989515.fig.001
Figure 1: Three-dimensional frequency space ( 𝜔 1 , 𝜔 2 , 𝜔 3 ) . The thick curves show solutions of the resonance conditions (17) for a bulk fluoride glass ( 𝜔 corresponds to 0 . 8 𝜇 m , 𝜖 ( 𝜔 ) is taken from [22]). The dashed regions correspond to 3 1 four-wave mixing processes which are neglected in this paper. The nondashed part of the resonance curves corresponds to 2 2 processes and is taken into account.