Coating development and plans for filter
cavity tests at TAMA
Daisuke TATSUMINational Astronomical Observatory of Japan
2014/08/02 KAGRA f2f August 2014 @ Toyama Univ. 1
2014/08/02 KAGRA f2f August 2014 @ Toyama Univ. 2
Filter cavity
2014/08/02 KAGRA 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.
2014/08/02 KAGRA f2f August 2014 @ Toyama Univ. 4
A demonstration by eLIGO
2dB
2014/08/02 KAGRA f2f August 2014 @ Toyama Univ. 5
Frequency independent squeezing
2014/08/02 KAGRA f2f August 2014 @ Toyama Univ. 6
Solution: Filter Cavity
2014/08/02 KAGRA f2f August 2014 @ Toyama Univ. 7
Frequency dependent squeezing
2014/08/02 KAGRA f2f August 2014 @ Toyama Univ. 8
Loss requirement (2)
2014/08/02 KAGRA f2f August 2014 @ Toyama Univ. 9
Loss requirements
2014/08/02 KAGRA f2f August 2014 @ Toyama Univ. 10
Rough design of the filter cavity
Cavity pole freq. = 40Hz
Roundtrip Loss < 1ppm/m
Cavity length 10m 300m
Finesse 4E+5 4E+4Mirror reflectance 5N=99.999% 4N=99.99%
Cavity Loss 10ppm 300ppm
2014/08/02 KAGRA f2f August 2014 @ Toyama Univ. 11
Coating developments
2014/08/02 KAGRA 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.
Cross section of the multi-layered coating
Pictures are taken by TEM microscopein Univ. of Tokyo
The films have clear edges.Each layer is dense and uniform.
X-ray Photoelectron Spectroscopy : XPS
Argon ion gun
Neutralizer
Soft X-ray
Soft X-ray
O K
LL
O 1
s
Ta 4
d5
O 2
s
Ta2O5 film
X-ray Photoelectron Spectroscopy : XPS
measured by A. Ueda at Institute of Engineering Innovations,
University of Tokyo
Ave. 8.0ppm
Scattering Loss
coated by SigmaKoki
world top class quality!
At least the best performance in Japan
446 J/cm2 with 10nsec pulse
44.6 GW/cm2 (peak power density)
This is tolerance for one shot pulse.
KAGRA IOO requireshigh power density (> 1 MW/cm2) tolerance for 10 year continuous operation.
Damage Threshold
2014/08/02 KAGRA 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.
End