Abstract

In-vacuum Faraday isolators (FIs) are used in gravitational wave interferometers to prevent the disturbance caused by light reflected back to the input port from the interferometer itself. The efficiency of the optical isolation is becoming more critical with the increase of laser input power. An in-vacuum FI, used in a gravitational wave experiment (Virgo), has a 20mm clear aperture and is illuminated by an almost 20W incoming beam, having a diameter of about 5mm. When going in vacuum at 106 mbar, a degradation of the isolation exceeding 10dB was observed. A remotely controlled system using a motorized λ/2 waveplate inserted between the first polarizer and the Faraday rotator has proven its capability to restore the optical isolation to a value close to the one set up in air.

© 2010 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. The Virgo Collaboration, “Virgo status,” Class. Quantum Grav. 25, 184001 (2008).
    [CrossRef]
  2. The Ligo Collaboration, “Status of the Ligo detectors,” Class. Quantum Grav. 25, 114041 (2008).
    [CrossRef]
  3. The GEO Collaboration, “The Geo–HF project,” Class. Quantum Grav. 23, S207–S214 (2006).
    [CrossRef]
  4. The TAMA Collaboration, “Status of TAMA300,” Class. Quantum Grav. 21, S403–S408 (2004).
    [CrossRef]
  5. J. D. Mansell, J. Hennawi, E. K. Gustafson, M. M. Fejer, R. L. Byer, D. Clubley, S. Yoshida, D. H. Reitze, “Evaluation the effect of transmissive optic thermal lensing on laser beam quality with a Shack–Hartmann wave-front sensor,” Appl. Opt. 40, 366–374 (2001).
    [CrossRef]
  6. E. A. Khazanov, A. Poteomkin, V. Zelenogorsky, A. Shaykin, A. Mal’shakov, O. Palashov, D. H. Reitze, “Adaptive compensation of thermal lens in Faraday isolators,” Proc. SPIE 5332, 271–282 (2004).
    [CrossRef]
  7. E. A. Khazanov, O. V. Kulagin, S. Yoshida, D. B. Tanner, D. H. Reitze, “Investigation of self-induced depolarization of laser radiation in terbium gallium garnet,” IEEE J. Quantum Electron. 35, 1116–1122 (1999).
    [CrossRef]
  8. V. V. Zelenogorsky, E. E. Kamenetsky, A. A. Shaykin, O. V. Palashov, E. A. Khazanov, “Adaptive compensation of thermally induced aberrations in Faraday isolator by means of a DKDP crystal,” Proc. SPIE 5975, 59750I (2006).
    [CrossRef]
  9. The Virgo Collaboration, “In-vacuum optical isolation changes by heating in a Faraday isolator,” Appl. Opt. 47, 5853–5861 (2008).
  10. N. P. Barnes, L. B. Petway, “Variation of Verdet constant with temperature in terbium gallium garnet,” J. Opt. Soc. Am. B 9, 1912–1915(1992).
    [CrossRef]
  11. A. Gatto, L. Escoubas, P. Roche, M. Commandré, “Simulation of the degradation of optical glass substrates caused by UV irradiation while coating,” Opt. Commun. 148, 347–354 (1998).
    [CrossRef]

2008 (3)

The Virgo Collaboration, “Virgo status,” Class. Quantum Grav. 25, 184001 (2008).
[CrossRef]

The Ligo Collaboration, “Status of the Ligo detectors,” Class. Quantum Grav. 25, 114041 (2008).
[CrossRef]

The Virgo Collaboration, “In-vacuum optical isolation changes by heating in a Faraday isolator,” Appl. Opt. 47, 5853–5861 (2008).

2006 (2)

V. V. Zelenogorsky, E. E. Kamenetsky, A. A. Shaykin, O. V. Palashov, E. A. Khazanov, “Adaptive compensation of thermally induced aberrations in Faraday isolator by means of a DKDP crystal,” Proc. SPIE 5975, 59750I (2006).
[CrossRef]

The GEO Collaboration, “The Geo–HF project,” Class. Quantum Grav. 23, S207–S214 (2006).
[CrossRef]

2004 (2)

The TAMA Collaboration, “Status of TAMA300,” Class. Quantum Grav. 21, S403–S408 (2004).
[CrossRef]

E. A. Khazanov, A. Poteomkin, V. Zelenogorsky, A. Shaykin, A. Mal’shakov, O. Palashov, D. H. Reitze, “Adaptive compensation of thermal lens in Faraday isolators,” Proc. SPIE 5332, 271–282 (2004).
[CrossRef]

2001 (1)

1999 (1)

E. A. Khazanov, O. V. Kulagin, S. Yoshida, D. B. Tanner, D. H. Reitze, “Investigation of self-induced depolarization of laser radiation in terbium gallium garnet,” IEEE J. Quantum Electron. 35, 1116–1122 (1999).
[CrossRef]

1998 (1)

A. Gatto, L. Escoubas, P. Roche, M. Commandré, “Simulation of the degradation of optical glass substrates caused by UV irradiation while coating,” Opt. Commun. 148, 347–354 (1998).
[CrossRef]

1992 (1)

Barnes, N. P.

Byer, R. L.

Clubley, D.

Commandré, M.

A. Gatto, L. Escoubas, P. Roche, M. Commandré, “Simulation of the degradation of optical glass substrates caused by UV irradiation while coating,” Opt. Commun. 148, 347–354 (1998).
[CrossRef]

Escoubas, L.

A. Gatto, L. Escoubas, P. Roche, M. Commandré, “Simulation of the degradation of optical glass substrates caused by UV irradiation while coating,” Opt. Commun. 148, 347–354 (1998).
[CrossRef]

Fejer, M. M.

Gatto, A.

A. Gatto, L. Escoubas, P. Roche, M. Commandré, “Simulation of the degradation of optical glass substrates caused by UV irradiation while coating,” Opt. Commun. 148, 347–354 (1998).
[CrossRef]

Gustafson, E. K.

Hennawi, J.

Kamenetsky, E. E.

V. V. Zelenogorsky, E. E. Kamenetsky, A. A. Shaykin, O. V. Palashov, E. A. Khazanov, “Adaptive compensation of thermally induced aberrations in Faraday isolator by means of a DKDP crystal,” Proc. SPIE 5975, 59750I (2006).
[CrossRef]

Khazanov, E. A.

V. V. Zelenogorsky, E. E. Kamenetsky, A. A. Shaykin, O. V. Palashov, E. A. Khazanov, “Adaptive compensation of thermally induced aberrations in Faraday isolator by means of a DKDP crystal,” Proc. SPIE 5975, 59750I (2006).
[CrossRef]

E. A. Khazanov, A. Poteomkin, V. Zelenogorsky, A. Shaykin, A. Mal’shakov, O. Palashov, D. H. Reitze, “Adaptive compensation of thermal lens in Faraday isolators,” Proc. SPIE 5332, 271–282 (2004).
[CrossRef]

E. A. Khazanov, O. V. Kulagin, S. Yoshida, D. B. Tanner, D. H. Reitze, “Investigation of self-induced depolarization of laser radiation in terbium gallium garnet,” IEEE J. Quantum Electron. 35, 1116–1122 (1999).
[CrossRef]

Kulagin, O. V.

E. A. Khazanov, O. V. Kulagin, S. Yoshida, D. B. Tanner, D. H. Reitze, “Investigation of self-induced depolarization of laser radiation in terbium gallium garnet,” IEEE J. Quantum Electron. 35, 1116–1122 (1999).
[CrossRef]

Mal’shakov, A.

E. A. Khazanov, A. Poteomkin, V. Zelenogorsky, A. Shaykin, A. Mal’shakov, O. Palashov, D. H. Reitze, “Adaptive compensation of thermal lens in Faraday isolators,” Proc. SPIE 5332, 271–282 (2004).
[CrossRef]

Mansell, J. D.

Palashov, O.

E. A. Khazanov, A. Poteomkin, V. Zelenogorsky, A. Shaykin, A. Mal’shakov, O. Palashov, D. H. Reitze, “Adaptive compensation of thermal lens in Faraday isolators,” Proc. SPIE 5332, 271–282 (2004).
[CrossRef]

Palashov, O. V.

V. V. Zelenogorsky, E. E. Kamenetsky, A. A. Shaykin, O. V. Palashov, E. A. Khazanov, “Adaptive compensation of thermally induced aberrations in Faraday isolator by means of a DKDP crystal,” Proc. SPIE 5975, 59750I (2006).
[CrossRef]

Petway, L. B.

Poteomkin, A.

E. A. Khazanov, A. Poteomkin, V. Zelenogorsky, A. Shaykin, A. Mal’shakov, O. Palashov, D. H. Reitze, “Adaptive compensation of thermal lens in Faraday isolators,” Proc. SPIE 5332, 271–282 (2004).
[CrossRef]

Reitze, D. H.

E. A. Khazanov, A. Poteomkin, V. Zelenogorsky, A. Shaykin, A. Mal’shakov, O. Palashov, D. H. Reitze, “Adaptive compensation of thermal lens in Faraday isolators,” Proc. SPIE 5332, 271–282 (2004).
[CrossRef]

J. D. Mansell, J. Hennawi, E. K. Gustafson, M. M. Fejer, R. L. Byer, D. Clubley, S. Yoshida, D. H. Reitze, “Evaluation the effect of transmissive optic thermal lensing on laser beam quality with a Shack–Hartmann wave-front sensor,” Appl. Opt. 40, 366–374 (2001).
[CrossRef]

E. A. Khazanov, O. V. Kulagin, S. Yoshida, D. B. Tanner, D. H. Reitze, “Investigation of self-induced depolarization of laser radiation in terbium gallium garnet,” IEEE J. Quantum Electron. 35, 1116–1122 (1999).
[CrossRef]

Roche, P.

A. Gatto, L. Escoubas, P. Roche, M. Commandré, “Simulation of the degradation of optical glass substrates caused by UV irradiation while coating,” Opt. Commun. 148, 347–354 (1998).
[CrossRef]

Shaykin, A.

E. A. Khazanov, A. Poteomkin, V. Zelenogorsky, A. Shaykin, A. Mal’shakov, O. Palashov, D. H. Reitze, “Adaptive compensation of thermal lens in Faraday isolators,” Proc. SPIE 5332, 271–282 (2004).
[CrossRef]

Shaykin, A. A.

V. V. Zelenogorsky, E. E. Kamenetsky, A. A. Shaykin, O. V. Palashov, E. A. Khazanov, “Adaptive compensation of thermally induced aberrations in Faraday isolator by means of a DKDP crystal,” Proc. SPIE 5975, 59750I (2006).
[CrossRef]

Tanner, D. B.

E. A. Khazanov, O. V. Kulagin, S. Yoshida, D. B. Tanner, D. H. Reitze, “Investigation of self-induced depolarization of laser radiation in terbium gallium garnet,” IEEE J. Quantum Electron. 35, 1116–1122 (1999).
[CrossRef]

Yoshida, S.

J. D. Mansell, J. Hennawi, E. K. Gustafson, M. M. Fejer, R. L. Byer, D. Clubley, S. Yoshida, D. H. Reitze, “Evaluation the effect of transmissive optic thermal lensing on laser beam quality with a Shack–Hartmann wave-front sensor,” Appl. Opt. 40, 366–374 (2001).
[CrossRef]

E. A. Khazanov, O. V. Kulagin, S. Yoshida, D. B. Tanner, D. H. Reitze, “Investigation of self-induced depolarization of laser radiation in terbium gallium garnet,” IEEE J. Quantum Electron. 35, 1116–1122 (1999).
[CrossRef]

Zelenogorsky, V.

E. A. Khazanov, A. Poteomkin, V. Zelenogorsky, A. Shaykin, A. Mal’shakov, O. Palashov, D. H. Reitze, “Adaptive compensation of thermal lens in Faraday isolators,” Proc. SPIE 5332, 271–282 (2004).
[CrossRef]

Zelenogorsky, V. V.

V. V. Zelenogorsky, E. E. Kamenetsky, A. A. Shaykin, O. V. Palashov, E. A. Khazanov, “Adaptive compensation of thermally induced aberrations in Faraday isolator by means of a DKDP crystal,” Proc. SPIE 5975, 59750I (2006).
[CrossRef]

Appl. Opt. (2)

Class. Quantum Grav. (4)

The Virgo Collaboration, “Virgo status,” Class. Quantum Grav. 25, 184001 (2008).
[CrossRef]

The Ligo Collaboration, “Status of the Ligo detectors,” Class. Quantum Grav. 25, 114041 (2008).
[CrossRef]

The GEO Collaboration, “The Geo–HF project,” Class. Quantum Grav. 23, S207–S214 (2006).
[CrossRef]

The TAMA Collaboration, “Status of TAMA300,” Class. Quantum Grav. 21, S403–S408 (2004).
[CrossRef]

IEEE J. Quantum Electron. (1)

E. A. Khazanov, O. V. Kulagin, S. Yoshida, D. B. Tanner, D. H. Reitze, “Investigation of self-induced depolarization of laser radiation in terbium gallium garnet,” IEEE J. Quantum Electron. 35, 1116–1122 (1999).
[CrossRef]

J. Opt. Soc. Am. B (1)

Opt. Commun. (1)

A. Gatto, L. Escoubas, P. Roche, M. Commandré, “Simulation of the degradation of optical glass substrates caused by UV irradiation while coating,” Opt. Commun. 148, 347–354 (1998).
[CrossRef]

Proc. SPIE (2)

V. V. Zelenogorsky, E. E. Kamenetsky, A. A. Shaykin, O. V. Palashov, E. A. Khazanov, “Adaptive compensation of thermally induced aberrations in Faraday isolator by means of a DKDP crystal,” Proc. SPIE 5975, 59750I (2006).
[CrossRef]

E. A. Khazanov, A. Poteomkin, V. Zelenogorsky, A. Shaykin, A. Mal’shakov, O. Palashov, D. H. Reitze, “Adaptive compensation of thermal lens in Faraday isolators,” Proc. SPIE 5332, 271–282 (2004).
[CrossRef]

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (8)

Fig. 1
Fig. 1

Position of the in-vacuum FI in Virgo: the Faraday isolator (FI) is placed on the in-vacuum suspended injection bench (SIB), between the interferometer input (power recycling mirror, PR) and the input mode cleaner (IMC). The beam diameter at the level of the FI is about 5 mm , and the FI input power about 18 W .

Fig. 2
Fig. 2

(a) Realistic scheme of a FI setup, taking into account a Faraday rotator action of 45 ° ε on the light polarization. The dashed line represents the coming back of the light after a round trip. (b) Faraday isolation is spoiled when going from air to vacuum. After being placed in vacuum, the rotation power of the Faraday rotator changes by an amount η . The losses at the level of the second polarizer increase, and the polarization, after a round trip, is no more cross polarized with respect to the first polarizer: part of the light goes through the first polarizer toward the input. The FI optical isolation is spoiled.

Fig. 3
Fig. 3

Change of the optical isolation of the FI for different polarizer extinction values 1 / σ , as a function of the additional in-vacuum angle η (for perfectly linearly polarized light).

Fig. 4
Fig. 4

Compensation of the in-vacuum reduced isolation level after additional half-waveplate. If a second half-waveplate is placed between the first polarizer and the Faraday rotator, the polarization of the light coming back after a round trip can be cross polarized with respect to the first polarizer if the waveplate is rotated by an angle ξ / 2 = η / 2 . The rotation of the waveplate can be finely tuned until the backreflection toward the input is minimized.

Fig. 5
Fig. 5

Setup of the FI system on the Virgo SIB, with the additional waveplate: the remotely rotated half-waveplate is placed between the housing of the first (input) polarizer and the Faraday rotator. The light coming back from the interferometer is reflected away by the first polarizer toward a horizontal mirror and then picked up and sent outside the vacuum vessel by another mirror.

Fig. 6
Fig. 6

Left: Evaluation of the optical isolation of the combined system FI and IMC. Right: Decrease of the power reflected back by the interferometer when rotating the waveplate; solid line, measured power; dash–Fdot line, waveplate rotation angle.

Fig. 7
Fig. 7

Spatial profile of the depolarization light generated in the FI TGG crystal.

Fig. 8
Fig. 8

Improvement in the interferometer signals: (left) The interferometer reflected power (a) after and (b) before FI optimization. (right) The IMC transmission (the light going into the interometer) (c) after and (d) before FI optimization. For the sake of clarity, an offset has been introduced between the two curves.

Equations (13)

Equations on this page are rendered with MathJax. Learn more.

θ Back = θ P 2 + θ FI = 45 ° + α + 45 ° ε ,
θ Back = 90 ° ,
R ( 0 ° ) T ( 0 ° ) = ( 1 σ ) σ 1 σ .
T ( 2 ε ) R ( 2 ε ) = ( 1 σ ) cos 2 ( 2 ε ) + σ sin 2 ( 2 ε ) ( 1 σ ) sin 2 ( 2 ε ) + σ cos 2 ( 2 ε ) .
θ P 2 θ FI = ( 45 ° + ε ) ( 45 ° ε η ) = 2 ε + η ,
T ( 2 ε + η ) R ( 2 ε + η ) = ( 1 σ ) cos 2 ( 2 ε + η ) + σ sin 2 ( 2 ε + η ) ( 1 σ ) sin 2 ( 2 ε + η ) + σ cos 2 ( 2 ε + η ) .
θ Back = θ P 2 + θ FI = 45 ° + ε + 45 ° ε η ,
θ Back = 90 ° η .
P 0 = A γ σ T 0 4 ,
T L = { P abs + P 0 A γ σ } 1 / 4 .
d θ d T = d V d T n L B = d V d T θ V .
η = d θ d T Δ T = 3.5 × 10 3 θ Δ T .
θ Back = θ P 2 + θ FI θ λ / 2 = ( 45 ° + ε ) + 45 ° ε η θ λ / 2 = 90 ° η θ λ / 2 .

Metrics