Phase-matched second-harmonic generation due to anomalous dispersion: tailoring of the refractive indices in three-component systems

Poled polymeric guest/host systems containing a nonlinear optical chromophore, which absorbs between the fundamental and second-harmonic frequency, have been studied at 1064 nm for phase-matched second-harmonic generation due to anomalous dispersion. The materials used typically consisted of two components, the chromophore and a polymeric binder. The dye concentration fulfilling the phase-matching condition does not necessarily coincide with the highest possible concentration. Thus the frequency-doubling power is not fully exploited. We propose that, by adding a second chromophore showing normal dispersion, it is possible to actively adjust the phase-matching concentration to optimize the frequency-doubling capabilities of a particular dye system. Phase-matched SHG coefficients as large as 37 pm/V have been obtained.