Time-resolved plasma measurements in Ge-doped silica exposed to infrared femtosecond laser

Abstract

Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers)Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication Citation for published version (APA):Lancry, M., Groothoff, N., Poumellec, B., Guizard, S., Fedorov, N., & Canning, J. (2011). Time-resolved plasma measurements in Ge-doped silica exposed to infrared femtosecond laser. Physical Review B: Condensed Matter, 84(24), 245103-1/8. DOI: 10.1103/PhysRevB.84.245103 General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Using a time-resolved interferometric technique, we study the laser-induced carrier-trapping dynamics in SiO 2 and Ge-doped SiO 2 . The fast trapping of electrons in the band gap is associated with the formation of self-trapped excitons (STE). The STE trapping is doping dependent in SiO 2 . The mean trapping time of electrons excited in the conduction band was found to be significantly lower in Ge-doped silica (75 ± 5 fs) when compared to pure silica (155 ± 5 fs). At our concentration level, this indicates that the plasma properties are determined by the presence of easily ionizable states such as the presence of Ge atoms in the glass network. Therefore, we suggest that in Ge-doped silica there exist an additional trapping pathway that leads to a significantly faster excitons trapping and a higher plasma density when compared to undoped silica.

Tailoring thermoelectric properties of nanostructured crystal silicon fabricated by infrared femtosecond laser direct writing

“…As a result no apparent structural change could be observed. Besides, due to the short plasma lifetime of ~150 fs in SiO 2 glass , the following formation mechanisms of nanogratings are proposed: the non‐radiative relaxation of excitons via relative long lifetime transition from self‐trapped excitons (STE) to point‐defecs (their lifetime is several hundred picoseconds at room temperature) . In particular, a common feature of periodic nanostructure formation between c‐Si and SiO 2 glass is the existence of a transition with a long relaxation time.…”

Size-controlled oriented crystallization in SiO_2-based glasses by femtosecond laser irradiation

“…In this case, the phase transition process is considered to take place due to high-repetition-rate fs-laserinduced heat accumulation. The electronic excitation is initiated by multiphoton ionization [12], and subsequent electron-phonon coupling leads to temperature increase. Then at high repetition rate (typ.…”

Compact Birefringent Waveplates Photo-Induced in Silica by Femtosecond Laser

“…Additionally, two intense absorption bands can be distinguished at short wavelengths, which are attributed to SiE' centers at 210 nm (≡Si, an unpaired electron in a silicon atom bound to three oxygen atoms), and oxygen deficiency center (ODC)(II) at 245 nm, (-O-Si-O-, a divalent silicon atom) [27,28]. A detailed description of their formation mechanism is given in [29]. In addition the absorption measurements of the sample after annealing at 600 °C for 2 h clearly indicated complete erasure of the E' and ODC(II) defects if attributed to the absorption bands observed at 210 and 240 nm, respectively (Figure 5a).…”