Extreme THz Science
Abstract
The scientific objective of this project is to conduct a fundamental study of extreme terahertz (THz) science. The far infrared region of the electromagnetic spectrum (0.3 to 10 THz), known as the THz frequency band, is a spectral range with rich scientific potential but limited technology. It has long been considered the last remaining scientific gap in the electromagnetic spectrum. Far from being fully exploited, it offers great opportunities in science and innovation by expanding horizons in new technology and applied fields. This field shows promise for a variety of reasons, namely that: (1) many molecules have structural resonances at these frequencies, making THz spectroscopy a unique tool to investigate matter, (2) conduction and displacement currents contribute almost equally to the dielectric response of matter, meaning that the THz range constitutes the ultimate limit of high-frequency electronics, and (3) the THz period corresponds to the time-scale of elementary chemical reactions, weak collective excitation in solids, relaxation time of phonons, and free carrier collision time, among others. THz science fundamentally enables technology that directly impacts our lives; from industrial quality control, to national security and environmental studies, and to medical diagnostic and treatment as a long-term prospect. Following the significant development of THz science and technology since the late 1980Õs, extreme THz science, including strong THz field-matter interaction, nonlinear spectroscopy, and imaging is the next frontier. After the significant development of pulsed THz science and technology in the late 1980s, the bottleneck that remains for exploring new cutting-edge research and advancing broader applications is the lack of bright, portable, high performance, and cost effective THz sources. We will develop a state-of-the-art, time-resolved tabletop bright THz source with several orders of magnitude increase of the THz peak field strength in comparison to the current best tabletop THz sources. This source will serve as the main vehicle (>100 MV/cm and 0.3 to 10 THz bandwidth) dedicated to the study of extreme THz science. The development of the bright THz source will initially use our recently purchased optical parametric amplifier (OPA) with a long-wavelength optical excitation (1.5 to 4 ?m) rather than conventional 800 nm optical excitation (from Ti: sapphire laser directly) to generate THz waves. We propose an investigation of micro-plasmas generated by tightly focused optical excitation beams. The micro-plasma serves as a new THz source with its unique radiation pattern and easy operation. We will study the laser energy threshold for THz wave generation, power scaling, and the generation efficiency from micro-plasmas. Additionally, we would like to use the flying focus method to enhance the THz wave generation. A flying focus may provide quasi-phase matching via a much easier experimental setup, and over a continuous range of values as opposed to a fixed value. The student will participate, design, and test new THz wave sources by using flying focus.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 15, 2018
- Source ID
- W911NF1710428
Entities
People
- Xi-Cheng Zhang
Organizations
- Army Contracting Command
- United States Army
- University of Rochester