vishnu vardhan krishnamacharipotma/vishnu060206.pdf · 2006. 6. 23. · vishnu krishnamachari group...

BERKELEY•DAVIS•IRVINE•LOS ANGELES•MERCED•RIVERSIDE•SAN DIEGO•SAN FRANCISCO•SANTA BARBARA•SANTA CRUZ

Department of ChemistryUNIVERSITY OF CALIFORNIA, IRVINE

Vishnu Vardhan Krishnamachari

Heterodyne CARS imaging:First results

Group SeminarJune 2, 2006

Vishnu Krishnamachari Group Seminar: June 2, 2006

Contents

Raman

CARS

HeterodyneCARS

Setup

Results



Contents

CARS is not Raman!

Heterodyne CARS

Experimental setup

DMSO-Glass Experiment

Contents


Contents

Raman

CARS

HeterodyneCARS

Setup

Results



CARS is not Raman!

Frequency dependence of third-order non-linearsusceptibility around a Raman transitionRaman


Contents

Raman

CARS

HeterodyneCARS

Setup

Results



CARS is not Raman!

Spontaneous Raman emission intensityRaman


Contents

Raman

CARS

HeterodyneCARS

Setup

Results



CARS is not Raman!

CARS intensity : Single peak

CARS


Contents

Raman

CARS

HeterodyneCARS

Setup

Results



CARS is not Raman!

CARS intensity : Double peak

CARS


Contents

Raman

CARS

HeterodyneCARS

Setup

Results



CARS is not Raman!

CARS intensity

Non-resonant and resonant signals interfere

Difficult to analyze the spectrum

Huge background => Poor SNR & sensitivity

CARS intensity is not proportional to the concentration

CARS


Contents

Raman

CARS

HeterodyneCARS

Setup

Results



Heterodyne CARS

Heterodyne detection:Detection of the desired signal by mixing it with a“known” or “well-characterized” signal.

HeterodyneCARS


Contents

Raman

CARS

HeterodyneCARS

Setup

Results



Heterodyne CARS

ωCARSωlo

Detector

• Δφ = π/2 ⇒ Ιout∝ Im{χ(3)}

∝ Conc • Δφ = 0 ⇒ Ιout∝ Re{χ(3)}

HeterodyneCARS


Contents

Raman

CARS

HeterodyneCARS

Setup

Results



Experimental Setup

Setup


Contents

Raman

CARS

HeterodyneCARS

Setup

Results



DMSO Interference

X

Y

X0

Interference between local oscillator and CARS signal

Results


Contents

Raman

CARS

HeterodyneCARS

Setup

Results



DMSO Interference

Time

X0

Interference between local oscillator and CARS signal

Results


Contents

Raman

CARS

HeterodyneCARS

Setup

Results




Glass DMSO

+ local oscillator

t

X0

Simultaneous observation of two heterodyne signals

Results


Contents

Raman

CARS

HeterodyneCARS

Setup

Results




Amplitude of oscillation

Phase difference

Results


Contents

Raman

CARS

HeterodyneCARS

Setup

Results




Results


Contents

Raman

CARS

HeterodyneCARS

Setup

Results




Discrepancies

Results


Contents

Raman

CARS

HeterodyneCARS

Setup

Results



Conclusion

Raman versus CARS

Non-resonant background and its role

CARS intensity is not proportional to conc.

CARS Heterodyne setup

Experiments with DMSO + Glass

vishnu vardhan krishnamacharipotma/vishnu060206.pdf · 2006. 6. 23. · vishnu krishnamachari group...

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