Fully-coherent terahertz detection method and system (Phase I)

点击翻译按钮获取中文摘要

Terahertz (THz) science and technology aims, in a broad context, at developing new research fields in the frequency gap between the infrared and microwaves, typically referred to as the frequencies ranging from 0.1 THz to 10 THz. Recent progresses in nonlinear optics have offered a great number of innovative and efficient generation and detection schemes, which have lately revitalized the field. The main detection method commonly used in THz science and named Air Biased Coherent Detection (ABCD), is based on the Terahertz Field Induced Second Harmonics (TFISH) technique, and allows to record THz fields with extremely large bandwidth (>20 THz). The system is composed of a pair of electrodes suspended in air and separated by a distance close to 1 millimeter, which correspond to the section where THz and optical beams are focused. In this region an intense AC external bias is applied to the optical focus in order to generate a bias field and to induce a second harmonic pulse. The higher the external bias, the better the signal. Unfortunately miniaturization and integration remains elusive. Not only the existing systems cannot be easily miniaturized (dimension of few cm or less) but current detection systems require the use of high voltage amplifiers (typically kV sources) thus affecting the accessibility to this technique. Moreover, since the detection occurs in air, the use of high voltage is limited by air breakdown. Our invention proposes to overcome these limitations by first miniaturizing the detection device, and second substituting the air by a centro-symmetric material, in this case the silica SiO2. The detector, fabricated using a CMOS compatible fabrication process, features two metallic electrodes separated by a distance of few tens of micrometers and filled with a nonlinear, high breakdown voltage medium. A proof of principle of such a device has already been demonstrated, that is why, in this project, we intend to improve and optimize the fabrication processes, with the aim to build and fully characterize a prototype in view of its commercialization. The simplicity of this concept will thus lead to the cost performance and mass-reproducible characteristics that are prerequisite to a successful commercialization.