Photonic Crystal Shrinks Prism Size

NEC Corp. in New York City, working with To-hoku University and NTT Optoelectronics Laboratories of Japan, has created a three-dimensional photonic crystal with a "super prism" effect. It offers increased light refraction in a prism one-hundredth the size of today's optical devices.

A conventional glass prism (left) has little refractive ability for light at about 1000 nm, but NEC's photonic crystal (right) is considerably more effective.

The crystal refracts light 100 to 1000 times more than does glass, depending on the angle and wavelength of the light. Whereas glass prisms have very little ability in the 900- to 1000-nm range, NEC's crystal refracts these wavelengths as much as 60°.
The three-dimensional periodic structure, with spacing of 300 to 400 nm, exploits layers of a high-refraction silicon film and a low-refraction silicon dioxide film. Applications could include multiplexing/demultiplexing equipment for telecommunications, and digital video disc players.