According to AV Watch, Mitsubishi Electric announced the development of 200mW laser for 16x DVD±RW on December 24, sample shipment to start from June 2003 and mass production from 2004. The company has also plans for 140mW laser for 8x DVD±RW to start 1.5 million units of monthly production from April 2003.
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* 1: DVD±R
The DVD±R (the Digital Versatile Disc Recordable) with the DVD-ROM interchangeable optical disk of postscript type, it is suitable for data retention use because it cannot eliminate the data. Record layer of the organic pigment which is formed on the disk is made to melt and by irradiating the laser light near 658 nm the pit of hole condition is formed and the data is recorded. The big semiconductor laser illuminant of optical output is necessary because of this.
* 2: Wave length 650nm band red high output semiconductor laser
As for the DVD device large capacity (the 4.7G
because it actualizes, the CD (capacity: The 650M
with the oscillation wave length which is used for the illuminant 780 nm (infrared light) changing into the semiconductor laser, near 658 nm (red) the semiconductor laser it can use oscillation wave length. In general, oscillation wave length calls the semiconductor laser of the 658±4 nm 650 nm band red semiconductor lasers.
* 3: Recording rate
As for recording rate of the DVD±R device you inscribe with the multiple data rate (approximately 11mbps) as a standard. 16 time speed reaches entry transfer rate of approximately 176mbps and the data quantity of the DVD±R disk amount 1 (the 4.7G
becomes the speed which can be recorded at approximately 3.5 amount.
* 4: End face window structure
The semiconductor laser while light going and returning between two optical radiation end faces, the laser oscillates by being expanded. Laser light from the optical radiation end face radiation is done outside, but this time portion of laser light is absorbed in the end face and changes to heat. As output of laser light is enlarged, it increases also this heat generation. When it exceeds the value which has optical output the crystal which forms the semiconductor laser instantaneously due to heat generation melts and reaches to breakdown. This phenomenon is called instantaneous end face destructive phenomenon. End face window structure devising the optical radiation end face of the semiconductor laser, it is the structure which laser light tries is not absorbed that in the end face. It can avoid instantaneous end face destructive phenomenon by applying this structure, it becomes possible to obtain bigger optical output.
* 5: Ridge structure
With kind of structure of the semiconductor laser, the optical waveguide (the pathway of laser light) with it is one of the technique which actualizes the actual refractive index derived wave road structure which can make the loss of light small. Relatively it is simple structure, but in order to maintain the oscillation state of laser light at stability, precision control of process technology becomes necessary. Because of this, at this corporation precise control possible dry etching technology is used for processing.
* 6: Kink
Optical output of the semiconductor laser - it points to the thing in the non- linearity in operating current quality. In the optical disk system as for the laser in order always to be able to obtain the optical output of desire, feedback is applied. When optical output - kink occurs in operating current quality, because it cannot apply feedback, kink level (the optical output which kink occurs) with it means that effective installed capacity is restricted. Kink those which it occurs cutoff condition of the guided wave road (the condition basic oscillation form being maintained) from with deviation has understood generally single transverse mode in the laser which oscillates. As for this corporation, the kink in the red laser by analyzing kink phenomenon in detail the optical output which rapidly causes kink by occurring with the temperature rise inside the laser guided wave road and controling the temperature rise inside the guided wave road already we discover the fact that it can improve.
* 7: Single transverse mode laser
Radiation of laser light with the small laser of the area where it is done, laser light it is the laser which can condense in small spot with the lens and the like. The semiconductor laser which is used for the illuminant for the optical disk unit has the necessity to be the single transverse mode laser.
* 8: Peak wave length
It is the wave length where strength of the laser light which radiation is done becomes maximum from the semiconductor laser.
More info:
hxxp://www.mitsubishielectric.co.jp/
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