First-principal analysis and design of TaPO5-based waveguides for photonic circuitry

Abstract

With the rapid development of telecommunication systems, supercomputers, and large data centers, there is a growing need for advanced photonic materials to overcome the limitations of traditional photonic circuitry. This paper introduces monoclinic TaPO5, an indirect-bandgap semiconductor material, as a compact platform for photonic integrated circuits. TaPO5, with a bandgap of 2.148 eV, is analyzed for its structural, vibrational, thermodynamic, and optical properties using pseudo-potential plane waves within the density functional theory (DFT) framework. Our analysis reveals that TaPO5's thermodynamic properties, such as entropy, internal energy, and heat capacity, increase with temperature, while Helmholtz's free energy decreases. The materials demonstrate favorable optical characteristics, including a refractive index (n) of 2.11, an extinction coefficient (k) of 1.2 × 10⁻⁵, and a dielectric function with a real part of 4.45 and an imaginary part of 5.1 × 10⁻⁵ at a wavelength of 1.55 μm. TaPO5 exhibits promising performance metrics for photonic applications. Specifically, a proposed 1 × 2 multimode interference (MMI) splitter demonstrates 0.03 dB excess loss, a compact footprint of 4 × 18 μm2, and a 50:50 splitting ratio at 1.55 μm. These findings indicate that TaPO5 is a viable material for next-generation photonic integrated circuits, offering theoretical and practical advantages for various applications in photonic technology.