Manipulation of Nonlinear Optical Properties of Graphene Bonded Fiber Devices by Thermally Engineering Fermi–Dirac Distribution

Abstract

Graphene, which is an allotrope of carbon in the form of a 2D atomic-scale, hexagonal lattice, has attracted intense attention because of its atomic thickness and unique fundamental physical properties, particularly in the context of applications in next-generation on-chip planar silicon waveguides or Graphene's atomic thickness, gapless Dirac-Fermionic band structure, and large thermal conductivity make it a promising element for applications in photonic integrated devices. Importantly, actively tunable graphene-waveguide-integrated optoelectronic devices can potentially be utilized for the realization of reconfigurable photonic systems. Since electrical device control is always preferred, researchers have previously demonstrated gate-variable graphene devices; however, electrical control remains challenging, particularly in all-fiber systems because of the required complicated configuration and fabrication techniques along with additional signal loss. Here, a graphene-fiberintegrated platform is proposed and the manipulation of its nonlinear optical properties is demonstrated by engineering the Fermi-Dirac distribution of graphene based on a convenient electric heating method. For the first time, it is experimentally shown that the nonlinear optical absorption of graphene is correlated to temperature via the thermal relaxation process. In the experiments, the modulation depth variation exceeds 60%. The configuration is simple, cost-effective, and can be readily extended to other 2D materials. It is believed that this work can contribute to building miniature and compact graphenefiber-integrated devices for actively tunable multifunctional applications.

Multifunctional integration on optical fiber tips: challenges and opportunities

“…34 Moreover, polishing techniques were also used to process metal structures on optical fibers. [35][36][37] As shown in Fig. 3, Chen et al 38 fabricated electrodes on optical fibers using lapping films and tapered tungsten needles to remove a portion of the precoated gold film on the fiber sidewall and facet.…”

Third-order nonlinear optical properties of graphene composites: A review*

“…The configuration is simple, cost-effective, and can be easily extended to other 2D materials (such as black phosphorus, transition metal disulfide, etc.). [88]…”

Gate‐Tunable Graphene Optical Modulator on Fiber Tip: Design and Demonstration

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thermal controlling, [12] to all-optical switching. [13] According to manipulating methods, phase and intensity of light go thorough anticipated change.

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“…Earlier work demonstrated dual-electrode on-facet configuration, where electric current introduced Joule heat and current doping to manipulate graphene's Fermi level. [12,24] The devices were incorporated in mode-locked ring fiber laser or FP cavity fiber comb for intracavity loss management or wavelength tuning. Nevertheless, dual electrodes provide only one active channel for applying manipulating signals like source-drain current, changing the optical absorption of graphene, fiber facet temperature, or other device parameters simultaneously, which is hard to be decoupled.…”