Photonic Crystal concept.

[Lord Loh.]

photonic band bloch analogy tutorial

I am researching the internet about the concept of photonic crystals.

Wikipedia definition says that the photonic crystals are crystals that have periodic dielectrics that control the photons just as the periodic electric field controls the electrons in semiconductor crystals.

However definition from answers.com tell me that it is a crystal that is full of tiny microscopic holes separated by distances in the order of the wavelength of light.

What is dielectric in this sense? In the electronic sense it is an insulator.

From all the literature I have read(internet), I understand that the principle of Photonic crystals is diffraction.

Can anyone please clarify this.

Where can I get more information about Photonic crystals?

I have been through the first 20 or so pages in Google.

Thank you.

Added after 9 minutes:

How does reflection occur at the atomic level?

 

[eogotenks]

photonic crystal concept

check out this sites:

http://ab-initio.mit.edu/photons/tutorial/

http://physicsweb.org/articles/world/13/8/9/1

http://www.icmm.csic.es/cefe/ourwork.htm

 

[pthoppay]

Principle of photonic crystal is analogous to the crystal lattice structure of any metal.

As in metal, you have a lattice and atoms are periodically placed. Due to this periodicity what happens is the valence band electron forms a continuos energy spectrum and making the electrons to travel far distance before collision. These wave function are called as Bloch wave functions.

In similar sense you reproduce periodic crystal structure with the help of peridoic arragement of dense and rarer dielectric materials.this periodic arrangement gives rise to Bloch wave functions and allows light travel to far distance without actually losing energy due to dispersion or by other means.

With this concept in mind if you approach any site it would help you understand photonic crystals better.

Regards,
Prakash.

 

[engmfarhat]

A crystal is a periodic arrangement of atoms or molecules. If a small basic building block of atoms or molecules is repeated spatially, a crystal lattice will be formed. As is well known, semiconductor materials have a bandgap between the valence and conduction energy bands. Electrons are forbidden to occupy any energy level within the bandgap. Similarly, if the dielectric constant of a material changes periodically in space, the material is referred to as a photonic crystal. A photonic crystal possesses a forbidden frequency band in which propagation of electromagnetic waves is prohibited. According to the number of directions in which dielectric materials exhibit periodicity, one-, two-, or three-dimensional photonic crystal structures are possible. Scattering of light by photonic crystals can produce many of the analogous phenomena for photons to the atomic potential acting on electrons.

The photonic bandgap (PBG) can be defined as a range of frequencies for which photons are forbidden to travel through a photonic crystal in any direction of propagation. In analogy to electrons in a crystal, electromagnetic waves propagating in a structure with periodically varying dielectric constants are organized into photonic bands. For certain crystal structures, that have high enough dielectric contrast ratios, these photonic bands are separated by (photonic) gaps in which propagating states are forbidden.

Regards

 

[Lord Loh.]

The periodically varying dielectric? How is this managed? Is the crystal made of two different material?

 

[engmfarhat]

There is many different designs for the photonic crystal. The structure can contain holes rather than the material it self with proper arrangement.

 

[malctt]

I think there is no difference.
the former is general concept.
the later is a specific illustration

 

[si14]

tanx Farhat.