Semiconductor laser element and laser device using the same element

Abstract

A semiconductor laser of this invention, having a structure of an element composed of: carrier block layers, formed bilaterally externally of an active layer in section which is formed in the vertical direction from the surface of the element, for reducing a light guiding function of the active layer; wave guide layers provided bilaterally externally of said carrier block layers and clad layers provided so that the wave guide layers are sandwiched in between the clad layers. This invention overcomes a dilemma inherent in the conventional weakly guiding laser and LOC structured laser in terms of designing the device for controlling a guided mode. The present invention also solves the problems in terms of attaining higher outputting and a low dispersion of the radiation beams and improving a beam profile.

What is claimed is: 
     
       1. A semiconductor laser element including an active layer having a light guiding function comprising: a pair of carrier block layers sandwiching said active layer, for reducing the light guiding function of said active layer,   a pair of wave guide layers sandwiching said pair of carrier block layers, and   a pair of clad layers sandwiching said pair of wave guide layers,   wherein V 2  corresponding to the normalized frequency of the wave guide layer is in the range of π/4-π, and is defined by   V.sub.2 =(πd.sub.2 /λ)·(N.sub.0.sup.2 -N.sub.3.sup.2).sup.0.5     where π is the ratio of the circumference of a circle to its diameter, d 2  is the effective thickness between said two clad layers, λ is the oscillation wave length, N 0  is the effective refractive index of said wave guide layer, and N 3  is the refractive index of said clad layer.     
     
     
       2. The semiconductor laser element according to claim 1, wherein the bandgap profile along the vertical direction of said wave guide layer is a planar or spherical oblique bandgap which becomes narrower with closer proximity to said carrier block layers from the horizontal exterior section. 
     
     
       3. The semiconductor laser element according to claims 1 or 2, wherein V 1  relative to the normalized frequency V in a guided mode are defined by:   V.sub.1 =π·d.sub.1 /λ·(N.sub.0.sup.2 -N.sub.2.sup.2).sup.0.5     where π is the ratio of the circumference of a circle to its diameter, d 1  is the thickness of said carrier block layer, λ is the oscillation wavelength, N 2  is the refractive index of said carrier block layer, wherein the relationship of V 1  <V 2  /10 is established.   
     
     
       4. The semiconductor laser element according to claim 3, wherein an energy gap difference E (eV) between said wave guide layer and said carrier block layer is given by:   E>(2.5·10.sup.3 /d.sub.1.sup.2)     where d 1  (angstrom) is the thickness of said carrier block layer.   
     
     
       5. The semiconductor laser element according to claim 4, wherein Al x  Ga 1-x  As(0≦x<1) is employed, and the composition of said wave guide layer is:   Al.sub.x Ga.sub.1-x As(0≦x<0.35).     
     
     
       6. The semiconductor layer element according to claim 4, wherein V 0  is given by:   V.sub.0 =π·d.sub.0 /λ·(N.sub.1.sup.2 -N.sub.0.sup.2).sup.0.5     where d 0  is the thickness of said active layer, when said active layer is a quantum well, V 0  is defined as     V.sub.0 =N·π·d.sub.w /λ(N.sub.1.sup.2 -N.sub.0.sup.2).sup.0.3     where d w  is the thickness of said quantum well layer, N 1  is the refractive index of said quantum well layer, N 0  is the refractive index of said wave guide layer, and N is the number of said quantum wells, and a relationship of .[.(V 0  /3)<V 1  <5V 0  .]. (.Iadd.V 0  /3)<V 1  <V 0  .Iaddend.is established.   
     
     
       7. A laser device using said semiconductor laser element according to any .Iadd.one .Iaddend.of claims 1.Iadd., .Iaddend..[.or.]. 2 .Iadd.or 12..Iaddend. 
     
     
       8. A semiconductor laser excitation solid-state laser device using said semiconductor laser element according to any .Iadd.one .Iaddend.of claims 1.Iadd., .Iaddend..[.or.]. 2 .Iadd.or 12, .Iaddend.as a laser excitation light source. 
     
     
       9. The semiconductor laser excitation solid-state laser device according to claim 8, wherein the excitation light outputted from said laser element enters a solid-state laser without employing a lens. 
     
     
       10. The semiconductor laser element according to claim 1, wherein the refractive index of said wave guide layer increases monotonously with approaching carrier block layer. 
     
     
       11. The semiconductor laser element according to claim 5, wherein the relationship between Δx and d 1  (angstrom) falls within the following range   2.2·10.sup.3 /d.sub.1.sup.2 <Δx<5.0·10.sup.4 /d.sub.1.sup.2     where Δx is aluminum composition difference between said carrier block layer (x 1 ) and said wave guide layer (x 2 );   (Δx=x 1  -x 2 ), and d 1  is the thickness of said carrier block layer. .Iadd.   
     
     
       12.  A semiconductor laser element including an active layer having a light guiding function comprising: a pair of carrier block layers sandwiching said active layer, for reducing the light guiding function of said active layer,   a pair of wave guide layers sandwiching said pair of carrier block layers, and   a pair of clad layers sandwiching said pair of wave guide layers,   wherein V 1  relative to the normalized frequency V in a guided mode are defined by:   V.sub.1 =π·d.sub.1 /λ·(N.sub.0.sup.2 -N.sub.2.sup.2)0.5     and V 2  corresponding to the normalized frequency of the waveguide layer is defined by:     V.sub.2 =π·d.sub.2 /λ)·(N.sub.2.sup.2 -N.sub.3.sup.2).sup.0.5     where π is the ratio of the circumference of a circle to its diameter, d 1  is the thickness of said carrier block layer, λ is the oscillation wavelength, N 2  is the refractive index of said carrier block layer, d 2  is the effective thickness between said two clad layers, N 0  is the effective refractive index of said wave guide layer, and N 3  is the refractive index of said clad layer, wherein the relationship of V 1  <V 2  /10 is established..Iaddend.