Ultrafast Graphene Light Emitters

Abstract

Ultrafast electrically driven nanoscale light sources are critical components in nanophotonics. Compound semiconductor-based light sources for the nanophotonic platforms have been extensively investigated over the past decades. However, monolithic ultrafast light sources with a small footprint remain a challenge. Here, we demonstrate electrically driven ultrafast graphene light emitters that achieve light pulse generation with up to 10 GHz bandwidth across a broad spectral range from the visible to the near-infrared. The fast response results from ultrafast charge-carrier dynamics in graphene and weak electron-acoustic phonon-mediated coupling between the electronic and lattice degrees of freedom. We also find that encapsulating graphene with hexagonal boron nitride (hBN) layers strongly modifies the emission spectrum by changing the local optical density of states, thus providing up to 460% enhancement compared to the gray-body thermal radiation for a broad peak centered at 720 nm. Furthermore, the hBN encapsulation layers permit stable and bright visible thermal radiation with electronic temperatures up to 2000 K under ambient conditions as well as efficient ultrafast electronic cooling via near-field coupling to hybrid polaritonic modes under electrical excitation. These high-speed graphene light emitters provide a promising path for on-chip light sources for optical communications and other optoelectronic applications.

Circularly Polarized Thermal Radiation From Nonequilibrium Coupled Antennas

“…Related to the tunability of device temperature in context of CP thermal emission, recent works [36,62,63] have explored dynamical modulation of thermal emission in two-dimensional opto-electronic platforms where ultra-fast switching rates 100MHz have been realized. We therefore envision that in the long run, the proposed mechanism can be combined with such newly emerging concepts to build a compact, high purity and dynamically reconfigurable source of CP light.…”

Graphene‐Based Devices for Thermal Energy Conversion and Utilization

“…Graphene's high thermal stability, low heat capacity, and ultrafast optoelectronic properties provide possibilities for realizing unusual fast and efficient thermal light emitter. In 2018, Kim et al demonstrated electrically driven ultrafast graphene light emitters that achieve light pulse generation with up to 10 GHz bandwidth ( Figure b) across a broad spectral range from the visible to the near‐infrared. Ultrafast charge‐carrier dynamics in graphene and weak electron‐acoustic phonon‐mediated coupling between the electronic and lattice degrees of freedom contributes a lot to the fast response.…”

“…Left inset: Schematic of energy relaxation of graphene. Reproduced with permission . Copyright 2018, American Chemical Society.…”

Nonlinear optical absorption and asymmetric charge carrier conduction in chemical vapor deposited single-layer graphene

“…Graphene was considered only as an electronic material in its early stages of research. However, during the last few years, researchers started exploring its application in photonics and optoelectronics [1][2][3][4]. It is well proved that the important characteristics of the synthesized graphene film depend strongly on its quality.…”