The deposition and characteristics of an external cavity semiconductor laser for the lensless optical memory system

The present optical memory system has been improved to realize high memory density, fast data transfer rate, and small head size. Compared to the magnetic memory, however, it has still some shortages such as slow tacking access speed and high fabrication cost due to the complicated optical parts and the relatively heavy weight of head. To overcome these limitations, the simple and small optical heads have been proposed using a semiconductor laser having thin films on the emitting facet. New ideas were based on the fact that a laser diode with good antireflection (AR) coating can act as an external cavity laser and oscillate with the media surface if it is close to the disk within a few micrometer distance. This simple optical head is good for both the phase change disk and the magneto-optical disk though the latter needs a lot of thin films on the semiconductor laser such as AR coatings, the quarter wave film, and Faraday rotator. In the presentation, we report the film deposition and characteristics on the emitting facet of semiconductor lasers and show same properties and possibility of our lensless optical memory system prepared at the research level.