A phase-correction approach for enhancing mid-infrared electro-optic sampling in highly nonlinear and dispersive birefringent crystals

Spectral content in the mid-infrared range is recorded experimentally via a (110)-cut ZnGeP2 electro-optic sampling crystal followed by a ZnGeP2 phase-correction crystal, with the two crystals oriented to exhibit offsetting birefringences on the electric fields associated with the electro-optic sampling process. An enhancement of >13 times is observed in the recorded electro-optic signal (when comparing the electro-optic signals obtained in the presence and absence of the phase-correction crystal). A transfer function embodying this phase-corrected electro-optic sampling approach is derived and subsequently implemented to identify unique spectral features observed in the experimentally recorded electro-optic spectra.