Designing multilayer dielectric filter based on TiO$_2$/SiO$_2$ for fluorescence microscopy applications

This study presents a new construction design of a distributed Bragg reflector (DBR) filter and a Fabry–Perot (FP) filter by using needle technique as a synthesis method. The optimized DBR and FP filters having a proper number of layers with controlling thickness TiO${_2}$/SiO${_2}$ are utilized to transmit only a certain narrow band of wavelengths while blocking the others. As a proof of concept, the filters are designed to selectively transmit only a very narrow band of wavelength at 780 nm which is the near infrared (NIR) fluorescent emission from Alexa Fluor 750 dye. The obtained results show that the optimized filters represent advanced spectral performance which can be used to improve the sensitivity and the imaging contrast in fluorescence microscopy.