Second‐harmonic generation of blue light by the nonlinear interaction of two counter‐propagating transverse electric‐polarized fundamental fields in a [112]‐oriented (Al,Ga)As/GaAs antiresonant waveguide is demonstrated. Theoretical calculations of the visible output power for given fundamental inputs are shown to agree with experiment. Our results show that GaAs‐based materials may offer another alternative for the development of blue/green light‐emitters. ©1996 American Institute of Physics.