Enhanced THz detection efficiency via grating-assisted noncollinear electro-optic sampling

The detection efficiency of phase-locked terahertz pulses resolved with electro-optic sampling is dramatically improved between 3 THz and 6 THz with the use of a phase-grating patterned onto the surface of the detection nonlinear crystal. The grating modifies the wavevector component of the near-infrared gating pulse, hence allowing phase-matching conditions to be optimized at a selected THz frequency. We demonstrate this concept numerically and experimentally and also show that noncollinear EOS leads to broader detection bandwidth.