Frequency doubling for near UV range

AbstractAlthough many materials are capable of generating laser light, few operate at the shorter wavelengths. Scientists from the Fraunhofer Institute have a laser that produces wavelengths of down to 370μ, near UV range, achieved by a frequency-doubling technique. Andreas Hofmann leads the IPM’s laser imaging research group, which has managed to achieve a selective effect by applying electric fields to crystals of lithium niobate. Using an IPM-patented drive system, they have been able to achieve several milliwatts for the first time. Frequency doubling offers the advantage of allowing commercial laser diodes to be used as the pumping device. These emit in the visible to near IR region, at wavelengths between 740μ and 1,100μ. At an output power of 100 milliwatts, the beams are of sufficiently high quality to enable the short-wavelength main laser to be used in imaging, analysis and diagnosis instruments. The beam can be directed and modulated by deliberately modifying the molecular structure of the lithium niobate crystal. Metal electrodes are placed on the two surfaces of the crystal slice. When an electric field is applied, the crystal axis between the two electrodes switches permanently to the opposite sense. Domain inversion produces lasing areas of a defined geometry within the crystal and is a prerequisite to volume processing of such crystal wafers.This is a short news story only. Visit www.three-fives.com for the latest advanced semiconductor industry news