Optimizing High Field Broadband Terahertz Generation

Enhancing terahertz (THz) light generation and accessibility may allow for many advances in bioimaging, chemical recognition, wireless communication, high-speed computing, and non-destructive testing. THz light can be generated effectively through optical rectification when a high power laser passes through a nonlinear organic crystal. Ideal THz generation crystals are high quality and non-centrosymmetric, made up of molecules with a large hyperpolarizability that are arranged with a crystal packing order parameter close to one. We use pump-probe spectroscopy to characterize THz generation crystals. Different types of crystals and pump wavelengths affect THz generation. Yellow crystals, such as BNA and MNA, achieve optimal output at shorter wavelengths, particularly 800 nm. Other crystals such as PNPA, DANPH, and DAST generate higher amplitude THz at longer wavelengths that can only be reached with an optical parametric amplifier. We will discuss the characteristics of an optimal THz generation setup to reach the high potential electric field strengths exceeding 1 MV/cm.