And this was also correlated o a higher absorption

  • No School
  • AA 1
  • 15

This preview shows page 6 - 8 out of 15 pages.

and this was also correlated o a higher absorption than other samples (see Ref [37] where the sample characterization is detailed). For all other samples, that were produced with the best parameters de- termined by the manufacturers, it can be seen that the measured LIDTs are within the margin of error
Image of page 6
6 of the experiment. On this material, that is one of the most important high index materials for the production of optical multilayer coatings for laser applications, the highest LIDT can be achieved af- ter optimization of deposition parameters and the intrinsic limits of the material are reached. Fig. 6. Laser Induced Damage Threshold of 11 different HfO 2 samples. The deposition technique is indicated for each sample. See table 2 for data and references. 3.B. Surface of bulk materials The interest to compare thin films and the sur- face of bulk samples LIDTs is to determine if for a same material the resistance of the film reaches the resistance of the bulk. The LIDT measured on the different bulk samples are reported on figure 7 with the results plotted again as a function of opti- cal bandgap. The previous results obtained on the thin film samples are also reported on this figure for comparison. To be more exhaustive, the thresh- olds of two metals (Platinum and silver thin films for which details can be found in Ref. [10]) are also given on this figure, indicated with a bandgap of 0eV. We recall that, as a difference of most reported data in other papers, the thresholds are given as ’internal’ threshold, i.e. taking into account the electric field value at the surface of the materials in order to make thin film and bulk material results comparable. The LIDTs for the case of thin films and the sur- face of bulk materials follows the same evolution as a function of bandgap and the LIDT values are comparable, with the exception of NaCl and KBr samples that have a low LIDT compared to the mean tendency. These two materials were tested in the air whereas they are known to be hygro- scopic and the low LIDT could be due to modifica- tions of the surface quality due to water absorption. Fig. 7. LIDT of optical thin film materials (color filled squares, with color code similar to previous figures) and bulk materials (gray filled circles) tested in single shot at 500fs and 1030nm, as a function of the optical bandgaps (measured or estimated). The values are expressed as the internal LIDT. The black line is reported from Fig. 4. For all other tested materials, the results have the same linear trend of LIDT versus bandgap. The dispersion of the results around this tendency can be due to the very different physical properties of the tested materials that can influence the dam- age process (electronic, thermal, mechanical and surface properties). In case of oxide coatings, the LIDT of films and the surface of bulk materials are comparable which means that the intrinsic limits of the materials are reached and it seems difficult to improve their LIDT with the optimization of the deposition parameters (as opposed to the case of the nanosecond regime). The highest damage resis-
Image of page 7
Image of page 8

You've reached the end of your free preview.

Want to read all 15 pages?

  • Fall '19
  • refractive index, bandgap, Ultrashort pulse, LIDTs

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern

Stuck? We have tutors online 24/7 who can help you get unstuck.
A+ icon
Ask Expert Tutors You can ask You can ask You can ask (will expire )
Answers in as fast as 15 minutes
A+ icon
Ask Expert Tutors