Advanced High Performance, Thin Film Coatings​

Our group expertise is in optical thin film coatings by reactive ion beam sputtering.We investigate the materials optical and structural  properties and design and characterize multilayer interference coatings for ultra-high power near infrared lasers and ultrastable cavities as in gravitational wave interferometers

We use ion beam sputtering to produce  thin film multilayers of amorphous oxides We specialize in understanding the materials optical and structural properties and in optimizing them.  For high average and peak power near infrared lasers we aim at achieving  high laser damage resistance using different pulse duration scenarios at wavelengths of 800 and 1030 nm.   

Our work on coatings for ultrastable cavities, is part of scientific effort of  the LIGO collaboration.  In these studies we investigate elastic properties of the amorphous oxides which produce unwanted Brownian noise in the coatings of the mirrors in the interferometers.   We have investigated ternary alloys of TiO2 doped Ta2O5 and more recently TiO2 doped GeO2 which is a very promising high index material for next generation interference coatings of gravitational wave detectors. 

Current Projects

  • Optical coatings for ultra-high intensity lasers
    • Stress in IBS coatings: Ongoing efforts are investigating how stress in amorphous thin films can be reduced.  Here we are exploring the use of assist beam assistance during deposition.
    • Multilayer dielectric coatings based on amorphous oxides are being developed for chirped pulse amplification lasers operating at 800 nm and 1030 nm.  
    • These studies have direct impact in the power scaling of high intensity near infrared lasers, in which interference coatings are one of the weakest components that limits their power scaling.
  • Optical coatings for LIGO (Laser Interferometer Gravitational-Wave Observatory)
    • We use a combination of diagnostics methods to investigate the morphology, bonding and optical properties of high index oxides as Ta2O5 which is the high index component of multilayer mirrors in the test masses of the interferometer. In this we have shown unique morphological changes occur when doping Ta2O5 with TiO2 at a concentration of Ti of 25%, which is the mixture that has the lowest mechanical loss angle.   We have also investigated doping Ta2O5 with other materials, i.e. TiO2 and in nanolaminates or nanolayers made by alternating nanometer thick Ta2O5 with for example TiO2.
      A study of the effect of simultaneous assist bombardment during the deposition of Ta2O5 was also carried out.  It was found the use of Ar and Xe assist did not modify the structural and optical properties of the amorphous Ta2O5.  Neither it modified the mechanical loss.
    • These investigations are contributing to advance the materials that are critical components of LIGO mirrors which is necessary to increase the sensitivity of the interferometer.
  • Surface sculpting with ion beams
    • In this work we use assist ion bombardment at oblique incidence to pattern surfaces with periodic features of controlled size and period.  These patterns have high uniformity over large areas.
    • This work has significance for applications in the engineering of photonics structures such as grating.

Selected Publications

  1. Gabriele Vajente, Le Yang, Aaron Davenport, Mariana Fazio, Alena Ananyeva, Liyuan Zhang, Garilynn Billingsley, Kiran Prasai, Ashot Markosyan, Riccardo Bassiri, Martin M. Fejer, Martin Chicoine, François Schiettekatte, and Carmen S. Menoni, “Low Mechanical Loss TiO2:GeO2 Coatings for Reduced Thermal Noise in Gravitational Wave Interferometers,” Phys. Rev. Lett. 127, 071101 – Published 10 August 2021.
  2. Mariana Fazio, Le Yang, Carmen S. Menoni, “Prediction of crystallized phases of amorphous Ta2O5-based mixed oxide thin films using density functional theory calculations,” Applied Physics Letters Materials 9, 031106 (2021);
  3. Le Yang, Mariana Fazio, Gabriele Vajente, Alena Ananyeva, GariLynn Billingsley, Ashot Markosyan, Riccardo Bassiri, Martin M. Fejer and Carmen S. Menoni, “Oxide Nanolaminates: Implications for Ultrastable Optical Cavities,”ACS Appl. Nano Mater. 2020, 3, 12, 12308–12313.
  4. Vajente; M. Fazio; L. Yang, L.; A. Gupta; A. Ananyeva; G. Billinsley; C.S. Menoni, “Method for the experimental measurement of bulk and shear loss angles in amorphous thin films,” PHYSICAL REVIEW D 101 Issue: 4, Article Number: 042004, 2020; DOI: 10.1103/PhysRevD.101.042004.
  5. Mariana A. Fazio, Gabriele Vajente, Alena Ananyeva, Ashot Markosyan, Riccardo Bassiri, Martin M. Fejer, and Carmen S. Menoni, “Structure and morphology of low mechanical loss TiO2-doped Ta2O5,” Opt. Mater. Express 10, 1687-1703 (2020).
  6. Hanchen Wang, Alexander R. Meadows, Elzbieta Jankowska, Emmett Randel, Brendan A. Reagan, Jorge J. Rocca, and Carmen S. Menoni, “Laser induced damage in coatings for cryogenic Yb:YAG active mirror amplifiers,” Opt. Lett. 45, 4476-4479 (2020).
  7. Noah Talisa, Abdallah Alshafey, Michael Tripepi, Jacob Krebs, Aaron Davenport, Emmett Randel, Carmen S. Menoni, and Enam A. Chowdhury, “Comparison of damage and ablation dynamics of multilayer dielectric films initiated by few-cycle pulses versus longer femtosecond pulses,” Opt. Lett. 45, 2672-2675 (2020).
  8. Yang, E. Randel, G. Vajente, A. Ananyeva, E. Gustafson, A. Markosyan, R. Bassiri, M.M. Fejer, and C.S. Menoni, “Investigation of effects of assisted ion bombardment on mechanical loss of sputtered tantala thin films for gravitational wave interferometers. Physical Review D, 100(12) 122004, (2019).
  9. Fazio, L. Yang, A. Markosyan, R. Bassiri, M.M. Fejer, and C.S. Menoni, “Growth and characterization of Sc2O3 doped Ta2O5 thin films,” Applied Optics, 2020. 59(5): p. A106-A111.
  10. Davenport, E. Randel, and C.S. Menoni, “Ultra-low stress SiO2 coatings by ion beam sputtering deposition,” Applied Optics, 59(7): p. 1871-1875, (2020).
  11. Yang, E. Randel, G. Vajente, A. Ananyeva, E. Gustafson, A. Markosyan, R. Bassiri, M. Fejer, and C.S. Menoni, “Optical properties and mechanical loss of amorphous Ta2O5 thin films bombarded with low energy assist ions,” Applied Optics, 59(7): A150-A154 (2020).
  12. Zaldivar Escola, N. Mingolo, O. E. Martínez, J. J. Rocca, and C. S. Menoni, “Investigation of laser annealing mechanisms in thin film coatings by photothermal microscopy,” Opt. Express 27, 5729-5744 (2019).
  13. Zaldivar Escola, N. Míngolo, O. E. Martínez, J. J. Rocca, and C. S. Menoni, “Characterization of absorptance homogeneity in thin-film coatings for high-power lasers by thermal lensing microscopy,” Appl. Opt. 58, 7233-7240 (2019).


DoD Office of Naval Research, National Science Foundation LIGO Program, DMR Program, and the NSF/Moore Foundation Center for Coatings Research; Department of Energy, Accelerator Program; XUV Lasers through a DoE Accelerator Program STTR.