Optical Modulation

Measurements of thallium and indium doped Silicon-On-Insulator rib waveguides show optical absorption at a wavelength of 1550nm, dependent on the charge state of the associated deep-level. Therefore, it is possible to use this effect to modulate waveguide transmission by means deep-level occupancy change induce by local depletion and/or injection of free-carriers. A one-dimensional model based on the generation and recombination process described by the modified Shockley-Read-Hall (SRH) mechanism was developed using MATLAB programming language in order to compute the optical absorption of a 1550nm wavelength as a function of the density of neutrally-charged thallium or indium centers. In addition, the influence of indium, as a dopant in silicon (utilizing the Impurity Photovoltaic Effect), as a means to increase the efficiency of a thin film silicon solar cell was investigated using the same samples.