CdSiP2: An Emerging Crystal for Electro-Optic Sampling from Terahertz to the Infrared

An emerging crystal, CdSiP2, is shown to exhibit a higher nonlinearity than other key electro-optic sampling crystals, while also satisfying the electro-optic sampling phase-matching conditions across the spectral range of ∼15–90 THz. Frequencies up to ∼65 THz are measured using an 800 nm central-wavelength probe electric field pulse and a (110) CdSiP2 crystal; however, a higher central-wavelength (i.e., 1.3 μm) probe pulse can be used to record frequencies up to 90 THz. Given the high nonlinearity and electro-optic phase-matching capabilities of CdSiP2, it is envisioned to emerge as the prominent crystal for detecting electric field waveforms within the high terahertz and infrared spectral regimes.