A hysteresis model for a VO2 variable optical attenuator

Variable optical attenuators are largely employed in high capacity optical network systems. The material used in these devices should permit control of its reflectance or transmittance. Thin film of vanadium dioxide VO₂ seems to be an attractive material to build active optical components. The optical transmittance and reflectance of a VO₂ thin film is known to depend on the film temperature. Besides, the transmittance versus film temperature characteristic exhibits a hysteresis nonlinearity. The limiting loop proximity (L²P) model, developed for magnetic hysteresis, is adapted for this hysteresis characteristics. The model parameters are estimated and the calculated optical transmittance is validated against experimental data.