This project will study the extraordinary way that common optical materials can respond to the electric and magnetic field components of intense light, which are capable of working together to surpass the traditional bounds of electrodynamics. It will focus on a process called magneto-electric (M-E) rectification, which induces a separation of the charges composing ordinary insulators in much the same way that application of an electric field causes a battery-like separation of charges in a capacitor. This process promises to enable the conversion of intense sunlight directly to electrical energy in a novel fashion (that does not require the light to be coherent), but will be investigated here for its potential to advance the field of photonics by mediating fast switching of light with the Lorentz force of light for the first time.
This research is expected to launch the field of magneto-photonics by providing ultrafast optical device technology based on magnetic rather than electric interactions of matter with electromagnetic radiation. The novelty of the proposed effort centers on switching a signal-carrying beam on and off on a sub-picosecond timescale with a control beam incident at right angles. Switching of light by light in a right-angle geometry is unprecedented and could lead in a single step to matrix-style signal processing and correlators for pattern recognition in exceptionally compact designs. This research will explore magnetic processes relevant to spin physics, energy conversion, high speed communication and quantum computation through its connections with fundamental topics like angular momentum and parity-time-symmetry in quantum mechanics. It will therefore foster advanced training of graduate students, provide an important pathway for promoting diversity in our workforce, and will emphasize inter-disciplinary research to match up new materials with the demanding objectives of modern photonics. This effort will culminate in ultrafast device technology that exploits the revolutionary properties of magneto-photonic materials and phenomena.
This experimental research program will undertake a systematic investigation of magneto-electric rectification to assess its utility for enabling ultrafast switching of light by light in new, compact geometries and to test our theoretical understanding of this process. A novel modulator designed to switch the transmission of a signal beam on or off will be subjected to a control beam propagating at ninety degrees with respect to the first in nonlinear media having large second-order, magneto-electric susceptibilities. Unlike conventional second-order photonic interactions, magneto-electric rectification can theoretically take place in all media, but experiences enhancement in materials with large, off-diagonal, third-order susceptibilities. So samples of two varieties will be compared – ones which are electro-optic (like KDP isomorphs) and ones which are not (like pentacene) – in an effort to verify and understand how this emerging class of magneto-optical interactions could spur photonic device technology in much broader classes of material than ever before. Because of its focus on transient dipole field generation in field-free media, this project will also exploit a sophisticated tilted wavefront technique to show that light can be converted to THz radiation without any external energy source other than the light itself. Since the magneto-electric process is mediated by the Lorentz force of light, this project will also shed light on mechanisms that enhance relativistic dynamics at modest light intensities, far below the customary threshold for relativistic optics at intensities of I~1018 W/cm2.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
