Long-period fiber grating spectrum based graphene complex refractive index measuring method

Abstract

The invention belongs to the field of photo-communication, relates to integration of a long-period fiber grating and graphene, and provides a long-period fiber grating spectrum based graphene complex refractive index measuring method. The graphene is transferred to the surface of the long-period fiber grating, the effective refractive index of a cladding mode is obviously changed through the mutual action of the graphene and an evanescent wave on the surface of a first-order each cladding mode, so that the shift of the resonant wavelength in a long-period fiber grating transmission spectrum is caused. The numerical values are compared to calculate to obtain a relationship table of the complex refractive index of the graphene and the offset of the resonant wavelength, so that the complex refractive index of the graphene is measured. A measuring system in the method is simple in structure, the influences of an optical fiber on the graphene are taken into full consideration in the measurement process, and as the long-period grating is written in an optical fiber core, the evanescent wave in the cladding mode is led to the surface of the graphene without corroding a cladding layer of the optical fiber, and therefore, the structure strength of the optical fiber is guaranteed. The method can also be popularized to measure the refractive indexes of other thin film materials and to design an optical fiber sensor.

Description

technical field [0001] The invention belongs to the field of optical communication, and relates to the integration of a long-period fiber grating and graphene. Background technique [0002] Graphene material is a carbon-based two-dimensional crystal, and single-layer graphene has many excellent optoelectronic properties. The absorption efficiency of graphene to light can reach 2.3%, and the transmittance in the visible light region is as high as 97%, which has excellent optical properties. Meanwhile, graphene has ultra-high carrier mobility and electrical conductivity. These excellent optoelectronic properties of graphene make it an ideal material for fabricating optoelectronic devices. [0003] In the design of graphene-based electro-optic modulators, the real and imaginary parts of graphene's complex refractive index affect the phase and intensity of the optical signal in the electro-optic modulator, respectively. The mechanism is particularly important. Due to the thi...

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Problems solved by technology

[0004] The present invention provides a method for measuring the complex refractive index of graphene based on long-period fiber grating spectroscopy, which aims to solve the method for measuring the complex refractive index of graphene provided by the prior art, without considering the integration of graphene and optical waveguides

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