Temporal Bragg Gratings: Broadband Reconfigurable Parametric Amplifiers

TL;DR

This paper proposes temporal Bragg gratings as broadband, reconfigurable parametric amplifiers, demonstrating tunable gain spectra and broadband amplification through systematic numerical simulations.

Contribution

It introduces a new class of broadband, reconfigurable amplifiers based on temporal Bragg gratings and explores their gain characteristics and tunability.

Findings

High-index modulation yields higher gain than low-index for similar depths.

Amplification is frequency-agile with tunable gain peaks.

Sub-Bragg regime requires stronger modulation, leading to broadband gain continuum.

Abstract

This paper introduces temporal Bragg gratings as a new class of broadband, reconfigurable parametric amplifiers. We present a comprehensive investigation of power amplification in temporal Bragg gratings, spatially periodic structures with refractive index modulated near the Bragg frequency. Through systematic numerical simulations, we explore the effects of modulation location (high-index vs. low-index layers), frequency, and amplitude on gain spectra and field dynamics. Both layer types yield significant parametric amplification, with high-index modulation providing higher gain for comparable depths. Amplification is frequency-agile, with gain peaks tunable across a broad range, and exhibits strong asymmetry: the sub-Bragg regime requires substantially stronger modulation than supra-Bragg for comparable gain. In the extreme sub-Bragg limit, the system transitions from discrete sidebands to a broadband gain continuum via multi-phase-matching. These results establish a unified framework for designing reconfigurable optical amplifiers, tunable frequency converters, and broadband light sources using temporally modulated photonic crystals.