Performance Estimation of Hybrid Plasmonic Waveguide in Presence of Stress

Abstract

In this paper, a detailed numerical investigation has been carried out to find the effect of stress on the optical performances of hybrid plasmonic waveguides (HPWs) operating at 1550 nm wavelength. In the HPWs, the stress is induced due to mismatch in lattice constant and thermal expansion coefficient (TEC) between its different layers. In this paper, optical performances of two HPWs having rectangular and triangular cross-section have been investigated using the finite-element method (FEM) in the presence of stress. For HPW with triangular cross-sections, 25° and 35° ridge angles (α) have been chosen categorically, as they are feasible to fabricate. The effect of stress on optical performance parameters, namely effective refractive index, propagation loss, propagation length, and temperature sensitivity for the HPWs, has been investigated. In this study, different metals (Au and Ag) and dielectric materials (SiO2 and Si3N4) have been introduced in HPWs to realize different magnitude of stresses, which alter the optical performances of the waveguide. Our simulation studies reveal that for all metal and dielectric materials the triangular HPW with 35° ridge angle introduces the highest magnitude of stress as compared to the triangular waveguide with 25° ridge angle and rectangular waveguide. Further, the results show that the presence of stress in the HPW reduces propagation loss and helps in achieving larger propagation length (LP). The work also shows that the largest magnitude of stress is exerted by the triangular HPW (α = 35°) having Si3N4 and Ag materials as dielectric and metal, respectively; and the stress-induced changes in effective index, propagation loss, propagation length and temperature sensitivity of effective index, and propagation length are 0.35%, 42%, 42%, 0.141 × 10− 4/°C (1.45 × 10− 4/°C to 1.309 × 10− 4/°C), and 15.6 nm/°C (5.5 nm/°C to 21.1 nm/°C), respectively. Significant performance variation in HPW in the presence of stress emphasizes the need for the consideration of stress-optic effect while designing HPWs, which can then be employed in photonic integrated circuits.