**4. References**

38 Photonic Crystals – Innovative Systems, Lasers and Waveguides

As mentioned before, photonic structures suffer from fundamental trade off between transmission bandwidth (FWHM of the transmitted resonance modes) and the optical delay,

The DBP variation in 1D-NCCW when the optical input intensity changes, is shown in Fig.7 As an example, for the second mode, it can be seen the DBP can be tuned from 17.4 to 15.6

The results of our theoretical study show that 1D-NCCWs can be considered as one of the

It can be seen that by introducing nonlinear defect medium in the one dimensional photonic crystals, three important tasks can be achieved. Firstly, in the presence of defect medium, a new mechanism for transferring optical data as coupled cavity waveguide can be achieved. It can be seen as a reason of intensity dependent of the refractive index in the defect medium, the resonance frequency (mini transmission band) can be tuned in the photonic

Secondly, as a reason of high slope of transmission at resonance bands, slow light in the order of 10-4 and group delay in nanosecond regime can be generated. It can be seen, as a reason of increasing the optical input intensity, not only the magnitude of the speed of light propagation and hence its group delay can be tuned, but also the propagation wavelength

Thirdly, from practical system point's of view, as a consequence of importance of DBP parameter, and necessity to tune it for different users with various technical requirements, the DBP parameter can be dynamically tuned by adjusting the optical input intensity.

best candidates for future all optical processing and high energy laser applications.

as delay bandwidth product (DBP).

by increasing the input optical intensity up to 6.4mW/cm2.

Fig. 7. DBP at the resonance modes versus input intensity.

bandgap zone of the basic one dimensional photonic crystal.

can be adjusted in wide range of photonic bandgap zone.

**3. Conclusion** 


**4** 

*Romania* 

**The Optical Transmission of** 

Petcu Andreea Cristina

**One-Dimensional Photonic Crystals** 

**Containing Double-Negative Materials** 

*National Research and Development Institute for Gas Turbines Bucharest\** 

A crystal is a periodic arrangement of atoms or molecules. The pattern with which the atoms or molecules are repeated in space is the crystal lattice. The crystal presents a periodic potential to an electron propagating through it, and both the constituents of the crystal and

Importantly, however, the lattice can also prohibit the propagation of certain waves. There may be gaps in the energy band structure of the crystal, meaning that electrons are forbidden to propagate with certain energies in certain directions. If the lattice potential is strong enough, the gap can extend to cover all possible propagation directions, resulting in a complete band gap. For example, a semiconductor has a complete band gap between the

The optical analogue is the photonic crystal, in which the atoms or molecules are replaced by macroscopic media with differing dielectric constants, and the periodic potential is replaced by a periodic dielectric function (or, equivalently, a periodic index of refraction). If the dielectric constants of the materials in the crystal are sufficiently different, and the absorption of light by the materials is minimal, then the refractions and reflections of light from all of the various interfaces can produce many of the same phenomena for photons (light modes) that the atomic potential produces for electrons. One solution to the problem of optical control and manipulation is thus a photonic crystal, a low-loss periodic dielectric

There has been growing interest in the development of easily fabricated photonic band gap materials operating at the optical frequencies. The reason for the interest in photonic band gap materials arises from the possible applications of those materials in several scientific and technical areas such as filters, waveguides, optical switches, cavities, design of more

The simplest possible photonic crystal consists of alternating layers of material with different dielectric constants: a one-dimensional photonic crystal or a multilayer film. This arrangement is not a new idea. Lord Rayleigh (1887) published one of the first analyses of

The publishing fee for Andreea Petcu was paid by the National Research and Development Institute

the geometry of the lattice dictate the conduction properties of the crystal.

**1. Introduction** 

valence and conduction energy bands.

medium. (Joannnopoulos et al, 2008).

 \*

for Gas Turbines Bucharest

efficient lasers, etc. ( Li et al., 2008; Wang et al., 2008).

