Ta2O5/SiO2 mixed film is a very promising material for the preparation of new optical and optoelectronic devices, but there are few reports on its etching characteristics. In this paper, Ta2O5/SiO2 mixed films with various proportions of Ta2O5 were prepared by ion-beam sputtering deposition. CHF3-based reactive ion etching (RIE) was used to etch Ta2O5/SiO2 mixed films. The etching profiles of Ta2O5/SiO2 mixed films were observed by using a field-emission scanning electron microscope (SEM). The RIE etch rates were investigated as a function of the Ta2O5/SiO2 mixture ratio, RIE power, chamber pressure and etching gas ratio. It is found that the etch rate of Ta2O5/SiO2 mixed films increase with an increase of RIE power and chamber pressure, and decrease with an increase of Ta2O5 composition in the Ta2O5/SiO2 mixed films. Moreover, it is also found that as the proportion of F-based gas increases, the etching rate of the Ta2O5/SiO2 mixed film first increases and then saturates. These results would be of importance for the fabrication of optical and optoelectronic devices based on Ta2O5/SiO2 mixed films.
High repetition rate picosecond laser induced damage properties of Ta2O5/SiO2 dielectric reflective optical coatings were investigated. The laser induced damage was attributed to the increase of the free electron density and temperature enhancement during the irradiation of high repetition rate picosecond laser. The correlation of laser induced damage threshold with pulse numbers was researched. At higher repetition rate, the laser induced damage threshold was reduced more with the increasing of pulsed number. We found that the defects absorption played an important role to the laser induced damage properties of dielectric reflective optical coatings. The damage morphology showed that the evolution of damage site was significantly influenced by the accumulation of laser energy. In order to enhance the resistance capacity, the dielectric reflective optical coatings were annealed with temperature of 260°C. The defect absorption was reduced after the annealing process. For the annealed coating, the laser induced damage threshold under high repetition rate picosecond laser was enhanced as a result of the suppression of defects in the coating.
In this paper, we designed the broadband all-dielectric reflection phase shifting mirror to convert the linear polarization incident light to circularly polarization reflected light in the design wavelength range (750nm~850nm) for ultra-high intensity laser application. The 48 multilayer coated mirror used Ta2O5 and SiO2 as high and low refractive index materials. The theoretical design results indicated that at the incident angle 45 degree, the reflectivity of s- polarization light exceeded 99.9% and p- polarization light exceeded 99.5%, and phase shift values between s- and p- polarization lights were -90±5 degrees in the design wavelength range. The all-dielectric broadband reflection phase shifting mirror was fabricated with an ion beam sputtering system. The measurement results indicated that the reflectivity of s-polarization light exceeded 99.9% and p- polarization light exceeded 99.3%, and phase shift values between s- and p-polarization lights were -95~-77 degrees. The reflectivity of s- polarization light and p- polarization light conform well to theoretical design values. However, the phase shift values slightly deviated from theoretical design results in part of the wavelength range. With features of high reflectivity and invertible linear to circular polarization conversion, the all-dielectric broadband reflection phase shifting mirror can be a good replacement for quarter wave plate in high intensity laser region, and offers a further step in developing polarization and phase manipulation devices.
Gd2O3 thin films were deposited by Ion-beam sputtering (IBS) under the oxygen flow of 0 sccm~30 sccm. The structure and optical properties of the Gd2O3 optical films were investigated by Lambdar950 spectrophotometer, laser calorimetry and atomic force microscopy (AFM). When oxygen flow was less than 10 sccm, with the increase of oxygen flow, the transmittance of the films increased, at the same time absorptance and the surface roughness of the films decreased. While the flow was more than 10 sccm, with the increase of the flow rate, the surface roughness of the films increased, but the transmittance and absorptance did not show any apparent change. The results show that both the structure and optical properties are closely related to the flow of oxygen. XPS measurements demonstrated that when the oxygen flow increase from 0 sccm to 10 sccm, the defect oxygen decreases. But when the oxygen flow increase from 10 sccm to 30 sccm, the defect oxygen increase. The XPS spectra show that when the oxygen flow was 10 sccm, the defect oxygen was the least. Thus when the oxygen flow was 10 sccm, the structure and optical properties of the Gd2O3 optical films were the best.
We present a model to describe the mechanism of laser induced electronic damage in optical coatings. Different from the classical laser damage models, the electron tunneling effect is taken into account in our model. The diffusion of free electron in the conduction band is enhanced if free electron tunnel effect happens in the optical coatings. Under some specific circumstance, the electron tunneling effect will make a great impact on the laser induced damage properties of the optical coatings. Under radiation of different duration and different power intensity lasers, the influence of free electron tunnel to the laser induced damage threshold is also different. Based on the calculation results, the tunnel effect can influence the laser induced damage properties of optical coating system at nanosecond and picosecond regime. In the femtosecond regime, the influence of the tunnel effect can be neglected.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.