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G R O U P M E E T I N G RE P O R T

1 3 JA N U A R Y2 0 1 4

B U E N S U C E S O, C L A R I S S E E L I C A

Non-Linear Opticsand

Second-Harmonic Generation1

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Non-Linear Optics2

Branch of optics that describes the behavior of lightin a non-linear media

LINEAR OPTICS vs NON-LINEAR OPTICS

F (x1+ x2+ ) = F (x1) + F (x2) +

F (ax) = aF (x)

Requirements for a linear system

*Linear optics can be described using linearequation while non-linear optics need higherorder equation

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Non-Linear Optics3

REQUIREMENT FOR A NON-LINEAR MEDIA

1. Very high intensity light (e.g. pulsed lasers)

2. Strongly birefringent

3. Specific crystal symmetry

4. Transparent

5. Have high damage thresholds

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Non-Linear Optics4

NON-LINEAR OPTICAL PROCESSES (examples)

Frequency mixing processes (e.g. SHG)

Optical Kerr effect

Cross-phase modulation

Four-wave mixing

Et c.

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Second Harmonic Generation5

aka Frequency Doubling

Two photons of the same frequency interacting witha nonlinear material are combined to generate anew photon whose frequency is twice the original

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Second Harmonic Generation6

Most common material for SHG: CRYSTAL

e.g. quasi-phase matching crystal like periodically-poled lithium niobate

THREE TYPES OF SHG IN CRSYTAL

starting photons resulting photon

TYPE 0 SHG Extraordinary polarization Extraordinary

polarization withfrequency twice theoriginal

TYPE I SHG Ordinary polarizationTYPE II SHG Orthogonal polarization

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Second Harmonic Generation7

BIREFRINGENCE

An optical property of a material with a refractiveindex is dependent on the polarization and

propagation of direction of lightDouble Refraction

wrt optic axis: ordinary ray

|| wrt optic axis: extraordinaryray

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Second Harmonic Generation8

Current SHG materials: ORGANIC POLYMERSand MATERIALS

ADVANTAGES:

1. Cheaper2. Have lower drive voltages

3. Superior performance

4. Wide applications in environmental science

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Surface Second Harmonic Generation9

Method for probing interfaces in atomic andmolecular systems

Conversion of two photons into a single photon byinteracting with a noncentrosymmetric media

CENTROSYMMETRY

refers to a point group which contains an inversioncenter as one of its symmetry elements

noncentrosymmetric materials =no inversion symmetry

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Surface Second Harmonic Generation10

Noncentrosymmetric material can be divided into twotypes:

1. Chiral type materials with no rotoinversion

symmetry elements2. Polar type points groups which are neither

centrosymmetry nor chiral; contains uniqueanisotropic axis

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Surface Second Harmonic Generation11

Surface SHG is possible for materials which do notexhibit SHG in the bulk.

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Surface Second Harmonic Generation

source: http://cnsm.kaist.ac.kr/facility.htm

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Application13

3D Imaging

Cox G, Gorrell MD, et.al. "3-Dimensional Imaging of Collagen Using SecondHarmonic Generation."Journal of Structural Biology141.1 (2003): 53-62.

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Application14

3D Imaging

Cox G, Gorrell MD, et.al. "3-Dimensional Imaging of Collagen Using SecondHarmonic Generation."Journal of Structural Biology141.1 (2003): 53-62.

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Application15

3D Imaging

Cox G, Gorrell MD, et.al. "3-Dimensional Imaging of Collagen Using SecondHarmonic Generation."Journal of Structural Biology141.1 (2003): 53-62.

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Application16

3D Imaging

Cox G, Gorrell MD, et.al. "3-Dimensional Imaging of Collagen Using SecondHarmonic Generation."Journal of Structural Biology141.1 (2003): 53-62.

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Application17

Adsorption Studies

Eckenrode HM, et.al. "Adsorption of a Cationic Dye Molecule on PolystyreneMicrospheres in Colloids: Effect of Surface Charge and Composition Probed bySecond Harmonic Generation."The Journal of Physical Chemistry B109.10(2005): 4646-653

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Application18

Adsorption Studies

Eckenrode HM, et.al. "Adsorption of a Cationic Dye Molecule on PolystyreneMicrospheres in Colloids: Effect of Surface Charge and Composition Probed bySecond Harmonic Generation."The Journal of Physical Chemistry B109.10(2005): 4646-653

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Application19

Molecular Chirality

Petralli-Mallow T, Hicks JM, etl.al. "Circular Dichroism Spectroscopy atInterfaces: A Surface Second Harmonic Generation Study." The Journal ofPhysical Chemistry 97.7 (1993): 1383-388.

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Application20

Molecular Chirality

Petralli-Mallow T, Hicks JM, etl.al. "Circular Dichroism Spectroscopy atInterfaces: A Surface Second Harmonic Generation Study." The Journal ofPhysical Chemistry 97.7 (1993): 1383-388.

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References21

Boyd, Robert W.Nonlinear Optics. San Diego, CA: Academic,2003.

Cox G, Gorrell MD, et.al. "3-Dimensional Imaging of CollagenUsing Second Harmonic Generation."Journal of Structural

Biology141.1 (2003): 53-62.

Eckenrode HM, et.al. "Adsorption of a Cationic Dye Moleculeon Polystyrene Microspheres in Colloids: Effect of SurfaceCharge and Composition Probed by Second HarmonicGeneration."The Journal of Physical Chemistry B109.10(2005): 4646-653.

Petralli-Mallow T, Hicks JM, etl.al. "Circular DichroismSpectroscopy at Interfaces: A Surface Second HarmonicGeneration Study." The Journal of Physical Chemistry97.7(1993): 1383-388.