Designing an electro-optical 8-to-3 encoder based on resonant cavity and graphene-Al2O3 stack in the photonic crystal platform
Subject Areas : Journal of Optoelectronical NanostructuresFatemeh Haddadan 1 , Mohammad Soroosh 2
1 - Department of Electrical Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran
2 - Department of Electrical Engineering, Shahid Chamran University of Ahvaz, Ahvaz,
Iran
Keywords: Contrast ratio, Electro-optical encoder, Graphene, Photonic crystal, Resonant cavity.,
Abstract :
In this paper, a new electro-optical 8-to-3 encoder based on the photonic crystal resonant cavity and graphene-Al2O3 stack is proposed. To control the light transmission, a resonant cavity parallel to the waveguide in a one-dimensional platform is utilized. Some air holes are assumed near the cavity for achieving an interference, and generating a notch filter at a resonance wavelength of 1.49 µm. To control the filter's quality factor, a graphene-Al2O3 stack is used at the cavity center. Dependency of the dielectric constant and the refractive index of the stack to the graphene chemical potential makes a possibility to modulate the light transmission through the waveguide. The pair of the waveguide and the photonic crystal cavity acts as an electro-optical switch, where its operation depends on the applied voltage to the stack. Five electro-optical switches are employed to control the light passing from input ports toward three output ports. The area and the contrast ratio are 150 µm2 and 11.62 dB, respectively. The modulation depth of 97.6% and the crosstalk of -14.63 dB are additional advantages of the designed encoder. The tuneability of the transmission efficiency for the designed switches as the basis block is an interesting feature of the designed encoder. Also, the proposed structure can be easily extended to higher orders which is highly needed for optical circuits and optical networks.