Broadband Terahertz Emission from Photoconductive Devices

Abstract

This chapter explores the terahertz (THz) emission from biased semiconductor photoconductive devices. The photoconductive device is an optoelectronic device that is able to emit broadband THz radiation under the optical excitation, by an ultrafast laser, in the existence of a bias field. This chapter explains the basic principle of photoconductive devices with focusing on the main device components, being the photoconductive material and the photoconductive structure. Then, various materials and structures are discussed toward improving the performance of the photoconductive THz emitters. Furthermore, the main limitations and considerations are presented with insight into the different saturation and screening effects due to the bias field and pump fluence. Ultimately, the recent advances and studies of photoconductive THz emitters are presented in terms of material and structure, including the quantum dots, the nanostructure, the use of dielectric materials, and the grating structure on the photoconductive surfaces.