Low Noise Crystalline Mirrors for Precision Metrology

• Applicants: Professor Achim Peters, Ph.D.; Professor Dr. Markus Weyers
• Co-Applicant: Professor Dr. Markus Aspelmeyer
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2012 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 213176671

• Final Report Year: 2020

Final Report Abstract

The ultimate performance of high-precision optical interferometers and optical reference cavities depends crucially on the mechanical damping in the constituent materials of the cavity end mirrors. Such systems are applicable to a variety of fields, including gravitational wave detection, laser stabilization for optical clocks, quantum optomechanics, as well as precision tests of modern physics. Unfortunately, existing high-quality optical coatings based on Ta2O5/SiO2 suffer from excessive mechanical loss, thus limiting the noise performance of these advanced optical systems. Recent investigations into monocrystalline Bragg mirrors based on AlGaAs heterostructures have revealed that this materials system is an extremely promising low phase-noise alternative to existing state-of-the-art dielectric mirrors for use in high-performance applications. We have investigated the limits with respect to both the optical and mechanical losses in this material system. Losses due to free carrier absorption were successfully reduced by compensating residual p-doping in AlGaAs by n-doping with Si. Using a bonding-based transfer process, which has also been studied, crystalline AlGaAs mirrors on bulk sapphire substrates can be created - including the possibility to realize curved mirrors. Strain compensation by adding P to the AlGaAs allows to adjust the curvature of the Bragg mirrors within certain limits. We have demonstrated optical cavities with the expected record low thermal noise performance, hence overcoming the impediment of high mechanical damping as found in Ta2O5/SiO2 multilayers. Some of the developments have by now been commercialized.

Publications

• “Quantum Optomechanics” In Optical Coatings and Thermal Noise in Precision Measurement, edited by G. M. Harry, T. P. Bodiya, R. DeSalvo, pp. 259–279. Cambridge University Press, 2012 ISNB: 9781107003385
  G. D. Cole and M. Aspelmeyer
  
• “Cooling-by-measurement and mechanical state tomography via pulsed optomechanics”, Nature Communications, vol. 4, article 2295, 15 August 2013
  M. R. Vanner, J. Hofer G. D. Cole, M. Aspelmeyer
  
• “Tenfold reduction of Brownian noise in high-reflectivity optical coatings”, Nature Photonics, vol. 7, no. 8, pp. 644-650, August 2013
  G. D. Cole, W. Zhang, M. J. Martin, J. Ye, M. Aspelmeyer,
  
• „MOVPE-grown AlxGa1-xAsyP1-y strain compensating layers on GaAs“, J. Crystal Growth 370 (2013) 150-153
  A. Maassdorf, U. Zeimer, M. Weyers
  
• “Reduction of residual amplitude modulation to 1×10^- 6 for frequency-modulation and laser stabilization”, Optics Letters, vol. 39, no. 7, pp. 1980-1983, April 2014
  W. Zhang, M. J. Martin, C. Benko, J. L. Hall, J. Ye, C. Hagemann, T. Legero, U. Sterr, F. Riehle, G. D. Cole, M. Aspelmeyer
  
• “Tensile strained InxGa1-xP membranes for cavity optomechanics”, Applied Physics Letters, vol. 104, no. 20, 201908, 19 May 2014
  G. D. Cole, P.-L. Yu, C. Gärtner, K. Siquans, R. Moghadas Nia, J. Schmöle, J. Hoelscher-Obermaier, T. P. Purdy, W. Wieczorek, C. A. Regal, M. Aspelmeyer
  
• “Technology for the next gravitational wave detectors”, Science China–Physics, Mechanics & Astronomy, vol. 58, no. 12, 120404, December 2015
  V. P. Mitrofanov, S. Chao, H.-W. Pan, L.-C. Kuo, G. Cole, J. Degallaix, B. Willke
  
• „AlAsP-based strain-balancing in MOVPE-grown distributed Bragg reflectors“, J. Crystal Growth 414 (2015) 10-14
  A. Maassdorf, M. Weyers
  
• “Coherent cancellation of thermo-optic noise in GaAs/Al0.92Ga0.08As Bragg mirrors”, Metrologia, vol. 53, no. 2, p. 860-868, April 2016
  T. Chalermsongsak, F. Seifert, E. D. Hall, K. Arai, D. Follman, G. D. Cole, M. Aspelmeyer, E. K. Gustafson, R. X. Adhikari
  
• “High-performance near- and mid-infrared crystalline coatings”, Optica, vol. 3, no. 6, pp. 647-656, June 2016
  G. D. Cole, W. Zhang, B. J. Bjork, D. Follman, P. Heu, C. Deutsch, L. Sonderhouse, J. Robinson, C. Franz, A. Alexandrovski, M. Notcutt, O. H. Heckl, J. Ye, M. Aspelmeyer
  
• “Optical resonators with ultra-high frequency stability using AlGaAs coatings”, DPG SAMOP Frühjahrstagung, Hannover, March 2016
  S. A. Pyka, M. Nagel, K. Döringshoff, S. Schikora, E. V. Kovalchuk, A. Peters
  
• „Reduction of absorption losses in MOVPE-grown AlGaAs Bragg mirrors“, Optics Letters 43(15) (2018) 3522 – 3525
  J. Pohl, G.D. Cole, U. Zeimer, M. Aspelmeyer, M. Weyers