PORTLAND, Ore. A new optical fiber material could enable laser-based devices to be built operating at multiple frequencies.
The new material--cesium zirconium phosphorus selenium (CsZrPSe6)--can add, subtract and double laser beam wavelengths, enabling devices with two laser sources to produce many usable wavelengths.
"Lasers today are basically limited to six frequencies, but our new material will double any frequency in the far visible and the near-infrared and infrared," claimed Argonne National Laboratory scientist Mercouri Kanatzidis. "It not only doubles frequencies, but when you use two lasers to put in two frequencies, you also get out their sum and difference. So with two lasers you could generate all the frequencies."
Argonne researchers claim the new technology could be used in sensors that detect biological and chemical weapons.
After combining zirconium, phosphorus and selenium they found that the new material acquired the optical doubling, adding and substracting abilities with the addition of either potassium, rubidium or cesium. Although the four-element compounds all had similar properties, the most successful of these compounds was CsZrPSe6.
"This compound is made with heavy elements--selenium, zirconium and cesium--elements that couple to light much more effectively, causing their harmonics to be much more intense, so the efficiency with which this material produces second harmonics is much, much higher than anything we have seen before," said Kanatzidis.
The new compound produced frequency-doubled beams 15 times more intense than those produced by the best commercial materials today, according to Kanatzidis.
The laboratory studied the structure of the new material using its Advanced Photon Source (APS), a synchrotron X-ray research facility funded by the U.S. Energy Department. They found that the new material naturally grows in long individual fibers. The growth rate for the fiber's lengthwise dimension is very rapid, but growth in diameter is much slower--the perfect combination for growing optical fibers.
"What we found with the APS is that the compounds crystals are one-dimensional, and extend forever with very thin molecular dimensions," said Kanatzidis.
Next the researchers plan to grow longer fibers--up to a meter compared to the centimeter-sized prototypes that they have built so far. Using the APS and other analytic tools they plan to perform a full characterization of CsZrPSe6.
Funding was provided by the National Science Foundation and DoE's Office of Basic Energy Sciences.