Osram stresses green light on projector lasers
Osram Opto Semiconductors has reaffirmed that it will introduce compact green lasers in 2009 after mobile projector company Microvision failed to complete its testing because of the lack of these components.
Each of the green lasers features an 808 nm AlGaAs laser diode that pumps a 1060 nm-emitting semiconductor disk laser, which Osram grows on a GaAs substrate. The disk laser s emission is then converted to green light by a process known as frequency doubling, or second harmonic generation.
“Today, we are preparing the ramp-up of green lasers with second harmonic generation,” said Thomas Hoefer, head of laser projection at the Regensburg-headquartered company.
After successfully demonstrating display engines using Osram s products in June 2007, Microvision is waiting for deliveries of green lasers before it can launch products.
Despite receiving lasers that Microvision put into its trial products in September 2008, CEO Alexander Tokman said during the company s full-year financial results announcement on March 5 that further progress was slower than hoped.
“The longer-than-expected development cycles and lack of a detailed delivery schedule for green lasers has made it challenging to complete final product testing and customer agreements,” he said.
Responding to compoundsemiconductor.net, Osram said that its lasers meet size and power consumption specifications and are making “substantial progress” towards commercialization.
“A green laser for small mobile projectors is much more challenging than conventional high power green lasers,” Hoefer said. “We have spent much effort following the fast increase in customer requirements.”
The German company says that second harmonic generation lasers will remain the technology of choice in coming years, but has also just reached a landmark for individual diodes.
In an Applied Physics Letters paper published February 27, Osram researchers describe an electrically pumped 500 nm emitting diode. Although this is not truly green, the company claims it is the longest-wavelength InGaN emitter reported to date.
“The demonstrated 500 nm laser is based on our blue laser technology,” commented Uwe Strauss, Osram s director of semiconductor laser technology. “To go to longer wavelengths, we put more indium into the quantum well, but we also needed a detailed understanding of the device as well as the growth processes to achieve high material quality.”
