# Nondegenerate two-photon absorption rate

by kenkhoo
Tags: absorption, nondegenerate, rate, twophoton
 P: 8 Hey guys, a quick one. I've noticed that you can compute the two photon absorption coefficient by $\beta = \frac{2 \hbar \omega}{I^2}W$ where W is the transition rate for TPA. (wiki link) Now my question is what about nondegenerate two photon absorption? by that i mean two different frequencies of light being absorbed, what will be the equation linking beta and W? Thanks in advance =)