Abstract
Today's pulsed THz sources enable us to excite, probe, and coherently control the vibrational or rotational dynamics of organic and inorganic materials on ultrafast time scales. Driven by standard laser sources THz electric field strengths of up to several MVm−1 have been reported and in order to reach even higher electric field strengths the use of dedicated electric field enhancement structures has been proposed. Here, we demonstrate resonant electric field enhancement structures, which concentrate the incident electric field in sub-diffraction size volumes and show an electric field enhancement as high as ~14,000 at 50 GHz. These values have been confirmed through a combination of near-field imaging experiments and electromagnetic simulations.
Highlights
Today’s pulsed THz sources enable us to excite, probe, and coherently control the vibrational or rotational dynamics of organic and inorganic materials on ultrafast time scales
Driven by standard laser sources THz electric field strengths of up to several MVm21 have been reported and in order to reach even higher electric field strengths the use of dedicated electric field enhancement structures has been proposed
At the lowest order resonance of the specific design we find that the THz electric field enhancement reaches 14,300 at 50 GHz for a 100 nm wide gap and is the highest reported to date in this frequency regime
Summary
Today’s pulsed THz sources enable us to excite, probe, and coherently control the vibrational or rotational dynamics of organic and inorganic materials on ultrafast time scales. Part of the incident radiation is typically converted to charge density oscillations, which in turn generate an enhanced and localized electric field distribution on a length scale well beyond the diffraction limit[20,21,22,23] At visible wavelengths this concept has turned into a key element for example for single-molecule spectroscopy, nano-imaging, or extreme nonlinear optics[24,25,26]. We report on a novel antenna design, i.e. a split ring resonator featuring a nanometer sized gap, which extends into the inner part of the split ring resonator Such structures, as outlined below, show promise for extremely high THz electric field enhancement at their resonance frequencies. By irradiating the structures with THz pulses from a standard femtosecond oscillator driven spectroscopy source we find in-gap electric field strengths of approximately 80 kVm21; such electric field strength are usually only achieved with amplified femtosecond laser systems
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
