New laser materials: Fabrication and characterisation

Transcription

1 New laser materials: Fabrication and characterisation Francesc Diaz Francesc Díaz. Menorca, setember 2004

2 Outline: Objectives of FiCMA Research Group Growth of KREW by TSSG method Structural and physical characterisation Spectroscopy of Ln 3+ in KREW Laser action experiments Francesc Díaz..Menorca, setember 2004

3 What are the research objectives in FiCMA? Obtaining process and physical-crystallographic characterisation of crystalline materials with laser NLO or photonic applications Francesc Díaz..Menorca, setember 2004

4 What are the research objectives in FiCMA? OBTAINING PROCESS BULK EPITAXY MICRO- AND NANO- STRUCTURED MATERIALS LASER KREW KLuW/KLuW:Yb KREW APLICATIONS HOST KYW/KYW:Yb nanopowder NLO KTP KTP/KTP:Ge PPRTP MATERIALS RTP RTP/RTP:Ge BBO PHOTONIC 2-D KTP PhC Francesc Díaz..Menorca, setember 2004

5 LASER MATERIALS (Bulk single crystals) KRE(WO 4 ) 2 family KGW:RE KYW:RE KYbW:RE KErW:RE KLuW:RE Francesc Díaz..Menorca, setember 2004

6 NLO MATERIALS (Bulk single crystals) RbTiOPO 4 family RTP RTP:Nb RTP:(Nb,Er) RTP:(Nb,Yb)

7 NLO MATERIALS (Bulk single crystals) KTiOPO 4 family KTP KTP:Nb KTP:(Nb,Er) KTP:(Nb,Yb) BBO BBO:Nd BBO:Er BaB 2 O 4 family

8 LASER+NLO MATERIALS (Bulk single crystals) KRE(PO 3 ) 4 family KNP KGP

9 THIN FILM MATERIALS (single crystal): Epitaxial layer of KYW:Yb on (010) faces of KYW substrate Francesc Díaz..Menorca, setember 2004

10 Preparation of Nanopowders of KREW by Sol-Gel Sol-Gel : Pechini Method KGdW Monoclinic Phase

11 Fabrication of photonic crystals of the KTP family 1-D photonic crystals in PPRTP 2-D photonic crystals in KTP Francesc Díaz..Menorca, setember 2004

12 OBTAINING PROCESS OF KREW:Ln 3+ Importance of KREW:Ln 3+ as laser host KREW stoichiometry assures a priori the RE 3+ substitution by Lanthanides, till 100 % of substitution. The monoclinic structure creates a strong anisotropy which allows the polarisation of the generated laser emissions. The presence of the groups (WO 4 ) 2- makes possible the multiplicity of emission channels for Raman scattering. Francesc Díaz. Menorca, setember 2004

13 CRYSTAL GROWTH FROM THE MELT Materials such as Si, GaAs and YAG among others Melting of the stoichiometric mixing of reagents and controlled solidification. CRYSTAL GROWTH FROM HIGH TEMPERATURE SOLUTION Some materials of interest show: - Phase transitions - Decomposition before melting (incongruent melting) or: - Melting at very high temperatures Francesc Díaz..Menorca, setember 2004

14 Solvent research Polimorphic transf. with T( ºC) Crystal growth in solution 1600 Looking for the suitable solvent Temperatura ( o C) 1473 Study of the binary system K 2 O - WO K 2 WO 4 + Liq K 2 W 2 O 7 E E' P 1 P 3 P P 2 ' K 2 W 4 O 13 79% % P K 2 W 6 O 19 Solid.solution K 2 W 8 O K 2 W 2 O 7 619ºC -LOW CRYSTAL GROWTH TEMPERATURES -LOW VISCOSITY - NO ALIEN ELEMENTS % Molar de WO 3 Francesc Díaz..Menorca, setember 2004

15 SOLVENT AND SOLUBILITY CURVE TEMPERATURE (ºC) % SOLUTO Solvent K 2 W 2 O 7 High temperature Phase Growth Point Economically Not profitable 15-85% mol SOLUTE/SOLVENT Growth Temperature ºC p

16 PHYSICAL PROCESSES INVOLVED IN TSSG HYDRODINAMICS OF CRYSTAL GROWTH AT HIGH TEMEPRATURE ACTION OF ELECTRIC AND MAGNETIC FIELDS NATURAL CONVECTION GRAVITATIONAL CONVECTION NON-GRAVITATIONAL CONVECTION FORCED CONVECTION THERMIC CONVECTION CONCENTRATIONAL CONVECTION CONCENTRATIONAL CAPILLAR CONVECTION THERMOCAPILLAR CONVECTION OTHERS Francesc Díaz..Menorca, setember 2004

17 TSSG CRYSTAL GROWTH - Steps PHYSICAL PROPERTIES OF THE SOLUTIONS AT HIGH TEMPERATURES SIMULATION OF THE THERMODYMANICS CONDITIONS OF CRYSTAL GROWTH (TSSGSP Utility configuration of the growth parameters) REAL GROWTH

18 DETERMINATION OF THE SOLUTION DENSITY AT HIGH TEMPERATURE ARQUÍMEDES METHOD

19 DETERMINATION OF THE SOLUTION VISCOSITY AT HIGH TEMPERATURES COAXIAL CYLINDERS METHOD

20 DETERMINATION OF THE SURFACE TENSION OF THE SOLUTION AT HIGH TEMPERATURES MENISC RUPTURE METHOD σ = β Wmax 4πR

21 EXPERIMENTAL SIMULATION (examples) Example of of horizontal visualization (nonaxisymmetric flux)

22 EXPERIMENTAL SIMULATION Example of axi-vertical visualization Example of axi-vertical visualization

23 NUMERIC SIMULATION OF THE TRANSFER OF THE MOVEMENT QUANTITY

24 Growth of Single crystals of KREW and KREW:Ln 3+ using a seed Method TSSG- slow cooling 200 g of solution 15% - 85% mol solute/solvent Homogenisation a T = 50 o C + T S Introduction of the oriented seed in the furnace. Rotation of the seed at 60 rpm Seeding procedure: Determination of T S (± 0.1o C) Cooling temperature ramp 0.1 o C/hour(2ºC) / 0.05 o C/hour(8ºC) Duration of around 8 days to growth 3-4 g

25 Growth of Single crystals in high viscous solutions RTP seed Alumina rod RTP grown crystals Platinum crucible Flux Platinum turbine Carvajal et al., Chem. Mater., 12 (2000) 3171 ACCENTRIC CRYSTAL GROWTH SYSTEM

26 STRUCTURAL AND MORPHOLOGICAL CHARACTERISATION X-Ray Powder Diffraction X-Ray Single crystal Diffraction Neutron diffraction Raman Spectroscopy Indexation of obtained faces Linear thermal expansion tensor by X-ray powder Diffraction

27 III. ESTRUCTURA DEL KGW CRYSTALLINE STRUCTURE OF KGW Resolution of the structure with X-ray diffraction of single crystal Monoclinic system Space- Group C2/c Point - Group 2/m a=10.652(4)å b=10.374(6)å c=7.582(2)å β =130.80(2)º Pujol et al. J. Appl. Crystallogr., 34 (2001) 1 x y z Gd (6) W (4) (3) (6) K (3) O(1) (14) (12) (18) O(2) (14) (12) (17) O(3) (13) (12) (17) O(4) (14) (12) (18)

28 STRUCTURE OF KGW: Potassium environment Pujol et al. J. Appl. Crystallogr., 34 (2001) 1 K-O Bond distances: 2.796(13)-3.309(12) Å Bidimensional layer of dodecahedra in the [101] and [110] directions

29 STRUCTURE OF KGW: Relation between polihedra Pujol et al. J. Appl. Crystallogr., 34 (2001) 1 Chaine of GdO8 and KO12 parallel to the c crystallographic direction KO12 shares 6 edges with3 double chaines WO6

30 CRYSTALLINE STRUCTURE OF KGW Entorno del gadolinio Pujol et al. J. Appl. Crystallogr., 34 (2001) 1 Chain of square antiprisms parallel to the direction [101] Distances Gd-O: 2.271(12) (11) Å

31 CRYSTALLINE STRUCTURE OF RTP:(Nb,Er) BY NEUTRON POWDER DIFFRACTION Only one phase existed with the same structure as KTP Er 3+ substituted Ti 4+ in Ti(1) and Ti(2) positions Nb 5+ substituted Ti 4+ only in Ti(1) positions Carvajal et al. Chem. Mater., 15 (2003) 2338

32 MORPHOLOGY OF KGW Donnay-Harker Law R hkl 1/d hkl {hkl} d hkl (Å) Pujol et al. J. Appl. Crystallogr., 34 (2001) 1

33 THERMAL CHARACTERISATION Lineal thermal expansion tensor Second order tensor Three principal directions (axes of the characteristic surface) A priori: Principal direction // b 2 principal directions located in the plane a-c Coefficients of the lineal thermal expansion (crystal-physic system) α = ( L / T) / L α 11 α 22 α 33 Thermo-optical coefficient dn/dt Study of the thermal evolution of the unit cell parameters of the KGW host with X-ray powder diffraction.

34 THERMAL CHARACTERISATION Values of the linear thermal expansion tensor at 25ºC (principal system) [106] X 3 12 o c Orientation of the Linear thermal expansion tensor at 25ºC α ij = º C -1 X 1 [302] b=x 2 [010] Pujol et al. Mat. Sci. Forum, (2001) o a

35 OPTICAL CHARACTERISATION Transparency window Optical Ellipsoid Chromatic dispersion curves Non-linear optical characterisation

36 OPTICAL CHARACTERISATION OF THE HOST Transparency window of the host ( 25ºC) TRANSMISSION TRANSMISIÓN (ua) radical OH - CO WAVELENGTH Longitud de onda (nm) Transparent material in the interest region Threshold: 310 nm (32258 cm -1 ) nm (1876 cm -1 ) Absorption bands: 2800 nm (3571 cm -1 ), absorption of the radical OH nm (2358 cm -1 ) contamination with CO 2

37 OPTICAL CHARACTERISATION Orientation of the optical indicatrix of KGW (25 ºC, λ = 632 nm) κ =21.5º A priori: Principal Direction // b 2 Principal directions located in a-c plane 62.3º Angle between N g and c (κ)= 21.5º Angle between N m and a = 62.3º Pujol et al. Appl. Phys. B, 68 (1999) 187

38 OPTICAL CHARACTERISATION Índice Refractive de refracción index Change of the refractive indices with wavelength: Chromatic dispersion curve (25ºC) n g n m n p Longitud Wavelength de onda (nm) (nm) A B C (nm) D (nm -2 ) n g x10-9 n m x10-9 n p x10-9 n 2 = A + 1 B ( C / λ) Pujol et al. Appl. Phys. B, 68 (1999) D 2 λ

39 SPECTROSCOPY AND LASER ACTION RESEARCH Optical absorption of lanthanides at room and low temperature Optical emission spectra of lanthanides at room and low temperature Lifetime studies

40 Distribution coefficiet of Ln in KREW

41 Solubility curve of KGW, KYW, KYbW and KLuW in K 2 W 2 O 7

42 SPECTROSCOPY OF THE ACTIVE IONS: Polarised absorption at RT σ abs [10-19 cm 2 ] 1.2 (a) energy [cm -1 ] ' ' ' 0 2' F 7/2 0 1' 2 F 5/2 0 0' 1 0' KYb(WO 4 ) 2 2 0' E//N m E//N p E//N g σ abs (maximum) is about 12 x cm 2 at 981 nm for E//N m. Absorption length of only 13.3 µm for Spectral range suitable KYbW. for diode pumping (InGaAs). wavelength [nm] Pujol et al. Physical Review B, 65, :1-11 (2002)

43 SPECTROSCOPY OF THE ACTIVE IONS Polarized optical absorption at 6 K O.D. 4,5 4,0 3,5 3,0 2,5 2,0 1,5 1,0 0,5 E//N m (0) (2') KLu(WO 4 ) 2 :Yb (0) (1') (0) (0') 0, Wavelength [nm] Vibronic peaks Yb 3+ (2 ) (1 ) (0 ) (0) Host Energy position (cm -1 ) KGW 10196, 10487, KYW 10187, 10490, KYbW 10188, 10500, KLuW 10187, 10498, Pujol et al. Physical Review B, 65, :1-11 (2002).

44 SPECTROSCOPY OF THE ACTIVE IONS Emission of Yb 3+ at RT and 10 K Yb 3+ intensity [arb. units] pump laser (0') (0) (0') (1) (0') (2) KLu(WO 4 ) 2 :Yb (0') (3) 300 K 10 K (0 ) (3) (2) (1) (0) wavelength [nm] Broad emission linewidth Host Energy position (cm -1 ) KGW 0, 163, 385, 535 KYW 0, 165, 410, 542 KYbW 0, 168, 438, 555 KLuW 0,175, 435, 559

45 SPECTROSCOPY OF THE ACTIVE IONS Emission of Yb 3+ σ e KLu(WO 4 ) 2 :Yb σ emis (maximum) is about 14.7 x cm 2 at 981 nm for E//N m calculated by means of the reciprocity method ( υ) = σ ( υ) abs Z Z l u exp ( E hυ) zl kt Mateos et al. IEEE J. Quantum Electron, 40 (2004) 1056 σ [10-20 cm 2 ] 2,0 1,5 E // Ng 1,0 0,5 0, E // Nm ,5 absorption emission ,0 E // N p 1,5 1,0 0,5 0, wavelength [nm]

46 SPECTROSCOPY OF THE ACTIVE IONS Lifetime of Er ,9 4 I 13/2 4 I 15/ ,9 S 4 3/2 I 15/2 Intensity ( a.u.) 0,8 0,7 0,6 0,5 0,4 Erbium concentration 0.5% 13.4 ms 1% 18.8 ms 3% 13.6 ms 5% 12.7 ms KYb(WO 4 ) 2 :Er 0,8 0,7 0,6 0,5 0,4 λ p = 488 nm 30 µs λ p =980 nm 140 µs KGd(WO 4 ) 2 :Yb,Er 0,000 0,003 0,006 0,009 0,012 Time (s) [Er 3+ ] τ 1.5 µm 0,0 2,0x10-5 4,0x10-5 6,0x10-5 8,0x10-5 1,0x10-4 Time (s) [Er 3+ ] τ 550 nm Mateos et al. Phys. Rev. B, 66 (2002) Mateos et al. Appl. Phys. Let.t, 80 (2002) 4510

47 SPECTROSCOPY OF THE ACTIVE IONS Energetic overlap Er 3+ 2 K 15/2 2 G 4 9/2 G 2 11/2 H 9/2 Energy transfer Upconversion Sensitisation Back-energy transfer ENERGY (cm -1 ) F 3/2 4 F 4 F 2 7/2 5/2 H 4 11/2 S 3/2 4 F 9/2 4 I 9/2 4 I 11/2 4 I 13/2 Yb 3+ 2 F 5/2 Optical Density KGW:Er 3+ 4 I 4 15/2 I 11/2 KGW:Yb 3+ 2 F 2 7/2 F 5/ I 15/2 Mateos et al. IEEE J. Quantum Electron, 40 (2004) F 7/ Energy (cm -1 )

48 SPECTROSCOPY OF THE ACTIVE IONS 1.5 µm emission of Er 3+ at RT σ (10-20 cm 2 ) 3,0 2,5 2,0 1,5 1,0 0,5 0,0 KGd(WO 4 ) 2 :Yb,Er Energy (cm -1 ) 1534 nm σ emis (maximum) is about 2.3 x cm 2 at 1534 nm for E//N m calculated by means of the Reciprocity method ENERGY (cm -1 ) Er 3+ 4 I 13/2 4 I 15/2 F 9/2 Yb 3+ 4 I 9/2 4 I 11/2 4 I 13/2 4 I 15/2 λ = 940 nm [Yb 3+ ] I (1.5 µm) 2 F 5/2 2 F 7/2 Mateos et al. Phys. Rev. B, 66 (2002)

49 SPECTROSCOPY OF THE ACTIVE IONS ENERGY (cm -1 ) KYb(WO 4 ) 2 :Er Er 3+ 2 K 15/2 2 G 4 9/2 G 2 11/2 H 9/2 4 F 3/2 4 F 4 F 2 7/2 5/2 H 4 11/2 S 3/2 4 F 9/2 4 I 9/2 4 I 11/2 4 I 13/2 4 I 13/2 6515, 6543, 6570, 6603, 6670, 6723, 6737 cm -1 4 I 9/ , 12441, 12468, 12498, cm -1 4 F 9/ , 15280, 15332, 15341, cm -1 4 S 3/ , cm -1 2 H 11/ , 19056, 19128, 19170, 19205, cm -1 4 F 7/ , 20471, 20497, cm -1 4 F 5/ , 22136, cm -1 4 F 3/ , cm -1 2 H 9/ , 24523, 24569, 24584, cm -1 4 G 11/ , 26223, 26326, 26386, 26434, cm -1 4 G 9/ , 27293, 27320, 27361, cm -1 2 K 15/ , 27568, 27641, 27735, 27936, 27978, cm I 15/2 Mateos et al. IEEE Journal of Quantum Electronics, 40 (2004) 759

50 SPECTROSCOPY OF THE ACTIVE IONS 1.5 µm emission of Er 3+ at 10 K Energy (cm -1 ) ' 6' 5' 4' 3' 2' ' 1 4 I 13/2 4 I 15/2 Intensity (a.u.) KYb(WO 4 ) 2 :Er X O * X O * X O * X O * X O * X O * X O * X O * Host Energy position (cm -1 ) KGW 0, 29, 64, 105, 139, 227, 282, 298 Energy (cm -1 ) KYW 0, 28, 62, 106, 137, 235, 291, 307 KYbW 0, 26, 61, 106, 138, 239, 298, 311 KErW 0, 27, 60, 103, 133, 230, 288, 302 Mateos et al. Phys. Rev. B, 66 (2002)

51 SPECTROSCOPY OF THE ACTIVE IONS 550 nm emission of Er 3+ at RT σ (10-20 cm 2 ) 2,4 2,2Absorption 2,0 Emission 1,8 1,6 1,4 1,2 1,0 0,8 0,6 0,4 0,2 0, Energy (cm -1 ) σ emis (maximum) is about 1.85 x cm 2 at 553 nm for E//N m calculated by means of the Füchtbauer- Ladenburg method KGd(WO 4 ) 2 :Yb, Er σ em ( λ) = 8πn [Yb 3+ ] I (550 nm) 2 λ 4 I cτ ( λ) I( λ) f dλ Mateos et al. Appl. Phys. Let.t, 80 (2002) 4510

52 LASER ACTION MEASUREMENTS Collaboration with the Max-Born Institute for Non-Linear Optics and Ultrafast Spectroscopy in Berlin, Germany Continuous-wave regime Pulsed regime (Quasi-CW) Pumping: Ti:sapphire Tunability Diode laser (InGaAs) Diode-pumped solid-state lasers (DPSSL)

53 SETUP CONTINUOUS WAVE KYbW LASER - Face-cooled (water) KYbW crystal 5 mm Ø, thermally annealed - Pump laser Ti:Sa, >1.5 nm LM - Laminar laser mount )

54 Yb:KLuW/KLuW LASER: Experimental setup output M 3 Yb:KLuW/KLuW M 4 without active cooling M 1 M 2 Lp Ti:sapphire pump laser Yb:KLuW epitaxial layer: 10% Yb-doped, (010) face polished down to 100µm KLuW substrate crystal: 1100µm thick, 8mm x 5mm Pump laser: Ti:sapphire, nm Output coupler transmission: 1% - 10%

55 LASER OPERATION OF Yb 3+ Continuous-wave regime (KLuW:Yb) output power [mw] Ti:sapphire laser pumping: η 0 =34.1%, λ P =986nm, λ L =1044nm linear fit: slope η=42.9% diode laser pumping: η 0 =14.5%, λ P =980nm, λ L =1043.4nm linear fit: slope η=35.6% KLu(WO 4 ) 2 :Yb Pump Laser 2 F 5/2 2 F 7/2 Laser operation for the first time to our knowledge absorbed pump power [mw] Mateos et al. IEEE J. Quantum Electron., 40 (2004) 1056

56 Thank you for your attention Menorca, setembre 2004.