I am working on the formation of high frequency periodic surface structures by using femtosecond lasers. I have read many papers about the formation mechanism of HSFL and LSFL structures. here are a lot of theories about these structures. I can't differentiate between these theories. i am little confused. If some one know the answer then please reply.
Thanks
Article Erratum: Mechanism for self-formation of periodic grating st...
Dear Nisar.
The LIPSS require an energy modulation to be formed. A large part of the community thinks that this modulation occurs during the laser irradiation and is due to electromagnetic surface waves (polaritons). A smaller part thinks that the modulation occurs after the energy deposition by non-resonant processes (thermal instability, melted layer instability, ablation instability, etc).
Characteristics of the structures are the following.
(i) The LSFL have a period near to the laser wavelength and have a direction perpendicular to the laser polarization. With my co-workers, we have recently demonstrated that LSFLs are formed by excitation of Surface Plasmon Polaritons. (ii) The HSFLs have a period very small in front of the laser wavelength and their orientation is rather parallel to the laser polarization, but this is material dependent. Their formation mechanisms are still under investigation. A good review can be found here : http://scitation.aip.org/content/lia/journal/jla/24/4/10.2351/1.4712658.
For more details, don't hesitate to ask questions.
Read you soon and best wishes.
Thibault
Some HSFL were observed on Ti.
With thin metallic films, several groups observed HSFL. Gakovic (Belgrade), Semmar (Orléans), etc.
The TF-SPP model [see http://scitation.aip.org/content/aip/journal/jap/116/7/10.1063/1.4887808] applies for these configurations. We can try if you want, because solving this formula is not very easy ;) See you :)
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