Mitsubishi Electric has developed a 638-nanometer (nm) wavelength red laser diode (LD) offering output power of 1.8 W at continuous-wave operation, the world's highest level among 638-nm LDs in this package size used as light sources for projectors. The company plans to release the diode in fiscal year ending in March 2016.
Light sources for color projectors, conventionally lamps, are being replaced with solid-state light sources offering higher energy efficiency, higher color reproduction and longer life. LDs deliver high output power while consuming low power because of their high power-conversion efficiency.
Previously, the output power of red LDs with wavelengths shorter than 640 nm was not sufficient for high-brightness projector applications at high temperatures. As a first step to overcome this limitation, Mitsubishi Electric applied specialized window-mirror structures and epitaxial growth technology to develop an LD capable of 0.5 W power output at continuous-wave operation, which is packaged in a 5.6-mm-diameter transistor-outline can (TO-can). Thereafter, it applied a new LD structure in a 9.0-mm TO-can package to achieve industry-leading output power of 1.8 W at a 638-nm lasing wavelength, which meets demands for bright projector systems.
The LD's luminosity as a red light source exceeds 220 lumens due to lasing at short wavelength. Its electrical conversion efficiency is 38% at 1.8 W at 25 degrees Celsius, helping to reduce power consumption
Besides emitting 1.8 W at continuous wave operation within an operating range of 0 to +45 degrees Celsius, the laser diode is able to emits 1.3 W at continuous wave operation above 55 degrees Celsius.