![]() ![]() → the isolation drop is about 6-7 dB at 250W ( W). Moreover the limited temperature increase of the TGG crystals (about 6 ⁰C with 250W laser power in the FI) can guarantee that we will not loose too much power (due to the half waveplate adjustment).ĩ Faraday isolator for AdV: High power tests (July/August 2010).Ĭomparison of in-vacuum performances of the Faraday isolator with and without compensation of the Verdet constant change with temperature. This is the proof that we are limited only by depolarization. Isolation could be further improved by a better adjustment of the axis of minimum depolarization of one TGG respect to the other.Ĩ Faraday isolator for AdV: High power tests (July/August 2010).Ĭomparison of in-air and in-vacuum performances of the Faraday isolator (optimal isolation at each power after waveplate adjustment). We could reach 38 dB in particularly good alignment conditions. UHV chamber → the isolation is about 36.5 dB with 240 W in the FI (120W+120W). In-vacuum performances of the Faraday isolator (residual pressure = mbar). Half waveplate Output Input Calcite wedge Polarizer 2 Calcite wedge Polarizer 1ħ Faraday isolator for AdV: High power tests (July/August 2010). → After assembling, we measured a transmission higher than 95% (within requirements) and an isolation factor higher than 45 dB at low power. All the optics of the Faraday isolator except DKDP crystals have been coated by LMA (to ensure a good transmission of the FI). Thermal lensing measurements: Absorption(TGG1) = 2300 ppm/cm (+-100ppm/cm) Absorption(TGG2) = 2600 ppm/cm (+-100ppm/cm) Depolarization measurements: For each crystal, found the orientation of the crystals that produces the minimum of depolarization (required to have the depolarization optimally compensated ). TGG crystals characterized in the High Power facility. Faraday magnetic system during the assembling TGG crystal installation in its copper holder The Faraday isolator prototype for Advanced Virgo Description and assembling procedure, Virgo internal note, VIR-0283A-10.Ħ TGG crystals characterization and FI final assembling → Assembly completed in March 2010 once the coated optics were available. Zheleznov) in January 2010 in Virgo clean rooms. Prototype assembled by our colleagues of IAP (O. → we chose to produce a 20 mm aperture with reinforced magnetic field Faraday isolator, half waveplate for compensation of Verdet constant change with temperature and DKDP crystal for thermal lensing compensation.ĥ High vacuum Faraday isolator for AdV: Magnetic system assembling. ![]() A collaboration between IAP and EGO started in July 2008 and a report on the study of different FI design with various aperture options delivered in March 2009 ( See IAP report “AdV Faraday isolator design study”, VIR-0245A-10). → in order to reach these performances, we have contacted Efim Khazanov (IAP, Russia) who already produced HP-compatible FI for LIGO. UHV compatible: residual pressure ≤10-6 mbar. Be insensitive to thermal conditions changes going from air to vacuum. The requirements for the AdV Faraday isolator (FI) are: Isolation factor > 40 dB with 250W laser power going through the FI. Input Power Control system (IPC 1) Beam pointing control system Beam analysis system (cameras, Hartmann sensor,…) In-vacuum optics: 144 m long Resonant Input Mode-Cleaner (IMC) High power Faraday isolator ITF Mode-Matching Telescope (MMT) PSL intensity stabilization photodiode Reference cavity (RFC) Steering optics Input Power Control system (IPC 2) For more information on the subsystem: AdV INJ preliminary design study, VIR-0023A-09 AdV INJ design requirements, VIR-0628A-09 - AdV baseline design, VIR-0027A-09 In-air optics: EOM system for IMC and ITF control IMC mode-matching telescope. High power compatible components: Faraday isolator for AdV High power beam dumps Electro Optical Modulator for AdV AdV Input Mode Cleaner: what to do to upgrade Virgo IMC for AdV. Outline Advanced INJ subsystem: overview. Paoletti LIGO-G VIR-0515A-10Ģ Advanced INJ subsystem: overview. Genin for AdV INJ team European Gravitational Observatory with the contribution of B. Genin for AdV INJ team European Gravitational."- Presentation transcript:ġ Advanced Virgo INJ: Faraday isolator, Electro-optical modulator, high power beam dump and Input mode-cleaner E. Presentation on theme: "Advanced Virgo INJ: Faraday isolator, Electro-optical modulator, high power beam dump and Input mode-cleaner E. ![]()
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