CN116826522A - Super-symmetrical semiconductor laser with lateral grating - Google Patents

Abstract

This application discloses a supersymmetric semiconductor laser with a lateral grating, which includes: an N-surface electrode, a substrate, a buffer layer, an N-type waveguide layer, an active layer, and a P-type waveguide layer stacked sequentially from bottom to top along the epitaxial direction. and a supersymmetric structure; the supersymmetric structure includes a P-type cover layer and an upper contact layer, the upper contact layer is stacked on the P-type cover layer, the middle part of the supersymmetric structure is a main waveguide, and sub-waveguides are provided on both sides of the main waveguide. ; A lateral grating is provided longitudinally between the sub-waveguide and the main waveguide, and the lateral grating is used to select the longitudinal mode; a P-plane electrode is provided on the main waveguide. It has the following advantages: It adopts a supersymmetric structure and achieves high-power base-side mode output without losing the base-side mode of the middle main waveguide. By designing the duty cycle of the lateral grating, standard photolithography manufacturing can be realized. , using a lateral grating structure, the grating structure is obtained by etching on both sides of the ridge waveguide, avoiding secondary epitaxial growth.

Description

A supersymmetric semiconductor laser with lateral grating

Technical field

The invention relates to the technical field of semiconductor lasers, and in particular to a supersymmetric semiconductor laser with a lateral grating.

Background technique

Semiconductor lasers have the advantages of low cost, small device size, high power conversion efficiency and high reliability. They are widely used in industrial processing, communication networks, laser sensing, aerospace and defense, safety protection and other fields. High-power narrow linewidth lasers have extremely high spectral purity, extremely high peak spectral density, ultra-long coherence length and extremely low phase noise. Therefore, they are used as core light sources in atomic magnetometers, atomic cooling, atomic clocks, and quantum applications. It has important applications in gyroscopes and other fields, so designing a semiconductor laser that is simple to manufacture, can be mass-produced, and has high power and narrow linewidth has become a research hotspot.

In the lateral direction, to achieve single-side mode output for ordinary ridge waveguide semiconductor lasers, the ridge width needs to be controlled below 2um, and the small ridge width is used to limit the occurrence of high-order side modes. However, the electrical injection area of the small ridge width is small, so As a result, the output power of the semiconductor laser is low, and the semiconductor laser with a large ridge width has a larger electrical injection area and a higher output power, but high-order modes will appear in the side direction, or two isolation lines can be deeply etched on both sides of the ridge waveguide. The etching depth of the trench sometimes exceeds the active area layer, providing the laser with a larger refractive index difference in the external structure. This condition can better confine electrons and photons in the emitting area; in addition, by placing the ridge The edge of the waveguide is serrated to achieve loss tailoring of high-order side modes. However, the disadvantage of these two processing methods is that they will also cause certain losses to the base-side mode.

In the vertical direction, traditional distributed feedback semiconductor lasers need to etch the grating structure in the P-type waveguide layer in order to select the desired longitudinal mode, then perform secondary epitaxial growth and continue to grow the epitaxial material on the grating. Due to the need for secondary epitaxial growth, Epitaxial growth, so the manufacturing cost is high and the process is complicated, which is not conducive to mass production. If the grating structure is etched on the ridge waveguide, secondary epitaxial growth is avoided, and at the same time it has good longitudinal mode selection ability, but because it is on the ridge waveguide The grating is etched on the waveguide, and sometimes the etching depth is even the same as the ridge height, which results in greater laser loss and lower output power.

Contents of the invention

The technical problem to be solved by the present invention is to solve the above shortcomings and provide a supersymmetric semiconductor laser with a lateral grating, which adopts a supersymmetric structure and realizes high-power base mode without losing the base-side mode of the middle main waveguide. Side mode output, by designing the duty cycle of the lateral grating, realizes the manufacturing of standard lithography. Using the lateral grating structure, the grating structure is obtained by etching on both sides of the ridge waveguide, which avoids secondary epitaxial growth and is beneficial to Reduce manufacturing costs and simplify manufacturing processes.

In order to solve the above technical problems, the present invention adopts the following technical solutions:

A supersymmetric semiconductor laser with lateral grating, including:

The N-plane electrode, substrate, buffer layer, N-type waveguide layer, active layer, P-type waveguide layer and supersymmetric structure are stacked from bottom to top along the epitaxial direction;

The supersymmetric structure includes a P-type cover layer and an upper contact layer. The upper contact layer is stacked on the P-type cover layer. The middle part of the supersymmetric structure is a main waveguide, and sub-waveguides are provided on both sides of the main waveguide;

A lateral grating is provided longitudinally between the sub-waveguide and the main waveguide, and the lateral grating is used to select the longitudinal mode;

The main waveguide is provided with a P-plane electrode;

The high-order side mode of the main waveguide is coupled with the modes of the two sub-waveguides to form a lossy mode, which is used to achieve high-power base-side mode output.

Furthermore, the supersymmetric structure is an etching structure, and the etching depth corresponds to the etching depth capable of accommodating a corresponding number of modes in the range of visible light to mid- and far-infrared bands.

Further, the width of the main waveguide corresponds to the width that can accommodate the corresponding number of modes in the range from visible light to mid-to-far infrared.

Furthermore, the width of the sub-waveguide located on the left side of the main waveguide corresponds to the width that can accommodate the corresponding number of modes in the range of visible light to mid-far infrared. The distance between the sub-waveguide on the left and the main waveguide is 1-6 μm.

Furthermore, the width of the sub-waveguide located on the right side of the main waveguide corresponds to the width that can accommodate the corresponding number of modes in the range of visible light to mid-far infrared. The distance between the sub-waveguide on the right and the main waveguide is 1-6 μm.

Furthermore, the structure of the lateral grating is an etching structure, and the etching depth corresponds to the etching depth capable of accommodating a corresponding number of modes in the range of visible light to mid-far infrared bands.

Further, the etching depth of the lateral grating is consistent with that of the supersymmetric structure.

Further, the lateral grating satisfies the grating Bragg condition:

, where m is the lateral grating order, λ is the wavelength, neff is the effective refractive index, and Λ is the lateral grating period.

Further, the distance between gratings in the lateral grating is greater than 1um.

The present invention adopts the above technical solution and has the following technical effects compared with the existing technology:

1. The invention provides a supersymmetric semiconductor laser with a lateral grating. The supersymmetric structure includes a central main waveguide and sub-waveguides on both sides. The sub-waveguides on both sides are used to couple the high-order side modes of the central main waveguide to both sides and lose them. , and because the middle main waveguide is wider and the electrical pumping area is larger, the middle main waveguide can achieve high-power base-side mode output without losing the base-side mode.

2. The supersymmetric semiconductor laser with lateral grating provided by the present invention is used to narrow the line width and realize longitudinal mode selection by designing the period of the lateral grating.

3. The supersymmetric semiconductor laser with lateral grating provided by the present invention can be manufactured by standard photolithography by designing the duty cycle of the lateral grating. The lateral grating structure is used and etched on both sides of the ridge waveguide to obtain The grating structure avoids secondary epitaxial growth, which is beneficial to reducing manufacturing costs, simplifying the manufacturing process, and enabling large-scale mass production.

4. The supersymmetric semiconductor laser with lateral grating provided by the present invention can achieve high-power narrow linewidth single-side mode output, and has important application prospects in the fields of atomic magnetometers, atomic cooling, atomic clocks, quantum gyroscopes, etc.

Description of the drawings

In order to more clearly explain the specific embodiments of the present invention or the technical solutions in the prior art, the drawings that need to be used in the description of the specific implementations or the prior art will be briefly introduced below. Throughout the drawings, similar elements or portions are generally identified by similar reference numerals. In the drawings, elements or parts are not necessarily drawn to actual scale.

Figure 1 is a schematic three-dimensional structural diagram of a supersymmetric semiconductor laser with a lateral grating provided according to an embodiment of the present invention;

Figure 2 is a schematic diagram of the xz plane structure of a supersymmetric semiconductor laser with a lateral grating provided according to an embodiment of the present invention;

Figure 3 shows the lateral mode supported by ordinary ridge waveguide structure semiconductor lasers in the prior art without adding a supersymmetric structure;

Figure 4 is a lateral mode supported by a supersymmetric semiconductor laser with a lateral grating provided according to an embodiment of the present invention;

Figure 5 is a reflection spectrum of a supersymmetric semiconductor laser with a lateral grating provided according to an embodiment of the present invention when the grating length is 27.5um.

Detailed ways

Embodiment, as shown in Figures 1 and 2, a supersymmetric semiconductor laser with lateral grating includes:

The N-surface electrode 201, the substrate 202, the buffer layer 203, the N-type waveguide layer 204, the active layer 205, the P-type waveguide layer 206 and the supersymmetric structure are stacked from bottom to top along the epitaxial direction. The supersymmetric structure includes a P-type cover. layer 207 and upper contact layer 208. The upper contact layer 208 is stacked on the P-type cover layer 207. The middle part of the supersymmetric structure is a main waveguide 212. There are sub-waveguides 211 on both sides of the main waveguide 212. The sub-waveguide 211 and the main waveguide A lateral grating 210 is provided longitudinally between 212 , and a P-plane electrode 209 is provided on the main waveguide 212 .

The high-order side mode of the main waveguide 212 is coupled with the modes of the two sub-waveguides 211 to form a lossy mode, which is used to achieve high-power base-side mode output.

The supersymmetric structure is an etching structure, and the etching depth corresponds to the etching depth capable of accommodating a corresponding number of modes in the range of visible light to mid-far infrared bands.

The width of the main waveguide 212 corresponds to the width that can accommodate the corresponding number of modes in the range from visible light to mid-to-far infrared.

The width of the sub-waveguide 211 located on the left side of the main waveguide 212 corresponds to the width that can accommodate the corresponding number of modes in the visible light to mid-far infrared band range. The distance between the sub-waveguide 211 on the left and the main waveguide 212 should be an appropriate coupling strength distance, and the distance is 1 -6μm.

The width of the sub-waveguide 211 located on the right side of the main waveguide 212 corresponds to the width that can accommodate the corresponding number of modes in the visible to mid-far infrared band range. The distance between the sub-waveguide 211 on the right and the main waveguide 212 should be an appropriate coupling strength distance, and the distance is 1 -6μm.

The lateral grating 210 is used to realize the selection of longitudinal modes. The structure of the lateral grating 210 is an etching structure, and the etching depth corresponds to the etching depth that can accommodate a corresponding number of modes in the range of visible light to mid-far infrared bands.

The lateral grating 210 has the same etching depth as the supersymmetric structure, which simplifies the production process and facilitates large-scale production and application.

The lateral grating 210 satisfies the grating Bragg condition:

, where m is the lateral grating order, λ is the wavelength, n _eff is the effective refractive index, and Λ is the lateral grating period.

The spacing between gratings in the lateral grating 210 is greater than 1 μm to meet the requirements of standard photolithography and dry etching.

The supersymmetric semiconductor laser with lateral grating according to the present invention uses a supersymmetric structure in limiting the lateral mode. The supersymmetric structure includes a middle main waveguide and two side sub-waveguides. The two side sub-waveguides are used to connect the middle main waveguide. The high-order side modes are coupled to both sides and lost, and because the middle main waveguide is wider and the electrical pumping area is larger, the middle main waveguide achieves high-power base-side mode output without losing the base-side mode. ; To limit the longitudinal mode, a lateral grating structure is used, and the grating structure is obtained by etching on both sides of the ridge waveguide. This avoids secondary epitaxy and etching on the waveguide, which would cause greater damage to the base-side mode. It has a large impact and has the ability to select molds. It can be produced by standard photolithography under the condition of controlling the grating duty cycle.

In order to describe the present invention more clearly, one of the situations is simulated using the finite element method in the embodiment of the present invention:

It includes: N-surface electrodes, substrate, buffer layer, N-type waveguide layer, active layer, P-type waveguide layer, supersymmetric-lateral grating structure stacked from bottom to top along the epitaxial direction; the supersymmetric structure consists of P-type The cover layer and the upper contact layer are stacked; the supersymmetric structure includes a main waveguide in the middle and sub-waveguides on both sides; the lateral grating is set between the main waveguide and the sub-waveguide; the P-plane electrode is set on the main waveguide, and the epitaxial wafer is electrically The lasing wavelength under injection is 795nm.

The supersymmetric structure is an etched structure, and the height from the upper contact layer to the active layer is 1.31um, so the etching depth h is selected as 1.2um to achieve better restriction of the light field.

The width W_m of the main waveguide is 6um, which is used to achieve a large electrical injection area and can accommodate the fundamental mode, first-order mode, and second-order mode. Using finite element analysis, the propagation constants of each mode are 26.5056um-1, 26.4953um- 1,26.4801um-1.

The width W_l of the sub-waveguide 211 located on the left side of the main waveguide 212 is 2.3um and is 1um away from the main waveguide. It can accommodate the existence of one mode of the fundamental mode and has a propagation constant of 26.4951um-1. It is used to update the first-order mode in the main waveguide. Good coupling.

The width W_r of the sub-waveguide 211 located on the right side of the main waveguide 212 is 3.5um and is 1.2um away from the middle main waveguide. It can accommodate the existence of two modes, the fundamental mode and the first-order mode. The propagation constants are 26.501um-1 and 26.4803um-1 respectively. It is used to achieve better coupling of the first-order mode in the right waveguide to the second-order mode in the main waveguide.

The lateral grating is an etching structure, and the etching depth h is 1.2um, which is used to improve the coupling strength of the lateral grating.

The period Λ of the lateral grating is 2.75um and the duty cycle is 0.5 to meet the requirements of standard photolithography and dry etching.

Figure 3 is calculated based on the finite element method, without adding supersymmetric structure, the lateral mode supported by the ordinary ridge waveguide structure semiconductor laser, the ridge width is 6um. At this time, it can be seen from Figure 3 that this structure allows the fundamental mode, first-order The existence of modules and second-order modes.

Figure 4 is the lateral mode supported by the supersymmetric semiconductor laser with lateral grating calculated based on the finite element method. At this time, the main waveguide supports the existence of the fundamental mode, the first-order mode, and the second-order mode, and the left waveguide only supports the existence of the fundamental mode. The right waveguide supports the existence of fundamental mode and first-order mode. It can be seen from Figure 4 that the first-order mode in the main waveguide couples with the fundamental mode in the left waveguide to form a pair of coupled modes; the second-order mode in the main waveguide couples with the first-order mode in the right waveguide to form another pair of coupled modes. , and since only electrodes are added to the middle main waveguide for electrical pumping, and there are no electrodes on the left and right sub-waveguides, loss waveguides are formed on both sides. Therefore, the two pairs of coupled modes and the fundamental mode in the right waveguide are not lased due to insufficient gain. , the fundamental mode in the middle main waveguide is lased, thereby achieving high-power single-mode output of this semiconductor laser.

Figure 5 is a reflection spectrum calculated based on the finite element method when the grating length of a supersymmetric semiconductor laser with a lateral grating is 27.5um and the grating period is 2.75um. As can be seen from Figure 5, the supersymmetric semiconductor laser with a lateral grating has the function of longitudinal mode selection. Based on this, we can design the period Λ of the lateral grating to achieve single longitudinal mode lasing at different wavelengths.

In summary, the supersymmetric semiconductor laser with lateral grating proposed by the present invention uses a supersymmetric structure to couple the high-order side mode of the middle main waveguide into the sub-waveguide and lose it in the lateral direction. Since the middle main waveguide The electrical pumping area is large, achieving high-power base-side mode output; in the longitudinal direction, the lateral grating structure is used to achieve longitudinal mode selection. This semiconductor laser has a simple structure and can be manufactured using standard photolithography and dry etching methods. It has important application prospects in atomic magnetometers, atomic cooling, atomic clocks, quantum gyroscopes and other fields.

The description of the present invention has been presented for the purposes of illustration and description, and is not intended to be exhaustive or to limit the invention to the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention and design various embodiments with various modifications as are suited to the particular use contemplated.

Claims (9)

1. A super-symmetrical semiconductor laser with lateral grating is characterized in that: comprising the following steps:

an N-face electrode (201), a substrate (202), a buffer layer (203), an N-type waveguide layer (204), an active layer (205), a P-type waveguide layer (206) and a super-symmetrical structure which are sequentially stacked from bottom to top along the epitaxial direction;

the super-symmetrical structure comprises a P-type cover layer (207) and an upper contact layer (208), wherein the upper contact layer (208) is stacked on the P-type cover layer (207), the middle part of the super-symmetrical structure is a main waveguide (212), and sub-waveguides (211) are arranged on two sides of the main waveguide (212);

a lateral grating (210) is longitudinally arranged between the sub waveguide (211) and the main waveguide (212), and the lateral grating (210) is used for realizing the selection of a longitudinal mode;

the main waveguide (212) is provided with a P-surface electrode (209);

the higher order side modes of the main waveguide (212) are coupled with modes of the two-measurement waveguide (211) to form a lossy mode for realizing high-power fundamental side mode output.

2. A super-symmetric semiconductor laser with lateral gratings as claimed in claim 1, wherein: the super-symmetrical structure is an etching structure, and the etching depth corresponds to the etching depth which can accommodate the corresponding mode number in the range from visible light to middle and far infrared.

3. A super-symmetric semiconductor laser with lateral gratings as claimed in claim 1, wherein: the main waveguide (212) has a width corresponding to a width in a range from visible light to mid-far infrared to accommodate a corresponding number of modes.

4. A super-symmetric semiconductor laser with lateral gratings as claimed in claim 1, wherein: the width of the sub-waveguide (211) positioned at the left side of the main waveguide (212) corresponds to the width of the visible light to the middle-far infrared band, the number of the corresponding modes can be accommodated, and the distance between the left sub-waveguide (211) and the main waveguide (212) is 1-6 mu m.

5. A super-symmetric semiconductor laser with lateral gratings as claimed in claim 1, wherein: the width of the sub waveguide (211) positioned on the right side of the main waveguide (212) corresponds to the width of the visible light to the middle-far infrared band, the number of the corresponding modes can be accommodated, and the distance between the sub waveguide (211) on the right side and the main waveguide (212) is 1-6 mu m.

6. A super-symmetric semiconductor laser with lateral gratings as claimed in claim 1, wherein: the structure of the lateral grating (210) is an etching structure, and the etching depth corresponds to the etching depth which can accommodate the corresponding mode number in the range from visible light to middle and far infrared.

7. A super-symmetric semiconductor laser with lateral gratings as claimed in claim 1, wherein: the lateral grating (210) is consistent with the etch depth of the super-symmetric structure.

8. A super-symmetric semiconductor laser with lateral gratings as claimed in claim 1, wherein: the lateral grating (210) satisfies a grating bragg condition:where m is the lateral grating order, λ is the wavelength, n _eff For effective index, Λ is the lateral grating period.

9. A super-symmetric semiconductor laser with lateral gratings as claimed in claim 1, wherein: the spacing between the gratings in the lateral gratings (210) is greater than 1um.