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High-Power
Red Laser Diode Supports x16-Speed DVD Recording
SLD1236VL
The DVD recording market is
developing rapidly. Following the x4, x8, and
x12 speeds, high-speed recording has already
evolved to the x16-speed level. To respond to
this market trend, Sony has now developed the
SLD1236VL 250 mW optical power output laser
diode that supports x16-speed DVD recording.
In addition to the optical power output being
increased by 50 mW over earlier products, the
SLD1236VL also achieves guaranteed operation
under the severe environmental conditions of
temperatures up to 75°C. |
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SLD1236VL |
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* Maximum optical
power output : 250 mW (in pulse drive mode)
* High-temperature (75°C) operation guaranteed
* New user-friendly actual refracting waveguide
window structure |
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Maximum Optical
Power Output: 250 mW (in pulse drive mode) |
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Increasing the recording
speed in DVD+R/RW and DVD-R/RW requires that
the optical power output of the laser diode
used as the light source be increased. This
is because the material characteristics of the
recording medium must be changed in a period
of time that becomes shorter as the recording
speed is increased. Sony has already released
laser diodes with optical power output levels
of 100, 140, and 200 mW to support recording
speeds of x4, x8, and x12. The SLD1236VL of
this release achieves an even higher optical
power output, and can be driven at an optical
power output of 250 mW, which supports x16-speed
recording. |
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High-Temperature
(75°C) Operation Guaranteed |
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When recording at
speeds as high as x16, the heat released by
the various system components increases due
to the spindle motor that turns the disc running
faster, the laser diode power being increased,
and other changes. As a result, the ambient
temperature inside the case increases. This
there is demand for laser diodes whose operation
is guaranteed at temperatures as high as 75°C.
Sony introduced new structures in the areas
surrounding the light emitting regions of the
newly-developed SLD1236VL, and as a result,
operation is guaranteed under severe operating
conditions up to 75°C. |
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User-Friendly
Actual Refracting Waveguide Window Structure |
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To respond to calls
for the lower aspect ratios demanded for optical
pickups, Sony has adopted, in the previously
released SLD1234VL (pulse drive: up to 140 mW)
and SLD1235VL (pulse drive: up to 200 mW), designs
that reduces the radiation angle in the perpendicular
direction (θ⊥) at the end surface
of the laser. The SLD1236VL inherits the structure
that results in the same θ⊥ angle
of 17.5 degrees (typical) achieved in the SLD1234VL
and SLD1235VL, thus creating a user friendly
laser diode product. In addition, the SLD1236VL
adopts a low-loss actual refracting waveguide
window structure that improves the low threshold
current and temperature characteristics. As
a result, the SLD1236VL achieves a threshold
current of 50 mA (typical) and current value
of 130 mA (typical) in 80 mW CW drive mode.
The reduction in the threshold current also
reduces the noise levels. |
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•••• Mr.TOJO ••••
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Despite this being
a difficult device to design, we only had a
short development period and the road to commercial
release was perilous. However, thanks to much
assistance from the staff and our cohesion as
a group, we succeed in making it safely to commercial
release. Our next step is to proceed with development
aimed at even higher output to support two-layer
discs. |
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See
all articles with figures and tables.  |
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Vol.37 |
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