Ultra-short bilayer graphene optical fiber intensity modulator based on silver-semicircular hybrid plasmonic waveguide

The intensity modulator is a key component in optical fiber communication. In this paper, an ultra-short graphene light intensity modulator based on hybrid plasmonic waveguide (HPW) array is proposed. Al2O3 embedded with double-layer graphene at a certain interval is placed on the side polishing surface of the microfiber Mach-Zehnder modulator (MZM), and the silver-semicircular array is placed on the surface of the transition material as hybrid plasmonic waveguide for the first time in all-fiber modulator. Analyzing by building a 3D model in finite difference time domain software, the hybrid surface plasmon polariton (HSPP) between silver-semicircles significantly enhances the subwavelength confinement and the light-graphene interaction. The modulation range of the real part of effective refractive index (Neff) can reach to 0.01984 by adjusting the Fermi level of graphene. Therefore, phase change can be achieved only in a modulation length of 45 tum, and the insert loss can be controlled below 0.0159 dB/tum through the analysis of the imaginary part of the Neff, which also leads to a low total loss of 0.7155 dB. Owing to the excellent phase modulation efficiency, high extinction ratios of 39.39 dB and 47.77 dB can be reached for port 1 and port 2, respectively. Double-layer graphene forms the flat capacitor, which brings high modulation efficiency while achieving a high modulation bandwidth of 59.945 GHz. The application of HPW in graphene optical fiber modulator greatly improves the working efficiency, reduces the difficulty of integration, overcomes high insert loss, improves the extinction ratio, this modulator can be widely used in the future optical fiber communication system.

Automated summary

In this paper, an ultra-short graphene light intensity modulator based on hybrid plasmonic waveguide (HPW) array is proposed. By placing Al2O3 embedded with double-layer graphene on the side polishing surface of the microfiber Mach-Zehnder modulator (MZM) and using the silver-semicircular array as the hybrid plasmonic waveguide, the subwavelength confinement and the light-graphene interaction are significantly enhanced. The modulator achieves high modulation efficiency and high modulation bandwidth, making it suitable for future optical fiber communication systems.