Optical scatter of quantum noise filter cavity optics

摘要: Optical cavities to filter squeezed light for quantum noise reduction require optics with very low scattering losses. We report on measured from two super-polished fused silica before and after applying highly-reflective ion-beam sputtered dielectric coatings. used an imaging scatterometer that illuminates the sample a linearly polarized 1064 nm wavelength laser at fixed angle of incidence records images back scatter azimuthal angles in plane beam. extract these bidirectional reflectance distribution function (BRDF) without coating estimate their integrated scatter. find application coatings led more than 50% increase wide-angle scatter, 5.00+/-0.30 3.38+/-0.20 ppm coated samples. In addition, BRDF takes pattern maxima versus angle. compare model show this is qualitatively consistent roughness layer interfaces. These results are part broader study understand minimize optical loss interferometric gravitational-wave detectors. The samples acceptable 16 m long envisioned Laser Interferometer Gravitational-wave Observatory (LIGO), though reducing further would improve LIGO's quantum-noise limited performance.