Photonic Crystals

The sharp bend waveguides in photonic crystals allow for the realization of circuits over one thousand times smaller than conventional optic devices.

Waveguide bends in conventional optics are realized on the basis of total internal reflection, an effect requiring very small angles of incidence. Therefore they can only be bent with very large radii. The photonic bandgap in photonic crystals allows light to be guided around bends with minimal losses.

The anomalous dispersion in photonic crystals allows us to realize wavelength (de-)multiplexers one hundred times smaller than comparable conventional optic devices.

A conventional prism can exhibit dispersion to the order of 10 degrees for wavelengths from blue to red. In a prism made of photonic crystal material (so-called superprism), dispersion is up to 500 times greater than in conventional optics. Even for wavelengths differing by only 1%, dispersion can reach 50 degrees.

Photonic crystals allow us to construct highly complex components, such as splitters, couplers, filters and demultiplexers, from basic building blocks. Photeon is currently working on a number of practical photonic crystal devices for use in data communications.

Photeon has already developed a planar polarization splitter based on photonic crystals (patented), which will enable us to double the rate of data transfer by the use of polarization demultiplexing. Three concepts for polarization splitting were presented by Photeon at the 30th European Conference on Optical Communications in Stockholm.

On a planar chip the size of just 30um x 30um, our polarization demultiplexer uses the inherent polarization sensitivity of photonic crystals to separate TE and TM polarization. The design is based on silicon-on-insulator technology, which is compatible with standard CMOS processes, and can be used as a building block for larger, polarization-sensitive circuits.

Imagine a computer which operates at the speed of light!

Defects in a photonic bandgap structure allow us to design small, but highly efficient microlasers. A point defect in the crystal gives rise to a resonant state with a defined resonant frequency in the bandgap. Light is trapped in this cavity as the photonic bandgap prevents it from escaping into the crystal.

In the future, it will be possible to implement optical manipulation, signal processing and electronic circuitry all in one chip. Photonic crystals may also be used for high-speed computers of the next generation. Progress has already been made towards replacing the slow copper connections in computers with ultra-fast optical interconnects. Then photons, rather than electrons, will pass signals from board to board, from chip to chip and even from one part of a chip to another.