An asymmetric coupled quantum well structure is theoretically investigated as a means of tailoring the conversion efficiency of the four‐wave mixing process at terahertz detuning rates. In this structure, a coherent electronic oscillation between the two wells can be excited that introduces a resonance peak in the four‐wave mixing frequency response. A calculation based on the density matrix formalism shows that an increase in the power conversion efficiency on the order of 10 dB can be attained at the selected resonance frequency for low temperature operation. Finally, we propose a novel technique for exciting the interwell oscillations that takes advantage of the polarization dependence of the interband optical transitions in alternating strain quantum wells. ©1995 American Institute of Physics.