What we do

Future gravitational wave detectors will utilize very high laser powers in the order of mega watts. Power absorption in the substrates of beam splitters and cavity couplers will therefor become a major problem (for example due to thermal lensing).

One way to address these problems is the construction of all-reflective interferometers.

We investigate new cavity coupling and interferometer concepts based on reflective diffraction gratings. The gratings used are manufactured by the Institute of Applied Physics (University of Jena).

This project is financed by Deutsche Forschungsgemeinschaft within Transregio 7, project C3 .

Another research activity addresses the urgent problem of coating thermal noise in interferometric gravitational wave detectors. Test masses in current interferometers use thick multi-layer high-reflection coating stacks which result in a significant increase of Brownian thermal noise and thermoelastic noise of the test mass. In this project thin single-layer waveguide structures will be designed and demonstrated as a high-reflection, but low thermal noise alternative to conventional coatings. We especially consider the optical wavelength of current gravitational wave detectors and investigate the compatibility of our concept with other strategies for thermal noise reduction.

This project is financed by Deutsche Forschungsgemeinschaft within SFB Transregio 7, project C5.

[1] A. Bunkowski, O. Burmeister, D. Friedrich, K. Danzmann, and R. Schnabel: High reflectivity grating waveguide coatings for 1064 nm, Class. Quantum Grav. 23, 7297 (2006)

[2] A. Bunkowski, O. Burmeister, K. Danzmann, R. Schnabel, T. Clausnitzer, E.-B. Kley, and Tünnermann: Demonstration of 3-port grating phase relations, Optics Letters 31, 2384 (2006)

[3] A. Bunkowski, O. Burmeister, T. Clausnitzer, E.-B. Kley, A. Tünnermann, K. Danzmann, and R. Schnabel: Optical Characterization of ultra-high efficiency gratings, Applied Optics 45, 5795 (2006)

[4] R. Schnabel, A. Bunkowski, O. Burmeister, and K. Danzmann: Three-port beam splitters/combiners for interferometer applications, Optics Letters, 31, 658 (2006)

[5] A. Bunkowski, O. Burmeister, K. Danzmann, and R. Schnabel: Input-output relations for a three-port grating coupled Fabry-Perot cavity, Optics Letters 30, 1183 (2005)

[6] A. Bunkowski, O. Burmeister, P. Beyersdorf, K. Danzmann, R. Schnabel, T. Clausnitzer, E.-B. Kley, and Tünnermann: Low-loss grating for coupling to a high-finesse cavity, Optics Letters 29, 2342 (2004)

People

The following students are involved in this project. Feel free to contact us!

Oliver Burmeister (Ph.D. Student)
Tel.: 49 (0)511 762 17169
email: oliver.burmeister@aei.mpg.de





Daniel Friedrich (Diploma Student)
Tel.: 49 (0)511 762 5848
email: daniel.friedrich@aei.mpg.de

Michael Britzger (Diploma Student)
Tel.: 49 (0)511 762 19556
email: michael.britzger@aei.mpg.de

Other

Guests: Peter Beyersdorf (TAMA) (April/Mai 2004)

Former staff:

Dr. Alexander Bunkowski

website by AF//c:2k+4;RS, May 2007