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May 01, 2023 438 likes •576 views

High power fiber laser research, with Advanced Virgo and ET applications Ali Hreibi & Walid CHAIBI , ARTEMIS, Observatoire de la Cte dAzur 18/04/2018 20/06/2018 1 Advanced Virgo Pre-Stabilized Laser 140 W 50 mW 100 W 190 W

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Ali Hreibi & Walid CHAIBI, ARTEMIS, Observatoire de la Côte d’Azur

18/04/2018

High power fiber laser research, with Advanced Virgo and ET applications

20/06/2018 1

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Wei et al. Optics Letters 41, 5817 (2016) 50 mW 100 W 100 W 190 W 140 W >190 W

Advanced Virgo Pre-Stabilized Laser

Advanced Virgo requirements : with parametric instabilities : < 50W

Input power : 125W
RIN : Relative intensity noise
Phase noise added by the amplification process : 7 orders of

magnitude with respect to NPRO (G. Santarelli LP2N)

Beam pointing noise : into intensity noise by the PMC
Long term operation : peak to peak fluctuations +/- 2% for months
Gaussian mode content : >90%

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Large mode area 760 µm² : Stimulated Brillouin Scattering (SBS) limits the power

>300 W.

NKT High power polarizing fiber
Custom design MFA (Alphanov)

100W single unit : All fibered design (ALS + Alphanov)

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NPRO

Pump LD Pump LD (4 x 60 W) 𝜇 4 𝜇 2 Fibered isolator Fibered isolator Free space isolator combiner combiner Mode Field adaptor (MFA) Nufern PM fiber : PLMA-YDF-10/125-VIII

NKT : DC-200/40-PZ-Yb

25 mW 4 W 110 W

Active core 40 µm Air clad Pump core

100 W

dichroic

preamplifier HP amplifier

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30cm

Combiner + MFA (27.5 °C) 𝜇/4 𝜇/2

isolator

Pre-amplifier

Pump LDs (2 independent modules)

pumps signal Chiller 1 Chiller 2

Heat extraction 18°C : stabilizing the fiber T° + controlling the combiner + MFA T° MFA T° Combiner T° Slow (50%) and fast (few %) control of the power

HP fiber coiled

All fibered design (ALS + Alphanov)

Datas : pumps current, seeder power, pre-amplifier power

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System characterization : RIN and Beam Pointing Noise

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Overall functioning time > 2500 h, 3W peak to peak

Coupling into a reference cavity. Finesse = 900

Beam shape, radius @ waist ~ 600 µm Zhao et al., App.Phys. B 124, 114 (2018)

System characterization : Beam quality and long term operation

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Triangular cavity as a mode reference cavity on which the two beams are adapted

Coherent beam combination CBC

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NPRO

Pump LD Pump LD (4 x 60 W) 𝜇 4 𝜇 2 Fibered isolator Fibered isolator Free space isolator combiner combiner Mode Field adaptor (MFA) Nufern PM fiber : PLMA-YDF-10/125-VIII

NKT : DC-200/40-PZ-Yb

25 mW 4 W 110 W 100 W

dichroic

preamplifier HP amplifier Critical points :

Signal and pumps combination and coupling into the High power fiber
Photodarkening
Transverse mode instability (TMI)

Einstein Telescope high power interferometer ~ 1kW input, 3MW intracavity

Towards ET…

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Koponen et al., Proc of SPIE 5990, 599008 (2005)

6 to 7 Yb3+ in excited level

Highly non linear
Depends on the pump &

signal spatial distribution

All fibered design (ALS + Alphanov)

Photodarkening : generation of color centers

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Eidam et al., OPTICS EXPRESS 19, 13218 (2011)

Jauregui et al., OPTICS EXPRESS 23, 20204(2015)

High power transverse mode Temperature gradient = index gradient Modification of the guiding structure Transverse mode instability

Irreversible grating inscription

@1.5 µm, less phtodarkening, but higher quantum defect…

Transverse Mode Instability (TMI)

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Pierre et al., Proc of SPIE 10512, 105122A-1 (2018)

200W amplifier based tapered fiber (Alphanov)

Free space counter- propagating pumping

Alumino-silicate Phospho-silicate, a better dilution of Yb : less photodarkening

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Conclusion

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100 W fiber laser fulfills the Advanced Virgo specifications as a single unit for coherent summation. Fiber technology is evolving fast enough. CBC as a back up