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High damage threshold single and double layer antireflection (AR) coatings for Nd:YAG Laser: conventional systems

S. M. JAVED AKHTAR1,* , D. RISTAU2, J. EBERT3, H. WELLING2

Affiliation

  1. Optics Laboratories, P.O. Nilore, Nilore, Islamabad, Pakistan
  2. Laser Zentrum Hannover e.V., Hollerithallee 8, 30419 Hannover, Germany
  3. Laseroptik GmbH, Gneisenaustr. 14, D-30826 Garbsen, Germany

Abstract

This paper gives a comprehensive study of designing, fabrication and determination of damage thresholds of single and double layer antireflection coatings. Single quarter wave layers were prepared form MgF2 and mixtures of MgF2 with other fluorides. An oxide-fluoride mixture was also tested. Double layer “V” coatings were studied taking SiO2 and MgF2 as low refractive index material in combination with HfO2, ZrO2, Ta2O5, Nd2O3, CeO2 and TiO2 as a high refractive index material next to the substrate. All coatings were prepared in a Leybold-Heraeus vacuum coating pant at a base pressure of < 1E-5 mbar on Suprasil substrates by conventional electron beam evaporation method. Film thickness was controlled by usual optical method. Reflectance, scattering, absorption and damage threshold were measured. Damage morphology was done by Nomarsky and scanning electron microscopy (SEM). Influence of barrier layers on damage thresholds of AR-2 systems was also investigated. Besides this, an overcoat effect on AR-2 systems with MgF2 as an outer layer was also observed. Substrate polishing effects on damage threshold of bare as well as AR-coated systems are also reported..

Keywords

Laser Damage, Antireflection coatings, High Damage Threshold Coatings.

Submitted at: Nov. 29, 2006
Accepted at: Aug. 18, 2007

Citation

S. M. JAVED AKHTAR, D. RISTAU, J. EBERT, H. WELLING, High damage threshold single and double layer antireflection (AR) coatings for Nd:YAG Laser: conventional systems, Journal of Optoelectronics and Advanced Materials Vol. 9, Iss. 8, pp. 2391-2399 (2007)