Optical Filters From Silicon Dioxide Doped Dyes

Abstract

In this work silicon dioxide powder of high purity 99.5% imported from china was used to fabricate optical filters by doping the SiO₂ with green and red phenol dyes with different concentrations of 0.25,0.5,0.75 and 1 in terms of mg, four samples of red SiO₂ doped phenol filters and four samples of green SiO₂ doped phenol filters were produced by pressing the mixture of silicon dioxide powder doped with the phenol dyes, the resulting discs has the dimensions of 1.5 cm in diameter and 0.15 mm in thickness. To investigate the filtering ability of the fabricated red and green filters transmission method was followed in which He-Ne 632.8 nm and diode laser 532 nm were used to record the transmission spectra as a function of doping concentrations. The transmission data recorded were used to deduce absorption coefficients of the  fabricated optical filters. The results showed that at high concentrations the transmission of SiO₂ red doped dye filters for 532 nm is decreased to 0.623 % which means that the filter worked properly while for 632.8 nm (red) the transmission increased to 0.921% at 1 mg, the deduced absorption coefficient’s ( 16.91 cm^-1 for 0.25 mg and 5.46 cm^-1 for 1 mg concentrations) support the  idea of using SiO₂ doped phenol red as an optical filter; the results also showed that SiO₂ doped Green dye filter has a high transmission for the 532 nm and low transmission for 632.8 nm wavelength