This document discusses using the Z-scan technique to characterize the third-order nonlinear optical properties of silver nano colloids. It introduces nonlinear optics and some of its applications. It then discusses how metal nanoparticles can be prepared using laser ablation or Z-scan techniques and how the Z-scan technique works to measure nonlinear optical properties. The document outlines an experiment using laser ablation to prepare silver nanoparticles and the Z-scan technique to characterize their nonlinear optical response.

1. Synthesis and estimation of third order non
linear optical parameters of silver nano
colloids using Z- Scan technique.

2. Introduction
 Nonlinear Optics is the study of various phenomena
related to the interaction of intense electromagnetic
radiation with matter

3. Applications of NLO
 Telecommunications
 Optical switching
 Sensor protections
 Optical information storage
 Optical computing.

4. Requirements
 Materials which are chosen for these applications
require excellent optical quality with large and stable
optical nonlinearity in the solid state form. So the
present need is to identify such materials

5. Nonlinear optical properties of metal
nanoparticles
 Recently there has been a growing interest in the
nonlinear optical properties of metal nanoparticles
particularly of metal nanoparticles in colloidal
solutions doped composite films.

6. Metal nanoparticles in colloidal
solutions can be prepared by
 Laser ablation.
 Z- Scan Techniques.

7. Laser ablation technique
 Laser ablation is the process of removing material
from a solid surface by irradiating it with a laser beam.

8. Experimental set up

9. Z-Scan
 The Z-scan technique is to measure intensity dependent nonlinear
susceptibilities of materials .
 The technique is particularly useful when the nonlinear refraction is
accompanied by nonlinear absorption and it allows the simultaneous
measurement of nonlinear refractive index and nonlinear absorption
coefficient.
 The sample is translated in the Z-direction along the axis of a focused
Gaussian beam and the far field intensity is measured as function of sample
position.
 The interaction of the medium with the laser light changes as the sample is
moved. This is because the sample experiences different intensities,
dependent on the sample position relative to the focus.
 By measuring the transmittance through the sample as a function of the -
position of the sample, information about the light-matter interaction can
be extracted.

10. Experimental set up

11. Preparation of Silver Metal
nanocomposites
SEM Image of Ag.

12. UV-Visible spectra of Ag nanocolloid

13. RESULT
 In the present work, metal nanoparticles of silver prepared by
laser ablation technique and nonlinear characterization were
performed using Z-scan experiment using a pulsed laser.

14. CONCLUSIONS AND FUTURE SCOPE
 The nanoparticle formation through laser ablation techniques
was confirmed with SEM and UV-Visible images .
 The result suggests that silver nanocolloids are one of the
suitable candidates for photonic applications.
 Future directions are to executing the time-resolved studies of
all these molecules to ascertain the response times.
 model the nonlinear absorption behavior based on a five level
model including all the possible absorption mechanisms such as
excited state absorption, 2PA, 3PA etc.
 fabricating the actual devices and testing their performance.