Design of graphene-based hybrid waveguides for nonlinear applications

• Published in: Optical and quantum electronics Vol. 51; no. 2; pp. 1 - 10
• Main Authors: Khalili Sadaghiani, Vahid, Zavvari, Mahdi, Tavakkoli, Mohammad Bagher, Horri, Ashkan
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.02.2019; Springer Nature B.V
• Subjects: Characterization and Evaluation of Materials; Chemical potential; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; Computer Communication Networks; DIELECTRIC MATERIALS; ELECTRIC FIELDS; ELECTRIC POTENTIAL; Electrical Engineering; GRAPHENE; HARMONIC GENERATION; Lasers; LAYERS; LITHIUM COMPOUNDS; Lithium niobates; NIOBATES; NIOBIUM OXIDES; NONLINEAR PROBLEMS; Optical Devices; Optical properties; Optics; OPTOELECTRONIC DEVICES; Organic chemistry; PERMITTIVITY; Photonics; Physics; Physics and Astronomy; Propagation; Propagation modes; REFRACTIVE INDEX; Refractivity; Second harmonic generation; SILVER; THICKNESS; WAVEGUIDES; WAVELENGTHS; Nonlinear applications; Graphene; Hybrid waveguide; Plasmonic
• ISSN: 0306-8919; 1572-817X
• DOI: 10.1007/s11082-019-1750-y

The extraordinary properties of a monolayer graphene can be effectively utilized in integrated optoelectronic devices. Therefore, the optical properties and the effective parameters on the graphene’s conductivity are calculated at the telecom wavelength 1.55 µm. Next, the different types of photonic and plasmonic hybrid waveguides based on graphene are designed for nonlinear applications such as frequency conversion processes. The fundamental proposed structure consists of a LiNbO 3 layer, a single graphene layer and a dielectric gap between the graphene and LiNbO 3 to support the nonlinear applications such as second harmonic generation. The waveguide’s performance is analyzed in terms of the intensity of electric field, LiNbO 3 thickness, the gap refractive index, mode effective index and propagation loss while the graphene’s chemical potential is varied with an applied gate voltage. According to the results, a sudden rise in propagation loss at µ c  = 0.493 eV (where the permittivity of graphene is almost zero) is observed. At last, a plasmonic hybrid waveguide consisting of a silver strip and a graphene layer placed between the metal and LiNbO 3 layer is presented and the effect of the graphene’s chemical potential on the mode effective index and the propagation length are studied.