Laser beam zooming and deflection using a nonlinear metamaterial refracting medium

Abstract

In-process control of the focal spot size and pointing position of a laser as it interacts with a target (beam zooming and deflection) offers the possibility of unprecedented efficiency improvements in a number of applications, such as inertial confinement fusion and laser micromachining. Here is described a system in which the focussing characteristics of a laser beam at one wavelength can be controlled by a lower-intensity beam at another wavelength, via their mutual interaction with a nonlinear metamaterial refracting medium. Such a metamaterial approach permits the optical response of the medium to be tailored according to the wavelengths of interest and time response required in a given application. A metamolecule unit cell design is described in terms of an equivalent circuit based on a pair of LCR (inductance, capacitance, resistance) circuits coupled by a common nonlinear capacitor. The circuit is studied using an analytical approach to obtain an understanding of its properties and design relationships between circuit parameters. Potential realisations of the circuit are discussed.