Nonreciprocal Structures with Phase-Change Components
Abstract
This project included two thrust areas: Reflective mm-wave photonic limiter and Magnetooptical composite materials with zero net magnetization. Jointly with the Directed Energy and Sensors Directorates of AFRL, we have demonstrated a free-space, reflective mm wave limiter based on a multilayer structure involving a nanolayer of a phase-change material, vanadium dioxide, which experiences a heat-related insulator-to-metal transition. The multilayer acts as a variable reflector, controlled by the incident wave intensity. At low intensities, VO2 remains dielectric, and the multilayer exhibits strong resonant transmittance. When the incident intensity exceeds a threshold level, the emerging metallic phase renders the multilayer highly reflective while safely dissipating a small portion of the input power without damage to the limiter. In addition, we have identified a way of cutting down the limiters activation time by more than three orders of magnitude, which is critically important for military applications. Pending further study, the proposed approach can lead to the experimental demonstration of ultrafast broadband limiters to protect sensitive electronics from high-power microwave radiation. We have designed and conducted proof-of-concept measurements of magnetic composite material with strong nonreciprocal characteristics, such as Faraday rotation, while having zero magnetization and not requiring a bias magnetic field. Our approach (U.S. patent pending) is based on a composite structure made of two different magnetic materials: magnetically hard and strongly anisotropic material (e.g., Nd) and magnetically soft material displaying low losses at operational frequencies (e.g., YIG at microwave frequencies). The idea is that only one (magnetically soft) of the two constitutive materials efficiently interacts with the electromagnetic oscillations and, thereby, contributes to the nonreciprocal properties, such as Faraday rotation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 02, 2022
- Accession Number
- AD1231161
Entities
People
- A. A. Chabanov
Organizations
- University of Texas at San Antonio