Parametric generation of high frequency coherent light in negative index materials and materials with strong anomalous dispersion

TL;DR

This paper explores a novel parametric process in specialized materials enabling the generation of tunable, high-frequency coherent light through difference combination resonance, expanding possibilities for new light sources.

Contribution

It introduces a new mechanism for high-frequency coherent light generation using difference combination resonance in negative index and strongly dispersive materials.

Findings

Resonance occurs in negative index materials with opposite signs of refractive index.

Resonance can also occur in positive index materials with strong anomalous dispersion.

The mechanism is equivalent to coupled parametric oscillators with opposite sign masses.

Abstract

We demonstrate the possibility of generation of coherent radiation with tunable frequencies higher than the frequency of the driving field $\nu _{d}$ in a nonlinear medium utilizing the difference combination resonance that occurs when $\nu _{d}$ matches the difference of the frequencies of the two generated fields $\omega _{1}$ and $\omega _{2}$. We find that such a resonance can appear in materials which have opposite signs of refractive index at $\omega _{1}$ and $\omega _{2}$. It can also occur in positive refractive index materials with strong anomalous dispersion if at one of the generated frequencies the group and phase velocities are opposite to each other. We show that the light amplification mechanism is equivalent to a combination resonance in a system of two coupled parametric oscillators with the opposite sign of masses. Such a mechanism holds promise for a new kind of light source that emits coherent radiation of tunable wavelengths by an optical parametric amplification process with the frequency higher than $\nu_{d}$.