network until reaching the receiver. In order to realize such network, optical cross-connects were proposed as switching nodes. [1] Wavelength conversion of signals from one carrier wavelength to another is needed as part of realization of these optical cross- connects. Wavelength conversion within the telecommunication band was demonstrated by applying quasi-phase matching (QPM) technique [2] to obtain an efficient nonlinear conversion of light from one frequency to another via a second- order nonlinearity w (2) in periodically poled LiNbO 3 (PPLN) waveguides by mixing a pump o p (at 0.78 mm) with signal o s (at 1.54 m) to obtain o out =o p o s (at 1.597 mm) [3]. A full converter using only 1.5 mm telecom sources was also demonstrated in PPLN by cascading second *Corresponding author. Tel.: +1-650 725 6911; fax: +1-650 723 4659. E-mail address: xjyu@snow.stanford.edu (X. Yu). 0022-0248/03/$ - see front matter r 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0022-0248(03)00829-7