Surface emitting quantum cascade laser

Abstract

To provide a surface-emitting quantum cascade laser capable of improving characteristics.SOLUTION: According to an embodiment, a surface-emitting quantum cascade laser includes a first electrode, a second electrode, and a laminate provided between the first electrode and the second electrode. The stacked body includes a first clad layer, a second clad layer, a light emitting layer provided between a part of the first clad layer and the second clad layer, and a photonic crystal layer including a plurality of structures provided between the light emitting layer and the second clad layer. The stacked body includes a mesa region. The mesa region includes the part of the first cladding layer and the light emitting layer. A planar shape of the mesa region in a first plane intersecting a first direction from the first cladding layer to the second cladding layer includes a recess.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION Embodiments of the present invention relate to surface-emitting quantum cascade lasers. [Background technology]

[0002] For example, there is a surface-emitting quantum cascade laser including a photonic crystal, and it is desirable to improve the characteristics of the surface-emitting quantum cascade laser. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-2245 Summary of the Invention [Problem to be solved by the invention]

[0004] The embodiments provide a surface-emitting quantum cascade laser capable of improving characteristics. [Means for solving the problem]

[0005] According to an embodiment, a surface-emitting quantum cascade laser includes a first electrode, a second electrode, and a stacked body provided between the first electrode and the second electrode. The stacked body includes a first cladding layer, a second cladding layer, a light-emitting layer provided between a portion of the first cladding layer and the second cladding layer, and a photonic crystal layer including a plurality of structures provided between the light-emitting layer and the second cladding layer. The stacked body includes a mesa region. The mesa region includes the portion of the first cladding layer and the light-emitting layer. The planar shape of the mesa region in a first plane intersecting a first direction from the first cladding layer to the second cladding layer includes a recess. [Brief explanation of the drawings]

[0006] [Figure 1]FIG. 1 is a schematic view illustrating a surface-emitting quantum cascade laser according to the first embodiment. [Figure 2] FIG. 2 is a schematic view illustrating the surface-emitting quantum cascade laser according to the first embodiment. [Figure 3] FIG. 3 is a schematic view illustrating the surface-emitting quantum cascade laser according to the first embodiment. [Figure 4] FIG. 4 is a schematic plan view illustrating a part of the surface-emitting quantum cascade laser according to the first embodiment. [Figure 5] FIG. 5 is a schematic view illustrating the characteristics of the surface-emitting quantum cascade laser according to the first embodiment. [Figure 6] FIG. 6 is a schematic plan view illustrating a part of the surface-emitting quantum cascade laser according to the first embodiment. [Figure 7] FIG. 7 is a schematic plan view illustrating a part of the surface-emitting quantum cascade laser according to the first embodiment. [Figure 8] FIG. 8 is a schematic plan view illustrating a part of the surface-emitting quantum cascade laser according to the first embodiment. [Figure 9] FIG. 9 is a schematic plan view illustrating a part of the surface-emitting quantum cascade laser according to the first embodiment. [Figure 10] FIG. 10 is a schematic plan view illustrating a part of the surface-emitting quantum cascade laser according to the first embodiment. [Figure 11] FIG. 11 is a schematic plan view illustrating a part of the surface-emitting quantum cascade laser according to the first embodiment. [Figure 12] FIG. 12 is a schematic plan view illustrating a part of the surface-emitting quantum cascade laser according to the first embodiment. [Figure 13] FIG. 13 is a schematic plan view illustrating a part of the surface-emitting quantum cascade laser according to the first embodiment. [Figure 14] FIG. 14 is a schematic plan view illustrating a part of the surface-emitting quantum cascade laser according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Even when the same part is shown, the dimensions and ratios may be different depending on the drawing. In this specification and in each drawing, elements similar to those previously described with reference to the previous drawings are designated by the same reference numerals, and detailed descriptions thereof will be omitted where appropriate.

[0008] (First embodiment) 1 to 3 are schematic views illustrating a surface-emitting quantum cascade laser according to the first embodiment. Fig. 1 is a plan view, Fig. 2 is a cross-sectional view corresponding to the cross section taken along line A1-A2 in Fig. 1, and Fig. 3 is a perspective view. FIG. 4 is a schematic plan view illustrating a part of the surface-emitting quantum cascade laser according to the first embodiment.

[0009] 1 to 3, the surface-emitting quantum cascade laser 110 according to the embodiment includes a first electrode 51, a second electrode 52, and a laminate 10. The laminate 10 is provided between the first electrode 51 and the second electrode 52.

[0010] The laminate 10 includes a first cladding layer 11, a second cladding layer 12, a light emitting layer 13, and a photonic crystal layer 15. The light emitting layer 13 is provided between a portion 11p of the first cladding layer 11 and the second cladding layer 12. The photonic crystal layer 15 is provided between the light emitting layer 13 and the second cladding layer 12. The photonic crystal layer 15 includes a plurality of structures 15C.

[0011] 1, the laminate 10 may include a substrate 10s. The substrate 10s is provided between the first electrode 51 and the first cladding layer 11. The substrate 10s includes a first substrate surface 10f. For example, the first electrode 51 is provided on the first substrate surface 10f.

[0012] 2, a first direction D1 from the first cladding layer 11 to the second cladding layer 12 is defined as the Z-axis direction. A direction perpendicular to the Z-axis direction is defined as the X-axis direction. A direction perpendicular to the Z-axis direction and the X-axis direction is defined as the Y-axis direction.

[0013] A portion 11p of the first cladding layer 11 and the light-emitting layer 13 lie along a first plane PL1 that intersects with the first direction D1. The first plane PL1 is the XY plane. At least a portion of the second cladding layer 12 lies along the first plane PL1. The first plane PL1 is substantially parallel to a second direction D2 that intersects with the first direction D1. The first plane PL1 is substantially parallel to a third direction D3. The second direction D2 is, for example, the X-axis direction. The third direction D3 intersects with a plane that includes the first direction D1 and the second direction. The third direction D3 is, for example, the Y-axis direction.

[0014] A portion of the second cladding layer 12 is provided between the plurality of structures 15C. The second cladding layer 12 contacts the plurality of structures 15C. The refractive index of the second cladding layer 12 is different from the refractive index of the plurality of structures 15C. For example, the refractive index of the second cladding layer 12 is lower than the refractive index of the plurality of structures 15C. For example, the size of the plurality of structures 15C is substantially equal to the wavelength of the light emitted from the light-emitting layer 13. Light is controlled in the plurality of structures 15C.

[0015] For example, when a voltage is applied between the first electrode 51 and the second electrode 52, light is emitted from the light-emitting layer 13. The light is controlled by the photonic crystal layer 15 including a plurality of structures 15C, and is emitted to the outside from, for example, the first substrate surface 10f. The first substrate surface 10f is, for example, a light-emitting surface. The emitted light 81L from the surface-emitting quantum cascade laser 110 is emitted from a planar region.

[0016] 1 and 2, for example, a region where a plurality of structures 15C are provided is defined as a photonic region 15R. The first substrate surface 10f includes a region that overlaps with the photonic region 15R in the Z-axis direction. Light is emitted from this region that overlaps with the photonic region 15R.

[0017] As shown in FIG. 2, the stack 10 includes a mesa region 10R. The mesa region 10R includes a portion 11p of the first cladding layer 11 and the light-emitting layer 13. The mesa region 10R is, for example, a current confinement region. By confining the current, light emission can be achieved with high efficiency. The mesa region 10R may further include a second cladding layer 12.

[0018] 1, the planar shape of the mesa region 10R on the first plane PL1 includes a recess 10d. This allows light of a substantially single wavelength to be obtained with high efficiency. According to the embodiment, a surface-emitting quantum cascade laser capable of improving characteristics can be provided.

[0019] For example, as shown in FIG. 2, the mesa region 10R includes a mesa side surface 10Rs. The mesa side surface 10Rs intersects with the first plane PL1. A portion of the light emitted from the light-emitting layer 13 is reflected by the mesa side surface 10Rs and returns to the region corresponding to the photonic region 15R. For example, a reference example is possible in which two opposing surfaces of the mesa side surface 10Rs within the first plane PL1 are substantially parallel. In this reference example, light is repeatedly reflected between these two surfaces. This can result in, for example, a Fabry-Perot mode. For example, a multiplexed mode can be generated. In this case, the light emitted to the outside includes light of a dominant wavelength and light of a wavelength different from the dominant wavelength. For example, in one application, light obtained from the surface-emitting quantum cascade laser 110 is used for analysis, etc. In this case, the light is required to have a single wavelength.

[0020] In this embodiment, the planar shape of the mesa region 10R on the first plane PL1 includes a recess 10d. For example, the traveling direction of light reflected by the mesa side surface 10Rs of the mesa region 10R is changed by the mesa side surface 10Rs, which includes the recess 10d. This changes the optical path length and the light propagation path, suppressing oscillation due to repeated reflection. This allows light of a substantially single wavelength to be obtained with high efficiency.

[0021] As shown in FIG. 2, the surface-emitting quantum cascade laser 110 may further include a reflective film 31. The direction from the mesa side surface 10Rs to the reflective film 31 intersects with the first plane PL1. The reflectivity of the reflective film 31 at the wavelength of light emitted from the light-emitting layer 13 is higher than the reflectivity of the first cladding layer 11 at that wavelength. The provision of the reflective film 31 prevents the light emitted from the light-emitting layer 13 from emitting to the outside from the mesa side surface 10Rs. High efficiency is easily obtained.

[0022] Light emitted from the light-emitting layer 13 and traveling along the XY plane is reflected by the reflective film 31 and returns to the region corresponding to the photonic region 15R. When the reflective film 31 is provided, for example, in a rectangular resonator optical structure without a recess, the Fabry-Perot mode occurs more prominently. In this embodiment, the planar shape of the mesa region 10R on the first plane PL1 includes the recess 10d. Therefore, the traveling direction of the light is changed by the mesa side surface 10Rs including the recess 10d. This changes the optical path length and the light propagation path, suppressing oscillation due to repeated reflection. As a result, light of a substantially single wavelength can be obtained with high efficiency.

[0023] For example, the planar shape of the mesa region 10R corresponds to the planar shape of the mesa side surface 10Rs. In this embodiment, for example, the planar shape (outer edge) of the mesa region 10R does not have vertical reflective surfaces at positions facing each other. This effectively suppresses Fabry-Perot modes due to repeated reflections.

[0024] As shown in FIG. 1, the planar shape of the mesa region 10R includes a first outer edge portion 10a and a second outer edge portion 10b. A recess 10d is located between the first outer edge portion 10a and the second outer edge portion 10b. For example, the curvature of the first outer edge portion 10a is different from the curvature of the second outer edge portion 10b. Fabry-Perot modes are effectively suppressed.

[0025] For example, the first outer edge portion 10a and the second outer edge portion 10b are convex from the inside to the outside of the planar shape. The recessed portion 10d is concave from the outside to the inside of the planar shape. For example, the recessed portion 10d is provided between multiple regions of the planar shape. The recessed portion 10d is, for example, a recessed portion.

[0026] 2, the reflective film 31 may be continuous with the second electrode 52. The reflective film 31 may include gold. The second electrode 52 may include gold. The second electrode 52 may include Ni and gold. The second electrode 52 may include a Ni film and a gold film. For example, low electrical resistance and high reflectivity can be obtained.

[0027] As shown in Fig. 2, the surface-emitting quantum cascade laser 110 may include an insulating film 31i. The insulating film 31i is provided between the mesa side surface 10Rs and the reflective film 31. The insulating film 31i contains, for example, silicon and oxygen. The insulating film 31i contains, for example, silicon oxide. The insulating film 31i is omitted in Fig. 1. Fig. 3 schematically illustrates the mesa region 10R.

[0028] FIG. 5 is a schematic view illustrating the characteristics of the surface-emitting quantum cascade laser according to the first embodiment. Fig. 5 illustrates the characteristics of the emitted light 81L (see Fig. 2) emitted from the surface-emitting quantum cascade laser 110. The horizontal axis of Fig. 5 represents the wavelength λ. The vertical axis of Fig. 5 represents the light intensity Int.

[0029] 5, the emitted light 81L emitted from the surface-emitting quantum cascade laser 110 includes a first peak pk1. In one example, the emitted light 81L does not include any peaks other than the first peak pk1. In another example, the intensity I2 of the other peak (e.g., the second peak pk2) is 1 / 100 or less of the intensity I1 of the first peak pk1. In this manner, in the embodiment, the emitted light 81L has a substantially single peak.

[0030] FIG. 4 illustrates a plurality of structures 15C. In the example of FIG. 4, a structure shape 15CS on the first plane PL1 of one of the plurality of structures 15C is substantially pentagonal. In an embodiment, the structure shape 15CS may be, for example, a polygon having five or more sides, a circle, or an oblate circle (including an ellipse). In the example of FIG. 4, the plurality of structures 15C have a square lattice arrangement.

[0031] 6 and 7 are schematic plan views illustrating a part of the surface-emitting quantum cascade laser according to the first embodiment. These figures illustrate a plurality of structures 15C. As shown in FIG. 6, in the surface-emitting quantum cascade laser 110p according to the embodiment, the plurality of structures 15C have a rectangular lattice arrangement. As shown in FIG. 7, in the surface-emitting quantum cascade laser 110q according to the embodiment, the plurality of structures 15C have a triangular lattice arrangement. Thus, in the embodiment, the plurality of structures 15C may be arranged in any of a square lattice arrangement, a rectangular lattice arrangement, and a triangular lattice arrangement. The plurality of structures 15C are arranged two-dimensionally along the first plane PL1. In one direction along the first plane PL1, the plurality of structures 15C are arranged at substantially one pitch.

[0032] Hereinafter, several examples of the planar shape of the mesa region 10R on the first plane PL1 will be described. 8 to 14 are schematic plan views illustrating a part of the surface-emitting quantum cascade laser according to the first embodiment. These figures illustrate the planar shape of the mesa region 10R on the first plane PL1. As shown in FIG. 8, in the surface-emitting quantum cascade laser 110a according to the embodiment, the planar shape of the mesa region 10R includes a recess 10d. The recess 10d is located between the first outer edge 10a and the second outer edge 10b. The curvature of the first outer edge 10a is different from the curvature of the second outer edge 10b. In this example, the center of the photonic region 15R in which the multiple structures 15C are provided is different from the center of the planar shape of the mesa region 10R. An eccentric configuration is applied.

[0033] As shown in FIG. 8, the planar shape of the mesa region 10R includes a first curve 10La and a second curve 10Lb. The first curve 10La may be, for example, at least a portion of the first outer edge portion 10a. The second curve 10Lb may be, for example, at least a portion of the second outer edge portion 10b. The first curve 10La has a first curvature. The second curve 10Lb has a second curvature that is different from the first curvature. This configuration also suppresses Fabry-Perot modes.

[0034] 9, in the surface-emitting quantum cascade laser 110b according to the embodiment, the planar shape of the mesa region 10R includes a first circular arc 10u, a second circular arc 10v, and a third circular arc 10w. The center position of the first circular arc 10u is different from the center position of the second circular arc 10v, and is different from the center position of the third circular arc 10w. The center position of the second circular arc 10v is different from the center position of the third circular arc 10w. In this example as well, the Fabry-Perot mode is suppressed.

[0035] As shown in FIG. 10 , in a surface-emitting quantum cascade laser 110c according to the embodiment, the planar shape of the mesa region 10R includes a first arc 10u, a second arc 10v, a third arc 10w, and a fourth arc 10x. The centers of these arcs are located at different positions. The planar shape of the mesa region 10R is asymmetric. For example, the planar shape of the mesa region 10R does not have an axis of symmetry. In this example, the Fabry-Perot mode is also suppressed. In this example, the center of the photonic region 15R is different from the center of the planar shape of the mesa region 10R. An asymmetric configuration is applied.

[0036] 11, in a surface-emitting quantum cascade laser 110d according to the embodiment, the planar shape of the mesa region 10R includes recesses 10d. In this example, the number of recesses 10d is three. One of the recesses 10d is provided between a plurality of first circular arcs 10u. In this example, the Fabry-Perot mode is also suppressed.

[0037] 12, in a surface-emitting quantum cascade laser 110e according to the embodiment, the planar shape of the mesa region 10R includes a recess 10d. In this example as well, the Fabry-Perot mode is suppressed.

[0038] As shown in FIG. 13, in a surface-emitting quantum cascade laser 110f according to the embodiment, the planar shape of the mesa region 10R includes a first curve 10La and a second curve 10Lb. The first curve 10La has a first curvature. The second curve 10Lb has a second curvature different from the first curvature. This configuration also suppresses Fabry-Perot modes. In this example, at least one of the first curve 10La and the second curve 10Lb is a curve that is at least a part of a quadratic function. For example, at least one of the first curve 10La and the second curve 10Lb may include a part of a polynomial function. In this example, the center of the photonic region 15R is different from the center of the planar shape of the mesa region 10R. An asymmetric configuration is applied.

[0039] In the examples of FIG. 1 and FIGS. 8 to 13, the planar shape of the mesa region 10R may include a region that does not overlap with the photonic region 15R in the first direction D1.

[0040] As shown in Fig. 14, in a surface-emitting quantum cascade laser 110g according to the embodiment, the planar shape of the mesa region 10R includes a recess 10d. In this example, the planar shape of the mesa region 10R substantially coincides with the photonic region 15R in which a plurality of structures 15C are provided. In this configuration, oscillation due to repeated reflection does not substantially occur, and light is efficiently emitted to the outside from the region corresponding to the photonic region 15R. Fabry-Perot modes are suppressed, and high-intensity single-wavelength light is obtained.

[0041] As described above, in the embodiment, the planar shape of the mesa region 10R on the first plane PL1 may satisfy at least one of the following first, second, third, and fourth conditions.

[0042] In the first condition, the planar shape includes a first curve 10La having a first curvature and a second curve 10Lb having a second curvature different from the first curvature (see FIG. 8, etc.).

[0043] In the second condition, the planar shape includes a first circular arc 10u, a second circular arc 10v, and a third circular arc 10w (see FIG. 9, etc.). The position of the center of the first circular arc 10u is different from the position of the center of the second circular arc 10v, and is different from the position of the center of the third circular arc 10w. The position of the center of the second circular arc 10v is different from the position of the center of the third circular arc 10w.

[0044] In the third condition, the planar shape includes a recess 10d (see FIGS. 1 and 8, etc.).

[0045] In the fourth condition, the planar shape coincides with the photonic region 15R in which the plurality of structures 15C are provided (see FIG. 14).

[0046] When the planar shape satisfies at least one of the first, second, third, and fourth conditions, the Fabry-Perot mode is suppressed, and for example, high-intensity light of a single wavelength can be obtained.

[0047] When the planar shape satisfies the third condition, the planar shape may include a first outer edge portion 10a and a second outer edge portion 10b. The recess 10d is provided between the first outer edge portion 10a and the second outer edge portion 10b. For example, the curvature of the first outer edge portion 10a is different from the curvature of the second outer edge portion 10b.

[0048] As already described, the first outer edge portion 10a and the second outer edge portion 10b are convex from the inside to the outside of the planar shape. The recessed portion 10d is concave from the outside to the inside. For example, the recessed portion 10d is provided between multiple regions of the planar shape.

[0049] For example, if the planar shape satisfies the first condition, the first curve 10La may be part of the outer edge of the first circle. The second curve 10Lb may be part of the outer edge of the second circle. The first position of the first center of the first circle is different from the second position of the second center of the second circle. The centers of multiple circles are set at shifted positions.

[0050] For example, when the planar shape satisfies the first condition, at least one of the first curve 10La and the second curve 10Lb may include a part of a polynomial function. For example, the polynomial function may include a quadratic function.

[0051] For example, when the planar shape of the mesa region 10R satisfies at least one of the first condition, the second condition, and the third condition, the planar shape may include a region that does not overlap with the photonic region 15R in the first direction D1.

[0052] The configurations described with reference to FIGS. 4, 6, and 7 may be applied to the surface-emitting quantum cascade lasers 110a to 110g.

[0053] As shown in FIG. 9, the outer edge 10r of the planar shape of the mesa region 10R includes a first portion p1 and a second portion p2. A first normal Ln1 to the first portion p1 of the outer edge 10r passes through the second portion p2. A second normal Ln2 to the second portion p2 of the outer edge 10r is inclined with respect to the first normal Ln1. For example, the second normal Ln2 is non-parallel to the first normal Ln1. This configuration suppresses oscillation due to repeated reflections.

[0054] In the embodiment, the light emitting layer 13 emits light due to intersubband transition. In one example, the first cladding layer 11 and the second cladding layer 12 contain In, P, and As. Meanwhile, the plurality of structures 15C contain In, Ga, and As. The surface-emitting quantum cascade laser according to the embodiment is, for example, a QCL (Quantum Cascade Laser). The wavelength of light emitted from the surface-emitting quantum cascade laser may be, for example, 4 μm or more and 11 μm or less. The surface-emitting quantum cascade laser can be used, for example, as a light source for gas analysis.

[0055] In the embodiment, for example, repeat reflection is suppressed. By suppressing repeat reflection, for example, Fabry-Perot modes are suppressed. For example, vertically opposing reflective surfaces (for example, mesa side surface 10Rs or reflective film 31) are substantially not provided. Or, the area of ​​the vertically opposing reflective surfaces is reduced.

[0056] In the embodiment, for example, it is preferable that the optical absorption loss is small. For example, it is preferable that the distance along the first plane PL1 between the mesa side surface 10Rs and the photonic region 15R is short. It is preferable that the reflectivity of the reflective film 31 is high. In the embodiment, for example, it is preferable that the planar shape of the mesa region 10R does not include a dead end. Light is extracted efficiently. The planar shape of the mesa region 10R may be formed by photolithography and etching. Etching includes dry etching, etc.

[0057] The outer edge of the planar shape of the mesa region 10R may be, for example, a curved shape based on a plurality of fine straight line segments.

[0058] The embodiments may include the following technical solutions. (Technical proposal 1) A first electrode; A second electrode; a laminate provided between the first electrode and the second electrode; Equipped with The laminate is a first cladding layer; a second cladding layer; a light emitting layer provided between a portion of the first cladding layer and the second cladding layer; a photonic crystal layer including a plurality of structures provided between the light emitting layer and the second cladding layer; Including, the stack includes a mesa region; a surface-emitting quantum cascade laser, the mesa region including the portion of the first cladding layer and the light-emitting layer, and the planar shape of the mesa region in a first plane intersecting a first direction from the first cladding layer to the second cladding layer includes a recess;

[0059] (Technical proposal 2) the planar shape includes a first outer edge portion and a second outer edge portion, the recess is between the first outer edge portion and the second outer edge portion, The surface-emitting quantum cascade laser according to Technical Solution 1, wherein the curvature of the first outer edge portion is different from the curvature of the second outer edge portion.

[0060] (Technical proposal 3) the first outer edge portion and the second outer edge portion are convex in a direction from the inside to the outside of the planar shape, A surface-emitting quantum cascade laser according to Technical Solution 2, wherein the recess is concave in the direction from the outside to the inside.

[0061] (Technical proposal 4) A first electrode; A second electrode; a laminate provided between the first electrode and the second electrode; Equipped with The laminate is a first cladding layer; a second cladding layer; a light emitting layer provided between a portion of the first cladding layer and the second cladding layer; a photonic crystal layer including a plurality of structures provided between the light emitting layer and the second cladding layer; Including, the stack includes a mesa region; the mesa region includes the portion of the first cladding layer and the light-emitting layer, and a planar shape of the mesa region in a first plane intersecting a first direction from the first cladding layer to the second cladding layer satisfies at least one of a first condition, a second condition, a third condition, and a fourth condition; In the first condition, the planar shape includes a first curved line having a first curvature and a second curved line having a second curvature different from the first curvature, In the second condition, the planar shape includes a first circular arc, a second circular arc, and a third circular arc, the position of the center of the first circular arc is different from the position of the center of the second circular arc and different from the position of the center of the third circular arc, the position of the center of the second circular arc is different from the position of the center of the third circular arc, In the third condition, the planar shape includes a recess, In the fourth condition, the planar shape of the surface-emitting quantum cascade laser coincides with a photonic region in which the plurality of structures are provided.

[0062] (Technical proposal 5) the planar shape satisfies the third condition, the planar shape includes a first outer edge portion and a second outer edge portion, the recess is between the first outer edge portion and the second outer edge portion, A surface-emitting quantum cascade laser according to Technical Solution 4, wherein the curvature of the first outer edge portion is different from the curvature of the second outer edge portion.

[0063] (Technical proposal 6) the first outer edge portion and the second outer edge portion are convex in a direction from the inside to the outside of the planar shape, A surface-emitting quantum cascade laser according to Technical Solution 5, wherein the recess is concave in the direction from the outside to the inside.

[0064] (Technical proposal 7) the planar shape satisfies the first condition, the first curve is a portion of the periphery of a first circle; the second curve is a portion of the periphery of a second circle; A surface-emitting quantum cascade laser according to Technical Solution 4, wherein a first position of a first center of the first circle is different from a second position of a second center of the second circle.

[0065] (Technical proposal 8) the planar shape satisfies the first condition, The surface-emitting quantum cascade laser according to Technical Solution 4, wherein at least one of the first curve and the second curve includes a portion of a polynomial function.

[0066] (Technical proposal 9) the planar shape satisfies at least one of the first condition, the second condition, and the third condition, A surface-emitting quantum cascade laser according to Technical Solution 4, wherein the planar shape includes an area that does not overlap with the photonic area in the first direction.

[0067] (Technical proposal 10) Further comprising a reflective film; the mesa region includes a mesa side surface that intersects with the first plane; a direction from the mesa side surface to the reflective film intersects with the first plane; 10. A surface-emitting quantum cascade laser according to any one of Technical Solutions 1 to 9, wherein the reflectance of the reflective film at the wavelength of light emitted from the light-emitting layer is higher than the reflectance of the first cladding layer at the wavelength.

[0068] (Technical proposal 11) A surface-emitting quantum cascade laser according to Technical Solution 10, wherein the reflective film is continuous with the second electrode.

[0069] (Technical proposal 12) The surface-emitting quantum cascade laser according to Technical Solution 10 or 11, wherein the reflective film contains gold.

[0070] (Technical proposal 13) The surface-emitting quantum cascade laser according to any one of Technical Solutions 10 to 12, further comprising an insulating film provided between the mesa side surface and the reflective film.

[0071] (Technical proposal 14) 14. The surface-emitting quantum cascade laser according to any one of Technical Schemes 1 to 13, wherein the plurality of structures are arranged in any one of a square lattice array, a rectangular lattice array, and a triangular lattice array.

[0072] (Technical proposal 15) The light emitted from the surface-emitting quantum cascade laser includes a first peak and does not include any other peaks other than the first peak, or 15. The surface-emitting quantum cascade laser according to any one of Technical Solutions 10 to 14, wherein the intensity of the other peak is 1 / 100 or less of the intensity of the first peak.

[0073] (Technical proposal 16) the outer edge of the planar shape includes a first portion and a second portion; a first normal to the first portion of the outer edge passes through the second portion; 16. The surface-emitting quantum cascade laser according to any one of Technical Solutions 1 to 15, wherein a second normal to the second portion of the outer edge is inclined with respect to the first normal.

[0074] (Technical proposal 17) 17. The surface-emitting quantum cascade laser according to any one of Technical Solutions 1 to 16, wherein the light-emitting layer emits light due to intersubband transition.

[0075] (Technical proposal 18) 18. The surface-emitting quantum cascade laser according to any one of Technical Solutions 1 to 17, wherein the first cladding layer and the second cladding layer contain In, P, and As.

[0076] (Technical proposal 19) The surface-emitting quantum cascade laser according to Technical Solution 18, wherein the plurality of structures include In, Ga, and As.

[0077] (Technical proposal 20) A surface-emitting quantum cascade laser described in any one of Technical Solutions 1 to 19, wherein the structure shape of one of the plurality of structures on the first plane is a polygon having five or more sides, a circle, or an oblate circle.

[0078] According to the embodiment, it is possible to provide a surface-emitting quantum cascade laser capable of improving characteristics.

[0079] In this specification, "vertical" and "parallel" do not only mean strictly vertical and strictly parallel, but also include variations in the manufacturing process, and may mean substantially vertical and substantially parallel.

[0080] The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. For example, the specific configurations of the elements included in the surface-emitting quantum cascade laser, such as the electrodes, stacked body, cladding layer, light-emitting layer, and photonic crystal layer, are within the scope of the present invention as long as a person skilled in the art can implement the present invention in a similar manner and obtain similar effects by appropriately selecting them from known ranges.

[0081] Furthermore, any combination of two or more elements of each specific example within the scope of technical feasibility is also included within the scope of the present invention as long as it includes the gist of the present invention.

[0082] In addition, all surface-emitting quantum cascade lasers that can be implemented by a person skilled in the art by appropriately modifying the design based on the surface-emitting quantum cascade laser described above as an embodiment of the present invention also fall within the scope of the present invention as long as they include the gist of the present invention.

[0083] In addition, within the scope of the concept of the present invention, a person skilled in the art may come up with various modifications and alterations, and it will be understood that these modifications and alterations also fall within the scope of the present invention.

[0084] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0085] 10: laminate, 10La, 10Lb: first and second curves, 10R: mesa region, 10Rs: mesa side surface, 10a, 10b: first and second outer edge portions, 10d: recess, 10f: first substrate surface, 10r: outer edge, 10s: substrate, 10u to 10x: first to fourth arcs, 11, 12: first and second cladding layers, 11p: part, 13: light-emitting layer, 15: photonic crystal layer, 15C: structure, 15CS: structure shape, 15R: photonic region, 31: reflective film, 31i: insulating film, 51, 52: first and second electrodes, 81L: emitted light, 110, 110a to 110g, 110p, 110q: surface-emitting quantum cascade laser, D1~D3: 1st~3rd direction, I1, I2: Intensity, Int: Intensity, Ln1, Ln2: 1st, 2nd normal, PL1: 1st plane, p1, p2: 1st, 2nd part, pk1, pk2: 1st, 2nd peak, λ: Wavelength

Claims

1. A first electrode; A second electrode; a laminate provided between the first electrode and the second electrode; Equipped with The laminate is a first cladding layer; a second cladding layer; a light emitting layer provided between a portion of the first cladding layer and the second cladding layer; a photonic crystal layer including a plurality of structures provided between the light emitting layer and the second cladding layer; Including, the stack includes a mesa region; a surface-emitting quantum cascade laser, the mesa region including the portion of the first cladding layer and the light-emitting layer, and the planar shape of the mesa region in a first plane intersecting a first direction from the first cladding layer to the second cladding layer includes a recess;

2. the planar shape includes a first outer edge portion and a second outer edge portion, the recess is between the first outer edge portion and the second outer edge portion, The surface-emitting quantum cascade laser of claim 1 , wherein the curvature of the first outer edge portion is different from the curvature of the second outer edge portion.

3. the first outer edge portion and the second outer edge portion are convex in a direction from the inside to the outside of the planar shape, The surface-emitting quantum cascade laser according to claim 2 , wherein the recess is concave in the direction from the outside to the inside.

4. A first electrode; A second electrode; a laminate provided between the first electrode and the second electrode; Equipped with The laminate is a first cladding layer; a second cladding layer; a light emitting layer provided between a portion of the first cladding layer and the second cladding layer; a photonic crystal layer including a plurality of structures provided between the light emitting layer and the second cladding layer; Including, the stack includes a mesa region; the mesa region includes the portion of the first cladding layer and the light-emitting layer, and a planar shape of the mesa region in a first plane intersecting a first direction from the first cladding layer to the second cladding layer satisfies at least one of a first condition, a second condition, a third condition, and a fourth condition; In the first condition, the planar shape includes a first curved line having a first curvature and a second curved line having a second curvature different from the first curvature, In the second condition, the planar shape includes a first circular arc, a second circular arc, and a third circular arc, the position of the center of the first circular arc is different from the position of the center of the second circular arc and different from the position of the center of the third circular arc, the position of the center of the second circular arc is different from the position of the center of the third circular arc, In the third condition, the planar shape includes a recess, In the fourth condition, the planar shape of the surface-emitting quantum cascade laser coincides with a photonic region in which the plurality of structures are provided.

5. the planar shape satisfies the first condition, the first curve is a portion of the periphery of a first circle; the second curve is a portion of the periphery of a second circle; The surface-emitting quantum cascade laser of claim 4 , wherein a first position of a first center of the first circle is different from a second position of a second center of the second circle.

6. the planar shape satisfies the first condition, 5. The surface-emitting quantum cascade laser of claim 4, wherein at least one of the first curve and the second curve includes a portion of a polynomial function.

7. Further comprising a reflective film; the mesa region includes a mesa side surface that intersects with the first plane; a direction from the mesa side surface to the reflective film intersects with the first plane; 7. The surface-emitting quantum cascade laser according to claim 1, wherein the reflectance of the reflective film at the wavelength of light emitted from the light-emitting layer is higher than the reflectance of the first cladding layer at the wavelength.

8. The light emitted from the surface-emitting quantum cascade laser includes a first peak and does not include any other peaks except for the first peak, or 8. The surface-emitting quantum cascade laser according to claim 7, wherein the intensity of the other peak is 1 / 100 or less of the intensity of the first peak.

9. the outer edge of the planar shape includes a first portion and a second portion; a first normal to the first portion of the outer edge passes through the second portion; The surface-emitting quantum cascade laser of claim 1 , wherein a second normal to the second portion of the outer edge is inclined with respect to the first normal.

10. 2. The surface-emitting quantum cascade laser according to claim 1, wherein the light-emitting layer emits light by intersubband transition.

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