Hitachi, Ltd. (TSE: 6501) today announced the HL6323MG high-output red laser diode, 
achieving the industry's first 35 mw rated optical output in the 635 nm band wavelength, 
for marker applications in laser levelers, etc., and sensor applications for optical 
fiber checkers and similar products.  Sample shipments will begin in March 2001 in 
Japan.

The high output of this new product enables long-distance use of laser markers and high-
speed measurement by equipment with a built-in sensor.  The 50¡ëC operating temperature 
and low current dissipation, with an operating current (Iop) of 95 mA (Po = 30 mW, 
Tc = 25¡ëC: Typ.), allow the user to keep the same operating environment as with 
previous Hitachi products and also to employ the same heat radiation design as before.

[Background]

Laser diodes, offering the laser features of monochromaticity (single-wavelength 
oscillation) and directivity (linearity) that are not present in spontaneous radiation, 
together with the advantage of smaller size than other laser devices, are employed 
in such fields as digital information equipment and fiber-optic communications. 
In the red visible region with wavelengths of less than 800 nm, in particular, they 
offer improved visibility and shorter wavelengths for higher-density optical disk 
drives, and are currently used up to the 635 nm band.

In the 635 nm band wavelength, the recent advent of red laser diodes with a rated 
optical output of 15 mW has brought improved visibility which has led to widespread 
use of such devices in laser markers.  Hitachi currently produces the HL6321/22G, with 
a 15 mW rated optical output in the 635 nm band wavelength, but demand has grown for 
a drastic increase in output to enable use over longer distances.

In addition, laser diodes are used as position control sensors in equipment such as 
optical fiber checkers and chip mounters, and there is a demand for higher output 
in these applications to increase the measurement speed.

In response to these demands Hitachi has developed the HL6323MG high-output red laser 
diode, with a rated optical output of 35 mw in the 635 nm band wavelength, employing 
technology used in the development of the high-output HL6503MG (50 mW rated optical 
output in the 660 nm band wavelength) currently in mass production for use in optical 
disk products such as DVD-RAM.


[About this Product]

Optimization of structure parameters such as the active layer thickness and facet 
reflection ratio has enabled the HL6323MG to achieve the industry's first 35 mw rated 
optical output in the 635 nm band wavelength.  This makes possible a long-distance 
operating range for laser markers and higher speeds for position control sensors.

In addition, optimization of the multi-quantum well (MQW) structure* and guided wave 
path structure has been implemented to reduce the operating current, with a threshold 
current (Ith) and slope efficiency (ηs)--parameters that regulate the operating 
current (Iop) - approximately 20% lower than in the current HL6321/22G.

This has made it possible to hold down the operating current (Iop) to 95 mA 
(Po = 30 mW, Tc = 25¡ëC: Typ.) while achieving high output, and to maintain the same 
50¡ëC operating temperature as for the HL6321/22G.

The user can employ the same heat radiation design as before, and can achieve long-
distance operation and faster measurement by equipment with a built-in sensor while 
retaining the previous operating environment.  

The HL6323MG uses the small 5.6 mm o package that is standard for optical disk drive 
applications, enabling end-products to be kept small.  A monitoring photodiode is also 
incorporated, facilitating the configuration of an APC (auto power control) circuit.

The HL6323MG rounds out Hitachi's lineup of 635 nm band wavelength products, which now 
cover the range from 3 mW rated optical output for pointer applications to 35 mW high 
output.   Future developments will include the provision of higher added value by 
further reducing the operating current.

Note: * In MQW (multi-quantum well) structure, the active layer of the laser diode 
        is a laminated structure comprising quantum well layers and barrier layers 
        with a thickness of several nm.  By regulating the composition of the  quantum 
        well layers that constitute the light-emitting area, and using a crystal with 
        a smaller lattice constant than the substrate, tensile strain is introduced 
        into the quantum well layers.  The band structure varies due to this strain, 
        resulting in a lower threshold current and higher slope efficiency.

< Typical Applications >
• Laser markers (laser levelers, line markers, etc.)
• Laser sensors (optical fiber checkers, chip mounters, etc.)
• Educational and experimental equipment

< Prices in Japan > (For Reference)

Note : * Pulse conditions: Pw = 100 ns, duty = 20%

Note: * The kink-free condition has been confirmed at a temperature of 25¡ëC.