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June 4, 1998

Hitachi Releases Two High-output Red Semiconductor Laser Diodes for Laser Leveler

- Features are continuous optical output of 15 mW in the 635-nm band and wide operating temperature range -

Improved visibility, higher outputs, and wide operating temperature ranges have become important technological issues for red semiconductor laser diodes. This is especially true for products in which apparent brightness is an important sales point, such as laser levelers and laser markers, which are used outdoors, and for optical applications in general. Thus there is now strong demand for laser diode products with a high output in the 635-nm band.

Hitachi currently mass produces 635-nm band short wavelength semiconductor laser diodes with outputs of 5 and 10 mW for use in laser levelers and similar equipment. However, current applications that need high outputs are currently forced to use a 670-nm or 780-nm semiconductor laser diode, since these diodes are available in versions with outputs of 15 mW or higher, and to use a special-purpose receiver to verify the position of the laser beam. To respond to these market conditions, Hitachi has developed and is now releasing these two red semiconductor laser diodes, the HL6321G and the HL6322G, which provide a high output of 15 mW in the 635-nm band and also have a wide operating temperature range of -10 to 50 dgrees Celcius.

These products adopt an AlGaInP multi-quantum well structure active layer^*1 that uses an off angle and take full advantage of the MOCVD^*2 technology in the crystal growth used to fabricate those layers. This allowed Hitachi to optimize the control of the number of active layers, the thicknesses of those layers, the carrier density, and other structural parameters, which enabled the achievement of stable single mode^*3 oscillation in the 635-nm band. Furthermore, to achieve the high output of 15 mW, the reflective layers at the ends of the laser diode chip were optimized, and, at the same time a structure was adopted that prevents damage to the end surface of the laser diode chip. Introducing these new technologies, made it possible to achieve the highest output level (Po = 15 mW, continuous operation) in this device class and the high continuous operating temperature of Tc = 50 degrees Celcius. Thus these devices can be applied in areas that require high output levels and a wide operating temperature range.

The addition of these devices to the Hitachi laser diode product line means that the company now offers 5, 10, and 15-mW products, giving its users a wider choice to match the needs of their applications. These products are provided in a fully hermetically sealed package that includes a built-in monitor photodiode (Hitachi package code: G type, 9-mm diameter). The HL6321G is a positive power supply drive lead connection product and the HL6322G is a negative power supply drive lead connection product. This allows a product that matches an existing drive circuit to be selected. Future plans in this area include the development of even higher output products, including products in the 30-mW class.

Note:	1.	Multi-quantum well active layers: A structure in which the laser diode active layers are grown by repeated crystallization stages with modified material compositions. This increases the difference between the clad and active layer band gaps, and, in addition to providing a high light enclosing effect, reduces the threshold current and improves the temperature characteristics.
	2.	MOCVD (metal organic chemical vapor deposition): A gas-phase crystal growth technique that uses the decomposition of organometallic compounds. This crystal growth technology is superior for the mass production of semiconductor devices.
	3.	Single mode: The state in which only a single wavelength is output from a laser diode.

Application Product Examples

• Laser markers, laser pointers
• Guiding light beam sources for levelers and other test and measurement equipment, position detection equipment, and medical equipment
• Games and entertainment
• As the light source in educational optics experiments

Pricing in Japan

Catalog No.	Sample price (Yen) HL
6321G	13,000
HL6322G	13,000

Features

1. Achievement of a high output power of 15 mW in the 635-nm band
These devices feature an output power increased to 15 mW (maximum) at a wavelength of 635 nm (typical), thus allowing them to be used in a wider range of applications. Since these devices have a wavelength equivalent to that of He-Ne gas lasers, they provide increased visibility over earlier semiconductor lasers, and thus the illumination point can be seen more clearly.

2. Wide operating temperature range
These devices feature an operating temperature range of -10 to 50 degrees Celcius, which is appropriate for test and measurement equipment.

3. Internal circuits: support for positive and negative drive
The HL6321G is a positive power supply drive and the HL6322G is a negative power supply drive lead connection product. The availability of these two versions increases the options in end product drive circuit design. Users can select a device that matches an existing circuit.

Specifications

Structure	Function	Package
AlGaInP multi-quantum well structure	Red laser light source	Type G

Maximum Ratings (Tc = 25 degrees Celcius)

Item	Symbol	Rating	Units
Optical output	Po	15	mW
LD reverse voltage	VR(LD)	2	V
PD reverse voltage	VR(PD)	30	V
Operating temperature	Topr	-10 to 50	degree Celcius
Storage temperature	Tstg	-40 to 85	degree Celcius

Electrical and Optical Characteristics (Tc = 25 degree Celcius)

Item	Symbol	Test conditions	Rating			Units
			Min.	Typ.	Max.
Optical output	Po	Kink free	15	-	-	mW
Threshold current	Ith	The point where the straight line connecting thePo = 3 mW and the Po = 12 mW points intersects the power supply axis.	20	50	75	mA
Slope efficiency		9mW/ (I(12mW)-I(3mW))	0.3	-	0.7	mW/mA
Operating current	Iop	Po=15mW	-	80	105	mA
Wavelength		Po=15mW	625	635	642	nm
Beam divergence (horizontal)		Po=15mW	5	8	11	deg
Beam divergence (vertical)		Po=15mW	24	30	36	deg
Monitor current	Is	Po=15mW,VR(PD)=5V	0.07	0.26	0. 45	mA
LD operating voltage	Vop	Po=15mW	-	-	2.7	V

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