Advances in laser diode development for high resolution and high speed printing

Future high performance printing systems will require higher resolution, higher print speed, and better image quality. One way to enhance the bandwidth in raster-output printing systems is to reduce the wavelength of the laser diodes. Since the optical assembly in polygon scanner systems is diffraction limited. a reduction in wavelength of the scanning beam would significantly improve the optical resolution of the printing system compared to the currently used IR and red lasers. This paper discusses the design and performance characteristics of III-nitride based multi-quantum well (MQW) laser diodes grown on sapphire substrates by metalorganic chemical vapor deposition (MOCVD). Room-temperature continuous-wave operation with threshold currents as low as 45mA have been achieved with threshold voltages of 7.5V. CW operation was observed up to 60 degrees C with emission wavelength around 410 nm. By using short-period AlGaN/GaN superlattice the cladding layer thickness could be significantly increased resulting in an improved transverse far-field pattern.