Two-Photon Absorption in Gapped Bilayer Graphene with a Tunable Chemical Potential

TL;DR

This paper calculates one- and two-photon absorption coefficients in gapped bilayer graphene with tunable chemical potential, revealing complex absorption behaviors crucial for designing nonlinear optical devices.

Contribution

It provides a comprehensive analysis of two-photon absorption in bilayer graphene with adjustable parameters, highlighting its potential for optoelectronic applications.

Findings

Two-photon absorption coefficient shows rich structure depending on photon energy and band gap.

Multiple absorption pathways contribute to the complex absorption behavior.

Analysis covers wide ranges of temperature, chemical potential, and photon energy.

Abstract

Despite the now vast body of two-dimensional materials under study, bilayer graphene remains unique in two ways: it hosts a simultaneously tunable band gap and electron density; and stems from simple fabrication methods. These two advantages underscore why bilayer graphene is critical as a material for optoelectronic applications. In the work that follows, we calculate the one- and two-photon absorption coefficients for degenerate interband absorption in a graphene bilayer hosting an asymmetry gap and adjustable chemical potential--all at finite temperature. Our analysis is comprehensive, characterizing one- and two-photon absorptive behavior over wide ranges of photon energy, gap, chemical potential, and thermal broadening. The two-photon absorption coefficient for bilayer graphene displays a rich structure as a function of photon energy and band gap due to the existence of multiple absorption pathways and the nontrivial dispersion of the low energy bands. This systematic work will prove integral to the design of bilayer-graphene-based nonlinear optical devices.