No abstract

At first, we use an [Formula: see text] analyzer to measure the optical properties (including refractive index [Formula: see text] and extinction coefficient [Formula: see text]) of MgF2 and Nb2O5 single-layer films, in a wavelength range of 200–1700 nm for MgF2 film and in a wavelength range of 350–1500 nm for Nb2O5 film. After the refractive indexes of MgF2 and Nb2O5 single-layer films are measured, we use the measured results to calculate the needed thicknesses of the quarter-wave (1/4 wavelength) MgF2 and Nb2O5 films for the designed green-light (500 nm) distributed Bragg reflectors (DBRs). After that, an E-beam is used to deposit the MgF2-Nb2O5 bilayer films (called as one period) with different periods (two, four, and six periods are deposited in this study) on glass substrates to fabricate the DBRs with a central wavelength of 500 nm. Then we use the field emission scanning electron microscopy (FESEM) to observe the surface images of Nb2O5 films on the different periods of MgF2-Nb2O5 bilayer films. The important novelty is that we use a Focused Ion Beam (FIB) to prepare the samples for the observations of the cross-sections of MgF2-Nb2O5 bilayer films, and those results can be sued to confirm the thicknesses of the bilayer films with different periods. We also compare the reflective ratio of the fabricated DBRs at the designed central wavelength with those calculated values by using the equation investigated by Sheppard. We find that the measured reflective ratios of the fabricated DBRs meet the calculated results obtained from Sheppard’s equation.

In this study, glasses were used as substrates and an e-beam was used the method to deposit MgF2 and Nb2O5 single-layer films, and the optical properties, including extinction coefficients (k values) and refractive indices (n values), were measured by using the light wavelength as variable. The equation d = λ/(4n) was used to calculate the thickness (d) of 1/4 wavelength (λ) for each layer of the MgF2-Nb2O5 bilayer films in distributed Bragg reflectors (DBRs) with a designed reflective wavelength at blue light (~450nm). Each MgF2-Nb2O5 bilayer film was called a period, and the glass substrates were used to deposit the films with two, four, and six periods for fabricating the DBRs. The field emission scanning electron microscope equipped with a focused ion beam was used to measure the thickness of each MgF2-Nb2O5 layer in the DBRs with different periods. The measured maximum reflective ratios were compared with Sheppard’s approximate equation, which calculates only the maximum reflective ratio at a specific wavelength. An overall transfer matrix was investigated to calculate the reflective spectra by incorporating the variable n values and thicknesses of the MgF2-Nb2O5 films in each layer. We show that the measured results of the fabricated DBRs matched the results simulated using Sheppard’s approximate equation and the overall transfer matrix.

No abstract

In this study, by using the Corning 1737 glass as a substrate and an e-beam system, the optical properties of the deposit MgF2 and Nb2O5 single-layer film were investigated in terms of extinction coefficients ([Formula: see text] values) and refractive indices ([Formula: see text] values). The equation [Formula: see text]/(4[Formula: see text] was used to calculate the thickness ([Formula: see text] of 1/4 wavelength ([Formula: see text] for each layer of MgF2 and Nb2O5 layer in the MgF2–Nb2O5 bilayer films of the designed distributed Bragg reflectors (DBRs) with a reflective wavelength at blue light ([Formula: see text]450 nm). Each pair of MgF2–Nb2O5 bilayer film was defined as a period, and the glass substrates were used to deposit the films with two, four, and six periods for the fabrication of the DBRs. The field emission scanning electron microscope equipped with a focused ion beam was used to measure the thickness of each MgF2–Nb2O5 layer in the DBRs with different periods. The measured maximum reflective ratios were compared with Sheppard’s approximate equation, which calculates only the maximum reflective ratio at a specific wavelength. We would show that the measured results of the fabricated DBRs matched the results simulated using Sheppard’s approximate equation.