Enhanced nonlinear optical response of 1-D metal-dielectric photonic - PowerPoint PPT Presentation

Enhanced nonlinear optical response of 1-D metal-dielectric photonic band-gap structures Nick N. Lepeshkin, Aaron Schweinsberg, Ryan S. Bennink, Robert W. Boyd The Institute of Optics, University of Rochester, Rochester, NY 14627, USA Robert L. Nelson Materials and Manufacturing Directorate, Air Force Research Laboratory, (AFRL/MLPO) Wright-Patterson Air Force Base, Ohio 45433-7707 and The Institute of Optics, University of Rochester, Rochester, New York 14627

Outline 1. Motivation How to access nonlinearity of metals? Why 1-D MD-PBG? Optical transparency Nonlinear response? 2. How to Design 1-D MD PBG for NLO 3. Linear properties 4. Elements of nonlinear response High EM field strength Intrinsic susceptibility of metal Phase response of PBG 5. Experimental observation of enhancement of NLO response in 1-D MD PBG

How to access nonlinearity of metals? − ÷ χ ≅ − ( 3 ) 8 7 10 10 esu - opaque! metal − χ ≅ ( 3 ) 10 14 esu - transparent! SiO 2 Discontinuos composite materials: •colloidal solutions •metal doped glasses •granular metal films Layered periodic MD structures: High transparency within specified spectral range (PBG effect) Enhanced NLO response?

1-D Metal/Dielectric PBG structures T 1 0.6 2% 80 nm Cu film 0.4 3 22% 2 0.2 1 2 40/389 nm Cu/SiO 2 FP 0 500 600 700 800 50% 3 5 x 16/98 nm Cu/SiO 2 PBG Wavelength, nm M. Scalora et al . J. Appl. Phys. 83 , 2377-2383 (1998)

How to Design 1-D MD PBG for NLO ε ≅ ε + χ ⋅ η ⋅ ⋅ ( 3 ) 2 F E lin m η − F- phase factor field factor 2 λ = E 650 nm z, nm 5 x 16/196 nm Cu/SiO 2 PBG

Linear optical properties 1- 40 nm Cu film - bulk 2- 5 x 16/98 nm Cu/SiO 2 PBG - composite 0.7 Transmittance A 0.25 0.5 1 R 0.20 0.3 1 0.15 T 0.1 500 550 600 650 700 0.10 1.0 2 A 0.05 0.8 0 0.6 2 400 500 600 700 800 900 0.4 T R 0.2 Wavelength, nm 0 500 550 600 650 700

High EM field strength 1 - 5 x 16/98 nm Cu/SiO 2 PBG 2 - 40 nm Cu film 2.5 1 2.0 2 E 1.5 PBG 2 E Cu 1.0 2 0.5 500 550 600 650 700 Wavelength, nm

Nonlinear susceptibility of bulk metal NLO properties of copper -8 5x10 ⋅ − 8 4 10 esu @ 580 nm -8 @ interband threshold - 4x10 -8 χ Fermi smearing 3x10 ( 3 ) Im( ) -8 2x10 δ = g − ν − E E h ⋅ 9 2 10 esu @ 640 nm -8 1x10 χ << χ ( 3 ) ( 3 ) 0 Re( ) Im( ) 550 600 650 700 FS FS λ , nm δ E − δ k T hc E e B ∆λ ≅ χ = ( 3 ) k T Im( ) C δ FS B FS E 2 E k T − + B g k T 2 ( 1 e ) B E g =2.15 eV F. Hache et al . Appl. Phys. A 47 , 347-357 (1988)

Phase response ∆ φ = -phase sensitivity F π L 2 ∫ ∆ n dz λ 0 |F| 6 5 4 3 2 1 500 550 600 650 700 Wavelength, nm

NLO response of MD PBG ′ δφ = φ δ + ⋅ lin − i (ln( T ) ln( T ( I ) ) - complex nonlinear phase shift ′ ′ ′ δ φ << δ φ δφ ← Z - scan ′ ′ δ φ = 2 I 500 MW/cm ≅ PBG 35 = EKSPLA OPG ′ ′ δ φ ? 640 nm T norm E=2-5 uJ I=100 MW/cm 2 Cu = − t=25 ps ? 540 680 nm Im( δφ ) Cu 1.00 2.0 1.5 PBG 0.75 PBG 1.0 0.50 0.5 Cu 0 50 100 150 200 250 0 500 550 600 650 700 z,mm Wavelength, nm

Conclusions We introduced artificial, stable, solid state NLO material with tunable (by design) transmission band and high damage threshold. We experimentally demonstrated enhanced nonlinear response of 1-D MD PBG structure within the passband compared to that of bulk metal. The enhancement factor was measured to be as high as 35.