A high temperature optical filter using Si/Si3N4 one dimensional photonic crystal for GaSb thermophotovoltaic applications

Photonic crystals (PhCs) can control the light flow in certain directions and it can be used for different applications. Specific type of 1D PhC can be used in Thermophotovoltaic systems (TPVs), where PhC can act as an optical filter and can enhance the efficiency of the TPV system. In this work, GaSb is used as a semiconductor convertor in TPV system. The 1D PhC (Si/Si 3 N 4 ) optical filter reflects the photons whose wavelengths lie in the photonic bandgap range while transmits the photons which lie in its passband range. The reflected photons go back to the radiator for recycling and the transmitted photons go to the GaSb semiconductor convertor. Use of Si 3 N 4 has been proposed due to its excellent thermal shock absorbing capability and high temperature applications. In this study, the thicknesses of Si layers and Si 3 N 4 layers are considered as 145 nm and 200 nm respectively. The designed PhC optical filter has a stopband in the range 1788 nm to 2233 nm which corresponds to the bandgap of GaSb. The designed filter has a passband in the range of 991 nm to 1788 nm which makes it transmit the above bandgap photons to GaSb. The passband also makes it suitable for use in other optical communication applications.