Tokyo-based Mitsubishi Electric Corp is launching the ML562G84 638nm-wavelength red laser diode (LD), offering what is claimed to be record output power (under pulsed operation) of 2.5W for a 638nm projector light source.
The record output power - despite the small package size - is attributed to an improved laser diode structure (i.e. optimized layer structure and emitting-region size). Also, pulse operation is possible with a pulse duty ratio (proportion of time that laser light is on) of up to 40%.
Light sources for projectors are conventionally mercury and xenon lamps, but these are being replaced with solid-state light sources offering higher energy efficiency, a wider color range and longer life. In particular, laser diodes deliver high output power while consuming low power because of their high power-conversion efficiency, broad color gamut (due to the narrow spectrum), and superior picture quality with a high contrast ratio.
Picture: Mitsubishi Electric's ML562G84 638nm-wavelength high-power red laser diode.
Previously, the output power of red laser diodes with wavelengths shorter than 640nm was insufficient for high-brightness projector applications at high temperature. As a first step toward overcome this limitation, Mitsubishi Electric applied specialized window-mirror structures and epitaxial growth technology to develop a laser diode, packaged in a 5.6mm-diameter transistor-outline can (TO-can), achieving 1.0W power output under pulsed operation. The new laser diode structure has since been applied in a 9.0mm TO-CAN package to achieve what is claimed to be industry-leading output power of 2.5W at the 638nm lasing wavelength. Also, due to lasing at such a short wavelength, the luminosity from a single light source exceeds 120 lumens, meeting the demands for bright projector systems, says the firm.
Mitsubishi Electric also claims that the new 638nm red laser laser achieves record electrical conversion efficiency of 39% at 2.5W (at 25°C), helping to reduce power consumption. In addition, due to using the large 9.0mm-diameter TO-can package, good heat dissipation allows a wide operational temperature range (operating case temperature, TC) of 0°C to +45°C.
The 638nm red laser light and highly efficient operation contributes to laser projectors with a wide color range and low power consumption.
There are two types of laser projection system with spatial light modulators (SLMs). One is a single SLM type, which uses red, green and blue (RGB) laser sources under sequential pulse to express RGB pictures to get real color pictures. The other has three SLM devices, which uses the light sources under CW. Projectors using a pulse light source can be brought to the market relatively quickly. The new red laser diode is suitable as a red light source in single SLM projectors.
The product is also compliant with the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment (RoHS) directive 2011/65/EU. Sales will begin in September.
