JPH05267786A - Light source unit - Google Patents

Abstract

PURPOSE:To enable a beam to be easily set in direction and a large amount of data to be transmitted at a high speed by a method wherein laser chips which emit beams from chip junction planes towards the same prescribed point are provided, and the beam emitting parts of the chip junction planes of the laser chips are set not parallel with each other. CONSTITUTION:A laser chip 20 which emits a beam is provided inside each of semiconductor lasers 10, and laser beams are emitted from the chip junction planes 25 of the laser chips 20 towards the same prescribed point. Two through- holes 30 are provided on a fixing member 40, the heads of the semiconductor lasers 10 are inserted into the holes 30 and fixed to constitute a light source unit 100. The semiconductor lasers 10 are so arranged as to enable the laser beam emitting parts of the chip junction planes 25 of the laser chips 20 to face towards directions which cross each other at a right angle and fixed. By this setup, a light source unit of this design can be easily set in beam direction and transmits a large amount of data at a high speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source unit used in a remote control unit, an optical transmission unit, a high speed optical communication unit and the like.

[0002]

2. Description of the Related Art Conventionally, GaAs LEDs (wavelength 950 nm)
Is used as a remote control light source. This GaAsLE
The rise time of D is 1 μsec, while
AlGaAsL recently used for high-speed optical signal transmission
The rise time of ED (850 nm) is as fast as 0.3 μsec.

However, it is difficult for AlGaAs LEDs to transmit high frequency signals of 1 MHz or more. Therefore, AlGaAs LED
Infrared light cannot be used for spatial transmission of audio / video signals or optical signals for computer-to-computer communication that require transmission of a large amount of information.

Therefore, recently, a semiconductor laser that is faster than the above-mentioned infrared LED and capable of high-speed pulse transmission has been spotlighted.

[0005]

However, the divergence angle of the laser beam emitted from the semiconductor laser is directional, and the cross section of the light beam is not elliptical but circular. That is, an elliptical spot that is long in the direction perpendicular to the PN junction surface of the laser chip (hereinafter, also referred to as “chip junction surface”) is formed toward the light receiving surface.

As a result, it is easy to irradiate the beam to a predetermined position in the major axis direction of the ellipse (direction along the light intensity distribution), but the light is illuminated in the minor axis direction of the ellipse (parallel to the chip bonding surface). There is a problem that the intensity distribution is too flat and it is difficult to direct the beam. For example, it is difficult to adjust the position with respect to the light receiving surface when the semiconductor laser is installed, and it is particularly difficult to carry out the operation by holding the device by hand.

By increasing the divergence angle of the beam with the lens so that the elliptical spot becomes a perfect circle, such a problem can be solved, but in a semiconductor laser whose cost is being reduced. In comparison, lenses are still expensive.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a low-cost light source unit that can easily determine the direction of a beam and can transmit a large amount of information at high speed.

[0009]

To achieve the above object, a light source unit of the present invention is provided with at least two laser chips each of which emits a beam from a chip bonding surface toward the same predetermined position, and the chip bonding of each laser chip is carried out. It is characterized in that the portions of the surface that emit the beam are in a non-parallel relationship with each other. Particularly, it is preferable that the portions of the two laser chips that emit the beams are arranged in the directions orthogonal to each other.

Further, the light source unit of the present invention is provided with at least two laser chips which emit a beam from the chip bonding surface toward the same predetermined position, and the spot formed by the beam from each laser chip is at the predetermined position. It is characterized by intersecting. In particular, it is preferable that the two spots are orthogonal to each other.

[0011]

With this structure, a beam having an elliptical beam cross section that is long in the direction perpendicular to the beam emitting portion of the chip bonding surface emits light in a state where elliptical spots intersect at a predetermined position. Since the distribution is formed, it becomes easy for the predetermined position to be irradiated with the beam.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view schematically showing the configuration of this embodiment. The light source unit 100 of the present embodiment is mainly composed of two semiconductor lasers 10 and a fixing member (an outline is shown by a chain line in the figure) 40 for fixing the semiconductor lasers 10.

The semiconductor laser 10 is a can-type hermetically sealed laser diode of a general package type. Inside each semiconductor laser 10,
One laser chip 20 that emits one beam (wavelength: 850 nm) is provided, and the laser beam is emitted from the chip bonding surface 25 of the laser chip 20 toward the same predetermined position (Z direction). Since each semiconductor laser 10 is connected in parallel to a power source and turned on and off at the same time, the same signal is transmitted from both semiconductor lasers 10 at the same time.

The fixing member 40 has two through holes 30.
Is provided. As shown in the figure, the light source unit 100 is configured by inserting and fixing the head of the semiconductor laser 10 into the hole 30. The two holes 30 are formed in parallel with each other, and the position of the portion of the chip bonding surface 25 that emits the laser beam is along the penetrating direction (Z direction) so that the spread of the laser beam is not blocked. Has been adjusted.

The semiconductor laser 10 is arranged and fixed in a direction in which the laser beam emitting portions of the chip bonding surface 25 of each laser chip 20 are orthogonal to each other. That is, in this embodiment, the chip bonding surface of one laser chip 20 is on the ZY plane and the other laser chip 20 is
In the state where the chip bonding surface of 1 is on the ZX plane, the beam is emitted in the Z direction.

The laser beam emitted in the Z direction from the chip bonding surface 25 has an elliptical shape whose cross-section is long in the direction perpendicular to the chip bonding surface 25, and therefore has an elliptical shape toward the light receiving surface at a predetermined position. Spots will be formed. Therefore, the spots formed by the beams from the laser chips 20 intersect at the same predetermined position,
As shown in FIG. 2, a cross-shaped optical radiation distribution is formed by spots P ₁ and P ₂ which are orthogonal to each other. The beams from each laser chip 20 are both emitted along the Z direction, but since the predetermined position where the light receiving surface is arranged is usually much larger than the beam interval, it is particularly necessary to tilt the two beams. Absent. The diameter of the semiconductor laser is 5.6 mm.
When it is set, the distance between the two semiconductor lasers 10 is 10 m.
It is suitable for practical use to set it to about m.

The detection range of one semiconductor laser 10, that is, the beam divergence angle is ± 30 ° to 40 ° in the direction perpendicular to the junction,
If it is ± 10 ° to 15 ° in the horizontal direction, on the other hand, in this embodiment, it also extends ± 30 ° to ± 40 ° in the horizontal direction.

In this embodiment, the semiconductor laser 10 having one laser chip 20 in one package is used, but the semiconductor laser 10 having two or more laser chips in one package may be used. Good. Also,
In this embodiment, two semiconductor lasers 10 are fixed to one fixing member 40, but three or more semiconductor lasers 10 may be used. When the beam emitting portions of the chip bonding surface 25 are in a non-parallel relationship with each other, the spots intersect at the same predetermined position. Therefore, a plurality of laser chips should be positioned at a predetermined angle in the XY plane. For example, not only the cross-shaped light radiation distribution as shown in FIG. 2 but also a pattern close to a perfect circle can be formed.

As described above, according to the present embodiment, the signal detection range is expanded in the direction parallel to the chip joint surface 25, so that the direction of the beam can be easily determined. Further, since two semiconductor lasers are cheaper than one lens, it can be manufactured at a lower cost than when a lens is used. On the other hand, in the conventionally used light source unit for infrared light, it is not easy for the pin photodiode forming the light receiving surface to focus the light into a small spot with an optical system.
Therefore, a large pin photodiode is used. However, there is a problem that the background noise becomes large when the pin photodiode is large. When a laser beam is used as in the present embodiment, it is easy to focus on a small spot, so a small pin photodiode can be used, and as a result, the SN ratio can be improved.

[0020]

As described above, according to the present invention, a large amount of information can be transmitted at high speed by providing a laser chip that emits a beam from the chip bonding surface toward the same predetermined position. By making the beam emitting portions of the chip bonding surfaces of at least two laser chips non-parallel to each other, it becomes easy to determine the beam direction corresponding to the spread of each beam. Moreover, since it is not necessary to use an expensive optical system, cost reduction can be achieved. In particular, by arranging the beam emitting portions of the two laser chips in orthogonal directions, it is possible to more easily orient the beams.

Further, by arranging the spots formed by the beams from the respective laser chips to intersect at the same predetermined position, it becomes easy to determine the beam direction corresponding to the spread of the respective beams. In particular, when the two spots are orthogonal to each other, the beam can be more easily oriented.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a light radiation distribution formed by an embodiment of the present invention.

[Explanation of symbols]

10 ... Semiconductor laser 20 ... Laser chip 25 ... PN junction surface (chip junction surface) 30 ... Hole 40 ... Fixing member P ₁ , P ₂ ... Spot

Claims (4)

[Claims] 1. At least two laser chips each emitting a beam from a chip bonding surface toward the same predetermined position,
A light source unit, wherein portions of the chip bonding surface of each laser chip that emit the beam are in a non-parallel relationship with each other. 2. The light source unit according to claim 1, wherein the beam emitting portions of the two laser chips are arranged in directions orthogonal to each other. 3. At least two laser chips each emitting a beam from the chip bonding surface toward the same predetermined position are provided.
A light source unit, wherein spots formed by beams from the respective laser chips intersect at the predetermined position. 4. The light source unit according to claim 1, wherein the two spots are orthogonal to each other.