Adaptive compensation of thermal lens in Faraday isolators

Хазанов, Е. А.; Poteomkin, A.; Zelenogorsky, V. V.; Shaykin, A. A.; Mal'shakov, Anantoly; Palashov, Oleg; Reitze, D. H.

doi:10.1117/12.528251

Cited by 3 publications

(3 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The increase of laser power in the first generation of giant laser interferometers used to detect gravitational waves [1][2][3][4] showed that thermal effects are present in many optical components and can affect in a significant way the purity of the fundamental Gaussian mode used in those experiments [5][6][7][8]. These defects, if not compensated, can be the source of a noise that limits the performance of those detectors, or simply affect their power and signal loss budget.…”

Section: Introductionmentioning

confidence: 99%

Wavefront aberration compensation with a thermally deformable mirror

Canuel

Day

Genin

et al. 2012

Class. Quantum Grav.

View full text Add to dashboard Cite

First generation gravitational wave interferometer performances were affected by thermal effects and non-optimal coupling of the light into several optical cavities. Slow thermally induced beam-wavefront distortions can be compensated using deformable mirrors driven by thermal actuators. We propose a new device, where the set of heating actuators is placed in direct contact with the reflecting surface of the mirror, enabling an efficient control of its refractive index and shape. This system is particularly useful for an in-vacuum environment, where low noise remote actuation is required. It is therefore well suited for Advanced Gravitational Wave Detectors where many optical cavities will require active optimal coupling for optimizing their quantum noise sensitivity without producing motion of the rest of the optics, which could interrupt the control acquisition sequence. In this paper, a prototype for such a thermally deformable mirror is described, and first results are presented. The proposed system promises to perform with good stability and efficiency.

show abstract

Section: Introductionmentioning

confidence: 99%

Wavefront aberration compensation with a thermally deformable mirror

Canuel

Day

Genin

et al. 2012

Class. Quantum Grav.

View full text Add to dashboard Cite

show abstract

“…These effects have actually been taken into account and limited as much as possible by selecting Faraday crystals with low absorption: terbium gallium garnet (TGG) crystals with absorption in the range of 0:002=cm are used accordingly. Passive thermal lensing compensation systems have been proposed [6] and will become crucial in future applications with higher intensity input beams. A worsening of the optical isolation of the FI, caused by thermally induced depolarization [7], will also become critical in larger power applications and require a dedicated designed FI [8].…”

Section: Introductionmentioning

confidence: 99%

In-vacuum optical isolation changes by heating in a Faraday isolator

Acernese¹,

Alshourbagy²,

Amico³

et al. 2008

Appl. Opt.

View full text Add to dashboard Cite

We describe a model evaluating changes in the optical isolation of a Faraday isolator when passing from air to vacuum in terms of different thermal effects in the crystal. The changes are particularly significant in the crystal thermal lensing (refraction index and thermal expansion) and in its Verdet constant and can be ascribed to the less efficient convection cooling of the magneto-optic crystal of the Faraday isolator. An isolation decrease by a factor of 10 is experimentally observed in a Faraday isolator that is used in a gravitational wave experiment (Virgo) with a 10 W input laser when going from air to vacuum. A finite element model simulation reproduces with a great accuracy the experimental data measured on Virgo and on a test bench. A first set of measurements of the thermal lensing has been used to characterize the losses of the crystal, which depend on the sample. The isolation factor measured on Virgo confirms the simulation model and the absorption losses of 0.0016 +/- 0.0002/cm for the TGG magneto-optic crystal used in the Faraday isolator.

show abstract

“…This FI is operating in a 10 −6 mbar vacuum environment, and it has to accommodate a beam having a several millimeter diameter size and several Watts of power. Owing to the quite large light intensity in the FI crystal, thermally induced effects in the FI were expected and observed, as thermal lensing [5], with consequent beam/interferometer mismatching, and optical isolation degradation ( [6][7][8]). Reference [9] reports on the first observation of a further, formerly unexpected at this level, significant change of the optical isolation of an FI, which, having been tuned in air, once put in vacuum, experiences an isolation loss exceeding 10 dB.…”

Section: Introductionmentioning

confidence: 99%

In-vacuum Faraday isolation remote tuning

Accadia¹,

Acernese²,

Antonucci³

et al. 2010

Appl. Opt.

View full text Add to dashboard Cite

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 20 mm clear aperture and is illuminated by an almost 20 W incoming beam, having a diameter of about 5 mm. When going in vacuum at 10 −6 mbar, a degradation of the isolation exceeding 10 dB 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.

show abstract

Adaptive compensation of thermal lens in Faraday isolators

Cited by 3 publications

References 26 publications

Wavefront aberration compensation with a thermally deformable mirror

Wavefront aberration compensation with a thermally deformable mirror

In-vacuum optical isolation changes by heating in a Faraday isolator

In-vacuum Faraday isolation remote tuning

Contact Info

Product

Resources

About