JPH01152787A - Semiconductor laser light source - Google Patents

Abstract

PURPOSE:To efficiently produce oscillating laser light whose phases are put in order by providing a reflecting mirror on output reflecting members so as to put the effective light passage length of laser light which passes an effective light point at which near sightedness field image of semiconductor laser is formed. CONSTITUTION:An output reflecting member 12 has a reflecting mirror 12C so that the effective light passage lengths from each effective light point is put in order each other on the effective light points at which a near-sightedness field image is formed. Oscillating laser light LA1 emitted from each effective light point at which the near-sightedness field image 2 is formed is passed through a passage in which the effective light passage lengths are put in order and returned to the near-sightedness field image of semiconductor laser 1 while it is passed through the passage in which the respective effective light passage lengths are put in order each other and struck on the reflecting mirror 12C. Therefore, laser light which is passed on each effective light point performs oscillation operation in a prescribed phase corresponding to mutually arranged effective light passage lengths and the oscillating laser light LA1 whose phases are put in order in a lateral mode can be produced.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a semiconductor laser light source, and is particularly suitable for application to forming a linear light source.

B. Summary of the Invention The present invention provides a semiconductor laser light source in which the oscillation laser light emitted from the semiconductor laser is reflected by an output reflecting member provided externally, thereby producing oscillation laser light whose phase is aligned in the transverse mode. can occur.

C. Prior Art As shown in FIG. 1, a semiconductor laser 1 basically consists of an active layer IA in which holes and electrons recombine and emit light, and a cladding 1i1B.
A striped laser oscillation region ID is formed in the active layer IA by using the opposing front cleavage plane ICF and rear cleavage plane ICR as reflective surfaces.

Thus, the laser oscillation region ID exposed to the front cleavage plane ICF generates a near-field image 2 with a light intensity distribution in a direction parallel to the PN junction, and the near-field image 2 effectively arranges point light sources in a line. The laser beam LAI thus emitted from the laser oscillation region ID forms a far-field image 3 having a light intensity distribution corresponding to the horizontal transverse mode.

Here, the far-field image 3 is given by Fourier transform of the near-field image 2, has a width d0 in the short axis direction corresponding to the width dMI in the lateral direction of the near-field image 2, and has a width d0 in the short axis direction corresponding to the width dMI in the lateral direction of the near-field image 2.
The width dv in the major axis direction corresponds to the longitudinal width dV+ of ! It has an elliptical shape.

In this way, the semiconductor laser 1 has the advantage of being able to increase its output by emitting the output laser beam LAI from a linear light emitting source similar to that of an effective point light source arranged horizontally and laterally. be.

D Problems to be Solved by the Invention In order to generate a higher output laser beam LAI in the semiconductor laser 1 having such a configuration, it is sufficient to expand the current injection region by expanding the width dl11 of the laser oscillation region ID. it is conceivable that.

However, in this case, a so-called filament oscillation state occurs in which the effective oscillation modes of the point light sources arranged in the lateral direction of the laser oscillation region ID are uneven, and as a result, the control of the horizontal transverse mode of the output laser beam LAI becomes difficult. This may become insufficient, resulting in deterioration of the spatial coherence range in the direction parallel to the active layer IA.

Furthermore, even if an attempt is made to form a laser beam close to the diffraction limit by correcting the wavefront of the semiconductor laser 1, there is a problem that this cannot be achieved.

The present invention has been made in consideration of the above points, and aims to propose a semiconductor laser light source in which the oscillation state at each point in the lateral direction of a semiconductor laser, that is, the transverse mode, can be reliably controlled.

E Means for Solving the Problem In order to solve this problem, in the present invention, the oscillation laser beam LAI emitted from the laser oscillation region ID that forms the near-field image 2 of the semiconductor laser 1 is transmitted to the output reflection member 12. Oscillator CA that returns to near-field image 2 by reflection
V, and the output reflecting member 12 has a reflecting mirror portion 12C that aligns the effective optical path lengths from the effective light spots constituting the near-field image 2.

The oscillated laser beams LAI emitted from the respective effective light points constituting the 7-action near-field image 2 enter the reflecting mirror portion 12C through optical paths whose effective optical path lengths are the same, and
The light returns to the near-field image 2 of the semiconductor laser 1 through the optical path with the same effective optical path length.

In this way, the laser beams passing through each effective light point begin to oscillate with a predetermined phase corresponding to the mutually aligned effective optical path lengths, thus generating oscillated laser beams LAI whose phases are aligned in the transverse mode. be able to.

G example An embodiment of the present invention will be described in detail below with reference to the drawings.

[1] First Embodiment In FIG. 2, in which corresponding parts to those in FIG. .

In this embodiment, the semiconductor laser 1 has a front cleavage plane IC.
The reflectance of the laser oscillation region ID exposed to F is reduced, so that the laser light generated inside the active layer I of the semiconductor laser 1 is not reflected inward at the front cleavage plane ICF. The oscillated laser beam LAI is emitted to an output reflecting member 12 made of, for example, an abranatic lens.

In this embodiment, as shown in FIG. 3, the output reflection member 12 has a spherical entrance surface 12A, and a reflection mirror portion 12C is formed in a predetermined area passing approximately at the center thereof.

Here, the shape of the reflection mirror portion 12C on the entrance surface 12A is as follows:
When an image having a desired shape and phase distribution is generated as the near-field image 2, an image having a shape and reflectance distribution corresponding to the shape and phase distribution of the near-field image 2 is formed on the incident surface 12A of the output reflecting member 12. A reflecting mirror portion 12C is formed as shown in FIG.

In the above configuration, the active JilA of the semiconductor laser 1
The laser light generated in
A part of the laser light that enters the incident surface 12A of No. 2 and passes therethrough is sent out as output laser light LA 011 T.

Of the oscillation laser beam LAI, the laser beam reflected at the reflection mirror section 12C is redirected to the laser oscillation area ID.
and further returned to the inside of the active layer IA,
It passes through the laser oscillation region ID and is reflected at the rear cleavage plane ICR.

In this way, the oscillated laser beam LAI emitted from the active layer IA of the semiconductor laser 1 enters an oscillation state by reciprocating between the reflection mirror part 12C and the rear cleavage plane ICR, and thereby the reflection mirror part 12C and the laser beam Oscillation region I
A resonator is constructed between the rear cleavage planes ICR of D.

In such an oscillation state, when the near-field image 2 is considered to be equivalent to a linear array of light spots in the horizontal direction (this is called an effective light spot), the laser beam passing through the effective light spot is The optical path lengths R are equal to each other for all effective light spots. This is because the reflection mirror portion 12G of the output reflection member 12 forms a spherical surface centered on the near-field image 2.

Therefore, since the effective optical path lengths of the optical paths passing through each effective light point are equal to each other, even if laser beams are generated at different positions (inside the active layer IA) on each optical path, the laser beams strengthen each other. Only the light corresponding to the optical path length R is emitted, and thus the phase of the laser light LAI emitted from the laser oscillation region ID at each position in the lateral direction can be controlled to be uniform, and as a result, the semiconductor laser 1
This means that the transverse mode of the image can be controlled.

In this way, such control of the transverse mode is performed only for the laser beam reflected at the reflection mirror section 12C, so that the shape of the near-field image 2 corresponds to the shape of the reflection mirror section 12C.

According to the above configuration, a near-field image 2 is formed in the laser oscillation region ID, with the reflection mirror portion 12C as a far-field image 3, and the shape and phase distribution of the far-field image 3 can be adjusted as desired. By setting it to a certain value, the shape and phase distribution of the near-field image 2 can be controlled.

[2] Second Embodiment FIG. 4 shows another embodiment of the present invention, in which the rear side cleavage of the laser oscillation region ID is shown by assigning the same reference numerals to the parts corresponding to those in FIG. The laser beam LAI is emitted backward so as not to be reflected at the surface ICR, and the rear cleavage surface IC is
The reflective surface 2 of the rear reflective mirror 21 provided close to R
Reflect at 1A.

According to the configuration shown in FIG. 4, the oscillated laser beam LAI passing through the laser oscillation region ID of the semiconductor laser 1 is transmitted to the reflection mirror portion 12C provided on the incident surface 12A of the output reflection member 12 and the reflection surface of the rear reflection mirror 21. 21A, a near-field image 2 corresponding to the reflection mirror portion 12C can be formed on the front cleavage plane ICF.

Therefore, the phase of the oscillated laser beam LAI at the effective light spot in the lateral direction of the laser oscillation region ID can be controlled to a mode determined by the effective optical path length of the reflecting mirror 21 and the reflecting mirror section 12C.

[3] Third Embodiment FIG. 5 shows a third embodiment of the present invention, and as shown by assigning the same reference numerals to corresponding parts as in FIG. The surface 22A has a spherical surface similar to the output reflecting member 12.

Similarly to the output reflecting member 12, the rear reflecting mirror 22 is located at a position far enough away from the near-field image 23 formed on the rear cleavage plane ICR of the laser oscillation region ID to form a far-field image 24. The effective distance between the near-field image 23 formed on the rear cleavage plane ICR and the far-field image 24 formed on the reflective surface 22A is such that the effective light spot of the near-field image 23 is are selected to be equal.

According to the configuration shown in FIG. 5, the effective optical path length between the reflection mirror portion 12C of the output reflection member 12 and the reflection surface 22A of the rear reflection mirror 22 can be made equal for all light points in the lateral direction. Accordingly, it is possible to emit the output laser beam LAoutx with practically uniform transverse modes.

[4] Fourth Embodiment FIG. 6 shows still another embodiment of the present invention, in which the oscillation laser beam LA1 emitted from the semiconductor laser 1 is converted into parallel laser beam LAII by the collimator lens 25, and then output. The light is incident on the reflecting member 26.

The semiconductor laser 1 is disposed on the incident surface 26A of the output reflecting member 26.
A reflecting mirror portion 26C having the same shape and reflectance distribution as that obtained by projecting the near-field image 2 on the front cleavage plane ICF through the collimator lens 25 is formed. Hikari LAoot
x is sent out.

In the configuration shown in FIG.
is a parallel laser beam LA via the collimator lens 25
11, the light is reflected by the reflection mirror section 26C, passes through the collimator lens 25 again, and returns to each light point of the near-field image 2. In this way, the oscillation laser beam L passes through the effective light spot in the lateral direction of the near-field image 2 due to the refraction effect of the collimator lens 25.
By making the effective optical path lengths of A1 equal to each other,
The transverse mode of the oscillation laser beam LAI can be aligned.

[5] Fifth Embodiment FIGS. 7 and 8 show still another embodiment of the present invention, in which the same reference numerals are given to corresponding parts as in FIG. The oscillation laser beam LAI emitted from
However, due to the diffraction effect, the outer peripheral line portion of the oscillated laser beam LAI enters the output reflecting member 12 while being slightly diverged outward.

In this case, the horizontal radius of curvature RH and the vertical radius of curvature Rv of the incident surface 12A of the output reflecting member 12 have values corresponding to the amount of divergence at the outer peripheral edge of the oscillated laser beam LAI, as shown in FIG. Selected.

According to the configurations shown in FIGS. 7 and 8, the shape of the reflection mirror portion 12G formed on the incident surface 12A has the curvature of the outer peripheral portion adjusted in consideration of the diffraction phenomenon of the oscillated laser beam LAI. As a result, the effective optical path lengths of the oscillated laser beams LA1 passing through the effective light spots in the lateral direction of the near-field image 2 can be made to match each other, and thus the lateral modes of the oscillated laser beams LAI can be made to be the same.

[6] Sixth Embodiment FIG. 9 shows still another embodiment of the present invention. In this case, as shown by assigning the same reference numerals to corresponding parts as in FIG. 2, the front side of the semiconductor laser l is A nonlinear optical crystal element 31 is provided between the cleavage plane ICF and the incident surface 12A of the output reflecting member 12.
is provided, and when the oscillated laser beam LAI passes through the nonlinear optical crystal element 31 as a fundamental laser beam, it generates a second harmonic laser beam LA12.

The nonlinear optical crystal element 31 is set under conditions such that the second harmonic laser beam LA12 thus generated and the oscillation laser beam LAI as the fundamental laser beam are phase matched, and thus nonlinear optical A second harmonic laser beam LA12 is emitted from the crystal element 31 toward the output reflecting member 12.

In this embodiment, the reflection mirror portion 12 of the output reflection member 12
G is configured to transmit the second harmonic laser beam LA12 and at the same time reflect the oscillating laser beam LAI, so that the oscillating laser beam LAI cleaves the rear side of the semiconductor laser 1 in the same manner as described above with respect to FIG. It is repeatedly reflected between the surface ICR and the reflection mirror section 12C.

According to the configuration shown in FIG. 9, it is possible to obtain the oscillation laser light LA1 whose transverse mode is locked to a predetermined phase from the semiconductor laser 1, thereby efficiently generating the second harmonic laser light LA12 in the nonlinear optical crystal element 31. can be done.

H Effects of the Invention As described above, according to the present invention, a resonator is configured by reflecting the oscillated laser light emitted from the active part of the semiconductor laser by an output reflecting member provided outside the semiconductor laser, and By providing a reflective mirror section on the output reflecting member that equalizes the effective optical path length of the laser light that passes through the effective light spot that constitutes the near-field image of the laser, it is possible to efficiently oscillate laser light with a uniform phase. It can be generated well.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing a semiconductor laser used in a semiconductor laser light source according to the present invention, FIG. 2 is a plan view showing an embodiment of the semiconductor laser light source according to the present invention, and FIG. 3 is a configuration of its output reflecting member. 4 to 9 are a plan view and a perspective view showing other embodiments of the semiconductor laser light source according to the present invention. 1...Semiconductor laser, 2...Near field image, 3...Far field image, 11...Semiconductor laser light source, 12.26... ...Output reflecting member, 12
C...Reflection mirror section, 21.22...
Rear reflection mirror, 31...Nonlinear optical crystal element.

Claims (1)

[Scope of Claims] An oscillator includes an oscillator that returns oscillated laser light emitted from a laser oscillation region that forms a near-field image of a semiconductor laser to the near-field image by reflecting it on an output reflecting member, the output reflecting member A semiconductor laser light source characterized by comprising a reflecting mirror portion that aligns the effective optical path lengths from each effective light spot with respect to the effective light spots constituting the near-field image.