1. Coating development and plans for filter cavity tests at TAMA Daisuke TATSUMI National Astronomical Observatory of Japan 2014/08/02 KAGRA f2f August 2014 @ Toyama Univ. 1

2. 2014/08/02KAGRA f2f August 2014@ Toyama Univ. 2 Filter cavity

3. 2014/08/02KAGRA f2f August 2014@ Toyama Univ. 3 Squeezing Light and Filter cavity Squeezed vacuum injection is one of promising way to reduce the detector noises. As a R&D activity for beyond the KAGRA detector, we have a plan to develop the filter cavity at TAMA.

4. 2014/08/02KAGRA f2f August 2014@ Toyama Univ. 4 A demonstration by eLIGO 2dB

5. 2014/08/02KAGRA f2f August 2014@ Toyama Univ. 5 Frequency independent squeezing

6. 2014/08/02KAGRA f2f August 2014@ Toyama Univ. 6 Solution: Filter Cavity

7. 2014/08/02KAGRA f2f August 2014@ Toyama Univ. 7 Frequency dependent squeezing

8. 2014/08/02KAGRA f2f August 2014@ Toyama Univ. 8 Loss requirement (2)

9. 2014/08/02KAGRA f2f August 2014@ Toyama Univ. 9 Loss requirements

10. 2014/08/02KAGRA f2f August 2014@ Toyama Univ. 10 Rough design of the filter cavity Cavity pole freq. = 40Hz Roundtrip Loss < 1ppm/m Cavity length10m300m Finesse4E+54E+4 Mirror reflectance5N=99.999%4N=99.99% Cavity Loss10ppm300ppm

11. 2014/08/02KAGRA f2f August 2014@ Toyama Univ. 11 Coating developments

12. 2014/08/02KAGRA f2f August 2014@ Toyama Univ. 12 Low loss mirror developments NAOJ and UEC (Univ. of Electro-Communications) collaborate with Japanese coating companies for low-loss mirror coating developments.

13. Cross section of the multi-layered coating Pictures are taken by TEM microscope in Univ. of Tokyo The films have clear edges. Each layer is dense and uniform.

14. X-ray Photoelectron Spectroscopy：XPS Argon ion gun Neutralizer Soft X-ray

15. O KLL O 1s Ta 4d5 O 2s Ta 2 O 5 film X-ray Photoelectron Spectroscopy：XPS measured by A. Ueda at Institute of Engineering Innovations, University of Tokyo

16. Ave. 8.0ppm Scattering Loss coated by SigmaKoki world top class quality!

17. At least the best performance in Japan 446 J/cm 2 with 10nsec pulse  44.6 GW/cm 2 (peak power density) This is tolerance for one shot pulse. KAGRA IOO requires high power density (> 1 MW/cm 2 ) tolerance for 10 year continuous operation. Damage Threshold

18. 2014/08/02KAGRA f2f August 2014@ Toyama Univ. 18 SUMMARY Recent few years we develop low-loss mirror with Japanese companies. By using the mirror the filter cavity tests at TAMA are planned.

19. End