Low power loss semiconductor laser and preparation method thereof

Abstract

The present invention provides a low-power loss semiconductor laser and a preparation method thereof, wherein the device comprises: a semiconductor substrate layer, and an N-type confinement layer, an N-type waveguide layer, an active layer, a P-type waveguide layer, a P-type confinement layer and an ohmic contact layer which are sequentially stacked and epitaxially arranged on the semiconductor substrate layer; the P-type confinement layer comprises a first P-type sub-confinement layer and a second P-type sub-confinement layer which are stacked, and the first P-type sub-confinement layer is close to the P-type waveguide layer; wherein, along the epitaxial direction, the doping concentrations of the semiconductor substrate layer, the N-type confinement layer, the second P-type sub-confinement layer and the ohmic contact layer remain unchanged along the thickness variation, the variation of the doping gas flow rate with time is a constant, the doping concentrations and thicknesses of the N-type waveguide layer, the P-type waveguide layer and the first P-type sub-confinement layer all satisfy a quadratic function relationship, and the variation of the doping gas flow rate with time all satisfies a quadratic function relationship. The device can achieve very low power loss.

Description

Technical Field

[0001] The present disclosure relates to the technical field of semiconductor lasers, and in particular to a low-power loss semiconductor laser and a preparation method thereof. Background Art

[0002] Semiconductor lasers have many advantages such as high power, strong reliability, long life, small size and low cost, and are widely used in pumping, medical, communication and other fields.

[0003] Low power loss and high electro-optical conversion efficiency are important performance indicators in the research of high-power semiconductor lasers, which means less energy loss and greatly improved device stability and reliability.

[0004] When the thickness and material of each layer in the epitaxial direction of the semiconductor laser are determined, the doping concentration greatly affects the performance of the device. Too high a doping concentration can effectively reduce the series resistance of the device and reduce the Joule heat loss caused by the series resistance. However, too high a doping concentration will also increase the absorption loss of carriers. Therefore, it is very important to choose a suitable doping concentration. Summary of the invention

[0005] In view of the above technical problems, the first aspect of the present disclosure provides a low-power loss semiconductor laser, comprising: a semiconductor substrate layer, and an N-type confinement layer, an N-type waveguide layer, an active layer, a P-type waveguide layer, a P-type confinement layer and an ohmic contact layer stacked and epitaxially arranged on the semiconductor substrate layer in sequence; the P-type confinement layer comprises a first P-type sub-confinement layer and a second P-type sub-confinement layer stacked, and the first P-type sub-confinement layer is close to the P-type waveguide layer; wherein, along the epitaxial direction, the doping concentrations of the semiconductor substrate layer, the N-type confinement layer, the second P-type sub-confinement layer and the ohmic contact layer remain unchanged along the thickness variation, the variation of the doping gas flow rate with time is a constant, the doping concentrations and thicknesses of the N-type waveguide layer, the P-type waveguide layer and the first P-type sub-confinement layer all satisfy a quadratic function relationship, and the variation of the doping gas flow rate with time all satisfies a quadratic function relationship.

[0006] According to the embodiment of the present disclosure, along the epitaxial direction, the doping concentration of the semiconductor substrate layer and the N-type confinement layer is 2×10 18 cm -3 .

[0007] According to the embodiment of the present disclosure, along the epitaxial direction, the doping concentration of the second P-type sub-confinement layer and the ohmic contact layer is 10 19 cm -3 .

[0008] According to the embodiment of the present disclosure, the characteristic optical field intensity corresponding to the splitting points of the N-type waveguide layer, the P-type waveguide layer and the first P-type sub-confinement layer along the epitaxial direction is greater than 10 -7 .

[0009] According to the embodiment of the present disclosure, the characteristic optical field intensity corresponding to the division points of the semiconductor substrate layer, the N-type confinement layer, the second P-type sub-confinement layer and the ohmic contact layer along the epitaxial direction is less than 10 -7 .

[0010] According to an embodiment of the present disclosure, the active layer is undoped.

[0011] According to an embodiment of the present disclosure, the quadratic function relationship between the doping gas flow rates of the N-type waveguide layer, the P-type waveguide layer and the first P-type sub-confinement layer and time is determined by the doping concentration and growth rate of the corresponding layers.

[0012] According to an embodiment of the present disclosure, the N-type waveguide layer includes a plurality of stacked N-type sub-waveguide layers, the doping concentration and thickness of each N-type sub-waveguide layer satisfy a quadratic function relationship, and the change of the doping gas flow rate with time satisfies a quadratic function relationship.

[0013] According to an embodiment of the present disclosure, the thickness of the active layer is less than 100 nm.

[0014] A second aspect of the present disclosure provides a method for preparing a low-power loss semiconductor laser, comprising: epitaxially stacking an N-type confinement layer, an N-type waveguide layer, an active layer, a P-type waveguide layer, a P-type confinement layer and an ohmic contact layer in sequence on a semiconductor substrate layer; wherein the P-type confinement layer comprises a first P-type sub-confinement layer and a second P-type sub-confinement layer stacked, and the first P-type sub-confinement layer is close to the P-type waveguide layer; wherein during the epitaxial process, along the epitaxial direction, the doping concentrations of the semiconductor substrate layer, the N-type confinement layer, the second P-type sub-confinement layer and the ohmic contact layer remain unchanged along the thickness variation, the variation of the doping gas flow rate with time is a constant, the doping concentrations and thicknesses of the N-type waveguide layer, the P-type waveguide layer and the first P-type sub-confinement layer all satisfy a quadratic function relationship, and the variation of the doping gas flow rate with time all satisfies a quadratic function relationship.

[0015] The low power loss semiconductor laser provided by the embodiment of the present disclosure has at least the following beneficial effects:

[0016] Each layer of the semiconductor laser is divided along the epitaxial direction, and a suitable doping concentration is selected at each dividing point, so that the doping concentrations of the semiconductor substrate layer, the N-type confinement layer, the second P-type sub-confinement layer and the ohmic contact layer remain unchanged along the thickness change, the change of the doping gas flow rate with time is a constant, the doping concentration and thickness of the N-type waveguide layer, the P-type waveguide layer and the first P-type sub-confinement layer all satisfy a quadratic function relationship, and the change of the doping gas flow rate with time also satisfies a quadratic function relationship, thereby minimizing the power loss of the semiconductor laser and improving the performance of the semiconductor laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0018] Figure 1 The figure schematically shows a concept diagram for solving the optimal doping curve according to an embodiment of the present disclosure.

[0019] Figure 2 The structure of a low power loss semiconductor laser according to an embodiment of the present disclosure is schematically shown.

[0020] Figure 3 The diagram schematically shows a piecewise fitting diagram of a doping curve optimized for a low power loss target according to an embodiment of the present disclosure.

[0021] Figure 4A The optical field distribution diagram calculated according to the refractive index distribution diagram of the semiconductor laser in the epitaxial direction according to the embodiment of the present disclosure and the conventional doping curve diagram are schematically shown.

[0022] Figure 4B The optical field distribution diagram calculated based on the refractive index distribution diagram of the semiconductor laser in the epitaxial direction according to the embodiment of the present disclosure and the doping curve diagram optimized after calculation are schematically shown.

[0023] Figure 5A Schematically shows the corresponding Figure 4A The integral curve of the series resistance in the epitaxial direction calculated by conventional doping.

[0024] Figure 5B Schematically shows the corresponding Figure 4B Plot of the integral of the calculated series resistance in the epitaxial direction after doping is optimized for low power loss.

[0025] Fig. 6A Schematically shows the corresponding Figure 4A The integral curve of the internal loss in the epitaxial direction calculated by conventional doping.

[0026] Figure 6B Schematically shows the corresponding Figure 4B Integrated plot of the internal losses in the epitaxial direction calculated after optimizing doping for low power loss.

[0027] Fig. 7A Schematically shows the corresponding Figure 4A Integral curve of power loss in the epitaxial direction calculated by conventional doping.

[0028] Figure 7B Schematically shows the corresponding Figure 4BIntegral plot of power loss in the epitaxial direction calculated after doping is optimized for low power loss. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present disclosure.

[0030] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0031] In the present disclosure, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.

[0032] In the description of the present disclosure, it is necessary to understand that the terms "longitudinal", "length", "circumferential", "front", "rear", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the subsystem or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present disclosure.

[0033] Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or configurations will be omitted when they may cause confusion in the understanding of the present disclosure. The shapes, sizes, and positional relationships of the components in the drawings do not reflect the actual size, proportion, and actual positional relationship. In addition, in the present disclosure, any reference symbol between brackets should not be constructed as a limitation to the present disclosure.

[0034] Similarly, in order to simplify the present disclosure and help understand one or more of the various disclosed aspects, in the above description of the exemplary embodiments of the present disclosure, the various features of the present disclosure are sometimes grouped together into a single embodiment, figure, or description thereof. The description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0035] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the feature. In the description of the present disclosure, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0036] In order to solve the problems of the prior art, the embodiments of the present disclosure further analyze and study the relevant parameters of the semiconductor laser, as follows.

[0037] The series resistance of a semiconductor laser can be expressed as:

[0038]

[0039] Wherein, h is the total thickness of the epitaxial layer of the semiconductor laser, q is the electron charge, μ(y) is the majority carrier mobility of each layer in the epitaxial direction, dop(y) is the doping concentration of each layer in the epitaxial direction (the default doping concentration is the carrier concentration), W is the stripe width of the semiconductor laser, and L is the cavity length of the semiconductor laser.

[0040] The carrier mobility of a semiconductor laser can be expressed as:

[0041]

[0042] From this we can see that the carrier mobility is related to the doping concentration. The higher the doping concentration, the lower the mobility.

[0043] The internal loss of a semiconductor laser can be expressed as:

[0044]

[0045] Among them, I j(y) is the light field intensity in the epitaxial direction, and σ(y) is the absorption cross-section coefficient of carriers in each layer in the epitaxial direction.

[0046] Absorption cross section coefficient of carrier:

[0047]

[0048] It can be seen that the carrier absorption cross-section coefficient is related to mobility, and mobility is related to doping concentration. The higher the doping concentration, the lower the carrier mobility and the higher the absorption cross-section coefficient.

[0049] The power loss of semiconductor lasers mainly consists of two parts: Joule heat loss caused by series resistance and loss caused by carrier absorption:

[0050] P loss =I 2 R s +P0Lα i

[0051] Among them, I is the operating current of the semiconductor laser, P0 is the average power in the laser cavity, and L is the cavity length of the semiconductor laser (without considering the change of internal loss with current).

[0052] It can be seen from the above formula that the doping concentration will affect the carrier mobility, absorption cross-section coefficient, series resistance and internal loss, and thus affect the power loss of the semiconductor laser, so it is particularly important to choose the appropriate doping concentration.

[0053] Since the total power loss P is directly solved loss It is difficult to reach the minimum doping concentration dop(y) distribution function, but after the thickness is divided in the epitaxial direction, the total power loss is equal to the sum of the power loss at each division point, which can be expressed as:

[0054] P loss =∑p loss (j) = ∑I 2 r s (j)+P0Lα i (j)

[0055] P loss It is a monotonically increasing function of the epitaxial thickness. The total power loss P loss The minimum value of each split point is the minimum power loss p loss (j) add the sum. Therefore, the total power loss P can be directly solved loss Transformed into solving the power loss p at each segmentation point loss (j) The minimum doping concentration simplifies the solution process, and the total power loss P of the semiconductor laser device can be accurately solved. lossThe minimum corresponding doping concentration.

[0056] In order to better explain the solution of semiconductor laser doping concentration, combined with Figure 1 The schematic diagram better illustrates the idea in detail.

[0057] Figure 1 A graph schematically illustrates a solution for optimal doping of a semiconductor laser for a low power loss target according to an embodiment of the present disclosure.

[0058] like Figure 1 As shown, the horizontal axis is the thickness in the epitaxial direction, and the vertical axis is the power loss at each split point. The left figure shows the power loss curves corresponding to the two doping methods. The curve is x=0, x=h, and the area enclosed by the horizontal axis is the total power loss. When 0≤x≤m, the power loss caused by each point of the doping method dop2 is smaller than that of the doping method dop1. When m<x≤h, the power loss caused by each point of the doping method dop1 is smaller than that of the doping method dop2. In order to minimize the total power loss, that is, the enclosed area is minimized, the doping method dop2 can be used when 0≤x≤m, and the doping method dop1 can be used when m<x≤h. The optimized doping curve is shown in the right figure. Therefore, it can be compared that when there are multiple doping methods, in order to minimize the total power loss, it is only necessary to find the doping concentration with the minimum power loss at each split point. The combined doping concentration is the optimal doping curve.

[0059] When the material and thickness of each layer in the epitaxial direction of the semiconductor laser are determined, the optical field (Ij(y)) in the epitaxial direction is basically determined. The optical field distribution is not affected too much by the doping concentration.

[0060] Therefore, based on the above analysis, the embodiment of the present disclosure divides the epitaxial thickness into preset thicknesses, calculates the doping concentration that minimizes the power loss at the dividing point, and performs doping at the doping concentration to obtain a semiconductor laser with low total power loss. The low-loss semiconductor laser is introduced below.

[0061] Figure 2 The structure of a low power loss semiconductor laser according to an embodiment of the present disclosure is schematically shown.

[0062] like Figure 2 As shown, in this embodiment, the low power loss semiconductor laser may include, for example: a semiconductor substrate layer 100, an N-type confinement layer 200, an N-type waveguide layer 300, an active layer 400, a P-type waveguide layer 500, a P-type confinement layer 600 and an ohmic contact layer 700 stacked in sequence epitaxially on the semiconductor substrate layer 100.

[0063] The P-type confinement layer 600 may include a first P-type sub-confinement layer 601 and a second P-type sub-confinement layer 602 stacked, and the first P-type sub-confinement layer is close to the P-type waveguide layer 500. In the epitaxial direction, the doping concentrations of the semiconductor substrate layer 100, the N-type confinement layer 200, the second P-type sub-confinement layer 602 and the ohmic contact layer 700 remain unchanged along the thickness change, the change of the doping gas flow rate over time is a constant, the doping concentration and thickness of the N-type waveguide layer 300, the P-type waveguide layer 500 and the first P-type sub-confinement layer 601 all satisfy a quadratic function relationship, and the change of the doping gas flow rate over time all satisfies a quadratic function relationship.

[0064] In one embodiment of the present disclosure, the characteristic optical field intensity corresponding to the splitting points of the N-type waveguide layer 300, the P-type waveguide layer 500 and the first P-type sub-confinement layer 601 along the epitaxial direction is greater than 10 -7 The characteristic optical field intensity corresponding to the division points of the semiconductor substrate layer 100, the N-type confinement layer 200, the second P-type sub-confinement layer 602 and the ohmic contact layer 700 along the epitaxial direction is less than 10 -7 .

[0065] In one embodiment of the present disclosure, the N-type region segmentation point characteristic light field I j (y) less than 10 -7 The uniform doping concentration in the region can be 2*10 18 cm -3 For example, the doping concentration of the semiconductor substrate layer 100 and the N-type confinement layer 200 is 2×10 18 cm -3 .

[0066] In one embodiment of the present disclosure, the characteristic light field I of the P-type region segmentation point j (y) less than 10 -7 The uniform doping concentration can be 10 19 cm -3 For example, the doping concentration of the second P-type sub-confinement layer 602 and the ohmic contact layer 700 is 10 19 cm -3 .

[0067] In one embodiment of the present disclosure, the N-type region segmentation point characteristic light field I j (y) greater than 10 -7 The doping concentration of each segmentation point is 10 16 cm -3 -2*10 18 cm -3 Based on this, the doping concentration that minimizes the power loss at the split point is determined. For example, the doping concentration selected for each split point of the N-type waveguide layer 300 is 10 16 cm -3 -2*1018 cm -3 Based on this, the specific quadratic function relationship between the doping concentration and thickness of the N-type waveguide layer 300 along the epitaxial thickness direction is determined. That is, the quadratic function coefficients satisfied by the doping concentration of the N-type waveguide layer 300 are all determined by the specific values ​​of the calculated optimal doping concentration.

[0068] Furthermore, the N-type waveguide layer 300 includes a plurality of stacked N-type sub-waveguide layers, and the doping concentration and thickness of each N-type sub-waveguide layer satisfy a quadratic function relationship, and the doping gas flow rate changes with time in a quadratic function relationship. In this embodiment, the N-type waveguide layer 300 is divided into 6 sub-waveguide layers, including: a first N-type sub-waveguide layer 301, a second N-type sub-waveguide layer 302, a third N-type sub-waveguide layer 303, a fourth N-type sub-waveguide layer 304, a fifth N-type sub-waveguide layer 305, and a sixth N-type sub-waveguide layer 306. The quadratic function coefficients satisfied by the doping concentrations of each N-type sub-waveguide layer are determined by the specific values ​​of the calculated optimal doping concentrations, and the quadratic function coefficients may be the same or different, and may be determined specifically according to actual application requirements.

[0069] In one embodiment of the present disclosure, the characteristic light field I of the P-type region segmentation point j (y) greater than 10 -7 The doping concentration of each segmentation point is 10 16 cm -3 -10 19 cm -3 Based on this, the doping concentration that minimizes the power loss at the split point is determined. For example, the doping concentration selected at each split point of the P-type waveguide layer 500 and the first P-type sub-confinement layer 601 is 10 16 cm -3 -10 19 cm -3 Based on this, the specific quadratic function relationship between the doping concentration and thickness of the P-type waveguide layer 500 and the first P-type sub-confinement layer 601 along the epitaxial thickness direction is determined. That is, the quadratic function coefficients satisfied by the doping concentrations of the P-type waveguide layer 500 and the first P-type sub-confinement layer 601 are determined by the specific values ​​of the calculated optimal doping concentrations.

[0070] In the disclosed embodiment, the thickness of the active region 400 of the semiconductor laser can generally be less than 100 nm, and the overall series resistance is small. Since a large amount of carrier injection into the active region will inevitably cause a large amount of carrier absorption, in order to reduce the power loss caused by the active region, the active region is selected to be undoped.

[0071] Based on the above doping concentration method, this embodiment provides a doping method for each layer of a semiconductor laser.

[0072] Figure 3The diagram schematically shows a piecewise fitting diagram of a doping curve optimized for a low power loss target according to an embodiment of the present disclosure.

[0073] like Figure 3 As shown, the doping concentration of each layer can be specifically as follows:

[0074] The doping concentration of the semiconductor substrate layer 100 is 2*10 18 cm -3 , corresponding to the doping gas source Gas 100 The flow rate (t) changes with time to meet the Gas 100 (t) = C 100 , where C 100 Is a constant.

[0075] The doping concentration of the N-type confinement layer 200 is 2*10 18 cm -3 , corresponding to the doping gas source Gas 200 The flow rate (t) changes with time to meet the Gas 200 (t) = C 200 , where C 200 Is a constant.

[0076] The doping concentration of the first N-type sub-waveguide layer 301 is obtained by using the optimized doping function calculated by quadratic function fitting:

[0077] Dop 301 (y) = a1y 2 +b1y+c1, corresponding to the doping gas source Gas 301 The flow rate (t) changes with time to meet the Gas 301 (t) = A1t 2 +B1t+C1;

[0078] The doping concentration of the second N-type sub-waveguide layer 302 is obtained by using the optimized doping function calculated by quadratic function fitting:

[0079] Dop 302 (y) = a2y 2 +b2y+c2, corresponding to the doping gas source Gas 302 The flow rate (t) changes with time to meet the Gas 302 (t) = A2t 2 +B2t+C2;

[0080] The doping concentration of the third N-type sub-waveguide layer 303 is obtained by using the optimized doping function calculated by quadratic function fitting:

[0081] Dop 303 (y) = a3y 2 +b3y+c3, corresponding to the doping gas source Gas 303The flow rate (t) changes with time to meet the Gas 303 (t) = A3t 2 +B3t+C3;

[0082] The doping concentration of the fourth N-type sub-waveguide layer 304 is obtained by using the optimized doping function calculated by quadratic function fitting:

[0083] Dop 304 (y) = a4y 2 +b4y+c4, corresponding to the doping gas source Gas 304 The flow rate (t) changes with time to meet the Gas 304 (t) = A4y 2 +B4y+C4;

[0084] The doping concentration of the fifth N-type sub-waveguide layer 305 is obtained by using the optimized doping function calculated by quadratic function fitting:

[0085] Dop 305 (y) = a5y 2 +b5y+c5, corresponding to the doping gas source Gas 305 The flow rate (t) changes with time to meet the Gas 305 (t) = A5y 2 +B5y+C5;

[0086] The doping concentration of the sixth N-type sub-waveguide layer 306 is obtained by fitting the optimized doping function calculated by a quadratic function:

[0087] Dop 306 (y) = a6y 2 +b6y+c6, corresponding to the doping gas source Gas 306 The flow rate (t) changes with time to meet the Gas 306 (t) = A6y 2 +B6y+C6.

[0088] The active layer 400 is not doped.

[0089] The doping concentration of the P-type waveguide layer 500 is obtained by using the optimized doping function calculated by quadratic function fitting:

[0090] Dop 500 (y) = a7y 2 +b7y+c7, corresponding to the doping gas source Gas 500 The flow rate (t) changes with time to meet the Gas 500 (t) = A7y 2 +B7y+C7.

[0091] The doping concentration of the first P-type sub-confinement layer 601 is obtained by using the optimized doping function calculated by quadratic function fitting:

[0092] Dop 601 (y) = a8y 2 +b8y+c8, corresponding to the doping gas source Gas 601 The flow rate (t) changes with time to meet the requirements of GaS 601 (t) = A8y 2 +B8y+C8.

[0093] The doping concentration of the second P-type sub-confinement layer 602 is 10 19 cm -3 , corresponding to the doping gas source Gas 602 The flow rate (t) changes with time to meet the Gas 602 (t) = C 602 .

[0094] The doping concentration of the ohmic contact layer 700 is 10 19 cm -3 , corresponding to the doping gas source Gas 700 The flow rate (t) changes with time to meet the Gas 700 (t) = C 700 .

[0095] Based on the unified inventive concept, the embodiment of the present disclosure further provides a method for preparing a low power loss semiconductor laser, which may include, for example:

[0096] An N-type confinement layer 200, an N-type waveguide layer 300, an active layer 400, a P-type waveguide layer 500, a P-type confinement layer 600 and an ohmic contact layer 700 are sequentially epitaxially stacked on a semiconductor substrate layer 100. The P-type confinement layer 600 includes a first P-type sub-confinement layer 601 and a second P-type sub-confinement layer 602 stacked, and the first P-type sub-confinement layer is close to the P-type waveguide layer 500.

[0097] During the epitaxial growth process, along the epitaxial growth direction, the doping concentrations of the semiconductor substrate layer 100, the N-type confinement layer 200, the second P-type sub-confinement layer 602 and the ohmic contact layer 700 remain unchanged along the thickness variation, the change of the doping gas flow rate over time is a constant, the doping concentration and thickness of the N-type waveguide layer 300, the P-type waveguide layer 500 and the first P-type sub-confinement layer 601 all satisfy a quadratic function relationship, and the change of the doping gas flow rate over time all satisfies a quadratic function relationship.

[0098] It should be noted that the details not covered in the method embodiment section are similar or identical to those in the device embodiment section. Please refer to the device embodiment section for details and will not be repeated here.

[0099] In order to further verify that the low power consumption of the low power semiconductor laser device provided by the embodiment of the present disclosure is low, the embodiment of the present disclosure also provides some experimental data to prove it.

[0100] Figure 4A The optical field distribution diagram calculated according to the refractive index distribution diagram of the semiconductor laser in the epitaxial direction according to the embodiment of the present disclosure and the conventional doping curve diagram are schematically shown.

[0101] Figure 4B The optical field distribution diagram calculated based on the refractive index distribution diagram of the semiconductor laser in the epitaxial direction according to the embodiment of the present disclosure and the doping curve diagram optimized after calculation are schematically shown.

[0102] Figure 5A Schematically shows the corresponding Figure 4A The integral curve of the series resistance in the epitaxial direction calculated by conventional doping.

[0103] Figure 5B Schematically shows the corresponding Figure 4B Plot of the integral of the calculated series resistance in the epitaxial direction after doping is optimized for low power loss.

[0104] like Figure 4A-Figure 5B As shown, based on conventional doping, the total resistance of the semiconductor laser is 15.98 mΩ. With the optimized doping method, the total resistance of the semiconductor laser is 6.35 mΩ. After doping optimization, the series resistance of the semiconductor laser is reduced by 9.63 mΩ.

[0105] Fig. 6A Schematically shows the corresponding Figure 4A The integral curve of the internal loss in the epitaxial direction calculated by conventional doping.

[0106] Figure 6B Schematically shows the corresponding Figure 4B Integrated plot of the internal losses in the epitaxial direction calculated after optimizing doping for low power loss.

[0107] like Figure 6A-6B As shown, based on conventional doping, the total internal loss of the semiconductor laser is 0.39 cm -1 With the optimized doping method, the total internal loss of the semiconductor laser is 0.57cm -1 After doping optimization, the internal loss of the semiconductor laser increased by 0.18 cm -1 .

[0108] Fig. 7A Schematically shows the corresponding Figure 4A Integral curve of power loss in the epitaxial direction calculated by conventional doping.

[0109] Figure 7BSchematically shows the corresponding Figure 4B Integral plot of power loss in the epitaxial direction calculated after doping is optimized for low power loss.

[0110] like Figure 7A-7B As shown, based on conventional doping, the total power loss of the semiconductor laser is 7.95W. With the optimized doping method, the total power loss of the semiconductor laser is 4.82W. After doping optimization, the total power loss of the semiconductor laser is reduced by 3.13W.

[0111] The electro-optical conversion efficiency of semiconductor lasers:

[0112]

[0113] Among them, η i is the internal quantum efficiency, α m is the cavity surface loss, U0 is the turn-on voltage, I th is the threshold current. Substituting various parameters of the semiconductor structure of the embodiment of the present disclosure into the above formula, when using Figure 4A When the conventional doping curve is used, it is calculated that the electro-optical conversion efficiency of the semiconductor laser is 67% at a current of 20A; Figure 4B When the corresponding optimized doping curve is used, it is calculated that the electro-optical conversion efficiency of the semiconductor laser is 73% at a current of 20 A. After doping optimization, the electro-optical conversion efficiency of the semiconductor laser increases by 6%.

[0114] In summary, in the low-power semiconductor laser device provided by the embodiment of the present disclosure, each layer of the semiconductor laser is divided along the epitaxial direction, and a suitable doping concentration is selected at each dividing point, so that the doping concentrations of the semiconductor substrate layer, the N-type confinement layer, the second P-type sub-confinement layer and the ohmic contact layer remain unchanged along the thickness change, the change of the doping gas flow rate with time is a constant, the doping concentration and thickness of the N-type waveguide layer, the P-type waveguide layer and the first P-type sub-confinement layer all satisfy a quadratic function relationship, and the change of the doping gas flow rate with time all satisfies a quadratic function relationship, thereby minimizing the power loss of the semiconductor laser and improving the performance of the semiconductor laser.

[0115] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above description is only a specific embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A low power loss semiconductor laser, characterized in that: include: A semiconductor substrate layer (100), and an N-type confinement layer (200), an N-type waveguide layer (300), an active layer (400), a P-type waveguide layer (500), a P-type confinement layer (600), and an ohmic contact layer (700) sequentially stacked and epitaxially arranged on the semiconductor substrate layer (100); the P-type confinement layer (600) comprises a first P-type sub-confinement layer (601) and a second P-type sub-confinement layer (602) stacked, and the first P-type sub-confinement layer (601) is close to the P-type waveguide layer (500); Wherein, along the epitaxial direction, the doping concentrations of the semiconductor substrate layer (100), the N-type confinement layer (200), the second P-type sub-confinement layer (602) and the ohmic contact layer (700) remain unchanged along the thickness variation, the variation of the doping gas flow rate with time is a constant, the doping concentration and thickness of the N-type waveguide layer (300), the P-type waveguide layer (500) and the first P-type sub-confinement layer (601) all satisfy a quadratic function relationship, and the variation of the doping gas flow rate with time all satisfies a quadratic function relationship.

2. The low power loss semiconductor laser according to claim 1, characterized in that: Along the epitaxial direction, the doping concentration of the semiconductor substrate layer (100) and the N-type confinement layer (200) is 2×10 18 cm -3 .

3. The low power loss semiconductor laser according to claim 1, characterized in that: Along the epitaxial direction, the doping concentration of the second P-type sub-confinement layer (602) and the ohmic contact layer (700) is 10 19 cm -3 .

4. The low power loss semiconductor laser according to claim 1, characterized in that: The characteristic optical field intensity corresponding to the splitting points of the N-type waveguide layer (300), the P-type waveguide layer (500) and the first P-type sub-limiting layer (601) along the epitaxial direction is greater than 10 -7 .

5. The low power loss semiconductor laser according to claim 1, characterized in that: The characteristic optical field intensity corresponding to the splitting points of the semiconductor substrate layer (100), the N-type confinement layer (200), the second P-type sub-confinement layer (602) and the ohmic contact layer (700) along the epitaxial direction is less than 10 -7 .

6. The low power loss semiconductor laser according to claim 1, characterized in that: The active layer (400) is undoped.

7. The low power loss semiconductor laser according to claim 1, characterized in that: The quadratic function relationship between the change in the doping gas flow rate of the N-type waveguide layer (300), the P-type waveguide layer (500) and the first P-type sub-confinement layer (601) over time is determined by the doping concentration and growth rate of the corresponding layers.

8. The low power loss semiconductor laser according to claim 1, characterized in that: The N-type waveguide layer (300) comprises a plurality of stacked N-type sub-waveguide layers, the doping concentration and thickness of each N-type sub-waveguide layer satisfy a quadratic function relationship, and the change of the doping gas flow rate with time satisfies a quadratic function relationship.

9. The low power loss semiconductor laser according to claim 1, characterized in that: The thickness of the active layer (400) is less than 100 nm.

10. A method for preparing a low power loss semiconductor laser, characterized in that: include: An N-type confinement layer (200), an N-type waveguide layer (300), an active layer (400), a P-type waveguide layer (500), a P-type confinement layer (600) and an ohmic contact layer (700) are sequentially epitaxially stacked on a semiconductor substrate layer (100); wherein the P-type confinement layer (600) comprises a first P-type sub-confinement layer (601) and a second P-type sub-confinement layer (602) stacked, and the first P-type sub-confinement layer (601) is close to the P-type waveguide layer (500); During the epitaxial growth process, along the epitaxial growth direction, the doping concentrations of the semiconductor substrate layer (100), the N-type confinement layer (200), the second P-type sub-confinement layer (602) and the ohmic contact layer (700) remain unchanged along the thickness variation, the variation of the doping gas flow rate over time is a constant, the doping concentration and thickness of the N-type waveguide layer (300), the P-type waveguide layer (500) and the first P-type sub-confinement layer (601) all satisfy a quadratic function relationship, and the variation of the doping gas flow rate over time all satisfies a quadratic function relationship.

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