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Worshop : LasINOF, June 14th 2010 Aurélien Delestre, E. Fargin, M. Lahaye (ICMCB, Bordeaux, France) V. Rodriguez, F. Adamietz, M. Dussauze (ISM, Bordeaux,

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Présentation au sujet: "Worshop : LasINOF, June 14th 2010 Aurélien Delestre, E. Fargin, M. Lahaye (ICMCB, Bordeaux, France) V. Rodriguez, F. Adamietz, M. Dussauze (ISM, Bordeaux,"— Transcription de la présentation:

1 Worshop : LasINOF, June 14th 2010 Aurélien Delestre, E. Fargin, M. Lahaye (ICMCB, Bordeaux, France) V. Rodriguez, F. Adamietz, M. Dussauze (ISM, Bordeaux, France) M.Bellec, A. Royon, L.Canioni (CPMOH, Bordeaux, France) PATTERNED SECOND HARMONIC GENERATION ON OXIDE GLASSES SURFACE BY THERMAL POLING

2 Outline I / Thermal poling and Second Harmonic Generation (SHG) II / Silver injection by thermal poling and SHG - Samples elaboration and preparation for silver injection - poling voltage and SHG efficiency - Results and interpretation III / Efficient structuring of SHG - Laser ablation, poling - µSHG patterning measurements - Results and interpretation 02 /15

3 Thermal poling for Internal field engraving 03 / 15 Anode Cathode A i ~ 0.5 mA U = 1kV 230°C G Negatively charged depletion zone Na + cations depletion zone creation (L=3-15 µm) Mobile cations can migrate from anode to cathode E int Embedded internal field induces Second Harmonic Generation in Glasses Glasses are centro-symmetric materials  (2) =0

4 Composition : sodium and niobium borophosphate glasses (BPN42) (1-x)[0,95NaPO 3 +0,05Na 2 B 4 O 7 ]+xNb 2 O 5 x = 0,42 Silver injection by poling : Silver layer deposition on the glass surface Glass samples elaboration + silver injection 04 / 15 Metallic silver film Glass SHG modified ? Why silver ? Na + and Ag + : Comparable diffusion coefficients in oxide glasses Structuration of silver electrode SHG structuration ~ 5 mm Poled surface after poling Zone outside the anode Zone under the anode *Référence : M. Dussauze Optics Express, Vol. 13, Issue 11, pp Thermal Poling induces - departure of sodium ions - injection of silver ions

5 Observation : Efficient poling leads to  (2) comparable to the reference Efficient polingNon efficientEfficient poling Sample Reference no AgAg Silver thin film thickness (nm) e ±10 nm   2) (pm/V) ± Nonlinear zone thickness (µm) L ± 0.1 µm  (2) values deduced from Maker Fringes simulations 05 / 15 Why poling is efficient? Why poling can be inefficient? Thermal poling 230 °C, t = 1 h, U ~ 1 kV, i 0 = 0.5 mA (sample thickness 1 mm)

6 Sodium depletion zone: 3 µm thickness Space charge zone identical to SHG efficient zone *Reference : M. Dussauze Optics Express, Vol. 13, Issue 11, pp Reference Without Ag Na, Nb, P atomic concentration profiles Cathode Anode Poled zone Quantitative X-ray analysis on the reference 06 / 15

7 Cations migrations : - Na + ions depletion (6 µm) - Ag + ions penetration (6 µm) Quantitative X-ray analysis 07 / 15 Sample efficient polingWith Ag Ag thickness(nm) ±10 nm170  (  2) (pm/V) ± Nonlinear zone thickness (µm) ± SHG profile correlated to total cations depletion - between 2.9 µm and 6 µm Ag substitutes to Na Efficient poling with Ag - the nonlinear zone producing SHG is located between 0 to 2.9 µm under the surface efficient SHG zone Na depletion zone Ag injection zone % Atomic Depth under the anode surface (µm) Na Ag P Nb Atomic concentration profiles under the anode

8 Cations migration : - Na + depletion ( 2 µm) - Ag + injection ( 2 µm) *reference : E. Fargin Advanced Materials Research Vols (2008) pp déplétion zone Quantitative X-ray analysis 08 / 15 Inefficient poling with Ag Ag + injection compensates Na + depletion No SHG % Atomic Depth under the anode surface (µm) Na Ag P Nb Atomic concentration profiles No space charge zone creation Poling voltage ~1 kV is the minimum to develop efficient poling

9 Influence of voltage on poling efficiency First polings mistake : special attention on the current Now big care on the voltage !!! Thermal poling 230 °C, t = 1 h, U = different voltage, i 0 < 0.6 mA (sample thickness 500µm) SHG efficiency is linked with poling tension 09 / 15

10 SHG architecture Surface profile image of ablated lines BPN42 + Ag thin film deposition Laser Ablation of silver lines (Length = 3 mm, width = 2 µm) Thermal poling 230 °C, t = 1 h, U = 1 kV, i 0 < 0.6 mA laser Yb : Wavelength = 1030 nm pulse duration= 470 fs Repetition rate = 10 MHz Mean power = 6 W Laser fs IR AOM Laser fs IR AOM Laser fs IR AOM Laser fs IR AOM Laser fs IR AOM Laser fs IR AOM Ag thin film Ablated line 100µ m 10 / 15 Image of ablated lines (optical microscopy)

11 µSHG Analysis Y (µm) X (µm) Ag Ablated Poled lines Ag Non ablated poled zone 2ω ( polarization of reflected SHG field ) ω (polarization of incident beam field) µGSH allows different fields orientations Different components in Exemple : YXX Ablated lines 11/ 15

12 XXX polarization  SHG signal analysis on the surface SHG signal is very intense on the lines non ablated zone Intensité (u.a.) Nombre d’onde (cm -1 ) Ablated zone : Analysis Incident Surface 3 µm under the surface Z=0 Z=1 Z=2 Z=3 Z=4 3D mapping: 12 / 15 Wavenumber (cm -1 ) Intensité (u.a.) Nombre d’onde (cm-1) Flight intensity  xxx (2)  0

13 SHG signal for different pump and probe polarizations New Symmetry induced by poling 13 / 15 Usual symmetry obtained by poling C ∞v E int            )2( zzxzzzzyyzxx yyxyyz xxzxzzxyyxxx  Cs (symmetry plane: xz) *reference : A. Delestre, Applied Physics Letters, volume 96, Issue 9, id (2010)

14 Quantitative analysis of elements under anode Silver concentration mapping 14 / 15 Lifted lines Silver concentration variation through ablated lines Ablated lines Silver layer Silver injection [Ag + ] z x Ionic profile in the non ablated area Ionic profile in the ablated area

15 Conclusion and perspectives 15 / 15 + Silver ions introduction by thermal poling : Silver injection is compatible with SHG Control the applied voltage (threshold for efficiency) + Surface SHG architecture obtained by structured silver deposited electrode: - creation of new symmetry in nonlinear poled surface Objective :

16 Laser ps 532 nm  /2 Prism Glan Taylor Laser ps 1064 nm Power regulation µSHG Setup 11 / 23 M1 Platine XYZ CCD polarization Pine hole /4 M2 M3 M4 M5 M6 M7 NIR Objective Filter 2 Filter Notch 1064 ou 532nm Advantages : - Mapping (platine XYZ + CCD) - Résolution ~ 1 µm (Objective NIR 100X, ON = 0,5) - Simultaneous µRaman spectroscopy Sample

17 Présence de signal GSH dans la zone polée Pas de variation de signal GSH dans la zone ablatée Polarisation YXX Y (µm) X (µm) Analyse Incident 1 µm X (µm) Y (µm) Pas de contraste de signal GSH Signal GSH dans/hors des lignes ablatées 24 / 30 Intensité (u.a.) Nombre d’onde (cm -1 )

18 5 µm Y (µm) X (µm) Echantillon tourné de 90° Analyse Incident Y (µm) X (µm) Polarisation YYY Signal GSH homogène Pas de contraste de signal GSH Intensité (a.u.) Nombre d’onde (cm-1) Zone ablatée XYY Signal GSH dans/hors des lignes ablatées 25 / 30 1 µm Y (µm) -5 0 X (µm) Polarisation XYY Variation de signal GSH Intensité (u.a.) Nombre d’onde (cm-1) Zone non ablatée XYY

19 Intensité (u.a.) Longueur d’onde (nm) Les échantillons sont coupés au travers des lignes d’ablation Polarisation ZZZ Lignes ablatées Zone non linéaire Surface d’analyse Signal GSH sur la tranche de l’échantillon Intensité (u.a.) Longueur d’onde (nm) Zone non ablatée XZZZone ablatée XZZ 5 µm Z (µm) X (µm) Analyse Incident 2 µm Z (µm) X (µm) µm Z (µm) X (µm) Polarisation XZZ ONL perpendiculaire aux lignes d’ablation 26 / 30

20 µSHG on cross section with a 90° sample rotation Polarisation XXX Polarisation ZXX 1 µm X (µm) Z (µm) µm X (µm) Z (µm)

21 Hypothèse L’augmentation de GSH dans les lignes ablatées viendrait d’un champ interne perpendiculaire à ces lignes GSH par polarisation thermique + ablation Variation de la concentration d’argent au travers des lignes ablatées Lignes ablatées Couche d’argent Pénétration d’argent [Ag + ] Champ interne additionnel perpendiculaire aux lignes ablatées Z=0 Polarisation YYY Polarisation YXX Résultats de µGSH 2 µm Z (µm) X (µm) Polarisation d ’ analyse lignes d ’ ablation Variations GSH dans la zone d ’ ablation Polarisation XZZ déplétion Migration des cations depuis l’anode Création d’une zone de déplétion (L=3-15µm) anode Création d’un champ interne GSH par polarisation thermique cathode 28 / 30

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