JP2005216925A - Vertical cavity surface emitting laser array - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vertical cavity surface emitting laser array reducing a temperature difference between laser elements as much as possible and having more uniform characteristics. <P>SOLUTION: The vertical cavity surface emitting laser array 110 has a substrate 120, a plurality of the laser elements 130 disposed in a matrix shape on the substrate and an electrode E for supplying a plurality of the laser elements with a current. A plurality of the laser elements 130 are arranged in regions excepting at least a central section. Accordingly, the temperature differences among each laser element are reduced by inhibiting the effect of the temperature rise of the central section, and the characteristics of the array, that is, an oscillation wavelength, an optical output and an average life can be equalized. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a surface emitting semiconductor laser array used for a light source such as optical communication, and more particularly to a layout of a laser element.

  A surface-emitting semiconductor laser (Vertical-Cavity Surface-Emitting Laser diode, hereinafter referred to as VCSEL) has a low threshold current, low power consumption, and a circular light spot can be easily obtained. It has excellent features such as being possible. On the other hand, since the light output from each laser element is small, when a large output is required, multiple laser elements are arranged in an array, and these are driven at the same time, or grouped elements are time-shared. Is driving.

  Various reports have been made on VCSELs that output such multi-spot laser beams. For example, in Patent Document 1, an upper electrode having four openings (2 × 2 array) is provided on the end face of a single columnar portion formed on a substrate at a simple square shape to cover the opening. Thus, a surface emitting semiconductor laser having an upper reflecting mirror is disclosed. This makes it possible to reduce the radiation angle by bringing light emitting spots close to each other.

  Patent Document 2 relates to a transmission apparatus that includes a two-dimensional laser array in which 2 × 2 laser elements are arranged at simple square positions and makes light from these lasers enter a multimode optical fiber.

  In Patent Document 3, a regular hexagonal columnar waveguide made of a semiconductor crystal is formed by a selective growth technique, and a light emitting active layer that can be driven independently is provided on each side surface to constitute a surface emitting laser.

  In Patent Document 4, a light emitting region is divided into a plurality of 2 × 2 regions, and currents are divided and injected to operate each light emitting region in a highly efficient state. A resonant light emitting diode is obtained.

JP-A-8-340156 JP 2000-299534 A JP 10-308552 A JP 2002-270960 A

  However, the conventional surface emitting semiconductor laser array has the following problems. FIG. 13 is a schematic plan view when laser elements are arranged in a matrix of 5 rows × 5 columns. A circular portion represents a post of each laser element, and each laser element is arranged at an interval of 50 μm. When a drive current of 10 mA is supplied to each laser element via the electrode E and all the laser elements are turned on simultaneously, a temperature change occurs between the laser elements due to heat generated from each laser element. For example, a temperature difference of about 10 ° C. occurs between the center laser element C and the four corner laser elements A, B, D, and E. When a temperature difference occurs between laser elements, the wavelength, light output, and average life of each laser element change, and there is a problem that uniform laser oscillation cannot be obtained from the laser array.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and provide a surface emitting semiconductor laser array having a more uniform characteristic by minimizing a temperature difference between laser elements.

  In order to solve the above conventional problems, the present invention has been analyzed as follows. FIG. 14A is a graph in which the wavelengths of the laser elements A, B, C, D, and E shown in FIG. 13 arranged in a 5 × 5 matrix are measured. The horizontal axis indicates the wavelength, and the vertical axis indicates the optical output. Is shown. The table of FIG. 14B shows the wavelength difference (Δλp) with reference to the peak wavelength (λp) of the laser elements A, B, C, D, and E and the wavelength of the central laser element C (859.72 nm). The temperature difference (ΔT ° C.) estimated from the wavelength difference is shown. As is clear from the table, the wavelengths of the laser elements A, B, D, and E are −0.6 nm, −0.64 nm, −0.6 nm, and −0.52 nm, respectively, as compared with the laser element C. Only shortened. It is well known that the oscillation wavelength of laser light transitions due to a temperature change, and the relationship between the wavelength change and the temperature difference can be expressed by an equation of 0.6 nm / ° C. Using this equation, the temperature difference between the laser elements A, B, D, and E at the four corners is estimated with reference to the center laser element C, and −10 ° C., −10.6667 ° C., −10 ° C., − 8.66667 ° C.

  Further, when a 10 mA drive current is supplied to each laser element, the temperature rise of the laser element itself is about 30 degrees. Each laser element has a mesa or post projecting from the GaAs substrate, and the heat generated from each post is considered to conduct heat uniformly to the GaAs substrate. The reason why the temperature of the central laser element C is relatively higher than the other laser elements is presumed to be affected by the heat from the adjacent laser elements.

  Focusing on the laser element C (see FIG. 13), there are eight adjacent laser elements C1 to C8 around the laser element C. The laser elements C2, C4, C6, and C8 are separated from the laser element C by 50 μm, and the laser elements C1, C3, C5, and C7 are separated from the laser element C by about 70 μm. Hereinafter, laser elements separated by 50 μm are referred to as “adjacent laser elements”, and laser elements separated by 70 μm are referred to as “diagonal adjacent laser elements”.

  On the other hand, paying attention to the laser element A located at the corner, there are two adjacent laser elements A1 and A2 and one diagonally adjacent laser element C1 around the laser element A. Regarding the laser elements B, D, and E at the other corners, there are two adjacent laser elements and one diagonal adjacent laser element, respectively.

  The laser elements arranged in a matrix form have different numbers of adjacent laser elements and diagonally adjacent laser elements that are thermally affected depending on their positions, and this difference in quantity results in each laser element. It is considered that a temperature difference is caused. Assuming that the above is isotropically heat-diffused with measured values based on experimental data and calculating the heat inflow from each laser element, the temperature rise (heat inflow) received from one adjacent laser element is 2.5 ° C. The temperature rise (heat inflow) received from one diagonally adjacent laser element can be expressed as 1.67 ° C.

  The table shown in FIG. 15A is obtained when the number of adjacent laser elements and the number of diagonally adjacent laser elements for laser elements A to E, the temperature rise calculated according to the above assumption, and self-heating (30 ° C.) are added. Represents the temperature. FIG. 2B shows the relationship between the beam interval (laser element interval) and heat inflow. Comparing the center laser element C with the corner laser elements A, B, D, and E, the number of adjacent laser elements and the diagonally adjacent laser elements for the laser element C are larger than the number of corner laser elements. The difference between them is 2 for the number of adjacent laser elements and 3 for the number of diagonally adjacent laser elements, and the temperature difference due to heat inflow is 10 ° C.

  Based on the above analysis, the present invention employs the following means. A surface emitting semiconductor laser array according to the present invention includes a substrate, a plurality of laser elements two-dimensionally arranged on the substrate, and an electrode portion for supplying current to the plurality of laser elements, The plurality of laser elements are arranged in a region excluding at least the central portion. By suppressing the influence of the temperature rise at the center, the temperature difference between the laser elements can be reduced, and the characteristics of the array, that is, the oscillation wavelength, the optical output, and the average life can be made uniform.

  Preferably, the plurality of laser elements are arranged in a matrix, and the laser elements are arranged in a region excluding the center thereof. Preferably, the laser elements are arranged in a region excluding the corners in the matrix arrangement. The matrix array has at least 3 rows x 3 columns. Since the temperature rise of the laser elements arranged in the corners is smaller than that of other elements, the temperature difference between the laser elements can be reduced by eliminating these laser elements, and the uniformity of the array characteristics can be achieved.

  Furthermore, the surface emitting semiconductor laser array according to the present invention includes a substrate, a plurality of laser elements arranged two-dimensionally on the substrate, and an electrode portion for supplying current to the plurality of laser elements, The plurality of laser elements are all arranged at equal intervals. As a result, the influence of heat received by each laser element from other laser elements can be made uniform, the temperature difference between the laser elements can be reduced, and the characteristics of the array can be made uniform.

  Furthermore, the surface emitting semiconductor laser array according to the present invention includes a substrate, a plurality of laser elements arranged two-dimensionally on the substrate, and an electrode portion for supplying current to the plurality of laser elements, Each laser element has a post protruding from the substrate, the post having a current confinement layer including an oxidized region selectively oxidized and a conductive region surrounded by the oxidized region. The diameter of the conductive region of the laser element located inside is larger than the diameter of the conductive region of the laser element located outside. Since the generation of heat decreases as the diameter of the conductive region increases, the temperature difference between the laser elements can be reduced by increasing the diameter of the conductive region of the inner laser element.

  Preferably, the post diameter of the laser element located on the inside is larger than the post diameter of the laser element located on the outside, and the oxidized regions of all the laser elements are oxidized by a substantially equal distance from the side surface of the post. Thereby, the oxidation region of each post can be formed in the same oxidation step.

  According to the present invention, by arranging the laser elements in the above-described manner, the temperature difference between the laser elements can be reduced, thereby achieving uniformity in characteristics as an array.

  The surface-emitting type semiconductor laser array according to the present invention preferably has a plurality of laser elements arranged in a matrix on a semiconductor substrate, and each laser element has a cylindrical post or mesa including a selectively oxidized current confinement layer. doing. Each laser element is preferably driven to emit light at the same time, and is used as a light source for an optical communication device or the like. Hereinafter, it will be described in detail with reference to the drawings.

  FIG. 1 is a schematic plan view of a surface-emitting type semiconductor laser array according to the first embodiment of the present invention as viewed from above. A surface-emitting type semiconductor laser array 110 shown in FIG. 1 includes a plurality of laser elements 130 arranged in a matrix of 5 rows × 5 columns on a semiconductor substrate 120 such as GaAs. However, the laser array 110 of the present embodiment does not form a laser element at the center of the matrix arrangement, which is different from the conventional matrix arrangement.

  Each laser element 130 is arranged at an interval of 50 μm from an adjacent laser element, and therefore, an interval between adjacent laser elements in a diagonal direction is about 70 μm. Further, the injection current to the laser element 120 is performed from the electrode part E, but the wiring between the electrode part E and the laser element is omitted. The wiring may have a pattern shape common to all the laser elements, or may have a pattern shape that is individual to the laser elements.

  As described above, when a plurality of laser elements are arranged in a matrix, the heat flow into the central laser element is the largest (the number of adjacent laser elements and the number of diagonally adjacent laser elements is 8), and the temperature rises the most. To do. For this reason, in this embodiment, the temperature difference between the laser elements on the array is reduced by adopting an arrangement excluding the central laser element.

  FIG. 2 shows the total of the number of adjacent laser elements and the number of diagonally adjacent laser elements to be heat-inflowed into each laser element in the matrix arrangement of FIG. The sum of the number of adjacent laser elements and the number of diagonal laser elements of the laser element located at the corner is the smallest (three), and the sum of the number of laser elements located on the inside is seven, which is the largest. The difference between the two is 4, which is smaller than the difference 5 of the conventional example (see FIG. 15A). The total number of laser elements 132 and 134 located on the inside is equal to 7, but the number of adjacent laser elements is 4 and the number of diagonally adjacent laser elements is 3, and the laser element 134 is an adjacent laser element. The number is 3, and the number of diagonally adjacent laser elements is 3. As a result, the temperature rise due to the heat inflow of the laser element 132 is about 15 ° C., the temperature rise of the laser element 134 is about 14 ° C., and the temperature rise of the laser element 132 becomes somewhat higher.

  FIG. 3 is a view showing a surface emitting semiconductor laser array according to a second embodiment of the present invention. The laser array 111 according to the second embodiment is obtained by deleting four laser elements A, B, D, and E located at four corners from the matrix arrangement of FIG. As described above, the laser elements located at the corners have the fewest number of adjacent laser elements to which heat should flow, so eliminating this can further reduce the temperature difference between the laser elements on the array. it can. In the case of the second embodiment, the heat flow into the laser element 136 (see FIG. 2) located on the outside is the smallest, and the temperature difference is about 11 ° C.

  FIG. 4 is a view showing a surface emitting semiconductor laser array according to a third embodiment of the present invention. In the laser array 112 according to the third embodiment, 14 laser elements arranged on the substrate 120 are separated by an equal distance d. FIG. 5 is a diagram showing the number of adjacent laser elements in which each laser element is affected by heat inflow. The number of the laser elements 140 arranged on the inner side is 6, the number of the corner laser elements 142 is 3, and the number of the other laser elements 144 is 4. When the distance d is 50 μm, the temperature difference between the laser elements is 7.5 ° C., and the temperature change between the laser elements can be further reduced.

  FIG. 6 shows another layout of laser elements arranged at equal intervals. Twelve laser elements are arranged on the substrate 120 at a distance d along the hexagonal outer periphery, but no laser elements are arranged at the center or inside. As a result, the number of adjacent laser elements to which each laser element is to receive heat flow becomes 2, and the temperature difference due to heat flow becomes zero. For this reason, the temperature difference between lasers can be substantially eliminated.

  FIG. 7 is a diagram showing a surface emitting semiconductor laser array according to a fourth embodiment of the present invention. The laser array 113 according to the fourth embodiment includes laser elements arranged in a matrix of 5 rows × 5 columns, but the sizes of the oxidation diameters of the laser elements are different (in the figure, the circular broken line is the oxidation line). Represents the diameter).

  FIG. 8 is a plan view schematically showing a current confinement layer formed in the post. The current confinement layer 50 includes an oxidized region 52 that is selectively oxidized by a certain distance from the side surface of the post, and a conductive region (oxidized diameter) 54 that is surrounded by the oxidized region 52. The oxidized diameter 54 has a circular shape corresponding to the outer shape of the post, and the size S of the oxidized diameter 54 can be changed by adjusting the oxidation distance of the oxidized region 52. Since the oxidized region 52 has higher reflectivity than the conductive region 54 and is non-conductive, it functions to confine current and laser light in the vertical resonator in the post.

  FIG. 9 is a table showing the relationship between the oxidation diameter and the temperature rise when the laser element is energized. As is apparent from this table, the temperature rise decreases as the oxidation diameter increases. This is presumably because the resistance increases and the current density increases when the oxidized diameter is small.

  Therefore, in the fourth embodiment, the post diameters of the respective laser elements are made equal, the oxidation diameter 54 of the central laser element is made larger, and the oxidation diameter 54 of the laser element located outside is made smaller. For example, when the oxidation diameter of the central laser element 160 is S1, the oxidation diameter of the laser element 162 surrounding the laser element 160 is S2, and the oxidation diameter of the laser element 164 surrounding the laser element 162 is S3, S1> S2> The relationship is S3. Alternatively, the oxidation diameter S1 of the central laser element 160 may be increased, and the oxidation diameters of all other laser elements may be smaller than S1.

  By increasing the center oxidation diameter, the self-heating of the center laser element, which has a large temperature rise due to heat inflow, can be suppressed, and as a result, the temperature difference between the laser elements on the array can be reduced.

  FIG. 10 is a diagram showing a surface emitting semiconductor laser array according to a fifth embodiment of the present invention. As shown in the drawing, the laser array 114 according to the fifth embodiment includes laser elements arranged in a matrix of 5 rows × 5 columns, but the post diameters of the laser elements are made different. When the post diameter of the central laser element 170 is P1, the post diameter of the laser element 172 surrounding this is P2, and the post diameter of the outer laser element 174 surrounding the laser element 172 is P3, the relation of P1 <P2 <P3 is established. is there. The post diameter here is an outer diameter before the formation of a protective film (insulating film) covering the outer periphery of the post, as will be described later.

  While the post diameter is varied, in the fifth embodiment, the oxidation is controlled so that the oxidation distance oxidized from the side surface of the post, that is, the oxidation region 52 of the current confinement layer becomes a constant distance. As a result, the oxidation diameter of the laser element 70 having the largest post diameter becomes the largest, and the oxidation diameter becomes smaller in the order of the laser elements 72 and 74. Thereby, the temperature rise of the laser element 170 at the center of the matrix array can be made smaller than that of the conventional matrix array, and the temperature difference between the laser elements can be reduced.

  Next, effects of the surface emitting semiconductor laser array according to each embodiment of the present invention and the conventional laser array will be described.

  The precondition is that an equilibrium state of chip heat generation after all laser elements are turned on simultaneously is assumed. Strictly speaking, it is necessary to consider the structure of the laser emission part, the chip thickness material, the wiring wire wiring material / layout, and the effect of the air surrounding the chip, but the heat conduction to the air and the wire is compared to the heat conduction in the chip. Since it is negligibly small (several percent), attention is paid to the heat inflow between the laser elements. In the conventional array shown in FIG. 13, the adjacent beam interval is 50 μm, and the diagonal beam is 70.7 μm. Since the thickness of the substrate is about 100 μm, considering that the heat conduction into the substrate is uniform, the beam that has a large influence on the heat inflow may be considered by the adjacent laser element diagonally adjacent laser element.

  In the array of FIG. 13, as described above, the number of adjacent laser elements and the number of diagonally adjacent laser elements for the central laser element C are four, and the laser elements at the four corners are two adjacent laser elements and one laser element. This is the number of diagonally adjacent laser elements. Assuming that the heat inflow difference of the number of elements is 10 ° C. (Iop = 10 mA) and the distance ratio between adjacent laser elements and diagonally adjacent laser elements is 50 μm / 70 μm, it is assumed that heat is evenly distributed. The heat inflow per laser element can be estimated as 2.5 ° C./adjacent laser element and 1.67 ° C./diagonal adjacent laser element. A table in which the maximum temperature difference and the laser characteristic change amount due to the temperature difference for the element layout of the array of each example are calculated using this heat inflow estimation is shown in FIG.

  The fourth and fifth examples are also estimated using the same concept for temperature change as described above. In both the fourth and fifth embodiments, the oxidized diameter of the central post is made 2 μm larger than the oxidized diameter of the other posts. The difference between the two examples is the difference in the post diameter, but the post diameter with a large oxidation diameter is 30 μm, whereas the post diameter with a small oxidation diameter is 28 μm, and there is no large difference in the post diameter. Had almost no effect and was treated the same way. Based on this assumption, the maximum temperature difference between the center laser element and the four corner laser elements is expected to be 4.6 ° C.

  The table shows comparison values when the layout of the laser elements shown in FIG. 6 is used as a reference (because the heat inflow of each laser element is equal). As is clear from this, the surface emitting semiconductor laser array according to each example has a smaller temperature difference between the laser elements as compared with the conventional matrix array laser array. , Change in wavelength, decrease in light output (IL characteristic) and average life (life ratio) can be made more uniform.

Next, the structure and manufacturing method of the laser element formed on the surface emitting semiconductor laser array of this example will be described. FIG. 12 shows a vertical cross-sectional structure of a post of a surface emitting laser element in which current is confined by selective oxidation of an AlAs layer. In the figure, first, an n-type GaAs buffer layer 3 is provided on an n-type GaAs substrate 2, and an n-type Al _0.9 Ga _0.1 As / Al _0.3 Ga _0.7 As multilayer is formed on the buffer layer as a lower mirror layer constituting the resonator. Film distribution Bragg (DBR) mirror layers 4-1 and 4-2 are provided.

An undoped Al _0.6 Ga _0.4 As lower spacer layer 5 is formed on the DBR mirror layer, and further, for example, an undoped Al _0.12 Ga _0.88 As quantum well layer 7 having a thickness of 9 nm and an undoped Al having a thickness of 5 nm, for example. _A quantum well active layer made of _0.3 Ga _0.7 As barrier layer 6 is formed. In FIG. 12, the simplest single quantum well active layer structure is used. For example, a double quantum well (Double quantum well) such as a barrier layer-quantum well layer-barrier layer-quantum well layer-barrier layer is used. (Quantum Well) structure or a multiple quantum well structure may be used.

On the active layer, an undoped Al _0.6 Ga _0.4 As upper spacer layer 8 is formed. On the upper spacer layer 8, p-type Al _0.9 Ga _0.1 As layer / p-type AlAs layer / p-type Al _0.9 Ga _0.1 As layer 9, 10, 11 are formed. The p-type AlAs layer 10 is selectively oxidized to form a current confinement portion 10a that is an oxidation region. On the current confinement layer 10, p-type Al _0.9 Ga _0.1 As / Al _0.3 Ga _0.7 As multilayer distributed Bragg (DBR) mirror layers 12-1 and 12-2 are formed as the upper mirror layer constituting the resonator, A p-type GaAs contact layer 13 is formed on the DBR mirror layer. A p-side electrode 14 made of Au / Ti is formed on the contact layer 13, and a protective film 15 is formed so as to cover the post, and p is formed through an opening formed in the protective film 15 at the top of the post. A current injection lead electrode 16 connected to the side electrode 14 is formed. An n-side electrode 1 made of Au / AuGe is formed on the back side of the n-type GaAs substrate 2.

In the above configuration, the film thickness of each layer is the optical film thickness. If the oscillation wavelength is λ, each film thickness constituting the lower DBR mirror layers 4-1 and 4-2 is λ / 4, and the lower spacer layer. 5, the total thickness of the upper spacer layer 8 and the quantum well active layers 6 and 7 is λ, the thicknesses of the p-type current confinement layer 10 and the crystal defect suppression layer are λ / 4, and the p-type GaAs contact layer 13 is a film. The thickness is λ / 4, and the thicknesses of the upper DBR mirror layers 12-1 and 12-2 after selective oxidation are λ / 4. The carrier concentration is 2 × 10 ¹⁸ cm ^{−3 for} n-type, 1 × 10 ¹⁹ cm ^{−3 for} GaAs contact layer 13 for p-type, 2 × 10 ¹⁸ cm ⁻³ for other p-type, and the laser post size is It is about 30 μmΦ.

Next, a method for manufacturing a laser element will be described. First, an n-type GaAs buffer layer 3 is stacked on an n-type GaAs substrate 2 by metal organic chemical vapor deposition (MOCVD), and the lower part of the resonator is formed on the buffer layer 3. Multi-layer distributed Bragg (DBR) mirror layers 4-1 and 4-2 in which n-type Al _0.9 Ga _0.1 As / Al _0.3 Ga _0.7 As constituting the mirror layer are laminated at 40.5 periods are formed, and this DBR mirror layer An undoped Al _0.6 Ga _0.4 As lower spacer layer 5 is laminated thereon, and an undoped Al _0.12 Ga _0.88 As quantum well layer 7 (thickness 9 nm) and an undoped Al _0.3 Ga _0.7 As barrier layer 6 ( A quantum well active layer having a thickness of 5 nm) is stacked, an undoped Al _0.6 Ga _0.4 As upper spacer layer 8 is stacked on the active layer, and p-type Al _0.9 G is stacked on the upper spacer layer 8. a _0.1 As layer / p-type AlAs layer / p-type Al _0.9 Ga _0.1 As layers 9, 10, and 11 are stacked, and a p-type Al _0.9 Ga _0.1 As / Al _0.3 layer constituting the upper mirror layer of the resonator is formed thereon. Ga _0.7 As multilayer distributed Bragg (DBR) mirror layers 12-1 and 12-2 are stacked, and a p-type GaAs contact layer 13 is stacked on the upper DBR mirror layer to complete the epitaxial growth.

  Next, the p-side electrode layer 14 is deposited by sputtering, vapor deposition, or the like, patterned by photolithography to form a laser emission window, and a post is formed by dry etching the resist pattern by photolithography. In particular, in the case of the fifth embodiment, each post diameter is different, so that each post diameter is etched using a corresponding mask pattern. The dry etching depth penetrates the quantum well active layer and reaches a part of the lower DBR layer. The substrate in this state is exposed to high temperature oxidation furnace (high temperature steam oxidation) for a certain period of time, whereby the AlAs layer 10 is selectively oxidized and the current confinement oxidation portion 10a is formed. Thereafter, a protective film 15 is deposited by sputtering, plasma CVD or the like, and is patterned by photolithography so that an opening is formed at the top of the post. Then, Ti / Au is vapor-deposited using the lift-off method to form the external extraction current injection electrode 16. Chip dicing and back surface polishing to a specified size are performed, and Au / AuGe is deposited on the back surface side of the n-type GaAs substrate 2 to form the n-side electrode 1, and the process is completed.

  The P-side electrode of each laser element may be a common wiring commonly connected to all the laser elements, or may be an individual wiring that is separated from each laser element. A similar effect can be obtained when all the beams are turned on simultaneously.

  When the surface emitting semiconductor laser arrays according to the first to third embodiments are formed, a post is formed at a corresponding position on the substrate by using a mask pattern corresponding to the layout pattern of the laser element. The distance between the posts is 50 μm, but the distance may be 50 μm or less.

  When forming the surface emitting semiconductor laser array according to the fourth embodiment, the high temperature oxidation process is repeated a plurality of times in order to make the current confinement layer 10 of each post have a predetermined oxidation diameter. At this time, in order to prevent water vapor from penetrating into the AlAs layer 10, masking with a photoresist is performed every time it is repeated, and the steps of resist masking-oxidation-resist mask removal-resist masking are repeated.

  The surface emitting semiconductor laser array according to the fifth embodiment can be manufactured by a simpler process than that of the fourth embodiment. Since the post diameter decreases as going outward from the central laser element, the oxidized diameter can be created in one high-temperature steam oxidation step. The design rule of the post diameter depends on the array interval and the energization current, and in the case of the array interval of 50 μm or less and the rating of 5 mA, the rule of 1.5 ° C./μm is adopted. In the 5 × 5 matrix laser array, since there is a temperature change of 5 ° C. between the central laser element and the outer laser element, the 3.3 μm post diameter is made smaller than the oxidized diameter of the central laser element. Since the peripheral laser elements of the central laser element have a planar arrangement in which heat flows in in the same manner as the central laser element, there is almost no temperature drop, so the post diameter is the same as the central laser element.

  In this example, two types of post diameters are used. However, the present invention is not limited to this, and when there are many temperature distributions between laser elements on the array, the post diameters can be set according to the temperature distribution.

  Also in the case of the fourth and fifth embodiments, the P-side electrode may be a common wiring for each laser element, or may be individually wired for each laser element. The effect of the invention does not change.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific embodiments, and various modifications can be made within the scope of the gist of the present invention described in the claims. Deformation / change is possible.

  It is of course possible to combine the idea of changing the size of the oxidation diameter shown in the fourth and fifth embodiments with the layout of the laser elements shown in the first to third embodiments.

  The surface-emitting type semiconductor laser array according to the present invention can be widely used for a light source of an optical communication device, a light source of other electronic devices, and the like.

1 is a schematic plan view of a surface emitting semiconductor laser array according to a first embodiment of the present invention. It is a figure which shows the number of the laser elements which should be heat flowed in into each laser element in the matrix arrangement | sequence of FIG. It is a typical top view of the surface emitting semiconductor laser array which concerns on a 2nd Example. FIG. 6 is a schematic plan view of a surface emitting semiconductor laser array according to a third embodiment. It is a figure which shows the number of the laser elements which should be made to heat-in into each laser element in the arrangement | sequence of FIG. It is another layout example of the surface emitting semiconductor laser array according to the third embodiment. It is a typical top view of the surface emitting semiconductor laser array which concerns on a 4th Example. It is a typical top view of a current confinement layer. It is a figure which shows the relationship between an oxidation diameter and a temperature rise. It is a typical top view of the surface emitting semiconductor laser array which concerns on a 5th Example. It is the table | surface which computed the laser characteristic variation | change_quantity by the maximum temperature difference and temperature difference of the element layout of the array of each Example. It is sectional drawing which shows the structure of the laser element based on the Example of this invention. It is a typical top view of the conventional surface emitting semiconductor laser array. FIG. 14A is a graph in which the wavelengths of the laser elements A, B, C, D, and E are measured, and FIG. 14B is a table that shows the temperature difference estimated from the wavelength change measurement values. FIG. 15A is a graph showing the temperature change of the laser elements A to E, and FIG. 15B is a diagram showing the relationship between the laser element interval and the temperature rise due to heat inflow.

Explanation of symbols

1: n-side electrode 2: GaAs substrate 3: buffer layer 4-1, 4-2: lower DBR mirror layer 5: lower spacer layer 6: barrier layer 7: quantum well layer 8: upper spacer layers 12-1, 12- 2: upper DBR mirror layer 13: contact layer 14: p-side electrode 15: protective film 16: extraction electrodes 110, 111, 112, 113, 114: surface emitting semiconductor laser array 120: substrate 130 laser element 150: current confinement layer 152: Oxidized region 154: Conductive region (oxidized diameter)

Claims (11)

A substrate,
A plurality of laser elements arranged two-dimensionally on a substrate;
An electrode portion for supplying current to a plurality of laser elements,
The plurality of laser elements are arranged in a region excluding at least the central portion,
Surface emitting semiconductor laser array. 2. The surface emitting semiconductor laser array according to claim 1, wherein the plurality of laser elements are arranged in a matrix, and the laser elements are arranged in a region excluding the center thereof. The surface emitting semiconductor laser array according to claim 2, wherein laser elements are arranged in a region excluding corners in the matrix arrangement. The surface emitting semiconductor laser device according to claim 2, wherein the matrix array has an array pattern of at least 3 rows × 3 columns. A substrate,
A plurality of laser elements arranged two-dimensionally on a substrate;
An electrode portion for supplying current to a plurality of laser elements,
The plurality of laser elements are all arranged at equal intervals.
Surface emitting semiconductor laser array. The laser element has a current confinement layer including an oxidized region selectively oxidized and a conductive region surrounded by the oxidized region, and the diameter of the conductive region of the laser element located inside the laser element array is outside. The surface-emitting type semiconductor laser array according to claim 1, wherein the surface-emitting type semiconductor laser array is larger than a diameter of a conductive region of a laser element located at a position. A substrate,
A plurality of laser elements arranged two-dimensionally on a substrate;
An electrode portion for supplying current to a plurality of laser elements,
Each laser element has a post protruding from the substrate, the post having a current confinement layer including an oxidized region selectively oxidized and a conductive region surrounded by the oxidized region. The diameter of the conductive region of the laser element located inside is larger than the diameter of the conductive region of the laser element located outside,
Surface emitting semiconductor laser array. 8. The surface emitting semiconductor laser array according to claim 7, wherein the plurality of laser elements are arranged in a matrix and the diameter of the conductive region of the laser element located at the center thereof is the largest. 8. The post diameter of the laser element located on the inside is larger than the post diameter of the laser element located on the outside, and the oxidation regions of all the laser elements are oxidized by a substantially equal distance from the side surface of the post. The surface emitting semiconductor laser array described. 8. The surface-emitting type semiconductor laser array according to claim 7, wherein each of the plurality of laser elements has the same post diameter, and an oxidation region of the laser element located inside is smaller than an oxidation region of the laser element located outside. The surface-emitting type semiconductor laser array according to claim 1, wherein the plurality of laser elements are simultaneously driven by a current supplied to an electrode portion.

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