Decadal bandwidth phase matching for frequency resolved optical gating from the near to the long wavelength infrared

Ultra-fast laser pulses have made possible the study of extreme nonlinear processes. Many of these experiments however require a full characterization of the electric field, which typically requires a separate parametric optical process. As the central wavelength range of new sources continues to increase so too does the need for nonlinear crystals suited for characterizing these differing wavelengths. Here we report on the use of polycrystalline Zinc Selenide as a universal nonlinear crystal in the frequency resolved optical gating characterization technique from the near to long-wavelength infrared, capable of phase matching second-harmonic generation and sum-frequency generation over a decade of bandwidth, as well as ultra-broadband pulses, all of which being crystal orientation and input polarization independent. With the majority of ultra-fast laser sources being in this span of wavelengths, this work demonstrates a greatly simplified approach towards ultra-fast pulse characterization in the mid to long-wavelength infrared.