Abstract:
To stabilize the near field pattern (NFP) in a semiconductor laser emitting apparatus which emits a laser beam in a multi-lateral mode and extend the application fields of the apparatus. A semiconductor laser emitting apparatus, which emits a laser beam in a multi-lateral mode, and comprises a cladding layer in a stripe form formed on an active layer, wherein a current injection region of the semiconductor laser emitting apparatus has a difference in optical absorption loss between the inside and the outside of the current injection region, wherein the cladding layer disposed on the outside of the current injection region is formed so as to have a thickness of 0.7 μm or less.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a semiconductor laser emitting apparatus. More particularly, the present invention is concerned with a semiconductor laser emitting apparatus which emits a laser beam in a multilateral mode, in which the near field pattern (hereinafter, frequently referred to simply as “NFP”) is stabilized.  
           [0003]    2. Description of the Related Art  
           [0004]    A conventional semiconductor laser emitting apparatus which emits a laser beam in a multi-lateral mode has, on an active layer, a cladding layer having a stripe structure such that the width is as large as 10 μm or more (i.e., wide-stripe structure), and has a structure shown in FIG. 8.  
           [0005]    As shown in FIG. 8, in a conventional semiconductor laser emitting apparatus  101  which emits a laser beam in a multi-lateral mode, a part of a cladding layer  112  formed on an active layer  111  is in a stripe form, and this stripe-form portion constitutes a current injection region  121 . On both sides of the current injection region  121 , current non-injection regions  122  having implanted thereinto, for example, boron ions (B + ) are formed. The cladding layer  112  is formed so that the thickness t of the portions of the cladding layer  112  under the current non-injection regions  122  becomes 1 μm or more, for example, about 1.3 μm.  
           [0006]    However, in the conventional semiconductor laser emitting apparatus which emits a laser beam in a multilateral mode, the NFP is unstable at a certain injection current value (output). This phenomenon is described below with reference to FIGS. 9A and 9B.  
           [0007]    In a semiconductor laser emitting apparatus  101  shown in FIG. 9A, light portions L and dark portions D are formed in the NFP. As the injection current value (or an optical output) is changed, the light portions L are seen so that they fluctuate in the right and left directions (as indicated by arrows). Alternatively, a part of or a whole of the light portions and dark portions in the NFP is changed, so that, as shown in FIG. 9B, the semiconductor laser emitting apparatus  101  is in a state such that the light portions L and the dark portions D in the NFP are reversed. That is, the light portions L and the dark portions D irregularly change places with one another with a lapse of time. In addition, a change in the light emission strength is observed at the edge of the NFP. Thus, the NFP becomes unstable with time.  
           [0008]    The above phenomenon in which the light and dark portions in the NFP fluctuate is a problem inherent in the multi-lateral-mode semiconductor laser emitting apparatus, and does not arise in the semiconductor laser emitting apparatus having a narrower stripe width (for example, about 3 μm or less), i.e., the so-called single mode oscillation semiconductor laser emitting apparatus.  
           [0009]    In addition, in a conventional semiconductor laser emitting apparatus having a gain waveguide structure, a difference in refractive index is not made between the portion directly under the portion in a stripe form and the outside thereof. Therefore, the NFP broadens also in the direction of the outside of the portion directly under the portion in a stripe form, so that there occurs the above phenomenon in which the NFP becomes unstable.  
           [0010]    When the above semiconductor laser emitting apparatus is used in a machine required to achieve a uniformity of light emission, such as a printer, the phenomenon in which the NFP becomes unstable causes unevenness (for example, printing unevenness in a case of a printer). For obtaining the uniformity of light emission, there is a method in which an oscillated laser beam is once passed through an optical fiber so that it becomes uniform, and the resultant uniform laser beam is used. However, the use of this method disadvantageously causes an increase in cost.  
           [0011]    Further, the current value at which the NFP becomes unstable varies depending on operation conditions, such as a temperature of the environment for operation, and, the semiconductor laser emitting apparatuses produced from the same materials under the same conditions respectively have different current values at which the phenomenon in which the NFP becomes unstable occurs. Therefore, it has been difficult to operate the semiconductor laser emitting apparatus while avoiding the operating point at which the NFP becomes unstable.  
         SUMMARY OF THE INVENTION  
         [0012]    The present invention is a semiconductor laser emitting apparatus which has been made for solving the above-mentioned problems accompanying the conventional art.  
           [0013]    The semiconductor laser emitting apparatus of the present invention emits a laser beam in a multi-lateral mode and comprises a cladding layer in a stripe form formed on an active layer, wherein a current injection region of the semiconductor laser emitting apparatus has a difference in optical absorption loss between the inside and the outside of the current injection region, wherein the cladding layer disposed on the outside of the current injection region is formed so as to have a thickness of 0.7 μm or less. Alternatively, in the semiconductor laser emitting apparatus of the present invention, a current injection region has a difference in optical absorption loss between the inside and the outside of the current injection region, and the cladding layer is formed only in the current injection region.  
           [0014]    In the semiconductor laser emitting apparatus of the present invention, the cladding layer disposed on the outside of the current injection region is formed so as to have a thickness of 0.7 μm or less. Therefore, a current is efficiently injected into the current injection region, so that the current leakage amount is suppressed. Further, the current injection region of the semiconductor laser emitting apparatus has a difference in optical absorption loss between the inside and the outside of the current injection region. Therefore, the waveguide of a laser can be changed between the inside and the outside of the current injection region in a stripe form, so that the laser is efficiently kept directly under the portion in a stripe form, thus making it possible to obtain a stable NFP free of fluctuation in the light portions and the dark portions therein.  
           [0015]    As mentioned above, in the semiconductor laser emitting apparatus of the present invention, the cladding layer disposed on the outside of the current injection region is formed so as to have a thickness of 0.7 μm or less, or the cladding layer is formed only in the current injection region. Therefore, the current leakage amount can be suppressed, making it possible to efficiently inject a current into the current injection region. In addition, the current injection region of the semiconductor laser emitting apparatus has a difference in optical absorption loss between the inside and the outside of the current injection region. Therefore, the waveguide of a laser can be changed between the inside and the outside of the current injection region in a stripe form, so that the laser is efficiently kept directly under the portion in a stripe form, rendering it possible to obtain a stable NFP without problems of a change with time in the light emission pattern, a change in the strength at an edge of the NFP, and the like caused by the changing of the optical output or current injection amount, which problems have been inevitably encountered in the conventional semiconductor laser emitting apparatus which emits a laser beam in a multilateral mode.  
           [0016]    Thus, the semiconductor laser emitting apparatus which emits a laser beam in a multi-lateral mode can be applied to the fields which are required to achieve a uniformity of light emission. Further, the uniformity of light emission can be achieved without using an optical fiber, and hence, an increase in cost can be prevented.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    The foregoing and other objects, features and advantages of the present invention will be apparent to those skilled in the art from the following description of the presently preferred exemplary embodiments of the invention taken in connection with the accompanying drawings, in which:  
         [0018]    [0018]FIG. 1 is a diagrammatic cross-sectional view showing a semiconductor laser emitting apparatus according to the first embodiment of the present invention;  
         [0019]    [0019]FIGS. 2A to  2 C are diagrammatic cross-sectional views showing a process for producing a semiconductor laser emitting apparatus of the present invention;  
         [0020]    [0020]FIG. 3 is a diagrammatic cross-sectional view showing a semiconductor laser emitting apparatus according to the second embodiment of the present invention;  
         [0021]    [0021]FIG. 4 is a diagrammatic cross-sectional view showing a semiconductor laser emitting apparatus according to the third embodiment of the present invention;  
         [0022]    [0022]FIG. 5 is a diagrammatic cross-sectional view showing a semiconductor laser emitting apparatus according to the fourth embodiment of the present invention;  
         [0023]    [0023]FIG. 6 is a diagrammatic cross-sectional view showing a semiconductor laser emitting apparatus according to the fifth embodiment of the present invention;  
         [0024]    [0024]FIG. 7 is a diagrammatic cross-sectional view showing a semiconductor laser emitting apparatus according to the sixth embodiment of the present invention;  
         [0025]    [0025]FIG. 8 is a diagrammatic cross-sectional view showing a conventional semiconductor laser emitting apparatus; and  
         [0026]    [0026]FIGS. 9A and 9B are diagrammatic explanatory views illustrating a problem of a conventional semiconductor laser emitting apparatus. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0027]    The semiconductor laser emitting apparatus according to the first embodiment of the present invention is described below with reference to the diagrammatic cross-sectional view of FIG. 1.  
         [0028]    As shown in FIG. 1, in a first semiconductor laser emitting apparatus  1 , on a surface side of a substrate  11  comprised of a GaAs substrate, a first n-type buffer layer  12 , a second n-type buffer layer  13 , an n-type cladding layer  14 , a guide layer  15 , an active layer  16 , a guide layer  17 , a p-type cladding layer  18 , and a p-type cap layer  19  comprised of p-type GaAs are formed in this order from bottom. On the other hand, on a back side of the substrate  11 , an n-type electrode layer  91  is formed.  
         [0029]    As examples of the above layers, the following can be mentioned. The first n-type buffer layer  12  is formed by depositing n-type GaAs so as to have a thickness of, for example, 0.5 μm, and the second n-type buffer layer  13  is formed by depositing n-type Al 0.3 Ga 0.7 As so as to have a thickness of, for example, 0.5 μm. In addition, the n-type cladding layer  14  is formed by depositing n-type Al x Ga 1-x As so as to have a thickness of, for example, 1.8 μm. Further, the guide layer  15  is formed by depositing Al 0.3 Ga 0.7 As so as to have a thickness of, for example, 60 to 65 nm, and the active layer  16  is formed by depositing Al 0.1 Ga 0.9 As so as to have a thickness of, for example, 10 nm, and the guide layer  17  is formed by depositing Al 0.3 Ga 0.7 As so as to have a thickness of, for example, 60 to 65 nm. Furthermore, the p-type cladding layer  18  is formed by depositing p-type Al x Ga 1-x As so as to have a thickness of, for example, 1.8 μm. In the above chemical formulae for the layer materials, the atomic ratio x of aluminum (Al) is, for example, 0.5 (x=0.5).  
         [0030]    The p-type cap layer  19  and the p-type cladding layer  18  are formed in a stripe form such that the width is, for example, 10 μm, to thereby constitute a current injection region  21 . On both sides of the current injection region  21 , current non-injection regions  22  are formed in a groove form. The thickness t of the portions of the p-type cladding layer  18  remaining for the current non-injection regions  22  is 0.7 μm or less. Alternatively, the grooves constituting the current non-injection regions  22  may be formed so as to penetrate the active layer  16 .  
         [0031]    Further, a GaAs layer  31 , a p-type Al 0.5 Ga 0.5 As layer  32 , and an n-type GaAs layer  33  are stacked on one another so as to cover the current injection region  21  in a stripe form and the portions of the p-type cladding layer  18  for the current non-injection regions  22 , and an opening portion  34  is formed in the n-type GaAs layer  33  on the current injection region  21 . A p-type electrode (p-type ohmic electrode)(not shown) is formed in the opening portion  34 .  
         [0032]    The first semiconductor laser emitting apparatus  1  emits a laser beam in a multi-lateral mode. Therefore, the width of the stripe-form portion constituting the current injection region  21  is set, for example, in the range of from 10 to 500 μm.  
         [0033]    In the first semiconductor laser emitting apparatus  1  having the above-mentioned construction, the thickness t of the portions of the p-type cladding layer  18  for the current non-injection regions  22  is 0.7 μm or less. Therefore, the current leakage amount is suppressed. In addition, the waveguide of a laser is changed between the current injection region  21  in a stripe form and the current non-injection regions  22 , so that a difference in optical absorption loss between the current injection region  21  and the current non-injection regions  22  keeps the laser directly under the portion in a stripe form, thus making it possible to obtain a stable NFP.  
         [0034]    In contrast, when the thickness t of the portions of the p-type cladding layer  18  for the current non-injection regions  22  exceeds 0.7 μm, the current leakage amount is increased, and it becomes difficult to obtain a stable NFP.  
         [0035]    Next, a process for producing the first semiconductor laser emitting apparatus  1  is described below with reference to FIGS. 2A to  2 C. In FIGS. 2A to  2 C and FIG. 1, similar parts or portions are indicated by the same reference numerals. In addition, in FIGS. 2B and  2 C, the lower layer portion is not shown.  
         [0036]    As shown in FIG. 2A, on a surface side of a substrate  11  comprised of a GaAs substrate, a first n-type buffer layer  12 , a second n-type buffer layer  13 , an n-type cladding layer  14 , a guide layer  15 , an active layer  16 , a guide layer  17 , a p-type cladding layer  18 , and a p-type cap layer  19  comprised of p-type GaAs are successively formed by a metal organic chemical vapor deposition (hereinafter, frequently referred to simply as “MOCVD”) process under a reduced pressure of, for example, about 133 kPa.  
         [0037]    As examples of the above layers, on the surface side of the substrate  11 , n-type GaAs is deposited so as to have a thickness of, for example, 0.5 μm, to thereby form the first n-type buffer layer  12 , and n-type Al 0.3 Ga 0.7 As is deposited thereon so as to have a thickness of, for example, 0.5 μm, to thereby form the second n-type buffer layer  13 . Then, n-type Al x Ga 1-x As is deposited thereon so as to have a thickness of, for example, 1.8 μm, to thereby form the n-type cladding layer  14 . Subsequently, Al 0.3 Ga 0.7 As is deposited thereon so as to have a thickness of, for example, 60 to 65 nm, to thereby form the guide layer  15 , and Al 0.1 Ga 0.9 As is deposited thereon so as to have a thickness of, for example, 10 nm, to thereby form the active layer  16 , and Al 0.3 Ga 0.7 As is deposited thereon so as to have a thickness of, for example, 60 to 65 nm, to thereby form the guide layer  17 . Then, p-type Al x Ga 1-x As is deposited thereon so as to have a thickness of, for example, 1.8 μm, to thereby form the p-type cladding layer  18 . In the above chemical formulae for the layer materials, the Al atomic ratio x is, for example, 0.5 (x=0.5).  
         [0038]    Then, as shown in FIG. 2B, the p-type cap layer  19  and the p-type cladding layer  18  are processed using a lithography technique and an etching technique, to thereby form a current injection region  21  in a stripe form and current non-injection regions  22  in a groove form on both sides of the current injection region  21 . The thickness t of the portions of the p-type cladding layer  18  remaining for the current non-injection regions  22  is 0.7 μm or less. Alternatively, the grooves constituting the current non-injection regions  22  may be formed so as to penetrate the active layer  16 .  
         [0039]    Then, as shown in FIG. 2C, a GaAs layer  31 , a p-type Al 0.5 Ga 0.5 As layer  32 , and an n-type GaAs layer  33  are successively deposited so as to cover the current injection region  21  in a stripe form and the p-type cladding layer  18  by a MOCVD process.  
         [0040]    Subsequently, the n-type GaAs layer  31  on the current injection region  21  in a stripe form is removed using a lithography technique and an etching technique, to thereby form an opening portion  34 . Then, a step for diffusing zinc (Zn) is performed, and then, a p-type electrode (for example, p-type ohmic electrode)(not shown) and an n-type electrode (for example, n-type ohmic electrode)(not shown) are formed. With respect to the materials for the layers which are deposited after forming the stripe structure, there is no particular limitation, and, for example, these layers may be formed from only GaAs.  
         [0041]    Next, another semiconductor laser emitting apparatus according to the second embodiment of the present invention is described below with reference to the diagrammatic cross-sectional view of FIG. 3. In FIG. 3 and FIG. 1, similar parts or portions are indicated by the same reference numerals. In addition, the portion lower than the active layer in the apparatus of the second embodiment is the same as that in the apparatus of the first embodiment. Therefore, in the second embodiment, the description in detail about the above portion is omitted, and a reference can be made to the corresponding descriptive portion in the first embodiment.  
         [0042]    As shown in FIG. 3, in a second semiconductor laser emitting apparatus  2 , on a surface side of a substrate  11  comprised of a GaAs substrate, a first n-type buffer layer  12 , a second n-type buffer layer  13 , an n-type cladding layer  14 , a guide layer  15 , an active layer  16 , and a guide layer  17  are stacked on one another in this order. In the layers of from the first n-type buffer layer  12  to the guide layer  17 , for example, the same materials as those for the corresponding layers in the semiconductor laser emitting apparatus of the first embodiment are used. On the other hand, on a back side of the substrate  11 , an n-type electrode layer  91  is formed.  
         [0043]    A p-type cladding layer  18  is formed on the guide layer  17  from, for example, a p-type Al x Ga 1-x As layer, and a layer  41  having a refractive index larger than that of the layer therearound is formed from, for example, a p-type Al y Ga 1-y As layer in the p-type cladding layer  18 . In the above chemical formulae for the layer materials, the Al atomic ratios x and y satisfy, for example, a requirement that x be 0.5 (x=0.5) and x be larger than y (x&gt;y). Accordingly, the p-type cladding layer  18  ( 18 A), the layer  41  having a larger refractive index, the p-type cladding layer  18  ( 18 B), and a p-type cap layer  19  are stacked on one another on the guide layer  17 , and the layer  41  having a larger refractive index, the p-type cladding layer  18 B and the p-type cap layer  19  constitute a current injection region  21  having a stripe structure such that the width is, for example, 10 μm. In the second semiconductor laser emitting apparatus  2 , the thickness t of the p-type cladding layer  18  ( 18 A) for current non-injection regions  22  is 0.7 μm or less. Alternatively, the grooves constituting the current non-injection regions  22  may be formed so as to penetrate the active layer  16 .  
         [0044]    Further, a GaAs layer  31 , a p-type Al 0.5 Ga 0.5 As layer  32 , and an n-type GaAs layer  33  are stacked on one another so as to cover the p-type cladding layer  18  for the current injection region  21  in a stripe form and the current non-injection regions  22 , and the p-type cap layer  19 , and an opening portion  34  is formed in the n-type GaAs layer  33  on the current injection region  21 . A p-type electrode (p-type ohmic electrode)(not shown) is formed in the opening portion  34 .  
         [0045]    The second semiconductor laser emitting apparatus  2  emits a laser beam in a multi-lateral mode. Therefore, the width of the stripe-form portion constituting the current injection region  21  is set, for example, in the range of from 10 to 500 μm.  
         [0046]    In the second semiconductor laser emitting apparatus  2  having the above-mentioned construction, the thickness t of the p-type cladding layer  18 A for the current non-injection regions  22  is 0.7 μm or less. Therefore, the current leakage amount is suppressed. In addition, the waveguide of a laser is changed between the current injection region  21  in a stripe form and the current non-injection regions  22 , so that a difference in optical absorption loss between the current injection region  21  and the current non-injection regions  22  keeps the laser directly under the portion in a stripe form, thus making it possible to obtain a stable NFP.  
         [0047]    In contrast, when the thickness t of the p-type cladding layer  18 A for the current non-injection regions  22  exceeds 0.7 μm, the current leakage amount is increased, and it becomes difficult to obtain a stable NFP.  
         [0048]    The second semiconductor laser emitting apparatus  2  may be produced by the following process. The layers of from the first n-type buffer layer  12  to the p-type cap layer  19  are formed on the substrate  11  by a MOCVD process under a reduced pressure, and then, a stripe structure is formed in the resultant layers using a lithography technique and an etching technique. Then, the GaAs layer  31 , the p-type Al 0.5 G 0.5 As layer  32 , and the n-type GaAs layer  33  are successively formed thereon, and the opening portion  34  is formed in the same manner as that described in the first embodiment. Then, the p-type electrode (not shown) and the n-type electrode  91  are formed.  
         [0049]    Next, another semiconductor laser emitting apparatus according to the third embodiment of the present invention is described below with reference to the diagrammatic cross-sectional view of FIG. 4. In FIG. 4 and FIG. 1, similar parts or portions are indicated by the same reference numerals. In addition, the portion lower than the active layer in the apparatus of the third embodiment is the same as that in the apparatus of the first embodiment. Therefore, in the third embodiment, the description in detail about the above portion is omitted, and a reference can be made to the corresponding descriptive portion in the first embodiment.  
         [0050]    As shown in FIG. 4, in a third semiconductor laser emitting apparatus  3 , on a surface side of a substrate  11  comprised of a GaAs substrate, a first n-type buffer layer  12 , a second n-type buffer layer  13 , an n-type cladding layer  14 , a guide layer  15 , an active layer  16 , a guide layer  17 , and a p-type cladding layer  18  are stacked on one another in this order.  
         [0051]    Current constriction grooves  51 ,  52  which constitute current non-injection regions  22  are formed in the p-type cladding layer  18 , and the portion in a stripe form between the current constriction grooves  51 ,  52  constitutes a current injection region  21 . In the third semiconductor laser emitting apparatus  3 , the thickness t of the portions of the p-type cladding layer  18  under the current constriction grooves  51 ,  52  is 0.7 μm or less. Alternatively, the current constriction grooves  51 ,  52  may be formed in a state such that they penetrate the active layer  16 , and such a structure does not affect the properties of the third semiconductor laser emitting apparatus  3 .  
         [0052]    Further, a p-type cap layer  19  and a p-type electrode (p-type ohmic electrode)  35  are formed on the p-type cladding layer  18  for the current injection region  21  in a stripe form. On the other hand, on a back side of the substrate  11 , an n-type electrode layer  91  is formed.  
         [0053]    The third semiconductor laser emitting apparatus  3  emits a laser beam in a multi-lateral mode. Therefore, the width of the stripe-form portion constituting the current injection region  21  is set, for example, in the range of from 10 to 500 μm.  
         [0054]    In the third semiconductor laser emitting apparatus  3  having the above-mentioned construction, the thickness t of the portions of the p-type cladding layer  18  under the current constriction grooves  51 ,  52  is 0.7 μm or less. Therefore, the current leakage amount is suppressed. In addition, the waveguide of a laser is changed between the inside and the outside of the current injection region  21  in a stripe form, so that a difference in optical absorption loss between the current injection region  21  and the current non-injection regions  22  keeps the laser directly under the portion in a stripe form, thus making it possible to obtain a stable NFP.  
         [0055]    In contrast, when the thickness t of the portions of the p-type cladding layer  18  under the current constriction grooves  51 ,  52  exceeds 0.7 μm, the current leakage amount is increased, and it becomes difficult to obtain a stable NFP.  
         [0056]    The third semiconductor laser emitting apparatus  3  may be produced by the following process. The layers of from the first n-type buffer layer  12  to the p-type cap layer  19  are formed on the substrate  11  by a reduced pressure CVD process, and then, the current constriction grooves  51 ,  52  are formed in the resultant layers using a lithography technique and an etching technique, to thereby form a stripe structure. Then, the p-type electrode  35  and the n-type electrode  91  are formed.  
         [0057]    Next, another semiconductor laser emitting apparatus according to the fourth embodiment of the present invention is described below with reference to the diagrammatic cross-sectional view of FIG. 5. In FIG. 5 and FIG. 1, similar parts or portions are indicated by the same reference numerals. In addition, the portion lower than the active layer in the apparatus of the fourth embodiment is the same as that in the apparatus of the first embodiment. Therefore, in the fourth embodiment, the description in detail about the above portion is omitted, and a reference can be made to the corresponding descriptive portion in the first embodiment.  
         [0058]    As shown in FIG. 5, in a fourth semiconductor laser emitting apparatus  4 , on a surface side of a substrate  11  comprised of a GaAs substrate, a first n-type buffer layer  12 , a second n-type buffer layer  13 , an n-type cladding layer  14 , a guide layer  15 , an active layer  16 , a guide layer  17 , and a p-type cladding layer  18  are stacked on one another in this order. On the other hand, on a back side of the substrate  11 , an n-type electrode layer  91  is formed.  
         [0059]    Ion implantation regions  61 ,  62  which constitute current non-injection regions  22  are formed in the p-type cladding layer  18 , and the portion in a stripe form between the ion implantation regions  61 ,  62  constitutes a current injection region  21 . In the fourth semiconductor laser emitting apparatus  4 , the thickness t of the portions of the p-type cladding layer  18  under the ion implantation regions  61 ,  62  is 0.7 μm or less. Alternatively, the ion implantation regions  61 ,  62  may be formed in a state such that they penetrate the active layer  16 , and such a structure does not affect the properties of the fourth semiconductor laser emitting apparatus  4 .  
         [0060]    Further, a p-type cap layer  19  is formed on the p-type cladding layer  18  for the current injection region  21  in a stripe form.  
         [0061]    The fourth semiconductor laser emitting apparatus  4  emits a laser beam in a multi-lateral mode. Therefore, the width of the stripe-form portion constituting the current injection region  21  is set, for example, in the range of from 10 to 500 μm.  
         [0062]    In the fourth semiconductor laser emitting apparatus  4  having the above-mentioned construction, the thickness t of the portions of the p-type cladding layer  18  under the ion implantation regions  61 ,  62  is 0.7 μm or less. Therefore, the current leakage amount is suppressed. In addition, the waveguide of a laser is changed between the inside and the outside of the current injection region  21  in a stripe form, so that a difference in optical absorption loss between the current injection region  21  and the current non-injection regions  22  keeps the laser directly under the portion in a stripe form, thus making it possible to obtain a stable NFP.  
         [0063]    In contrast, when the thickness t of the portions of the p-type cladding layer  18  under the ion implantation regions  61 ,  62  exceeds 0.7 μm, the current leakage amount is increased, and it becomes difficult to obtain a stable NFP.  
         [0064]    The forth semiconductor laser emitting apparatus  4  may be produced by the following process. The layers of from the first n-type buffer layer  12  to the p-type cap layer  19  are formed on the substrate  11  by a reduced pressure CVD process, and then, the ion implantation regions  61 ,  62  are formed in the resultant layers using an ion implantation technique, to thereby form a stripe structure. Then, the p-type electrode (not shown) and the n-type electrode  91  are formed.  
         [0065]    In each of the above embodiments, an explanation is made on the GaAs/AlGaAs semiconductor laser emitting apparatus which is obtained by allowing AlGaAs to grow on a GaAs substrate, but the construction of the semiconductor laser emitting apparatus of the present invention can be applied to a semiconductor laser emitting apparatus obtained using different substrates and materials. For example, a GaInP/AlGaInP semiconductor laser emitting apparatus or an AlGaN/InGaN semiconductor laser emitting apparatus to which the construction of the semiconductor laser emitting apparatus of the present invention is applied can be prevented from suffering the unfavorable phenomenon in which the NFP is unstable.  
         [0066]    As examples of such semiconductor laser emitting apparatuses, a GaInP/AlGaInP semiconductor laser emitting apparatus which emits a red light is described below as the fifth embodiment of the present invention, with reference to the diagrammatic cross-sectional view of FIG. 6, and an AlGaN/InGaN semiconductor laser emitting apparatus which emits a blue light is described below as the sixth embodiment of the present invention, with reference to the diagrammatic cross-sectional view of FIG. 7.  
         [0067]    As shown in FIG. 6, in a GaInP/AlGaInP semiconductor laser emitting apparatus (fifth semiconductor laser emitting apparatus)  5  which emits a red light, on a surface side of an n-type substrate  11 , an n-type cladding layer  72 , a guide layer  73 , an active layer  74 , and a guide layer  75  are stacked on one another in this order. A p-type cladding layer  76  ( 76 A,  76 B) is formed on the guide layer  75 , and a layer  77  having a refractive index larger than that of the layer therearound is formed in the p-type cladding layer  76  from, for example, a p-type Al x GaInP layer.  
         [0068]    The n-type cladding layer  72  is formed from, for example, an n-type AlGaInP layer. The guide layer  73  is formed from, for example, a GaInP layer. The active layer  74  is formed from, for example, an AlGaInP layer. The guide layer  75  is formed from, for example, a GaInP layer. The p-type cladding layers  76 A,  76 B are formed from, for example, a p-type Al x GaInP layer. The layer  77  having a larger refractive index is formed from, for example, a p-type Al y GaInP layer. In the above chemical formulae for the layer materials, the Al atomic ratios x and y satisfy, for example, a requirement that x be larger than y (x&gt;y).  
         [0069]    Accordingly, the p-type cladding layer  76  ( 76 A), the layer  77  having a larger refractive index, the p-type cladding layer  76  ( 76 B), and a p-type cap layer (for example, a p-type GaAs layer)  78  are stacked on one another on the guide layer  75 , and the layer  77  having a larger refractive index, the p-type cladding layer  76 B, and the p-type cap layer  78  constitute a current injection region  21  having a stripe structure. In the fifth semiconductor laser emitting apparatus  5 , the thickness t of the p-type cladding layer  76 A is 0.7 μm or less.  
         [0070]    In addition, for example, GaAs layers  79  are formed on current non-injection regions  22  on both sides of the current injection region  21 .  
         [0071]    The fifth semiconductor laser emitting apparatus  5  emits a laser beam in a multi-lateral mode. Therefore, the width of the stripe-form portion constituting the current injection region  21  is set, for example, in the range of from 10 to 500 μm.  
         [0072]    In the fifth semiconductor laser emitting apparatus  5  having the above-mentioned construction, the thickness t of the p-type cladding layer  76 A for the current non-injection regions  22  is 0.7 μm or less. Therefore, the current leakage amount is suppressed. In addition, the waveguide of a laser is changed between the inside and the outside of the current injection region  21  in a stripe form, so that a difference in optical absorption loss between the current injection region  21  and the current non-injection regions  22  keeps the laser directly under the portion in a stripe form, thus making it possible to obtain a stable NFP.  
         [0073]    In contrast, when the thickness t of the p-type cladding layer  76 A for the current non-injection regions  22  exceeds 0.7 μm, the current leakage amount is increased, and it becomes difficult to obtain a stable NFP.  
         [0074]    The fifth semiconductor laser emitting apparatus  5  may be produced by the following process. The layers of from the n-type cladding layer  72  to the p-type cap layer  78  are formed on the substrate  11  by, for example, a reduced pressure CVD process, and then, the grooves which constitute the current non-injection regions  22  are formed using a lithography technique and an etching technique, to thereby form the current injection region  21  having a stripe structure. Then, electrodes are individually formed.  
         [0075]    Next, as shown in FIG. 7, in an AlGaN/InGaN semiconductor laser emitting apparatus (sixth semiconductor laser emitting apparatus)  6  which emits a blue light, on a surface side of an n-type substrate  11 , an n-type cladding layer  82  and an active layer  83  are stacked on one another in this order. A p-type cladding layer  84  is formed on the active layer  83 , and a part of the p-type cladding layer  84  is in a stripe form, and this stripe-form portion constitutes a current injection region  21 . In the sixth semiconductor laser emitting apparatus  6 , the thickness t of the portions of the p-type cladding layer  84  at a bottom portion of the current non-injection regions  22  on both sides of the current injection region  21  having a stripe structure is 0.7 μm or less.  
         [0076]    The n-type cladding layer  82  is formed from, for example, an n-type AlGaN layer having a thickness of 1.5 μm. The active layer  83  is formed from, for example, an InGaN layer having a thickness of 50 nm. The p-type cladding layer  84  is formed from, for example, a p-type AlGaN layer, and the stripe-form portions of the p-type cladding layer  84  is formed so as to have a thickness of, for example, 1.5 μm.  
         [0077]    In addition, for example, AlGaN layers  85  are formed on the current non-injection regions  22  on both sides of the current injection region  21 .  
         [0078]    The current non-injection regions  22  on both sides of the current injection region  21  are formed from, for example, a GaAs layer.  
         [0079]    The sixth semiconductor laser emitting apparatus  6  emits a laser beam in a multi-lateral mode. Therefore, the width of the stripe-form portion constituting the current injection region  21  is set, for example, in the range of from 10 to 500 μm.  
         [0080]    In the sixth semiconductor laser emitting apparatus  6  having the above-mentioned construction, the thickness t of the portions of the p-type cladding layer  84  for the current non-injection regions  22  is 0.7 μm or less. Therefore, the current leakage amount is suppressed. In addition, the waveguide of a laser is changed between the inside and the outside of the current injection region  21  in a stripe form, so that a difference in optical absorption loss between the current injection region  21  and the current non-injection regions  22  keeps the laser directly under the portion in a stripe form, thus making it possible to obtain a stable NFP.  
         [0081]    In contrast, when the thickness t of the portions of the p-type cladding layer  84  for the current non-injection regions  22  exceeds 0.7 μm, the current leakage amount is increased, and it becomes difficult to obtain a stable NFP.  
         [0082]    The sixth semiconductor laser emitting apparatus  6  may be produced by the following process. The layers of from the n-type cladding layer  82  to the p-type cladding layer  84  are formed on the substrate  11  by, for example, a reduced pressure CVD process, and then, the grooves which constitute the current non-injection regions  22  are formed using a lithography technique and an etching technique, to thereby form the current injection region  21  having a stripe structure. Then, electrodes (not shown) are individually formed.