Investigations of Al2O3–Nb2O5 bi-layer Bragg reflector investigations for blue and green lights

Abstract

At first, the single-layer Al2O3 and Nb2O5 films were deposited to find their refractive indices. After the indices of the single-layer Al2O3 and Nb2O5 films were measured, the thickness of 1/4 wavelength ([Formula: see text] for each layer of the Al2O3–Nb2O5 bi-layer Bragg reflectors of blue (450-nm) and green (550-nm) lights could be obtained. E-beam was used to deposit the bi-layer Al2O3–Nb2O films (called as one period) with two, four, and six periods on glass substrates to fabricate the Bragg reflectors of blue and green lights. The measured results had proven that the reflectance ratio increased and the bandwidth and full-width at half-depth (FWHD) decreased with the increase of number of periods. The measured results had also proven that as the designed central wavelength increased (changed from blue to green light) and same periods were deposited, the reflectance ratio decreased and the bandwidth and FWHD values increased.