Ta2O5 film has low absorption in the range of visible wavelength and it has high refractive index and thermal stability. So it is widely used to prepare low loss films. Ta2O5 single layer with different oxygen flow rates were prepared by ion beam sputtering technique. The refractive index and absorption characteristics of metal oxide films were compared at different oxygen flow rates. The refractive index and absorption of thin film materials were studied by ellipsometry technology and surface thermal lens technology. The results show that: the absorption of Ta2O5 film is decreased first and then increased with the increase of oxygen flow. When oxygen flow is 40 sccm, the absorption is smallest, only 4.4ppm. And the refractive index is decreased with oxygen flow increasing, after oxygen flow reached 40 sccm, the refractive index tend to be stable.
Bandpass filters are indispensable to the development of advanced optical and electro-optical systems used in space, defense, and terrestrial applications. In this paper, wideband deep cutoff bandpass filter of 750-900nm was designed and prepared by ion beam sputtering deposition technology. Long wave pass filter with high transmittance from 750 to 900nm and low transmittance from 400 to 730nm was designed and prepared on one side of the HB720 substrate. Short wave pass filter with high transmittance from 750 to 900nm and low transmittance from 930 to 1100nm was designed and prepared on the other side of the HB720 substrate. From the measured transmittance curve, the average transmittance was above 96% from 750nm to 900nm, the transmittance at the wavelength of 728nm and 928nm was less than 0.1%. The results indicated that high quality bandpass filter can be manufactured using the combination method of long-wave and short-wave filters.
HfO2 thin films were deposited on ZS1 silica by Ion Beam Sputtering (IBS) technique. Optical constants of
HfO2 thin films were obtained by multiple spectrum analysis method, which combined the transmittance
spectrum and ellipsometry spectrum of the film. The refractive index and extinction coiefficient of HfO2 thin
films were evaluated by etching experiments of the film. The analysis spectral range was between 250nm and
Coating for double wavelength is one of the important elements in frequency-doubled solid state laser. In this paper, the normal design and whole numerical optimal design were compared. With the same total number of layers, the waviness of coating for double wavelength is more than 0.4139% based on normal design method, while it will be reduced to 0.0109% by whole numerical design, and also the bandwidth can reach 50nm. In experiments, the HfO2/SiO2 multilayer films were prepared by IBS. The test results of film designed by the
second method show that the transmissivity is above 99% at 532nm, waviness is 0.4%, and the reflectivity is
above 99.9% at 1064nm.
A high temperature infrared spectra measuring equipment connected with a FTIR spectrometer (PE) was designed and manufactured. The measuring temperature can range from room-temperature to 500°C and the infrared spectra of substrates and thin films under different temperature can be real-time measured. The Fourier transform infrared transmission spectra of Si substrate under different working temperature were measured in the wavelength region from 2μm to 20μm using high temperature infrared spectra measuring equipment. The measured temperature ranged from room temperature to 500°C with a step of 50°C. Complex dielectric functions of Si substrate under different temperature condition are calculated from FTIR transmittance spectra by WVASE32 software, and the best fitted method was obtained for calculating optical constants of dielectric materials in the high temperature condition. As the increase of working temperature, the refractive index and extinction coefficient of Si substrate increase, when the working temperature reach 300°C, the various quantity of extinction coefficient sharply increase, so Si substrate can be used in the condition below the temperature of 300°C. Thus, through the exact calculated complex dielectric functions under different working temperature condition, we can design and manufacture different thin films using Si as substrate, and applied in in the high temperature condition.
SiO2 is a very important low refractive index material and usually used in combination with high refractive index
material to manufacture the coatings with low optical loss. In this paper, SiO2 films were deposited on Si substrates by an
ion beam sputtering (IBS) technique and SiO2 target with purity of 99.99% was used as SiO2 thin films forming material.
The thickness of SiO2 films grown onto Si substrates are about 900 nm. Aging optical properties of SiO2 films were
investigated as a function of time placed in the air. Spectroscopic ellipsometry was used to measure optical constants of
SiO2 films. The refractive index of SiO2 films change with the increase of placed time. When the placed time reaches
more than 200 days, the value of refractive index tends to be constant and the corresponding variation rate is about 0.5%.
As the placed time increases, the physical thickness and optical thickness also drive to be stabilization. It can be seen that
optical properties of SiO2 films prepared by IBS technique under some process parameters are very stability.
Annealing is an important method to alter the properties of thin films. The effects of thermal treatment in air on optical
properties of SiO2 thin films were investigated. SiO2 thin films were deposited on Si (110) substrates by an ion beam
sputtering (IBS) technique, and then annealed in air under different thermal annealing time of 16 hours, 24 hours, 36
hours, 64 hours and the temperature from 100℃ to 600℃ with 24 hours. Optical properties refractive index and
thickness are studied directly after deposition and after thermal treatment, and they are measured by spectroscopic
ellipsometry. When the thermal annealing temperature was fixed at 300℃, the refractive index of SiO2 films would
reduce with the increase of the thermal annealing time, the optical thickness also reduced but the various quantities are
almost the same. The refractive index of SiO2 films changed with the different thermal annealing temperature. As the
annealing temperature increased, the refractive index of SiO2 films reduced gradually. When the selected annealing
temperature is 500℃, the refractive index of SiO2 films reached minimum. It can be found that the optical properties of
SiO2 thin films can be improved by an adapted annealing procedure.
With increasing of the laser power, higher demand for high reflective thin films in cavity is needed. Higher reflectivity is
beneficial to obtaining higher output power and reducing the heat from the cavity. The reflectivity of metal substrate
itself is much higher, and much higher reflectivity can be obtained through depositing thin film. Due to good thermal
conductivity of metal, the thin film deposition on metal substrate is usually used in high power laser system. Due to
existing absorption, we must design proper film system structure and reduce the output heat from the laser cavity.
Copper was used as substrate material. Optimizing the film system can reduce the absorption. High reflective coatings
were deposited on copper substrate by ion beam sputtering. When the operating angles are from 10 to 35 degrees, the
obtained reflectivity reaches over 99.5% at 941nm, and the reflective band is wide.