Work Package 4: Development of low loss dielectric coatings for advanced detectors

• Scientific motivation: Mechanical dissipation from dielectric mirror coatings is predicted to be a significant source of thermal noise for advanced detectors. Coatings must also be of low optical loss.

- Main workpackage outcomes/long term aim: Definition of a low-mechanical-loss optical coating

design/production process suitable for advanced detectors operating at either room or cryogenic temperatures

- Groups involved: Institute for Gravitational Research, University of GlasgowLaboratoire des Matériaux Avancés, (LMA) LyonsAURIGA group, Laboratori Natzionali di Legnaro (+Leiden/Rome)Materials group, VIRGO, PerugiaESPCI, Laboratoire d'Optique, Paris

Work Package 4: Development of low loss dielectric coatings for advanced detectors

Milestones Year 1 Report from Glasgow Group (IGR)

4.1 - Production of the first SiO2/Ta2O5 and SiO2 /Al2O3 coatings

     Status: Coatings procured from REO and Waveprecision.

Deliverables Year 14.2 - Loss measurements on SiO2 /Ta2O5 at room T      Status: Given the availability of results from work by the LIGO project on

SiO2/Ta2O5 we chose to pursue studies of Al2O3/Ta2O5 coatings (relevant for use with sapphire mirror substrates)We have previous experimental measurements which we are re-

analysing in greater depth for this project given our new work on FEA and improved interpretation of sources of coating dissipation.

This work is continuing as planned.

4.3 - Loss measurements on SiO2 /Al2O3 at room T     Status: A  SiO2/Al2O3 coating on sapphire has been procured – we plan to

carry out measurements of the coating mechanical loss. This work is continuing as planned.   

Facility to measure the Q of coated membranes realized under theEGO R&D program and delivered to Lyon

Report from INFN Perugia

The Michelson Morley Interferometer

Data analysis program

Preliminary measurements in Perugia for clamping design

Work Package 4: Development of low loss dielectric coatings for advanced detectors

Milestones of STREGA proposal for next year:

• Milestone Year 2 production of first SiO2 /high index material

• Deliverables Year 2 measurements on silica substrate

identification of diffraction coating production process

Scientific plan for next year:

• Some EGO funding is approved for coating research - LMA Lyons • We propose

– Substrates to be provided by collaborating STREGA institutions – Thin ‘membranes’ to be used initially for fast test measurements (INFN

Perugia)

Work Package 4: Development of low loss dielectric coatings for advanced detectors

Scientific plan for next year, cont.

- Smaller number of larger ‘mirror-like’ samples for further study in more realistic configurations INFN Perugia, Glasgow (participation by Legnaro/Leiden/Rome)

- Move over coming year to study coatings on some silicon substrates (for use at 1064nm initially)

- Choice of specific coatings – doping etc – subject of near future discussion – propose WP4 meeting in Lyons

• Costs an issue..