Thomas E. Maybour | Searcharxiv

arXiv2021

Grating-Induced Slow-Light Enhancement of Second Harmonic Generation in Periodically Poled Crystals

The effect of slow light on second harmonic generation in a periodically poled $χ^{(2)}$ nonlinear medium is investigated theoretically. A linear $π$ phase shifted grating is used to slow the group velocity of the fundamental frequency and the resulting field enhancement greatly increases the second harmonic conversion efficiency. A second linear grating at the input end ensures that all output is in the forward direction. We show that almost 100\% conversion efficiency can be achieved for continuous wave pumping at low intensities that generate negligible conversion in the absence of the slow-light grating.

physics.optics↗

arXiv2021

Slow and Stopped Light in Dynamic Moiré Gratings

We investigate a theoretical model for a dynamic Moiré grating which is capable of producing slow and stopped light with improved performance when compared with a static Moiré grating. A Moiré grating superimposes two grating periods which creates a narrow slow light resonance between two band gaps. A Moiré grating can be made dynamic by varying its coupling strength in time. By increasing the coupling strength the reduction in group velocity in the slow light resonance can be improved by many orders of magnitude while still maintaining the wide bandwidth of the initial, weak grating. We show that for a pulse propagating through the grating this is a consequence of altering the pulse spectrum and therefore the grating can also perform bandwidth modulation. Finally we present a possible realization of the system via an electro-optic grating by applying a quasi-static electric field to a poled $χ^{(2)}$ nonlinear medium.

physics.optics↗