Development of 450mW Blue Violet Laser Diode by Sanyo
It hasn’t been long that the whole world decided to go Blu-ray and manufacturers of consumer electronics already has a long list of improvement in their product development roadmap. Sanyo Electric Co Ltd is no exception by making its announcement on development of blue violet laser diode which comes with a pulse oscillation output power of 450mW. Its emission wavelength is at 405nm making it possible for Blu-ray Disc drives to record up to 4 layer discs at 12x speed which translates to a storage capacity of 100 Gbytes sufficient to store a eight hours of HDTV. It would also be possible to dub a two hour program in only ten minutes. The current Blu-ray systems use 2 layer discs at speed of 6x. Future enhancement for Blu-ray drives will be in increase number of recording layers, rotation speed as well as other characteristics. Key for introducing such enhancements is increasing exposure to HDTV programming. Sanyo is still several years away in commercializing the 4-layer concept. There have been several obstacles for manufacturers of laser diodes to go from 300mW 2-layer to 4-layer 12x drives. One being the laser diode device life that tends to be reduced with increase in output and other is the reduced conversion efficiency which is caused by light absorption in the light guide and finally what is known as “Kinking” which is loss of optical output and current linearity. Sanyo Electric overcame these issues by designing a ridge structures that maintains a much more stable carrier density distribution even in presence of high drive currents plus an improved fabrication precision to form these types of ridges. Sanyo’s future plan is in increasing disc layers to eight with the storage capacity of 200 Gbytes.
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