Liquid Crystals

Chapter 11 - Introduction to Nonlinear Optics

11.1.   NONLINEAR SUSCEPTIBILITY AND
INTENSITY-DEPENDENT REFRACTIVE INDEX


In Chapter 2, we discuss the refractive indices of liquid crystals in terms of the
induced polarization P and the optical electric field E, where P is linearly related to
E. Generally speaking, a material is said to be optically nonlinear when the induced
polarization P is not linearly dependent on E. This could happen if the optical field
is very intense. It could also happen if the physical properties of the material are easily
perturbed by the optical field. In this chapter we describe the general theoretical
framework for studying these processes. Specific nonlinear optical phenomena
observed in liquid crystalline systems will be presented in Chapter 12.

There are two basic approaches. In many systems (e.g., atoms, molecules, and
semiconductors), the primary processes responsible for nonlinear polarizations
are associated with electronic transitions. To describe such processes and obtain
the correct polarization, it is necessary to employ quantum mechanical theories.
On the other hand, many processes are essentially classical in nature. In liquid
crystals, for example, processes such as thermal and density effects, molecular
reorientations, flows, and electrostrictive effects require only classical mechanics
and electromagnetic theories. In this chapter the fundamentals of nonlinear optics
are described within the framework of classical electromagnetic theories. Some of
the quantum mechanical aspects of electronic nonlinearities were given in
Chapter 10.

UNLIMITED FREE ACCESS TO THE WORLD'S BEST IDEAS

close
Already an Engineering360 user? Log in.

This is embarrasing...

An error occurred while processing the form. Please try again in a few minutes.

Customize Your Engineering360 Experience

close
Category: Liquid Crystal Display (LCD) Modules
Privacy Policy

This is embarrasing...

An error occurred while processing the form. Please try again in a few minutes.