Large optical third-order nonlinearities in a switchable Prussian blue analogue

We report on the observation of an efficient coherent up-conversion via third harmonic generation (THG) in Rb sub(0.94) Mn[Fe(CN) sub(6)] sub(0.98).0.3H sub(2) O material. Our THG measurements at fundamental wavelengths ranging from 1200 to 2400 nm show that, in this spectral range, the THG signal overcomes the signal generated by frequency doubling. This demonstrates that this material possesses significant third-order nonlinear optical (NLO) responses. Its effective [chi] super((3)) value is at least two orders of magnitude greater than [alpha]-Quartz. We also demonstrate that this material exhibits a broad thermal hysteresis loop around room temperature, which makes it possible to simultaneously photo-commute its linear and third-order nonlinear optical properties.