Exalos of Zurich Switzerland, reports that it has successfully tested long-life gallium nitride (GaN) superluminescent light-emitting diodes (SLEDs). The company found that under specific test conditions, an estimated lifetime of more than 5,000 hours. According to the company, applications such as direct retina display, 3D printing, or pico projectors, might benefit from employing reliable, long-life LEDs that generate extreme brightness.
Exalos will introduce the findings at the Photonic West Conference in San Francisco, at the Moscone Center North & South, which runs from Monday, February 15th through Thursday, February 18th. At the Photonics West exhibition, the company will demonstrate its SLED products at Booth #430.
Exalos tested the GaN-based SLEDs emitting at a wavelength of 405 nanometers (nm). The company found that optimized doping levels offer decreased operating voltage on single-mode devices. According to Exalos, optimizing the doping levels reduced the operating voltage from more than 6 volts to less than 5 volts for an injection current of 100 mA. The tests showed that magnesium (Mg) doping levels in the p-type (positive) layers impact both the device electro-optical characteristics and their reliability.
The company tested the lifetime output of SLED modules with standard and optimized p-type layers at a constant output power of 10 milliwatts (mW), in continuous wave (cw) operation and at a case temperature of 25 degrees C. The modules with non-optimized p-type doping demonstrated a fast and remarkable increase in the drive current and device series resistance during the first hundreds of hours. The company found no degradation of the electrical characteristics after 2,000 hours on devices with optimized p-type layers.
Under the specific test conditions, the company found the estimated lifetime for those devices was higher than 5,000 hours. Furthermore, with an injection current of 500mA, the SLEDs showed maximum output powers as high as 350 mW in continuouswave operation (cw) at room temperature.
“We have seen, in recent years, tremendous improvement in the performance and reliability of GaN-based laser diodes in the 405-nanometer wavelength, which have been successfully commercialized in markets including medical and industrial applications, as well as laser projection and automotive head lamp design,” said Dr. Christian Velez, CEO of Exalos.
“Our tests now show that the GaN-based SLEDs can deliver high output power with ideal directional beams with higher power levels for applications such as direct retina projection and pico projection. This is what we believe new markets are seeking for light sources.”
In addition to Velez, authors of the Exalos paper included Antonino Castiglia; Marco Rossetti; Nicolai Matuschek; Raffaele Rezzonico; Marcus Duelk, Jean-François Carlin, and Nicolas Grandjean.