Highly efficient semiconductor grating structure for SOI optical circuits

This paper explores high efficiency of semiconductor grating structure at wavelength, 1550 nm for silicon on insulator (SOI) optical circuits. Here semiconductor grating structure is realized by the combination of silicon and compound semiconductor materials, where compound semiconductor gratings are envisaged by indium phosphide, Al80Ga20As and Al42Ga58As. Different types of losses in terms of absorption, reflection and diffraction including polarization are cogitated to investigate the efficiency of grating SOI structure at wavelength, 1550 nm. Interestingly, the absorption loss of above semiconductor grating is found to be zero at the above wavelength. Also the simulation was accomplished using plane wave expansion method, which leads to zero reflectance for the aforementioned structures at same wavelength. Simulation is also made for diffraction and polarization losses of above three semiconductor grating SOI structures. Simulation results reveal that diffraction efficiency is 1, (diffraction loss is zero) with respect to detune from Bragg's angle which ranges from −12° to +12°. Additionally, the proposed structures encountered polarization losses. Present simulation results showed that polarization efficiency is more than 90% (polarization loss is less than 10%)in silicon −indium phosphide (Si-InP),silicon-Al80Ga20As (Si-Al80Ga20As) and silicon - Al42Ga58As (Si-Al42Ga58As) grating SOI structures with respect to same deviation. Since absorption, reflection and diffraction losses are zero, the overall transmitted efficiency depends on polarization efficiency and finally, with the combination of both absorption, reflection,diffraction and polarization loss,it is inferred that overall transmitted efficiency of semiconductor grating SOI structure is more than 90% with respect to same angle.