This could open the way to sophisticated and cheap biosensors mounted onto a single microchip. Such biosensors are used to run blood tests, detectchemicals in water supplies or for drug testing.
The device, called a wavelength-demultiplier (WD), measures less than amillimetre rather than the several centimetres of other currently availableWDs but is still able to function at very high resolution.
The new WD should not cost more to produce and can be integrated for several other functionalities on a single chip for signal processing,communications, or sensing and lab-on-a-chip applications.
In compact communication, signal processing and sensing optics technologies,multiple wavelengths of light are combined as a space-saving measure as they carry information.
The wavelengths must then be separated again when they reach their destinations.
Wavelengths used for these applications have very high spectral resolution,which means that the distance between wavelengths is very small. The devicethat sorts out these crowded wavelengths is called a wavelength-demultiplier(WD).
"We believe we have developed the most compact WD that has been reported to date," said Ali Adibi, associate professor at Georgia Tech and lead researcher on the project.
"If you want to have many optical functions on a single micro- or nano-sized chip, you have to be able to practically integrate all those functions in the smallest amount of space possible. Our WD solves many problems associated with combining delicate optical functions in such a small space."
The team was able to shrink its WD by combining three unique properties ofphotonics crystals into one. Photonic crystals are highly periodicstructures typically etched in very thin silicon that are designed tocontrol light.
By combining the superprism effect, negative diffraction and negativerefraction, the new WD takes an expanded beam of light and focuses thewavelength into different locations, rather than expanding it further
According to Georgia Tech, the project really demonstrates the importance of dispersion engineering in photonic crystals, which allows combiningproperties into one material.
The research has been published in Laser Focus World and Optics Express.