The O3 Pre-Stabilized Laser System delivers an extremely stable (in frequency, power and position) beam to Advanced VIRGO interferometer. The system described in this page has been running since January 2018 and has been in operation for gravitational wave detection since the beginning of the O3 observation run the 1st april 2019 leading to the detection of approximately one binary merger candidate a week. It is based on Nd3+ doped cristals and provides around 65 W in a single frequency, continuous wave, single transverse mode. It replaces the O2 Pre-stabilized laser system

The developpement of the O3 Pre-Stabilized laser system has triggered different research projects concerning :

  • high power amplifier
  • ultra low noise power stabilization
  • high power pre-mode cleaner
  • laser beam coherent combination

new PSL AdvVIRGO bench dec 2017

Members of O3 PSL team :

Former members :

  • Dr. Catherine Nary Man : senior research fellow emeritus (now member of LISA project)
  • Dr Margherita Turconi : laser & optics engineer 2013-2015
  • Dr Li-Wei Wei : doctoral candidate 2012-2015 (now in AEI Hanovre)
  • Dr Alain Brillet : senior research fellow (retired)

image laser Lab Cleva Kéfélian (Front : Dr. Frédéric Cleva, Back : Dr. Fabien Kéfélian )

High power amplifier systems investigation and metrology 

In order to develop the O3 pre-stabilized laser system, two different high power amplifier technologies has been investigated and metrologicaly characterized :

  • 50 W Yb3+ doped fiber amplifier
  • 100 W Nd3+ YVO4 amplifier

Publications : 


 100W laser system Fig. 1 Test bench in ARTEMIS

new PSL bench

Fig. 2 New amplifier integrated in the PSL bench of Advanced VIRGO

Ultra low noise power stabilization

The goal is to reach a power spectral density of relative intensity noise of  1,2x10-9 1/Hz1/2 at 30 Hz at the input of Advanced VIRGO interferometer

 Pstab prototype


 Fig. 1 : Power stabilisation prototype







boite optique Fig. 2 : Optical box (without optics and photodiode)

P stab 25WFig. 3 : Performance of the power stabilization on site (with a power lower than the nominal power). The stabilization is limited by the shot noise between 10 Hz and 4000 Hz reaching 2.5E-9 /Hz^1/2 (out of loop result divided by 2^0.5)

High power Pre-Mode Cleaner

The pre-mode cleaner is a key component of Advanced VIRGO pre-stabilized laser bench. The purpose of the pre-mode cleaner is to filter all the higher order modes of the high power laser system (up to 200 W), to stabilize the laser beam spatial, angular and transverse characteristics and to filter high frequency components of the intensity and frequency noise.

 PMC      PMC2

Photo0983 (PMC on test bench in ARTEMIS)

PMC in new AdVIRGO bench

New PMC integrated in Advanced VIRGO PSL bench in decembre 2017 by Drs. F. Cleva & F. Kéfélian

Coherent beam combination

Coherent beam combination is a possible solution to manage current maximum power limit of optical amplifier and reach the target power of 200 W for the final configuration of Advanced VIRGO laser system. We have studied the principle of the technique with 50 W fiber lasers and performed detailed noise measurements regarding the power, frequency and spatial parameters on the combined beam

A combination efficiency of about 96% was achieved with two 35 W beams, without spurious noise (see Wei et al. Opt. Lett. 41, 5817)

Publications :

 CBC scheme