Electro-Optic Sampling with Percent-Level Detection Efficiency

Electro-optic sampling (EOS) [1] is widely used for broadband and sensitive characterization of mid-infrared (MIR) waveforms and spectroscopy [2] , [3] . GaSe as the nonlinear crystal and ~10-fs gate pulses at ~ 100-mW average power, generated in highly nonlinear fibres from Er-doped fibre lasers, are commonly employed for broadband sampling of MIR fields [4] . Using Yb-based laser systems to generate high-power, 1030-nm gate pulses allowed us to push the detection efficiency to a record-level of 0.5 %, limited by the damage threshold of GaSe [2] . However, the short gate pulse wavelength strongly limits the phase matching bandwidth [5] .