Graduate Exam Abstract

Peter Langston

Ph.D. Final

June 30, 2016, 10:00 am - 12:00 pm

A210 ERC Foothills Campus

A study of the influence of process parameter variations on the material properties and laser damage performance of ion beam sputtered Sc2O3 and HfO2 thin films.

Abstract: Our work at Colorado State University has given us a foundational understanding of how and what process parameters are most influential in producing low loss, high stability, high damage threshold metal oxide ion beam sputtered films. This work has probed the influence of excess oxygen incorporation in critical metal oxides used in high energy laser coatings from both a mechanical, optical and laser damage perspective. The results of this work led to the understanding that it is remarkably easy to exceed useful oxygen incorporation in these materials leading to increased stress, increased absorption at 1 µm and 515nm wavelengths, as well as to a reduced laser damage performance in both HfO2 and Sc2O3. We have further demonstrated that while ion deposition energy plays a role in altering the material’s defect concentrations it is not a significant influence as others have suggested. This dissertation describes a study of laser induced surface defect creation in three high index materials, Sc2O3, HfO2 and Ta2O5 both in air and in vacuum, which were grown by ion beam sputtering. It is shown that the laser damage behavior in air and vacuum can be altered with the addition of a ~ 10 nm capping layer, pointing to the significant role that surfaces and interfaces have in interference coatings. A thermal model is used to analyze the observed behavior.

Adviser: Dr. Carmen Menoni, Electrical Engineering
Co-Adviser: N/A
Non-ECE Member: Dr. Azer Yalin, Mechanical Engineering
Member 3: Dr. Jorge Rocca, Electrical Engineering
Addional Members: Dr. Mario Marconi, Electrical Engineering

P.F. Langston, E. Krous, D. Schiltz, D. Patel, L. Emmert, A. Markosyan, B. Reagan, K. Wernsing, Y. Xu, Z. Sun, R. Route, M. M. Fejer, J.J. Rocca, W. Rudolph, and C.S. Menoni, “Point Defects in Sc2O3 Thin Films by Ion Beam Sputtering,” Appl. Opt. 53, A278-A280 (2014).

D. Schiltz, P. Langston, D. Patel, L. Emmert, L. Acquaroli, C. Baumgarten, B.A. Reagan, W. Rudolph, A. Markosyan, R. Route, M.M. Fejer, J. Rocca, and C.S. Menoni. Enhanced laser damage behavior of laser mirror by modification of the top layer design. CLEO: 2014. 2014. San Jose, California: Optical Society of America.

W. Rudolph, L. A. Emmert, C. Rodriguez, Z. Sun, X. Zhang, Y. Xu, C. S. Menoni, P. F. Langston, E. Krous, D. Patel, "Femtosecond to nanosecond laser damage in dielectric materials", in Pacific Rim Laser Damage 2013: Optical Materials for High Power Lasers, Jianda Shao; Takahisa Jitsuno; Wolfgang Rudolph, Editors, Proceedings of SPIE Vol. 8786 (SPIE, Bellingham, WA 2013), 878602.

D. Patel; P.F. Langston; L. M. Imbler; L. A. Emmert; A. S. Markosyan; R.K. Route; M. M. Fejer; W. Rudolph; C. S. Menoni, “Ion beam sputtered Y2O3”, SPIE Proceedings Vol. 8530, Laser-Induced Damage in Optical Materials: 2012, Gregory J. Exarhos; Vitaly E. Gruzdev; Joseph A. Menapace; Detlev Ristau; M J Soileau, Editors, 85300Z.

C.S. Menoni, E.M. Krous, D. Patel, P. Langston, J. Tollerud, D.N. Nguyen, L.A. Emmert, A. Markosyan, R. Route, M. Fejer, and W. Rudolph, Advances in ion beam sputtered Sc(2)O(3) for optical interference coatings, in Laser-Induced Damage in Optical Materials: 2010, G.J. Exarhos, et al., Editors. 2010.

B. Langdon, D. Patel, E. Krous, J.J. Rocca, C.S. Menoni, F. Tomasel, S. Kholi, P.R. McCurdy, P. Langston, and A. Ogloza, Influence of process conditions on the optical properties HfO2/SiO2 thin films for high power laser coatings - art. no. 67200X, in Laser-Induced Damage in Optical Materials: 2007, G.J. Exarhos, et al., Editors. 2008. p. X7200-X7200.

C.S. Menoni, P. F. Langston, E. Krous , D, Patel, L. Emmert, A. Markosyan, B. Reagan, K. Wensing, R. Route, M.M Fejer, J.J. Rocca, and W. Rudolph, “What role do defects play in the laser damage behavior of metal oxides?”, SPIE Laser Damage 2012, Boulder, CO. (Best paper award, 2013).

C. S. Menoni, D. Patel, B. Langdon, D.Alessi, Y. Wang, F.Tomasel, J. J. Rocca, P. Langston, A. Ogloza, A. Markosyan, R. Route, M.M. Fejer, R. Cravetchi, D. Ngyuen, W. Rudolph, M. Shinn, “Influence of process conditions on the loss and resistance to laser damage of HfO2/SiO2 coatings for high power lasers”, Directed Energy Professional Society (DEPS) Annual Meeting, Huntsville, AL, Nov. 5-9, 2007.

P. Langston, "Influence of oxygen pressure variations on the optical properties of ion beam sputtered metal oxide coatings," FIO, OSA Technical Digest (Optical Society of America, 2011), paper JWA25.

J. Sanghera, S. Bayya, G. Villalobos, W. Kim, J. Frantz, B. Shaw, B. Sadowski, R. Miklos, C. Baker, M. Hunt, I. Aggarwal, F. Kung, D. Reicher, S. Peplinski, A. Ogloza, P. Langston, C. Lamar, P. Varmette, M. Dubinskiy, L. DeSandre, “Transparent ceramics for high-energy laser systems,” Optical materials, Vol. 33, Issue 3, pg. 511-518, 2011.

P. Langston, D. Patel, A. Markosyan, E. Krous, D. Nguyen, L. Emmert, W. Rudolph, R. Route, M. Fejer, M. Shinn, and C. Menoni, "Modifications in the Optical Properties of Thin Film Oxides with Annealing," FIO, OSA Technical Digest (CD) (Optical Society of America, 2009), paper FThS7.

P. Langston, D. Patel, A. Markosyan, E. M. Krous, B. Langdon, R. Route, M. Fejer and C. Menoni, “SiO2/HfO2 multilayers: impact of process parameters and stack geometry on the optical and structural properties,” Frontiers in Optics, OSA Technical Digest (CD) (Optical Society of America, 2008), paper JSuA27.

B. Langdon, D. Patel, E. Krous, P. Langston, C. Menoni, M. Shinn, “Electron spin resonance and x-ray photo electron spectroscopy investigation of ion beam sputtered HfO2 and SiO2 thin films,” Laser-Induced Damage in Optical Materials: 2008, Gregory J. Exarhos; Detlev Ristau; M. J. Soileau; Christopher J. Stolz, Editors, Proc. SPIE vol. 7132, 71320M.

Program of Study:
CHEM 577
CHEM 579
ECE 503
ECE 504
ECE 506
ECE 546
ECE 604
ECE 641