Silicon-on-insulator (SOI) technology has been a promising platform for photonic applications. However, the high index-contrast between silicon and the top cladding (SiO<sub>2</sub> or air) of the SOI waveguides makes the modal birefringence hard to control. Consequently, SOI based photonics integrated circuits (PICs) are in general highly polarization-sensitive, making polarization management important. In this paper, a polarization rotator (PR) design on the 220 nm SOI platform is demonstrated through numerical simulations and experiments. The demonstrated PR design is based on asymmetrical periodic loaded waveguide structures. The demonstrated design features compact device footprint and can be fabricated by CMOS compatible process. In addition, no special cladding is required to break the vertical symmetry of the waveguide. The design has shown promising performance over the C-band wavelengths (1530 nm-1565 nm) by simulations. However, the fabrication requirements are stringent for the design, thus the performance of the fabricated devices are limited by the current fabrication technology.
We present a design of implementing plasmonic nanoparticles made from silver onto the surface of amorphous silicon based solar cells. When adding these silver nanoparticles we expect to see enhancements to the solar cells due to the plasmonic effects induced by the metal nanoparticles. The nanoparticles are used as subwavelength scattering elements to couple and trap light within the cell. In addition, the excited surface plasmon-polaritons promote a strong localized field enhancement which increases the cells ability to absorb light. Our choice of geometry of the nanoparticle is cubic rather than the traditional spherical geometry. We expect to see the cell perform better with the cubic shape due to the larger surface area it spans. We investigate the effects of these particles on to the performance of the solar cells, as well as introduce an intrinsic layer between the active p and n region creating a p-i-n solar cell configuration. We report the use of an FDTD simulator to characterize the optical performance of the solar cell. Both cubical and spherical nanoparticles made from silver were studied. Our simulations predict an overall increase of 67% (from 7.5% to 12.5) based on the p-i-n configuration with inclusion of the plasmonic particles onto the surface of the cells. Experimentally we verified the results by first fabricating a crystalline silicon-based solar cell with a p-n configuration and then placing the silver nanocubes onto the surface of the cell. An overall increase of about 28% was experimentally demonstrated (from 3.97% to 5.081%). We anticipate further increases with the p-i-n configuration.
We report a novel plasmonic solar cell design implemented on an amorphous silicon platform. The enhancement of
the scattering and trapping of the light is achieved by embedding nano-metallic cubic particles within the cell’s
junction. Amorphous silicon cell with a thickness of 1200nm is used. The spectral absorption of the silicon cell is
limited to wavelengths larger than 1.1 u. Our proposed solar cell has a p-i-n configuration, with the amorphous
silicon as the photo-active layer. Silver cubic nanoparticles are embedded at different locations within the photoactive
layers of the solar cell. With the use of an FDTD simulator, we are able to characterize the optical
performance of the solar cell. Our results show that the plasmonic properties of the cubic nanoparticles are more
attractive for sensing applications compared to the traditional spherical configuration. The geometry of the cubic
nanoparticles enables control over plasmon resonances both in the resonant wavelength and the degree of field
enhancement. This is done by improving the refractive-index sensitivity on a thin silicon film, as well as increasing
the scattering and trapping of light. Our simulations predict that the silver metallic nanoparticles will enhance the
solar cell efficiency, by optimizing the plasmonic properties of the silver nanocube monolayer. We have achieved a
67% increase (from 7.5% to 12.5%) in the cell’s efficiency by adding plasmonics to traditional amorphous p-i-n