nonlinear opticsphysics.iitm.ac.in/~ph5110/files12/cvnlointro.pdf · 2012-10-02 · 10/2/2012 2 3...
TRANSCRIPT
![Page 1: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/1.jpg)
10/2/2012 1
a milestone in the journey from
Nonlinear Optics ---
![Page 2: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/2.jpg)
10/2/2012 2
The technology of
generating and harnessing light
and other forms of energy
whose quantum is the Photon
![Page 3: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/3.jpg)
10/2/2012 3
The Technology of Photonics : control, communications, computing
Control a large current
using a small current
Nonlinearity is required for light to control light
???
![Page 4: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/4.jpg)
10/2/2012 4
Linear vs nonlinear
Stimulus vs response, Extreme stimulus
Linear response theory
Transport properties, mass, charge, heat
Stress vs starin
Linear regime NonLinear regime
Electric field
Polarization
We are nonlinear!
![Page 5: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/5.jpg)
10/2/2012 5
Nonlinear optical properties (NLO)
Linear optical properties
intensity independent (eg., reflection, refraction and
absorption)
Nonlinear optical properties
depend on the intensity of incident light
eg., nonlinear absorption, nonlinear refractive index
Large optical intensity stronger perturbation of the Coulomb field in the medium nonlinear interaction optoelectronic applications
![Page 6: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/6.jpg)
10/2/2012 6
NL medium
2
SHG : Second harmonic generation
A simple example for NLO effects: Harmonic Generation
e.g. 694 nm (red) 347 nm (violet)
How do we understand this?
physical picture…an analogy
A small signal electronic amplifier produces higher harmonics
of the input signal is not centered around the linear region of the
transistor characteristic curve.
![Page 7: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/7.jpg)
10/2/2012 7
![Page 8: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/8.jpg)
![Page 9: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/9.jpg)
10/2/2012 9
Examples of nonlinear systems
2
20
d g
dt l
Linearised pendulum
Actual (= nonlinear) pendulum
![Page 10: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/10.jpg)
10/2/2012 1
0
0P E
0x xx x xy y xz zP E E E
0
0
y yx x yy y yz z
z zx x zy y zz z
P E E E
and
P E E E
What exactly is NON LINEAR? Nonlinear dependence of polarization
on optical field
Physical meaning, mathematical features
Polarization: dipole moment per unit volume of the medium.
Susceptibility : a characteristic property of the medium.
This is
linear!
![Page 11: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/11.jpg)
10/2/2012 1
1
0
0
y yx x yy y yz z
z zx x zy y zz z
P E E E
and
P E E E
x xx xy xz x
y yx yy xy y
z zx zy zz z
P E
P E
P E
0x xx x xy y xz zP E E E
0
z
i ij j
x
P E
0i ij jP E
Einstein’s summation notation: Summation over repeated/dummy variable
![Page 12: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/12.jpg)
10/2/2012 1
2
Linear optics : superposition
No energy transfer among waves
Nonlinearity Energy transfer; wave mixing
n th order, (n+1) wave mixing
(n) : susceptibility of n th order is an
(n+1) th rank tensor with [3(n+1)] components
(1) (2) (3)
0 ...i ij j ijk j k ijkl j k lP E E E E E E
• a tensor quantity • a complex quantity • a frequency-dependent quantity
( )n
What exactly is NON LINEAR? Nonlinear dependence of polarization on optical field
![Page 13: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/13.jpg)
10/2/2012 1
3
Second Order Nonlinear Optical Processes
• Second harmonic generation
• Linear electro-optic effect : Pockel’s effect
Large and fast nonlinearity: A materials problem
Third order Nonlinear Optical Effects
• Phase conjugation
• Stimulated Raman scattering
• Self focusing
• Bistability
• Quadratic electro-optic effect : Kerr Effect
(1) (2) (3)
0 ...i ij j ijk j k ijkl j k lP E E E E E E
![Page 14: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/14.jpg)
Second order NLO effects
(2) 2
SHG : Second harmonic generation
(2) 1
Sum and difference frequency generation
2
1+2
12
• Optical parametric oscillation • Applications of wave mixing
Latest solid state tunable lasers commercially available today are based on wave-mixing
e.g. Ti:Saphire
![Page 15: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/15.jpg)
10/2/2012 1
5
The first ever experiment on Nonlinear optics
![Page 16: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/16.jpg)
10/2/2012 1
6
Second Harmonic Generation
![Page 17: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/17.jpg)
10/2/2012 1
7
![Page 18: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/18.jpg)
10/2/2012 1
8
Optical Phase Conjugation : idea
The phase of wave 4 is conjugated w.r.t that of wave 3 i.e. 4 is a time-reversed replica of 3
1 2
3
4
beam 1 beam 2
beam 3
beam 4
Scheme of DWFM
beam 1 beam 2
beam 3
beam 4
Scheme of DWFM
Three input waves inside a medium
generate a fourth wave as output
(3)
(3)
(3)
![Page 19: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/19.jpg)
10/2/2012 1
9
Optical Phase Conjugation : implementation
![Page 20: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/20.jpg)
Plane wave distorter ord. mirror
Reflection of a distorted wave from an ordinary mirror
distorted
distorted,
reflected further
distorted
incident
![Page 21: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/21.jpg)
Reflection of a distorted wave from a OPC mirror
Plane wave distorter OPC mirror
distorted
distorted,
‘reflected’ from OPCM distortion-corrected
incident
Remember:
‘OPC mirror’ is not a
mirror,
but an OPC setup
![Page 22: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/22.jpg)
10/2/2012 2
2
A picture from Wikipedia
![Page 23: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/23.jpg)
10/2/2012 2
3
Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection
Ordinary mirror
Optical Phase conjugate mirror Note: OPC mirror is not actually any mirror, but an OPC set up; with beam 3 as input and beam 4 as output. Beam 4 results from NL wave mixing and emerges out in a direction exactly
opposite to that of beam 3.
beam 1 beam 2
beam 3
beam 4
Scheme of DWFM
beam 1 beam 2
beam 3
beam 4
Scheme of DWFM
![Page 24: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/24.jpg)
10/2/2012 2
4
Optical Phase Conjugation: Applications
Apart from measurement of chi-3 to characterize the NL material, wave front reversal (time-reversal) and distortion-healing properties of OPC are used in Adaptive Optics applications such as
Precise targeting of a beam,
Precise beam control in lithography,
Aberration-correction in amplifiers in fiber-optic communications etc
Optical data and image processing
![Page 25: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/25.jpg)
10/2/2012 2
5
![Page 26: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/26.jpg)
10/2/2012 2
6
![Page 27: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/27.jpg)
10/2/2012 2
7
![Page 28: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/28.jpg)
Guassian laser beam
Nonlinear medium
Self focusing n(I) = n0 + n2I
IIIIIIII ((((((
Applications :
•Beam shaping •Pulse shaping – soliton propagation •Optical limiting •Measurement of n2
An NLO phenomenon of the third order
![Page 29: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/29.jpg)
10/2/2012 2
9
Implications of self focusing: a) The beam gets focused into one or more extremely narrow filaments with high intensity, sometime damaging the medium. b) The focusing effect can be used to compensate for the
beam spreading effect due to diffraction over large
distances, e.g. in fiber optic communications.
Thus a shape-maintaining beam (spatial soliton) can be
obtained.
c) By measuring the changes in beam profile in a self focusing experiment, it is possible to measure
(3)
An NLO phenomenon of the third order
![Page 30: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/30.jpg)
10/2/2012 3
0
An NLO phenomenon of the third order:
Self focusing: A medium behaves like a lens
and a parallel beam gets focused (without any lens)
medium (3)
Refractive index becomes dependent on intensity I for large I
n(I) = n0 + n2I
![Page 31: Nonlinear Opticsphysics.iitm.ac.in/~PH5110/files12/CVnlointro.pdf · 2012-10-02 · 10/2/2012 2 3 Ordinary mirror vs. “OPC mirror” i.e. linear reflection versus nonlinear reflection](https://reader034.vdocument.in/reader034/viewer/2022042304/5ecfee4f7bb5e662a52eae51/html5/thumbnails/31.jpg)
10/2/2012 3
1
Conventional Materials
•Inorganic salts KDP, ADP, BaTiO3, BBO
•Semiconductors GaAs, Si, Ge, InSb
•Organic Materials Polymers, dyes, urea
Figure of Merit Large and Fast nonlinearity
Novel Materials QD, CNT, PBG
Materials for Nonlinear Optics