Blue-blocking optical thin films with controllable cutoff slope

To reduce the damage to human eyes and ensure the beneficial regulation of the human rhythm by short-wave blue light, accurate control of the transmission slope of the 400~500 nm wavelength is particularly important in blue light protection. In this paper, a nonlinear Boltzmann function fitting method for long wave-pass thin films is proposed, and thin films (Z1) and (Z2) are obtained by optimizing the nonlinear and linear target, respectively. Admittance and transmittance diagrams of thin films (Z1) and (Z2) are shown that the thin film optimized by a nonlinear target has a controllable slope and better passband spectral performance. The blue-blocking thin film of 14 layers is fabricated using electron-beam evaporation assisted by an ion beam, which met the technical requirements of the new GB/T38120—2019 national standard. The results present that the average transmittance of the single-side thin film is less than 3.2% at 385~415 nm, less than 30.88% at 415~445 nm, more than 81.9% at 445~475 nm, and more than 95.5% at 500~800 nm. These promising results indicate that this design method provide a new solution for vision protection applications such as eyeglasses, computer desktop and mobile digital screens.