Metal multilayer dielectric gratings (MMDGs) for pulse compressors used in high-energy laser systems should enable
high efficiency, as well as provide broad bandwidths and high laser-induced damage thresholds. The non-uniform optical
near-field distribution of MMDGs is an important factor that limits damage resistance capabilities. The efficiency and
electric field distributions of MMDGs with a corrugated SiO2 layer and operated at 800 nm are analyzed by rigorous
coupled-wave analysis. The maximum electric field in the grating ridge, match layer, and metal layer decreases with
increasing grating diffraction efficiency. High efficiency and a low electric field are obtained with a 90° slope angle in
the grating ridge. The bandwidth and maximum electric field in the metal layer decrease with increasing high- and
low-index material pairs, and the maximum electric fields in the grating ridge and match layer initially decrease and then
increase. The peak electric field in the grating is optimized with a merit function; the optimization covers the
enhancement of diffraction efficiency, bandwidth, and reduction of electric field. The bandwidth of the optimized
MMDGs is 160 nm with a diffraction efficiency exceeding 90%. The largest electric field is modulated in air to obtain a
low electric field and high laser-induced damage threshold.
On the basis of theoretical analysis of biaxial birefringent thin films, this study investigates the optical
properties of phase shift on reflection and/or transmission through slanted columnar TiO2 sculptured
anisotropic thin film (ATF) deposited with glancing angle deposition (GLAD) technique via reactive
electron-beam evaporation. The tilted nanocolumn microstructures of thin film induce the optical
anisotropy. The optical constants dispersion equations of TiO2 ATF are determined from fitting the
transmittance spectra for s- and p-polarized waves measured at normal and oblique incidence within
400-1200nm. With the extracted structure parameters, the phase shifts of polarized light are analyzed
with the characteristic matrix and then measured with spectroscopic ellipsometry in the deposition
plane. A reasonably good agreement between the theoretical studies and experimental measurements is
obtained. In addition, the dependence of the phase shift on oblique incidence angle is also discussed.
The results show a greater generality and superiority of the characteristic matrix method. Birefringence
of the biaxial ATF performed a sophisticated phase modulation with varied incidence angles over a
broad range to have a wide-angle phase shift.
Fine control of Optical Thin Film Stress is critical to develop an expected profile parameters of large aperture
coated optics. In our latest effort, the evolution of stress and force per unit width of multilayer thin film formulas,
(H2L)6, (H2L)5H and (HL)7, consisted of HfO2 and SiO2 were researched. The stresses of SiO2 single layers deposited on
the HfO2 were small than those grew on glass and get smaller as the multilayer thin film deposited. While the stresses of
HfO2 films deposited on the SiO2 were positive correlation with the stress of SiO2.
Hafnium oxide/silicon dioxide (HfO2/SiO2) multilayers were prepared by electron-beam evaporation. The total force per
unit width (F/w) during and after deposition was determined by the change of the substrate curvature measured in situ.
Stress induced by water absorption is a major component of the film stress evolution in atmospheric environment.
Growth stress was analyzed to understand the role of the sublayers and the influence of the underlayers’ structural
features. The substrate material affects the stress evolutions in both HfO2 films and SiO2 films. The structural feature of
the HfO2 layer onto which SiO2 was deposited has a significant effect on the stress evolution of the SiO2 layer.
Nb2O5 thin films at various cathode power and substrate bias voltages were deposited by pulsed DC reactive magnetron
sputtering of a metallic Nb target in a pure oxygen atmosphere. The characteristics of the films have been studied using
spectrometer, atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM). Laser damage
tests at 1064 nm wavelength with pulse duration of 12 ns were conducted on the single-layer systems. Results indicate
that the cathode power may not be an important impact-factor of the LIDT of Nb2O5 thin films but substrate bias voltage has significant influence on the laser resistance of Niobium oxides films. The maximum laser induced damage threshold
(LIDT) of 28.8 J/cm2 was obtained for the film deposited at substrate bias voltage of -60V.
Many fields of high technology take advantage of conductor-dielectric interface properties. Deeper knowledge of
physical processes that determine the optical response of the structures containing metal-dielectric interfaces is important
for improving the performance of thin film devices containing such materials.
Here we present a study on optical properties of several ultrathin metal oxides deposited over thin silver layers. Some
widely used materials (Al2O3, SiO2, Y2O3, HfO2) were selected for deposition by r.f. sputtering, and the created metal-dielectric
structures with two of them, alumina and silica, were investigated in this work using attenuated total reflectance
(ATR) technique and by variable-angle spectroscopic ellipsometry (VASE). VASE was performed with a help of a
commercial ellipsometer at various incident angles and in a wide spectral range. A home-made sample holder
manufactured for WVASE ellipsometer and operational in Otto configuration has been implemented for angle-resolved
and spectral ATR measurements. Simultaneous analysis of data obtained by these two independent techniques allows
elaboration of a representative model for plasmonic-related phenomena at metal-dielectric interface. The optical constants
of the interface layers formed between metal and ultrathin oxide layers are investigated. A series of oxides chosen for this
study allows a comparative analysis aimed for selection of the most appropriate materials for different applications.
The use of magnetic capping effect can enhance the head sensitivity of the heat assisted magnetic recording (HAMR). The principle of this effect was analyzed theoretically. The GdFeCo film was used as the capping layer and TbFeCo film was used as the recording layer. Through theoretical calculation we found that a large capping field in the same direction with the external field can be generated at the interface because of the exchange coupling effect, which had increased the effective strength of the external field. Thus, the head sensitivity was improved greatly and the data transfer rate could be faster. We expected that this idea can be used to help write the medium with much larger cocervity such as L10FePt.