A theoretical study is presented on planar micro-optic solar concentrators. These can be inexpensively fabricated using nanoimprinting techniques and can provide indoor illumination. Multiple combinations of lenslet array designs and coupling features are optimized, and full system efficiencies are evaluated by ray-tracing simulations. Concentrator designs are optimized with considerations of suitability to tropical regions. A design capable of near-unity efficiency at up to 18-deg field angles and up to 92.14% collection efficiency within ±30-deg incident angle is reported. A cost analysis is then performed using meteorological data.
We have successfully fabricated and measured our silicon bridge waveguide polarization beam splitter (PBS). Our proposed PBS is based on a bend directional coupler with a bend bridge waveguide and is experimentally realized using silicon waveguide thickness of 220 nm and 250 nm, which are the commonly used silicon thickness for silicon photonics manufacturing. Our experimental results demonstrated high extinction ratio of > 20 dB for the TE-like mode, and > 15 dB for the TM-like mode across a broad bandwidth of 90 nm that covers the entire C-band with a small footprint of ~18×9 μm<sup>2</sup>. On-chip high performance PBS is important for polarization diversity in integrated photonics, and for communication applications such as dual-polarization quadrature phase-shift keying (DP-QPSK) modulation.
Thin form-factor planar sunlight concentrators fabricated using low-cost materials in conjunction with high-efficiency solar cells may prove economically competitive with silicon photovoltaics. A periodic structure with planar interfaces employing an array of microlenses and coupling structures is amenable to high-volume imprint manufacturing and hence a drastic cost reduction. A numerical study of periodic prismatic void structures aligned with microlenses to efficiently couple incoming light into a constant cross-section channel waveguide is reported. Three different prism-like cut-out structures: a bare prism, a planar connected prism, and a pointed prism are proposed. Numerical results show that the proposed pointed prism design offers a high-efficiency coupling with one-sided output (90.8% and 85.4% peak efficiency at concentration ratios of 320× and 400×, respectively).