Small quartz mirrors with high reflectance and design of a kind of micro Fabry-Perot interferometer

Abstract

We report small reflecting mirrors with high reflectance, which are fabricated by using square quartz chips. These quartz mirrors are going to be used in the construction of a miniaturized Fabry Perot Interferometer (FPI) with a commercial ring type PZT from Fuji Ceramic Company. The dimension of quartz substrates is 10×10mm with a thickness of 1mm. The high reflectance of mirrors is obtained by depositing multi-layer thin films on quartz substrates. Magnetron RF sputtering machine is used to ensure that the thickness of dielectric coatings can be precisely controlled. These mirrors are measured by SEM and AFM and the reflectance is detected by a visible light spectrometer. The maximum reflectance of these mirrors is about 99.4% on the designed wavelength 553nm. A small FPI set up by this kind of mirror can have a theoretical finesse of 522, and if a PZT resonator with a length of 7.22mm is used, the resolution of this small interferometer can reach 4.06×10 -5 nm, in another word, the resolving power is 1.36×10 7 .