Investigation of the limits of Diffraction-Free Space-Time Optical Beams
Abstract
ABSTRACT: The proposed effort has three main thrusts that build on our previous achievements and make use of the unique theoretical and experimental expertise and skillset we have developed over the courseof our previous work.Thrust 1: Long-distance propagation of ST wave packets: This thrust has a theoretical and experimental component. We will establish a comprehensive theoretical model of ST wave packets that identifies the impact of the various characteristic features of ST wave packets on their propagation. These features are: the spectral uncertainty, the spectral tilt angle, the bandwidth, andthe central wavelength. Paramount among these is the spectral uncertainty, since the other parameters are essentially dictated by the application at hand. Additionally, we will construct a theoretical model for the dependence of the spectral uncertainty on the physical parameters of the optical setup; specifically, the size of the diffraction gratings, the optical apertures, and the spatialresolution of the spatial light modulators or lithographically fabricated phase plates.The experimental component of this thrust will make use of our theoretical model in designing an experimental arrangement for producing ST wave packets that propagate for at least 2 kilometers in free space. After laboratory testing of this optical setup up to ~ 50 m, we will move it out to the TISTEF facility for testing it on a laser range.Thrust 2: Synthesis of ST needles: To date, our work on ST wave packets has been confined to optical sheets; that is, beams in which one transverse dimension is manipulated while the other dimension is left uniform. In this thrust we will make use of previous work in the area of spatial transformations of optical fields to synthesize for the first time ST wave packets that are confinedin all dimensions, so-called (3+1)D wave packets. The beam will then have the form of an optical needle in lieu of an optical sheet. This thrust will require the use of multiple spatial light modulators and hence also the design of new phase plates to manipulate both transverse spatial dimensions instead of only one.Once the approach for synthesizing ST needles is established, the design will then be utilized in the long-range experiments carried out at TISTEF.Thrust 3: Synthesis of mid-infrared ST wave packets: All previous experiments on producing diffraction-free pulsed beams, including our group~s work on ST wave packets, have been carried out in the visible and near-infrared. However, the general synthesis methodology that we have developed in inherently wavelength-agnostic. We thus propose to carry out an experiment todemonstrate mid-infrared ST wave packets exploiting phase plates because of the lack of mid infrared SLMs. Indeed, because of their long wavelength, mid-infrared beams diffract at a faster rate compared to a beam of the same transverse width but shorter wavelength, which makes diffraction-free mid-infrared beams particularly useful. We will produce two mid-infrared STwave lengths that target the narrow-beam/short-range and the wide-beam/long-range limits.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 24, 2019
- Source ID
- N000141912192
Entities
People
- Ayman F Abouraddy
Organizations
- Office of Naval Research
- United States Navy
- University of Central Florida Board of Trustees