Frequency doubling is observed in an aluminum nitride waveguide deposited by dc reactive magnetron sputtering. Phase‐matching conditions are obtained by tuning the wavelength of an optical parametric oscillator pumped by a pulsed Nd:YAG laser. The maximum second harmonic generation efficiency is obtained for the TM0(&ohgr;)‐TM2(2&ohgr;) conversion process and is estimated to be around 4×10−8W−1. ©1995 American Institute of Physics.