Graphene and thin graphite films for ultrafast optical Kerr gating at 1 GHz repetition rate under focused illumination

TL;DR

This paper demonstrates ultrafast optical Kerr gating at 1 GHz using graphene and thin graphite films, achieving 141 fs resolution with high efficiency and broadband operation, suitable for nano-optics and integrated photonics.

Contribution

It introduces the use of graphene and thin graphite films for high-repetition-rate ultrafast Kerr gating with enhanced nonlinear response and compact integration capabilities.

Findings

Achieved 141 fs temporal resolution at 1 GHz repetition rate.

Demonstrated broadband operation with high nonlinear refractive index.

Enabled compact, integrated ultrafast optical gating platforms.

Abstract

The ability to address sub-picosecond events of weak optical signals is essential for progress in quantum science, nonlinear optics, and ultrafast spectroscopy. While up-conversion and optical Kerr gating (OKG) offer femtosecond resolution, they are generally limited to ensemble measurements, making ultrafast detection in nano-optics challenging. OKG, with its broadband response and high throughput without phase-matching, is especially promising when used at high repetition rates under focused illumination. Here, we demonstrate an ultrafast detection scheme using the third-order nonlinearity of graphene and thin graphite films, operating at 1 GHz with sub-nanojoule pulses and achieving 141 fs temporal resolution. Their exceptionally large nonlinear refractive index, orders of magnitude higher than conventional Kerr media, enhances detection efficiency at smaller thicknesses, enables sub-picosecond response, and supports broadband operation. Their atomic-scale thickness minimizes dispersion and simplifies integration with microscopy platforms, optical fibers, and nanophotonic circuits, making them a compact, practical material platform for nano-optical and on-chip ultrafast Kerr gating.