Examination of the spatial and temporal field distributions of single-cycle terahertz pulses at a beam focus

Abstract

Measurements of spatially resolved beam profiles of single-cycle terahertz pulses are presented. In the approach here the terahertz beam is scanned over the stationary electro-optic detector using a gimbal-mounted mirror. A detailed study of the temporal- and frequency-dependent field in the region of the terahertz focus reveals field patterns which are dominated by diffraction and absorption. The observed field distribution is reproduced in model calculations. The exceptionally high signal to noise ratio and the high frequency and spatial resolution of the experiment here facilitate the observation of minute field distortions caused by the anomalous dispersion of absorbers in the beam path from the spatially resolved field pattern.

Review of Near-Field Terahertz Measurement Methods and Their Applications

“…0.5 mm. Similar measurements of the THz field pattern in focus have been done by Bitzer et al with the identical limitation [81]. An improvement of spatial resolution has been achieved by the same group, using a photogated gap detector.…”

Terahertz near-field imaging of metallic subwavelength holes and hole arrays

“…In this case, however, one would expect also a nonvanishing tan-a͒ Electronic mail: andreas.bitzer@gmail.com. 10 Due to the strong frequency dependence of the beam waist, a homogeneous illumination of our samples is only given for frequencies below 1 THz. gential field component along the y axis.…”

Analysis of a hyperprism for exciting high- k modes and subdiffraction imaging

“…The intensity reduction for the resonant case strongly depends on the wavelength. To show this, we now present the images as a function of wavelength and position, which we refer to as a line scan [36].…”