Chapter 6Terahertz Broadband Micro-antennas forContinuous Wave Imaging1

 

 

 

6.1. Introduction

Terahertz waves (THz, 500 GHz to 5,000 GHz, typically) offer a steadily growing range of applications. Traditionally exploited by the radio astronomy and remote sensing communities for the last four decades, they are now expanding over various areas such as atmospheric and environment studies, plasma diagnostics, security, health, transport, etc. [SIE 06].

This growth has led to the introduction into the market of imaging systems based on transient THz waves generated from IR short-pulse sources (femtosecond lasers). However, those systems have begun to exhibit some limitations, in terms of sensitivity, resolution and fast image acquisition, among others.

The two approaches proposed in this chapter are dedicated to the detection of continuous THz waves (CW) using innovative bolometric sensors, to which the incident radiation is coupled by means of wideband micro-antennas, as developed in the NANOTIME project (NANostructures of Oxides for Terahertz IMaging Exploration) [NAN 05].

6.1.1. First approach

This first approach relies basically on the need for high sensitivity heterodyne THz receivers for radio astronomy and remote sensing. The superconducting hot electron bolometer (HEB) — the principle of which was introduced two decades ago [GER 90, PRO 93] — offers a competitive alternative to traditional heterodyne mixing technologies at THz frequencies. Our goal here was to design planar ...

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