THE REFLECTIVE PROPERTIES OF BROADBAND OPTICAL MULTILAYERS

Binary multilayers with a certain kind of disorder may exhibit high reflection range over a very wide bandwidth. The dependencies of this bandwidth on the center wavelength, random layers sequence, refractive contrast of the coating materials, layer thickness errors and the angle of incidence have been studied numerically. Our simulations have shown that broadband reflectors can be designed for various applications. The reflective curves for staggered multilayers are also computed. The results show that the broadening effect of irregular multilayers is dominated by its degree of disorder. A broadband TiO₂-SiO₂ multilayer is fabricated. The measured width of the transmittance less than 1% for this multilayer covers 400 nm, from 700 to 1100 nm, which is just the tuning range of T_i: sapphire lasers.