Multilayer dielectric stack Notch filter for 450-700 nm wavelength spectrum

In this work, a multilayer dielectric optical notch filters design is proposed based on TiO2 and SiO2 alternating layers. Titanium dioxide (TiO2) is selected for its high refractive index value (2.5) and Silicon dioxide (SiO2) as a low refractive index layer (1.45). These filters are conventionally envisioned for overpowering of powerful laser beams in research experiments, to obtain good signal-to-noise ratios in Raman laser spectroscopy. It is precarious that light from the pump laser should be blocked. This is attained by inserting a notch filter in the detection channel of the setup. In addition to spectroscopy, notch filters are also useful in laser-based florescence instrumentation and biomedical laser systems. The designed filter shows a high quality with an average transmission of more than 90% in 450-535 and 587-700 nm bandwidths. And a stop band region between 536-586 nm shows a transmission of 3% only with an optical density of greater than 3, which makes it a promising element to be used as a notch filter.