Design and simulation of optical micro-structures in silicon integrated circuitry with Si avalanche-mode light emitters, EXCEL optical ray tracing, and RSOFT optical simulation

A two junction micro p+-np+ Silicon Avalanche based Light Emitting Device (Si AM LED) structure was analyzed in terms of dispersion emission characteristics, resulting in different wavelengths of light (colors) being emitted at different angles from the structure. Si AM LEDs can be integrated in on-chip bipolar RF integrated circuitry at micron and even submicron dimensions and have furthermore modulation frequencies into the GHz rang. As a first analyses, the optical propagation mechanisms were modelled by developing a custom designed EXCEL Progressive Ray Tracing Design Tool. (EPRTDT), whereby the positioning of the optical source, the initial launch direction of a particular optical wave fronts, and the subsequent refraction of planar ray fronts into subsequent layers of different refractive indices, in the structure could be progressively modelled. Subsequently, more exact simulations could be obtained by using an existing advanced simulation tool, RSOFT, as is generally available on the free market. The specific approach enabled the design of basic optical microstructures in a silicon 0.35 micron RF bipolar process, determining the dispersion behavior of propagation at different wavelengths, coupling of radiation into adjacently lying waveguides, determining propagation behavior into different type of waveguides, studying interaction with secondary regions of different refractive index, as well as design specific structures that could propagate radiation vertically out of the micro-structures into free space. The analyses have important applications for the realization of wavelength dispersers, couplers of SiAMLEDs into waveguides, realization of optical link structures on silicon chip, as well as micro vertical emitters of radiation out of the chip.