Research progress of super-continuum terahertz source based on nano-structures and terahertz lab on-chip system

Abstract

The terahertz applications of bio-materials and energetic materials are hindered by the low power-intensity of the terahertz output and the narrow band of terahertz emission. So the crucial part of the development of terahertz time-domain spectroscopy (TDS) systems is the new terahertz source with broadband frequency range and high power output. As to the free-space TDS system, the system is necessarily purged by dried nitrogen gas to remove the absorbed water vapor. In addition, the low detection sensitivity also exists because of the free-space interactions between the terahertz emission and the substances. To address these problems, terahertz lab on-chip system is proposed. The local field effect in the nano-structures of on-chip system can contribute to the detection of low concentration of the substance. The present paper is composed of two sections. Firstly, a new terahertz source based on the metal nano-film can produce an intense and broad-band terahertz-infrared emission, which is comprised of incoherent terahertz-infrared signals and coherent terahertz signals. This emission can cover more than 100 THz and has an output power of up to 10 mW. This optical phenomenon mainly arises from the incoherent thermal radiation effect. Secondly, the terahertz lab on-chip systems with different transmission lines and different substrates are clarified. There exists lower loss on the on-chip system with coplanar stripline structure and copolymer substrate. High sensitivity of biological detection in terahertz band of up to 2 THz can be achieved by using this system.