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 * See [https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=8214&version=14|here].  * See [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=8214&version=14|here]].

Output Faraday isolator

Requirement

  • Transmittance > 90% for the first phase, 97% for the second phase

  • Isolation ratio > 25dB for the first phase, 35dB for the second phase

Optical Design (updated 19/7/10)

item

diameter

thickness

refraction index

AR reflectivity

misc

OFR

12mm

unknown

1.95

unknown

T>98%

QR1

25.4mm

14.2mm

1.45

<2000ppm

90deg pol rotation

QR2

25.4mm

7.13mm

1.45

<2000ppm

45deg pol rotation

PBS1/2

25.4mm

6.35mm

1.45

unknown

Tp>98%, Ts<0.1%, extinction ratio>5000:1

  • Tp of PBS comes from the value with +/- 2 deg error in AOI. The value at a right AOI is Tp>99.4% and Ts<0.05%.

  • Refractive indices of QR and PBS are nominal values for quartz and fused silica.
  • In the ray trace calculation, the OFR thickness is set to 10mm.

Space

Distance

AOI

QR1-PBS1

62.2mm

56deg

PBS1-OFR

99.6mm

0deg

OFR-QR2

28.5m

0deg

QR2-PBS2

63.4m

-56deg

  • The distance is from the second surface of the first item to the first surface of the second item.

Measured result

Transmittance

95%

Isolation ratio

28dB

AR reflection could not be perfectly removed at the measurement so it may be higher in reality.

KAGRA/Subgroups/IOO/OFI (last edited 2020-01-17 10:41:38 by KentaroSomiya)