A ridge waveguide laser structure and a method of fabricating the same

Abstract

The present application relates to the field of semiconductor optoelectronics, and particularly relates to a ridge waveguide laser structure and a preparation method thereof. The ridge waveguide laser structure comprises, from bottom to top, a substrate and a stack structure. A ridge waveguide structure is arranged above the stack structure. The ridge waveguide structure comprises a ridge region and non-ridge regions on both sides of the ridge region. An insulating medium layer is arranged above the ridge waveguide structure. The insulating medium layer comprises a refractive index buffer region and an insulating material region. The refractive index buffer region is distributed in the non-ridge regions on both sides of the ridge region. The refractive index buffer region is composed of a plurality of refractive index buffer blocks arranged periodically along the cavity length direction. A P-face metal electrode is arranged above the insulating medium layer. The present application can effectively suppress high-order transverse mode lasing, improve the stability of the fundamental mode, and improve the far-field beam quality. The present application is highly compatible with the traditional ridge waveguide preparation process and is suitable for the fields of optical communication and laser radar.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronics technology, specifically to a ridge waveguide laser structure and its fabrication method. Background Technology

[0002] Ridge waveguide (RWG) structure is the mainstream technology for achieving lateral confinement of optical field and charge carriers in semiconductor lasers. Compared with buried heterojunction structure, ridge waveguide has advantages such as simple process, no need for secondary epitaxy, low manufacturing cost, and good mass production, and is widely used in optical communication, lidar and other fields.

[0003] Traditional ridge waveguide lasers typically employ the following process: a ridge-like protrusion (i.e., the ridge region) is formed in the P-type contact layer region through etching. A SiO2 insulating layer is deposited on the non-protruding regions (i.e., the non-ridge regions) on both sides of the ridge to achieve current confinement and electrical isolation, leaving only the top opening of the ridge for current injection. In this approach, the refractive index of the SiO2 insulating layer is approximately 1.45, while the refractive index of the semiconductor material in the ridge region (such as InP with a refractive index of approximately 3.17 and GaAs with a refractive index of approximately 3.5) is much higher than that of the SiO2 insulating layer, resulting in a very strong refractive index step between the ridge and non-ridge regions. According to the waveguide theory of ridge waveguides, the transverse distribution of the optical field in the waveguide is determined by the transverse equivalent refractive index distribution. According to the Helmholtz equation: d 2 E / dx 2 +K0 2 (n (x) 2 n eff 2 E=0; where K0 represents the vacuum wavenumber, x represents the position along the cavity length direction, and n （x） n represents the refractive index of the material at position x. eff Let represent the effective refractive index, and E represent the amplitude distribution function of the transverse component of the electric field intensity of the light field, which is a function of x; At the refractive index step interface, the first derivative of the optical field is discontinuous, causing distortion of the mode field and introducing a large number of higher-order Fourier components, making higher-order side modes easily excited. As the injected current increases, charge carriers diffuse laterally to both sides of the ridge, and the gain distribution broadens accordingly, further exacerbating the lasing of higher-order side modes, ultimately leading to a "multi-lobed" structure in the far-field beam and a significant deterioration in beam quality. Existing research shows that the lateral mode characteristics of a ridge waveguide are directly determined by the ratio of ridge depth to ridge width (depth-to-width ratio). Only when this ratio is controlled within a specific narrow range can stable output of the base-side modes be guaranteed, greatly limiting the design flexibility of the device structure.

[0004] To address the aforementioned issues, existing technologies have undertaken the following research: 1. Employing an isolated double-groove structure, adding isolation trenches on both sides of the ridge to suppress lateral carrier diffusion; 2. Adjusting the refractive index distribution by introducing ion implantation regions or replacing different dielectric materials in the trench area. However, none of these studies can completely resolve the mode distortion problem caused by refractive index steps, and the potential risks of high-order mode lasing remain. Summary of the Invention

[0005] To address the technical problems of existing ridge waveguide lasers, such as optical field distortion, easy lasing of higher-order modes, poor mode stability and significant deterioration of beam quality under high injection current due to the refractive index step between the ridge region and the non-ridge region, this invention provides a ridge waveguide laser structure and its fabrication method.

[0006] The technical solution of this invention is as follows: In a first aspect, the present invention provides a ridge waveguide laser structure, comprising, from bottom to top, a substrate and a stacked structure, wherein a ridge waveguide structure is disposed above the stacked structure, the ridge waveguide structure includes a ridge region and non-ridge regions located on both sides of the ridge region, an insulating dielectric layer is disposed above the ridge waveguide structure, the insulating dielectric layer includes a refractive index buffer region and an insulating material region, the refractive index buffer region is distributed in the non-ridge regions on both sides near the ridge region, the refractive index buffer region is composed of multiple refractive index buffer blocks periodically arranged along the cavity length direction, and a P-plane metal electrode is disposed above the insulating dielectric layer.

[0007] Furthermore, the material of the refractive index buffer block is SiN. x Its refractive index is 1.7~2.5.

[0008] Furthermore, the distance L between the refractive index buffer region and the ridge region is 0.5μm≤L≤5μm.

[0009] Furthermore, the cross-section of the refractive index buffer block is rhomboid, the long diagonal of the refractive index buffer block is parallel to the cavity length direction, and the short diagonal of the refractive index buffer block is parallel to the cavity surface.

[0010] Furthermore, the length H of the long diagonal of the refractive index buffer block and the depth U of the non-ridge region are 0.3≤H / U≤0.7, and 1μm≤U≤4μm.

[0011] Furthermore, the ratio of the short diagonal length Y of the refractive index buffer block to the width W of the ridge region is 0.15 ≤ Y / W ≤ 0.4.

[0012] Furthermore, the period Λ of the periodic arrangement of the refractive index buffer blocks is Λ=m·λ / 2n eff Where λ is the lasing wavelength, and n effFor the effective refractive index, m is an integer greater than or equal to 5.

[0013] Furthermore, the material of the insulating material region is SiO2.

[0014] Furthermore, the thickness of the insulating dielectric layer is 100~300nm.

[0015] Secondly, the present invention provides a method for fabricating the above-mentioned ridge waveguide laser structure, comprising the following steps: (1) A stacked structure is epitaxially grown on a substrate, and then a ridge waveguide structure is formed on the stacked structure by photolithography and etching techniques. The ridge waveguide structure includes a ridge region and non-ridge regions located on both sides of the ridge region. (2) An insulating dielectric layer is deposited on the ridge waveguide structure; then, a refractive index buffer region is deposited on the insulating dielectric layer by photolithography, etching and deposition. (3) Remove the insulating dielectric layer directly above the ridge region, then deposit a P-plane metal layer on the epitaxial surface and deposit an N-plane metal layer on the back side of the substrate. After cleaving and coating, a ridge waveguide laser is obtained.

[0016] The beneficial effects of this invention are as follows: 1. The ridge waveguide laser provided by this invention sets a refractive index buffer region in the non-ridge region near the ridge region, which can form a refractive index transition layer between the ridge semiconductor and the insulating material, effectively smoothing the sharp refractive index step in the traditional structure, eliminating optical field distortion and mode jump at the interface of refractive index change, and greatly improving the working stability of the side optical field mode; under high injection current conditions, it can effectively suppress high-order side mode lasing, widen the fundamental mode operating current range of the device, improve the linearity of output power, and improve the far-field beam quality.

[0017] 2. The ridge waveguide laser provided by the present invention has a refractive index buffer region composed of multiple discrete refractive index buffer blocks arranged periodically along the cavity length direction. The equivalent refractive index gradient can be flexibly adjusted by adjusting the arrangement density, position and size of the buffer blocks to adapt to different mode constraint requirements.

[0018] 3. The fabrication method provided by this invention does not require additional etching, ion implantation or other modification treatments on the semiconductor epitaxial layer, and is highly compatible with the fabrication process of traditional ridge waveguide lasers, without the need for additional equipment investment. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the vertical cross-section of the ridge waveguide laser provided by the present invention along the parallel cavity surface direction.

[0021] Figure 2 This is a partial structural schematic diagram of the ridge waveguide laser provided by the present invention. In the figure, (a) is a partial structural schematic diagram of the vertical cross-section of the ridge waveguide laser in the direction parallel to the cavity surface, where L is the distance between the refractive index buffer region and the ridge region, Y is the short diagonal length of the refractive index buffer block, W is the width of the ridge region, and U is the depth of the non-ridge region; (b) is a partial structural schematic diagram of the vertical cross-section of the ridge waveguide laser in the direction perpendicular to the cavity surface, where H is the long diagonal length of the refractive index buffer block.

[0022] Figure 3 This is a schematic diagram of the arrangement of the refractive index buffer region in the ridge waveguide laser provided by the present invention.

[0023] Figure 4 The diagram shows the transverse equivalent refractive index distribution in the ridge waveguide laser structures prepared in Example 1 and Comparative Example 1.

[0024] Figure 5 The figures show the far-field beam patterns of the ridge waveguide laser structures prepared in Examples 1-3 and Comparative Example 1. In the figures, (a) is the far-field beam pattern of the ridge waveguide laser structure prepared in Example 1; (b) is the far-field beam pattern of the ridge waveguide laser structure prepared in Example 2; (c) is the far-field beam pattern of the ridge waveguide laser structure prepared in Example 3; and (d) is the far-field beam pattern of the ridge waveguide laser structure prepared in Comparative Example 1.

[0025] In the figure, 1-substrate, 2-N-type cladding, 3-lower waveguide layer, 4-active layer, 5-upper waveguide layer, 6-P-type cladding, 7-P-type contact layer, 8-ridge region, 9-non-ridge region, 10-refractive index buffer region, 11-insulating material region, 12-P-plane metal electrode. Detailed Implementation

[0026] The design of the ridge waveguide laser structure in this invention is based on the waveguide theory and wave optics principle of ridge waveguides. It modifies the equivalent refractive index distribution of the non-ridge region 9 to suppress the excitation of higher-order modes from the source. Its specific working principle is as follows: According to the Effective Index Method (EIM), the transverse modes of a ridge waveguide are determined by the transverse equivalent refractive index distribution. In a traditional ridge waveguide laser structure, the equivalent refractive index n1 of the ridge region 8 is close to that of semiconductor materials (approximately 3.2), while the equivalent refractive index n2 of the SiO2 insulating dielectric layer is approximately 1.45. The difference between the two is as high as 1.75, forming a drastic step, which leads to optical field distortion, easy lasing of higher-order modes, and poor mode stability and significant deterioration of beam quality under high injection current.

[0027] This invention establishes a refractive index buffer region 10 within the non-ridge region 9 near the ridge region 8, introducing a buffer material with a refractive index between the semiconductor material and the SiO2 insulating dielectric layer. This constructs an intermediate refractive index level on the side of the ridge region 8, transforming the originally abrupt refractive index step into a smooth transition structure. This significantly reduces the refractive index difference between adjacent regions, weakening the optical field distortion caused by the refractive index step. The refractive index buffer region 10 is composed of multiple refractive index buffer blocks arranged periodically along the cavity length. This allows for flexible control of the equivalent refractive index gradient by adjusting the arrangement density, position, and size of the refractive index buffer blocks, adapting to different mode confinement requirements. It also avoids the negative impact of full coverage of high refractive index materials on the device's electrical isolation performance and optical field confinement capability, achieving a balance between mode control and the device's fundamental performance.

[0028] In a preferred embodiment, this invention sets the refractive index buffer block as a rhomboid cross-section structure. Utilizing the gradual geometric characteristics of the rhomboid's hypotenuse, continuous control of the equivalent refractive index is achieved. Specifically, the short diagonal of the rhomboid is distributed parallel to the cavity surface and perpendicular to the ridge extension direction. Along the ridge sidewall towards the outside of the groove, the transverse cross-section width of the rhomboid continuously narrows, and the volume proportion of the buffer material in the local medium continuously decreases, resulting in a continuous and smooth downward trend in the lateral equivalent refractive index, completely eliminating abrupt lateral refractive index changes. According to the wave optics principle, when the refractive index distribution n(x) is a continuous function, higher-order Fourier components of the optical field are effectively suppressed, the propagation loss of the fundamental transverse mode is significantly reduced, and the lasing threshold gain of first-order and higher-order transverse modes is greatly improved, thereby achieving stable fundamental mode output. The long diagonal of the rhomboid extends along the cavity length direction and perpendicular to the cavity surface, making the range of gradual change in the equivalent refractive index along the depth direction controllable, avoiding longitudinal distortion of the optical field caused by depth-direction refractive index steps, and further enhancing the stability of the optical field modes.

[0029] In a preferred embodiment, the periodic arrangement of multiple refractive index buffer blocks along the cavity length direction satisfies the following relationship: Λ=m·λ / 2n eff ; In the formula, λ is the lasing wavelength of the device, and n effWhere m is the effective refractive index of the waveguide and m is a positive integer greater than or equal to 5, this periodic design can ensure that the lateral equivalent refractive index modulation effect is uniform and consistent along the entire length of the resonant cavity, avoiding local mode jumps caused by structural differences in the cavity length direction, and achieving stable control of the optical field across the entire cavity length.

[0030] According to the ridge waveguide mode theory, the single-mode condition of a ridge waveguide can be expressed as: ; Where w is the width of the ridge, H is the height of the inner ridge, r = h / H, h is the height of the outer ridge, and r > 0.5. This invention effectively increases the equivalent refractive index of the non-ridge region 9 through the refractive index buffer region 10, effectively raising the effective waveguide height of the outer ridge, and ultimately increasing the equivalent r value, thus making it more advantageous for single-mode operation under the same ridge width conditions.

[0031] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0032] Example 1 A ridge waveguide laser structure, such as Figures 1-3 As shown, from bottom to top, the structure includes a substrate 1 and a stacked structure. The stacked structure, from bottom to top, includes an N-type cladding 2, a lower waveguide layer 3, an active layer 4, an upper waveguide layer 5, a P-type cladding 6, and a P-type contact layer 7. A ridge waveguide structure is provided above the stacked structure. The ridge waveguide structure includes a ridge region 8 and non-ridge regions 9 located on both sides of the ridge region 8. An insulating dielectric layer is provided above the ridge waveguide structure. The insulating dielectric layer includes a refractive index buffer region 10 and an insulating material region 11. The refractive index buffer region 10 is distributed within the non-ridge regions 9 near the ridge region 8. The refractive index buffer region 10 is composed of multiple rhomboid refractive index buffer blocks arranged periodically along the cavity length direction, with the long diagonal of the refractive index buffer block parallel to the cavity length direction and the short diagonal parallel to the cavity surface. The material of the refractive index buffer block is SiN. x The refractive index of the refractive index buffer block is 1.7~2.5, the material of the insulating material region 11 is SiO2, and a P-side metal electrode 12 is provided above the insulating dielectric layer.

[0033] The distance L between the refractive index buffer region 10 and the ridge region 8 is 0.5 μm, the length H of the long diagonal of the refractive index buffer block is 1 μm, the length Y of the short diagonal of the refractive index buffer block is 0.5 μm, the period Λ of the periodic arrangement of the refractive index buffer blocks is 2 μm, the total cavity length is 500 μm, the depth U of the non-ridge region 9 is 1.5 μm, the thickness of the insulating dielectric layer is 200 nm, and the width W of the ridge region 8 is 3 μm.

[0034] The fabrication method of the above-mentioned ridge waveguide laser structure includes the following steps: (1) A stacked structure is epitaxially grown on substrate 1, and then a ridge waveguide structure is formed on the stacked structure by photolithography and etching techniques. The ridge waveguide structure includes a ridge region 8 and non-ridge regions 9 located on both sides of the ridge region 8. (2) An insulating dielectric layer is deposited on the ridge waveguide structure; then, a refractive index buffer region 10 is deposited on the insulating dielectric layer by photolithography, etching and deposition. (3) Remove the insulating dielectric layer directly above the ridge region 8, then deposit the P-side metal electrode 12 on the epitaxial surface, deposit the N-side metal on the back side of the substrate 1, and obtain the ridge waveguide laser by cleaving and coating.

[0035] Example 2 A ridge waveguide laser structure, such as Figures 1-3 As shown, from bottom to top, the structure includes a substrate 1 and a stacked structure. The stacked structure, from bottom to top, includes an N-type cladding 2, a lower waveguide layer 3, an active layer 4, an upper waveguide layer 5, a P-type cladding 6, and a P-type contact layer 7. A ridge waveguide structure is provided above the stacked structure. The ridge waveguide structure includes a ridge region 8 and non-ridge regions 9 located on both sides of the ridge region 8. An insulating dielectric layer is provided above the ridge waveguide structure. The insulating dielectric layer includes a refractive index buffer region 10 and an insulating material region 11. The refractive index buffer region 10 is distributed within the non-ridge regions 9 near the ridge region 8. The refractive index buffer region 10 is composed of multiple rhomboid refractive index buffer blocks arranged periodically along the cavity length direction, with the long diagonal of the refractive index buffer block parallel to the cavity length direction and the short diagonal parallel to the cavity surface. The material of the refractive index buffer block is SiN. x The refractive index of the refractive index buffer block is 1.7~2.5, the material of the insulating material region 11 is SiO2, and a P-side metal electrode 12 is provided above the insulating dielectric layer.

[0036] The distance L between the refractive index buffer region 10 and the ridge region 8 is 2 μm, the length H of the long diagonal of the refractive index buffer block is 2 μm, the length Y of the short diagonal of the refractive index buffer block is 1 μm, the period Λ of the periodic arrangement of the refractive index buffer blocks is 5 μm, the cavity length is 2000 μm, the depth U of the non-ridge region 9 is 4 μm, the thickness of the insulating dielectric layer is 300 nm, and the width W of the ridge region 8 is 3.5 μm.

[0037] The fabrication method of the above-mentioned ridge waveguide laser structure includes the following steps: (1) A stacked structure is epitaxially grown on substrate 1, and then a ridge waveguide structure is formed on the stacked structure by photolithography and etching techniques. The ridge waveguide structure includes a ridge region 8 and non-ridge regions 9 located on both sides of the ridge region 8. (2) An insulating dielectric layer is deposited on the ridge waveguide structure; then, a refractive index buffer region 10 is deposited on the insulating dielectric layer by photolithography, etching and deposition. (3) Remove the insulating dielectric layer directly above the ridge region 8, then deposit the P-side metal electrode 12 on the epitaxial surface, deposit the N-side metal on the back side of the substrate 1, and obtain the ridge waveguide laser by cleaving and coating.

[0038] Example 3 A ridge waveguide laser structure, such as Figures 1-3 As shown, from bottom to top, the structure includes a substrate 1 and a stacked structure. The stacked structure, from bottom to top, includes an N-type cladding 2, a lower waveguide layer 3, an active layer 4, an upper waveguide layer 5, a P-type cladding 6, and a P-type contact layer 7. A ridge waveguide structure is provided above the stacked structure. The ridge waveguide structure includes a ridge region 8 and non-ridge regions 9 located on both sides of the ridge region 8. An insulating dielectric layer is provided above the ridge waveguide structure. The insulating dielectric layer includes a refractive index buffer region 10 and an insulating material region 11. The refractive index buffer region 10 is distributed within the non-ridge regions 9 near the ridge region 8. The refractive index buffer region 10 is composed of multiple rhomboid refractive index buffer blocks arranged periodically along the cavity length direction, with the long diagonal of the refractive index buffer block parallel to the cavity length direction and the short diagonal parallel to the cavity surface. The material of the refractive index buffer block is SiN. x The refractive index of the refractive index buffer block is 1.7~2.5, the material of the insulating material region 11 is SiO2, and a P-side metal electrode 12 is provided above the insulating dielectric layer.

[0039] The distance L between the refractive index buffer region 10 and the ridge region 8 is 5 μm, the length H of the long diagonal of the refractive index buffer block is 2 μm, the length Y of the short diagonal of the refractive index buffer block is 1 μm, the period Λ of the periodic arrangement of the refractive index buffer blocks is 10 μm, the cavity length is 3000 μm, the depth U of the non-ridge region 9 is 3 μm, the thickness of the insulating dielectric layer is 100 nm, and the width W of the ridge region 8 is 2.5 μm.

[0040] The fabrication method of the above-mentioned ridge waveguide laser structure includes the following steps: (1) A stacked structure is epitaxially grown on substrate 1, and then a ridge waveguide structure is formed on the stacked structure by photolithography and etching techniques. The ridge waveguide structure includes a ridge region 8 and non-ridge regions 9 located on both sides of the ridge region 8. (2) An insulating dielectric layer is deposited on the ridge waveguide structure; then, a refractive index buffer region 10 is deposited on the insulating dielectric layer by photolithography, etching and deposition. (3) Remove the insulating dielectric layer directly above the ridge region 8, then deposit the P-side metal electrode 12 on the epitaxial surface, deposit the N-side metal on the back side of the substrate 1, and obtain the ridge waveguide laser by cleaving and coating.

[0041] Comparative Example 1 A ridge waveguide laser structure comprises, from bottom to top, a substrate 1 and a stacked structure. The stacked structure comprises, from bottom to top, an N-type cladding 2, a lower waveguide layer 3, an active layer 4, an upper waveguide layer 5, a P-type cladding 6, and a P-type contact layer 7. A ridge waveguide structure is provided above the stacked structure. The ridge waveguide structure includes a ridge region 8 and non-ridge regions 9 located on both sides of the ridge region 8. An insulating dielectric layer is provided above the ridge waveguide structure. The insulating dielectric layer is made of SiO2 and has a thickness of 200 nm. A P-plane metal electrode 12 is provided above the insulating dielectric layer.

[0042] The fabrication method of the above-mentioned ridge waveguide laser structure includes the following steps: (1) A stacked structure is epitaxially grown on substrate 1, and then a ridge waveguide structure is formed on the stacked structure by photolithography and etching techniques. The ridge waveguide structure includes a ridge region 8 and non-ridge regions 9 located on both sides of the ridge region 8. (2) Deposit an insulating dielectric layer on the ridge waveguide structure; (3) Remove the insulating dielectric layer directly above the ridge region 8, then deposit the P-side metal electrode 12 on the epitaxial surface, deposit the N-side metal on the back side of the substrate 1, and obtain the ridge waveguide laser by cleaving and coating.

[0043] Test case The products from Examples 1-3 and Comparative Example 1 were used to collect the far-field light intensity distribution at the emitting end face of the device under room temperature and continuous current injection conditions. The test results are as follows: Figure 5 As shown.

[0044] Depend on Figure 5 As shown in (d), Comparative Example 1 is a traditional ridge waveguide structure. Its far-field beam exhibits a distinct multi-lobed splitting pattern, with significant higher-order side lobes on both sides of the central main lobe. The beam exhibits lateral stretching and trailing, accompanied by a diffuse stray light ring on the periphery. This corresponds to the characteristics of the fundamental mode and higher-order transverse modes being lased together, resulting in poor beam quality.

[0045] Depend on Figure 5 As shown in (a), Example 1 employs the refractive index buffer structure described in this invention, resulting in a well-defined and symmetrical far-field beam profile with no obvious side lobes, tails, or lateral stretching. The beam intensity decreases smoothly and monotonically from the center outwards, and the far-field intensity contour lines are regular concentric circles, closely resembling an ideal Gaussian distribution, corresponding to a stable fundamental transverse mode lasing state. The beam quality is significantly improved compared to Comparative Example 1. Figure 5 As can be seen from (b) and (c), the far-field beams of Examples 2 and 3 do not exhibit significant multi-lobe splitting, and their beam quality is still significantly better than that of Comparative Example 1.

[0046] The above test results show that by setting a refractive index buffer region in the non-ridge region, the present invention can effectively suppress high-order side-mode lasing, significantly improve the far-field spot morphology, and enhance beam quality.

[0047] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.

Claims

1. A ridge waveguide laser structure, comprising, from bottom to top, a substrate and a stacked structure, wherein a ridge waveguide structure is disposed above the stacked structure, the ridge waveguide structure comprising a ridge region and non-ridge regions located on both sides of the ridge region; an insulating dielectric layer is disposed above the ridge waveguide structure, characterized in that, The insulating dielectric layer includes a refractive index buffer region and an insulating material region. The refractive index buffer region is distributed in the non-ridge region on both sides of the ridge region. The refractive index buffer region is composed of multiple refractive index buffer blocks arranged periodically along the cavity length direction. A P-surface metal electrode is provided above the insulating dielectric layer.

2. The ridge waveguide laser structure as described in claim 1, characterized in that, The refractive index buffer block is made of SiN. x Its refractive index is 1.7~2.

5.

3. The ridge waveguide laser structure as described in claim 1, characterized in that, The distance L between the refractive index buffer region and the ridge region is 0.5μm≤L≤5μm.

4. The ridge waveguide laser structure as described in claim 1, characterized in that, The cross-section of the refractive index buffer block is rhomboid, with the long diagonal of the refractive index buffer block parallel to the cavity length direction and the short diagonal of the refractive index buffer block parallel to the cavity surface.

5. The ridge waveguide laser structure as described in claim 4, characterized in that, The length H of the long diagonal of the refractive index buffer block and the depth U of the non-ridge region are 0.3 ≤ H / U ≤ 0.

7.

6. The ridge waveguide laser structure as described in claim 4, characterized in that, The ratio of the short diagonal length Y of the refractive index buffer block to the width W of the ridge region is 0.15 ≤ Y / W ≤ 0.

4.

7. The ridge waveguide laser structure as described in claim 1, characterized in that, The periodic arrangement of the refractive index buffer blocks has a period Λ, where Λ = m·λ / 2n. eff Where λ is the lasing wavelength, and n eff For the effective refractive index, m is an integer greater than or equal to 5.

8. The ridge waveguide laser structure as described in claim 1, characterized in that, The insulating material region is made of SiO2.

9. The ridge waveguide laser structure as described in claim 1, characterized in that, The thickness of the insulating dielectric layer is 100~300nm.

10. A method for fabricating a ridge waveguide laser structure as described in any one of claims 1 to 9, characterized in that, Includes the following steps: (1) A stacked structure is epitaxially grown on a substrate, and then a ridge waveguide structure is formed on the stacked structure by photolithography and etching techniques. The ridge waveguide structure includes a ridge region and non-ridge regions located on both sides of the ridge region. (2) An insulating dielectric layer is deposited on the ridge waveguide structure; then, a refractive index buffer region is deposited on the insulating dielectric layer by photolithography, etching and deposition. (3) Remove the insulating dielectric layer directly above the ridge region, then deposit a P-plane metal layer on the epitaxial surface and deposit an N-plane metal layer on the back side of the substrate. After cleaving and coating, a ridge waveguide laser is obtained.

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