014502-9 Mueller et al. Rev.Sci.Instrum.87,014502(2016) TGG OR CWP HWP DKDP CWP H -22.5° -22.5°+67.5°-22.5 =0° +22.5° -22.5° -67.5°-22.5° =-90° CWP2 Faraday Rotatdr CWP1 DKDP N2 plate FIG.7.Advanced LIGO Faraday isolator(from top to bottom):optical layout,design,and final product. of the more optimum 3 mm because of concerns that a thinner The isolation ratio was also measured as a function of DKDP crystal might fracture inside the vacuum chamber un- input power.To do so the transmitted beam was reflected back der thermal stress.Both isolators meet the thermal lensing under a negligibly small angle to allow to separate the return requirements for aLIGO. beam from the incoming beam.The powers in the beam going 0.15 45 00为40 0091040158 FIG.8.Left graph:Thermal lens for various DKDP crystals measured in-air as a function of laser power.Right graph:Isolation ratio measured in-air at both sites.The power is the injected power while the power inside the Faraday isolator is twice as high.Therefore 70 W incident power corresponds to ~125 W injected power during science mode when the near impedance matched interferometer reflects less than 10%of the light. Reuse of AlP Publishing content is subject to the terms at https://publishing.aip.org/authors/rights-and-permissions Download to IP:183.195.251.6 On:Fri.22 Apr 20160051:35014502-9 Mueller et al. Rev. Sci. Instrum. 87, 014502 (2016) FIG. 7. Advanced LIGO Faraday isolator (from top to bottom): optical layout, design, and final product. of the more optimum 3 mm because of concerns that a thinner DKDP crystal might fracture inside the vacuum chamber un￾der thermal stress. Both isolators meet the thermal lensing requirements for aLIGO. The isolation ratio was also measured as a function of input power. To do so the transmitted beam was reflected back under a negligibly small angle to allow to separate the return beam from the incoming beam. The powers in the beam going FIG. 8. Left graph: Thermal lens for various DKDP crystals measured in-air as a function of laser power. Right graph: Isolation ratio measured in-air at both sites. The power is the injected power while the power inside the Faraday isolator is twice as high. Therefore 70 W incident power corresponds to ∼125 W injected power during science mode when the near impedance matched interferometer reflects less than 10% of the light. Reuse of AIP Publishing content is subject to the terms at: https://publishing.aip.org/authors/rights-and-permissions. Download to IP: 183.195.251.6 On: Fri, 22 Apr 2016 00:51:35