Optical filter based on a 1D photonic crystal with graphene defect layers: (BaTiO3/Y2O3)N/G/Y2O3/G/(BaTiO3/Y2O3)N for multispectral sensing

Juan Manuel Giraldo Millan, Speaker at Materials Conferences
MSc Student

Juan Manuel Giraldo Millan

Valley University, Colombia

Abstract:

The development of tunable optical filters in the visible range is highly relevant for applications in spectral sensors and integrated photonics. In this work, we present the design of a one-dimensional photonic crystal composed of Yttrium Oxide (Y2O3, insulator), Barium Titanate (BaTiO3, ferroelectric), and graphene (G), incorporated both as atomic layers and as thin-film defect modes. The structure was analyzed using the Transfer Matrix Method, considering periodicity, layer thickness, incidence angle, and the electronic properties of the constituent materials. For Y2O3 and BaTiO3, the dielectric permittivity was assumed to be constant according to their crystalline phase,

 

while for graphene the permittivity was described using the Kubo formalism, which relates interband and intraband transitions to its electrical conductivity. This approach evaluates the multiple interactions within the layered crystal structure. In the absence of defects, the system exhibits a reflector cavity in the visible region between 500 and 600 nm, centered at approximately 550 nm, consistent with the quarter-wave criterion. The inclusion of graphene breaks the periodic symmetry, leading to the appearance of resonant modes inside the cavity, observed as transmission peaks around 510 nm, 550–560 nm, and 600 nm. These modes highlight the critical role of graphene in spectral tuning, depending on the design parameters. The combination of ferroelectric, insulating materials, and graphene defects enables precise adjustment of the system’s optical response, supporting its potential use in dynamic optical filters and spectral sensors in the visible range, with applications in environmental monitoring, selective spectral detection, and integrated photonics.

Biography:

Juan Manuel Giraldo Millán is an MSc student in Physics at Universidad del Valle. He has a strong interest in radiation–matter interactions. During his undergraduate degree, he developed skills in studying and characterizing photonic crystals, applying the Transfer Matrix Method, Maxwell’s equations of electromagnetism, refractive indices of the structures, and Fresnel coefficients to evaluate the optical response of photonic crystals through purely theoretical models. He is currently complementing his academic training with experimental developments that allow him to contrast and validate his theoretical proposals.

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