Session Index

After the first detection of the gravitational waves on Sep. 2015, technology development of the laser interferometer gravitational waves detector is now moving toward cryogenic operation at 1550 nm or 2000nm wavelength. Brownian thermal noise of the mirror coatings is still one of the dominant factors for detector sensitivity. The technology trend and needs for the low thermal noise mirror coatings will be introduced and discussed.

 

Mismatch between simulations and coating results occurs time to time. This experiment exploit Simplex algorithm to analyze the results of coating, and compares the results with the target, identify the cause of two spectra do not match, and utilize the data to improve coating process.Simplex, optimization, simulation

 

The surface profile of 4-inch sapphire wafers was measured by a home-made Fizeau interferometer associated with fast Fourier transform method. The results were verified by a commercial surface profiler. We also analyzed the repeatability and reproducibility (R&R) for the measurement system, and the repeatability of the proposed system was 1.488%.

 

We designed and fabricated the (LH)2 multilayer coatings with high- and low- refractive index of TiO2 and SiO2 thin films. The multilayer coatings is based on electron beam evaporation combined with ion assisted deposition technique. The optical properties, surface roughness and residual stress of the multilayer films are discussed.

 

Different deposition methods and materials are used to design high reflection laser mirrors. Laser-induced damage experiment was conducted by 808 nm continuous wave laser, pulsed 800 nm laser and pulsed 532 nm laser. The typical damage morphologies were observed by using optical microscope and scanning electron microscope.