Bright THz Instrument and Nonlinear THz Science
Abstract
One of our most significant achievements under this grant is the achievement of broadband THz wave emission from a thin water film due to short laser pulses excitation. THz wave generation from solids, gases, and plasmas have been demonstrated previously. However, THz wave generation from liquid materials, especially from a polar liquid such as water, has never been reported. For developing bright, high performance and cost effective THz sources, liquid water is a promising choice. As one of the common condensed matter, liquid water has higher molecular density than gas, which could provide a plasma with higher density than one formed from a gas. Additionally, because each laser pulse interacts with a new section of water film, there is no theoretical upper damage threshold as there is in solid crystals. Our results have been published in Applied Physics Letters in August 2017. Our discovery has been highlighted by the American Physics SocietyÕs SciLight, Phys.org, Laser Focus World, Photonics Media, and many other public presses. According to our experimental results, the THz radiation from liquid water shows distinct characteristics as compared to the THz radiation from air plasmas with single color optical excitation. First, the THz field is maximized with longer laser pulse durations. In addition, the p-polarized component of the emitted THz waves will be influenced by the polarization of the optical excitation beam. It is also shown that the energy of the THz radiation is linearly dependent on the excitation pulse energy. Additionally, to control the thickness and stability of the water film, a water control system has been designed and constructed.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 14, 2019
- Source ID
- W911NF1610436
Entities
People
- Xi-Cheng Zhang
Organizations
- Army Contracting Command
- United States Army
- University of Rochester