Abstract
The functionality of a nanoscale silicon-based optoelectronic modulator is deeply analyzed while it appears that two competing processes, thermal and photonic, are occurring at the same time, and are preventing the optimization of the electro-optics coupling. While an incident illumination-beam first process is translated into photons, generating pairs of electrons–holes, a second process of thermal generation, creating phonons enables a loss of energy. Complementary studies, combining strong analytical models and numerical simulations, enabled to better understand this competition between photonic and thermal activities, in order to optimize the modulator. Moreover, in order to prevent unnecessary heating effects and to present a proposed solution, a picosecond pulsed laser is suggested and demonstrated as the ultimate solution so no energy will be wasted in heat, and still the photonic energy will be fully used. First ever-analytical solution to the heating produced due to the laser illumination applied on a nano-photonic device, while the illumination is produced in a periodic time changing function, e.g. a pulsed illumination, is presented. The present case study and proposed adapted solution can serve as a basis of generic approach in sensors’ activation towards optimized photonics absorption.
Highlights
Coupling of physical properties has always been a preferred domain of interest for researchers and engineers, because of the multi-disciplines challenge, and because it enables the study and application of combined properties in materials and devices, and of input–output conversion of signals
The bottom line of this mathematical analysis is that it provides an analytical solution to a complicated partial differential equation describing the temporal-spatial distribution of free carriers, which are directly associated with solving the localized heating of the proposed device as appears
Complementary and complex analytical and numerical models are presented for the analysis of the contest between two elementary physical processes, photonic and thermal, inside a Silicon On Insulator (SOI) photo-activated modulator
Summary
Where T—Temperature function, k—Thermal conductivity, H—Heat generation rate, ρ—Mass density, c—Specific heat. Heat generation rate in the structure is due to optical generation, the excess charge carriers’ recombination and the Joule heating resulting from the current:. For which Gopt—Optical generation rate, Eph—Average optical energy for electron–hole pair creation, Eeh—Average energy of electron–hole pair, Rnet—Net recombination rate of charge carriers in the material, Jn —Current produced by the electrons, E—Electric field. The boundary condition of this equation is the constant temperature at the both ends of the model. Note that all parameters of the equation are known except for the recombination rate, electrons’ current and the electric field. In order to calculate those parameters, the solution of the semiconductor equations needed to be found. The basic equations of semiconductors are the equation of continuity, transport, and Laplace (under quasistatic assumption).
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