Imprinting the complex dielectric permittivity of liquids into the spintronic terahertz emission

We report an approach in time-domain terahertz (THz) spectroscopy for measuring the dielectric response of liquids based on inherent properties of spintronic THz emitters (STEs). The THz electric field radiated from the STE is inversely proportional to the sum of the complex refractive indices of the media surrounding the thin metallic stack of the STE and the stack's conductivity. We demonstrate that by bringing a liquid in contact with the emitter, its complex refractive index and accordingly its dielectric response are imprinted into the radiated electromagnetic field from the emitter. We use water as the test liquid and ascertain its dielectric loss and permittivity in the range of similar to 0.3-15 THz.

Automated summary

The approach utilizes spintronic THz emitters to measure the dielectric response of liquids, imprinting the liquid's complex refractive index and dielectric response into the radiated electromagnetic field by bringing the liquid in contact with the emitter. Water is used as a test liquid, and its dielectric loss and permittivity in the range of 0.3-15 THz are determined.