Saturation of interband absorption in graphene

TL;DR

This paper theoretically investigates the ultrafast interband absorption saturation in intrinsic graphene, analyzing spectral and temporal responses, and compares the results with experimental data for near-IR lasers.

Contribution

It provides a theoretical analysis of the saturation behavior of interband absorption in graphene, including spectral, temporal, and phonon emission effects, with comparison to experimental results.

Findings

Identified characteristic saturation intensities in graphene.

Observed negative absorption during cascade phonon emission.

Compared theoretical predictions with experimental near-IR laser data.

Abstract

The transient response of an intrinsic graphene, which is caused by the ultrafast interband transitions, is studied theoretically for the range of pumping correspondent to the saturated absorption regime. Spectral and temporal dependencies of the photoexcited concentration as well as the transmission and relitive absotption coefficients are considered for mid-IR and visible (or near-IR) spectral regions at different durations of pulse and broadening energies. The characteristic intencities of saturation are calculated and the results are compared with the experimental data measured for the near-IR lasers with a saturable absorber. The negative absorption of a probe radiation during cascade emission of optical phonons is obtained.