Thermomechanical characterization of on-chip buckled dome Fabry-Perot microcavities

We report on the thermomechanical and thermal tuning properties of curved-mirror Fabry-Perot resonators, fabricated by the guided assembly of circular delamination buckles within a multilayer a-Si/SiO2 stack. Analytical models for temperature dependence, effective spring constants, and mechanical mode frequencies are described and shown to be in good agreement with experimental results. The cavities exhibit mode volumes as small as $\sim10\lambda^3$, reflectance-limited finesse $\sim3\times10^3$, and mechanical resonance frequencies in the MHz range. Monolithic cavity arrays of this type might be of interest for applications in sensing, cavity quantum electrodynamics, and optomechanics.Comment: \c{opyright} 2015 Optical Society of America. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibite

Stability of optical interference coatings exposed to low-fluence 193 nm ArF radiation

We report on our investigations on the long-term behaviour of optical coatings under 193 nm laser irradiation in dependence on coating materials, radiation conditions, and substrate properties. A wide variety of different highly reflective dielectric mirrors and antireflective coatings, deposited by an ultra low loss evaporation process onto calcium fluoride and fused silica, has been tested. Irradiation experiments with highly reflective coatings show that fluoride coatings exhibit nearly no changes of their optical function in air as well as in argon atmosphere due to low initial absorption levels. Temporal atmospheric contaminations can be removed by using appropriate irradiation conditions. Oxide layers tend to post-oxidize during 193 nm exposure in air and the DUV absorption level will be reduced. Effectively, reflectance of multilayer coatings on the basis of oxide materials can be improved through laser irradiation. Irradiation experiments with antireflective coatings point out the dominant role of bulk and surface properties of the substrate for prolonged laser irradiation. In addition, we present laser induced damage thresholds to demonstrate upper limits of laser radiation resistance that can be achieved nowadays with several types of coatings

ArF radiation resistance of optical coatings on CaF2 in relation to the surface finish of the substrate

CaF2 has received increasing attention as a promising substrate for coatings in the VUV range. Optimization of the optical properties of these optical components requires the study of basic characteristics of the coated and uncoated CaF2 substrates such as surface roughness, optical performance, absorption and scatter losses, and laser induced damage threshold. The investigations have revealed the influence of different substrate polishing grades on the quality of AR-193nm -and HR-193nm/0 degrees coated samples. LIDT values at the ArF-excimer laser wavelength were measured as high as 5.6 J/cm2 and 4.6 J/cm2 for the best AR- and HR-coated samples, respectively

193 nm laser induced luminescence in oxide thin films

Time resolved luminescence experiments have been set up in order to study the interaction of 193 nm laser radiation with dielectric thin films. At room temperature, Al2O3 coatings show photoluminescence upon ArF excimer laser irradiation with significant intensity contribution besides known substrate emission. Time and energy resolved measurements indicate oxygen defect centers in Al2O3 coatings, which suggest a strong single photon interaction at 193 nm by F+ and F center absorption. Measurements on high reflective thin film stacks, consisting of quarter wave Al2O3 and SiO2 layers, indicate similar UV excitations mainly from color centers of Al2O3

Large area PECVD process using dual rotatable magnetrons

Magnetron PECVD is an emerging technology targeting the possibility to perform a chemical vapor deposition process at fairly high rates over large areas. The paper presents a new setup based on rotatable magnetrons. The precursor hexamethydisiloxane was used to deposit SiOxCy layers on polymer substrates. It could be shown that the formation of redeposition zones on the target can be avoided completely. The discharge voltage drift as it is typical for planar configuration is damped. These advantages could be optained on expense of deposition rate. The maximum achieved value was 180 nm*m/min which is higher than sputtering but lower compared to planar magnetron based PECVD. It could be demonstrated that the technology is stable over several hours deposition time. The optical properties of the layers are well suited for the usage as low refractive index materials in optical layer stacks. All experiments have been carried out on a pilot coater of 600 mm deposition width. Scale-up experiments to 2100 mm targets in a production coater have been done