Distributed Bragg reflection laser and control method

Abstract

The embodiment of the invention provides a distributed Bragg reflection (DBR) laser and a control method, relates to the technical field of semiconductor lasers, and aims to solve the problem of high processing difficulty caused by improvement of modulation bandwidth of the DBR laser in the related technology. The DBR laser comprises a substrate, an active part and a grating part, and the grating part is coupled to one end of the active part in the light propagation direction and comprises a waveguide layer, a first electrode, a second electrode and a third electrode; the waveguide layer is arranged on one side of the substrate and provided with Bragg gratings arranged in the light propagation direction. The first electrode, the second electrode and the third electrode are arranged on the side, away from the substrate, of the Bragg grating and are arranged at intervals in the light propagation direction. And the first electrode, the second electrode and the third electrode are used for respectively controlling the effective refractive index of the Bragg grating below based on an input electrode signal. The DBR laser can be applied to the fields of optical communication, optical storage and the like.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor lasers, and in particular to a distributed Bragg reflection laser and a control method thereof. Background Art

[0002] Distributed Bragg Reflector (DBR) laser (DRB laser for short) is a type of directly modulated laser (DML) and can be used in the field of optical communications to convert electrical signals into optical signals.

[0003] With the development of optical communication technology, the requirements for modulation bandwidth are getting higher and higher; however, the modulation bandwidth of traditional DBR lasers is difficult to meet the requirements of large modulation bandwidth in current optical communication scenarios. Based on this, some DBR lasers in related technologies increase the modulation bandwidth by utilizing the PPR (photon-photon resonance) effect, but such products have the problem of high processing difficulty. Summary of the invention

[0004] The embodiments of the present application provide a distributed Bragg reflector laser and a control method, which are used to improve the problem in the related art that DBR lasers are difficult to process in order to increase the modulation bandwidth.

[0005] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions:

[0006] In a first aspect, an embodiment of the present application provides a distributed Bragg reflector laser, which includes a substrate and an active part and a grating part arranged on the substrate, and the active part and the grating part are arranged on the substrate along a light propagation direction.

[0007] The grating part is coupled to one end of the active part in the light propagation direction, and the grating part includes a waveguide layer, a first electrode, a second electrode and a third electrode; wherein the waveguide layer is arranged on one side of the substrate and is provided with a Bragg grating arranged along the light propagation direction.

[0008] The first electrode, the second electrode and the third electrode are all arranged on the side of the Bragg grating away from the substrate and are arranged at intervals along the light propagation direction; the first electrode, the second electrode and the third electrode are used to control the effective refractive index of the Bragg grating below based on the input electrode signal.

[0009] By using a distributed Bragg reflector laser having the above structure, the effective refractive index of different parts of the Bragg grating can be controlled by loading electrode signals to the first electrode, the second electrode and the third electrode, so that an equivalent phase shift can be generated in the middle position of the Bragg grating, so that the Bragg grating can generate a grating reflection spectrum with a depression, which is beneficial to using the PPR effect and the detuned loading effect to improve the modulation bandwidth; and, there is no need to separately make a structure for generating a phase shift in the Bragg grating, which is beneficial to reducing the processing difficulty of the Bragg grating, thereby improving the processing efficiency and reducing the production cost. In addition, the grating reflection spectrum of the Bragg grating can be adjusted by controlling and changing the equivalent phase shift, which is beneficial to the control of the DBR laser.

[0010] In some embodiments, the Bragg grating is a uniform Bragg grating arranged along the light propagation direction. Such a design is conducive to the processing of the Bragg grating, thereby reducing the processing difficulty of the Bragg grating, improving the processing efficiency and reducing the production cost. In addition, the uniform Bragg grating can reduce the control difficulty of adjusting the grating reflection spectrum, thereby facilitating the formation of a suitable grating reflection spectrum.

[0011] In some embodiments, the product of the length of the Bragg grating in the light propagation direction and the grating coupling coefficient is between 0.5 and 2. With such a design, on the one hand, by controlling the light loss of the Bragg grating, it is beneficial to improve the transmission performance of the Bragg grating, thereby improving the light extraction efficiency of the DBR laser. On the other hand, by controlling the relationship between the grating coupling coefficient of the Bragg grating and the length in the light propagation direction, it is beneficial to form a grating reflection spectrum that meets the working requirements. On the other hand, by controlling the grating coupling coefficient of the Bragg grating, the PPR frequency can be adjusted, which is beneficial to improve the modulation bandwidth of the DBR laser.

[0012] In some embodiments, in the direction of light propagation, the length of the active part is 50 microns to 150 microns; the length of the Bragg grating is equal to the length of the grating part, and the length of the grating part is 300 microns to 1000 microns. Such a design is conducive to the control of the longitudinal mode of the DBR laser in the cavity, so that the DBR laser can generate a longitudinal mode that meets the working requirements. In addition, it is conducive to the generation of the PPR effect, so that the DBR laser can use the PPR effect to increase the modulation bandwidth.

[0013] In some embodiments, in the light propagation direction, the length of the active part is 90 microns, the length of the grating part is 450 microns, and the coupling coefficient of the Bragg grating is 30 per centimeter. With such a design, the DBR laser can achieve a PPR frequency of about 55 GHz, which is beneficial to the improvement of the modulation bandwidth.

[0014] In some embodiments, the first electrode, the second electrode, and the third electrode are all electrically heated electrodes for adjusting the effective refractive index of the Bragg grating by thermal tuning; or, the first electrode, the second electrode, and the third electrode are all metal electrodes for adjusting the effective refractive index of the Bragg grating by carrier injection; or, some of the first electrode, the second electrode, and the third electrode are electrically heated electrodes and some are metal electrodes. In the DBR laser provided in the embodiment of the present application, the effective refractive index of different parts of the Bragg grating can be controlled by thermal tuning, carrier injection tuning, or a combination of the two, which can be applied to different application scenarios and has good adaptability.

[0015] In some embodiments, in the light propagation direction, the lengths of the first electrode and the third electrode are equal and both are greater than the length of the second electrode. Alternatively, in the light propagation direction, the length of the first electrode is greater than the length of the third electrode, and the difference is less than or equal to 30% of the length of the first electrode; the length of the first electrode and the length of the third electrode are both greater than the length of the second electrode. With such a design, when the grating reflection spectrum is controlled by the first electrode, the second electrode and the third electrode, it is beneficial to form a suitable grating reflection spectrum, thereby facilitating the improvement of the modulation bandwidth.

[0016] In some embodiments, in the light propagation direction, the length of the second electrode is 10 micrometers to 100 micrometers. Such a design is conducive to reducing the size of the DBR laser on the basis of being able to form a suitable grating reflection spectrum.

[0017] In some embodiments, the first electrode, the second electrode and the third electrode have the same shape. Such a design is conducive to reducing the difficulty of processing the first electrode, the second electrode and the third electrode, and facilitates the processing and manufacturing of the first electrode, the second electrode and the third electrode.

[0018] In some embodiments, the end face of the active part away from the grating part in the light propagation direction is a light output end face; the light output end face is a natural cleavage surface, or is coated with a first anti-reflection film. In the DBR laser provided in the embodiment of the present application, by providing the first anti-reflection film, the output power of the DBR laser can be improved.

[0019] In some embodiments, the end face of the active part away from the grating part in the light propagation direction is the light output end face, and the end face of the grating part away from the active part in the light propagation direction is provided with a second anti-reflection film, and the reflectivity of the second anti-reflection film is less than 1%.

[0020] In the DBR laser provided in the embodiment of the present application, by providing the second anti-reflection film, it is possible to avoid the random phase of the end face reflection from causing the grating reflection spectrum of the grating part to deteriorate.

[0021] In some embodiments, the active part includes an active layer disposed on one side of the substrate, the active layer is made of a multi-quantum well material, and the multi-quantum well material includes indium gallium aluminum arsenide or indium gallium arsenic phosphide. The embodiment of the present application can be applied to active layers formed of different materials and has good adaptability.

[0022] In a second aspect, an embodiment of the present application provides a control method, which is applied to the distributed Bragg reflector laser described in the embodiment of the first aspect; the control method includes:

[0023] Obtain target modulation bandwidth;

[0024] Based on the target modulation bandwidth, a first electrode signal, a second electrode signal, and a third electrode signal are input to the first electrode, the second electrode, and the third electrode, respectively.

[0025] Among them, the current density of the first electrode signal is the first current density; the current density of the second electrode signal is the second current density; the current density of the third electrode signal is the third current density; and the first current density and the third current density are both smaller than the second current density.

[0026] By adopting the above control method, an equivalent phase shift can be generated at the middle position of the Bragg grating, so that the Bragg grating can produce a grating reflection spectrum with a depression, which is beneficial to utilizing the PPR effect and the detuned loading effect to improve the modulation bandwidth; and, by controlling and changing the equivalent phase shift amount, the grating reflection spectrum of the Bragg grating can be adjusted, which is beneficial to the control of the DBR laser.

[0027] In some embodiments, the first electrode and the third electrode have the same structure, and the first electrode signal and the third electrode signal have the same current magnitude.

[0028] The ratio of the second current density to the first current density and the ratio of the second current density to the third current density are both between 1 and 1.1.

[0029] By adopting the control method provided in the embodiment of the present application, a grating reflection spectrum with a depression can be obtained, and the strength of the PPR effect can be adjusted by changing the current magnitude, which is conducive to adapting to different application scenarios and also conducive to improving the modulation bandwidth.

[0030] In some embodiments, the first current density is greater than the third current density, and the first current density and the third current density are both less than the second current density. By adopting the control method provided in the embodiment of the present application, a grating reflection spectrum with a depression can be obtained, and the depth of the depression in the grating reflection spectrum can be changed by adjusting the relationship between the first current density, the second current density and the third current density. By adjusting the depression depth in the grating reflection spectrum, it can be used to compensate for the influence of different grating waveguide loss coefficients on optical feedback.

[0031] In some embodiments, the first electrode and the third electrode have the same structure, and the first electrode signal is greater than the third electrode signal. Such a design is conducive to reducing the difficulty of controlling the adjustment of the grating reflection spectrum.

[0032] In a third aspect, an embodiment of the present application provides an optical module, which includes a distributed Bragg reflector laser as described in any one of the embodiments of the first aspect, and a driving circuit electrically connected to the distributed Bragg reflector laser, wherein the driving circuit is configured to output an electrode signal that controls the operation of the distributed Bragg reflector laser.

[0033] The technical effect that can be achieved by the optical module provided in the embodiment of the present application is the same as the technical effect that can be achieved by the DBR laser in any of the above embodiments, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic diagram of the structure of a DBR laser provided in an embodiment of the present application;

[0035] Figure 2 A schematic diagram of a grating reflection spectrum and an optical power spectrum in a DBR laser provided in an embodiment of the present application;

[0036] Figure 3 A relationship diagram of control current in a DBR laser provided in an embodiment of the present application;

[0037] Figure 4 A relationship diagram of control current, modulation frequency and signal response intensity in a DBR laser provided in an embodiment of the present application;

[0038] Figure 5 A graph showing the relationship between the small signal response intensity and the modulation frequency in a DBR laser provided in an embodiment of the present application;

[0039] Figure 6 A graph showing the relationship between the grating waveguide loss coefficient and the grating reflection spectrum in a DBR laser provided in an embodiment of the present application;

[0040] Figure 7 A graph showing the relationship between the grating waveguide loss coefficient and the small signal response intensity in a DBR laser provided in an embodiment of the present application;

[0041] Figure 8 A flow chart of a control method provided in an embodiment of the present application;

[0042] Fig. 9 A schematic diagram of the structure of an optical module provided in an embodiment of the present application. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0044] In the following, in the embodiments of the present application, the terms "first", "second", etc. are only used for convenience of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, "plurality" means two or more.

[0045] In the embodiments of the present application, "up", "down", "left" and "right" are not limited to being defined relative to the orientation of the components schematically placed in the drawings. It should be understood that these directional terms may be relative concepts. They are used for relative description and clarification, and may change accordingly according to changes in the orientation of the components placed in the drawings.

[0046] In the embodiments of the present application, unless the context requires otherwise, throughout the specification and claims, the term "including" is interpreted as an open, inclusive meaning, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "exemplarily" or "some examples" and the like are intended to indicate that specific features, structures, materials or characteristics associated with the embodiment or example are included in at least one embodiment or example of the present application. The schematic representation of the above terms does not necessarily refer to the same embodiment or example. In addition, the specific features, structures, materials or characteristics described may be included in any one or more embodiments or examples in any appropriate manner.

[0047] As used herein, "about," "substantially," or "approximately" includes the stated value and an average value that is within an acceptable range of variation from the particular value as determined by one of ordinary skill in the art taking into account the measurements in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system).

[0048] As used herein, "parallel", "perpendicular", and "equal" include the situations described and situations similar to the situations described, and the range of the similar situations is within the acceptable deviation range, wherein the acceptable deviation range is determined by a person of ordinary skill in the art taking into account the measurement in question and the errors associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, "parallel" includes absolute parallelism and approximate parallelism, wherein the acceptable deviation range of approximate parallelism may be, for example, a deviation within 5°; "perpendicular" includes absolute perpendicularity and approximate perpendicularity, wherein the acceptable deviation range of approximate perpendicularity may also be, for example, a deviation within 5°. "Equal" includes absolute equality and approximate equality, wherein the acceptable deviation range of approximate equality may be, for example, the difference between the two equalities is less than or equal to 5% of either one.

[0049] It will be understood that when a layer or an element is referred to as being on another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may be present between the layer or element and the other layer or substrate.

[0050] In the embodiments of the present application, exemplary embodiments are described with reference to cross-sectional views and / or plan views and / or equivalent circuit diagrams as idealized exemplary drawings. In the drawings, the thickness of the layers and regions is magnified for clarity. Therefore, it is conceivable that the shape changes relative to the drawings are caused by, for example, manufacturing technology and / or tolerances. Therefore, the exemplary embodiments should not be interpreted as being limited to the shapes of the regions shown herein, but include shape deviations caused by, for example, manufacturing. For example, an etched region shown as a rectangle will generally have curved features. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to illustrate the actual shapes of the regions of the device, and are not intended to limit the scope of the exemplary embodiments.

[0051] Figure 1 A schematic diagram of the structure of a distributed Bragg reflector laser provided in an embodiment of the present application is shown in FIG. Figure 1 As shown, the distributed Bragg reflector (abbreviated as DBR) laser (hereinafter referred to as DBR laser) 1 includes a substrate 100 and an active part 110 and a grating part 120 arranged on the substrate 100, and the active part 110 and the grating part 120 are arranged on the substrate 100 along the light propagation direction X. It should be noted that the light propagation direction X here refers to the propagation direction of light in the DBR laser 1, and the light can oscillate during the propagation process along the light propagation direction X in the DBR laser 1; and the output light generated by the DBR laser 1 is emitted from the DBR laser 1 along the light propagation direction X.

[0052] Please continue to refer to Figure 1The active part 110 of the DBR laser 1 includes an active layer 114, a first cladding layer 113 and an active region electrode 112; the active layer 114 is arranged on one side of the substrate 100, the first cladding layer 113 is arranged on the side of the active layer 114 away from the substrate 100, and the active region electrode 112 is arranged on the side of the first cladding layer 113 away from the substrate 100.

[0053] The active layer 114 can be made of a multiple quantum well (MQW) material to provide gain for the DBR laser 1; the multiple quantum well material for making the active layer 114 can be a quaternary material such as indium gallium aluminum arsenide (InGaAlAs) or indium gallium arsenide phosphide (InGaAsP). In this embodiment, the active layer 114 is made of indium gallium aluminum arsenide, which has good high-temperature characteristics when used to make the active layer 114, and is conducive to the active layer 114 having good performance under high-temperature conditions.

[0054] The active region electrode 112 is used to receive the current signal and realize the current injection into the active part 110. The active region electrode 112 can be a metal electrode of square, circular or other shapes. When the DBR laser 1 is working, applying a bias current to the active region electrode 112 can make the active part 110 of the DBR laser 1 produce a population inversion effect, thereby generating gain; when the gain is sufficient to overcome the loss in the cavity and the output light, the light beam will generate gain when it goes back and forth in the cavity of the DBR laser 1, and the DBR laser 1 can generate output light. In addition, the modulation signal can also be loaded on the active region electrode 112, so that the DBR laser 1 reflects the signal to be transmitted through the change in the output power; for example, when a high level is applied, the output power of the DBR laser 1 is higher, which is expressed as a "1" signal; conversely, when a low level is applied, the output power of the DBR laser 1 is lower, which is expressed as a "0" signal.

[0055] It can be seen from this that in the DBR laser 1 provided in the embodiment of the present application, a bias current and a modulation signal 111 can be loaded to the active region electrode 112 to control the DBR laser 1 to lasing and emit an optical signal.

[0056] The active portion 110 includes a first end surface and a second end surface opposite to each other along the light propagation direction X, and the grating portion 120 is coupled to the first end surface or the second end surface of the active portion 110. Figure 1 Taking the shown orientation as an example, the first end surface is the left end surface of the active part 110, the second end surface is the right end surface of the active part 110, and the grating part 120 is located on the right side of the active part 110 and coupled to the second end surface.

[0057] In this embodiment, the output light generated by the DBR laser 1 is emitted from the first end face of the active part 110, and the first end face of the active part 110 is the light output end face of the DBR laser 1. The first end face in the active part 110 is a natural cleavage surface, and the natural cleavage surface may have a certain reflectivity. For example, the natural cleavage surface has a reflectivity of about 0.32; such a design can improve the output power of the DBR laser 1. It has a reflectivity of about 0.32.

[0058] In some embodiments, the active part 110 is coated with a first anti-reflection (AR) film 140 on the first end face, and the first anti-reflection film 140 is provided to improve the output power of the DBR laser 1. The grating part 120 is coated with a second anti-reflection film 130 on the end face away from the active part 110, and the second anti-reflection film 130 has a reflectivity of 1% or less to prevent the random phase of the end face reflection from degrading the grating reflection spectrum of the grating part 120.

[0059] In other embodiments, the outgoing light generated by the DBR laser 1 is emitted from the end face of the grating part 120 away from the active part 110, that is, the end face of the grating part 120 away from the active part 110 is the light output end face.

[0060] Please continue to refer to Figure 1 In the DBR laser 1 provided in the embodiment of the present application, along the light propagation direction X, the length of the active part 110 is 50 microns to 150 microns, and the length of the grating part 120 is 300 microns to 1000 microns. Such a design is conducive to the control of the longitudinal mode of the DBR laser 1 in the cavity, so that the DBR laser 1 can generate a longitudinal mode that meets the working requirements.

[0061] The grating part 120 of the DBR laser 1 includes a waveguide layer 128, a second cladding layer 127, a first electrode 122, a second electrode 124 and a third electrode 126. The waveguide layer 128 is disposed on one side of the substrate 100, at the same height as the active layer 114, and in contact with the active layer 114 at one end close to the active layer 114. Such a design is conducive to controlling the transmission of the light beam in the active layer 114 and the waveguide layer 128, reducing the optical loss of the light beam during the propagation process, and thus is conducive to improving the light extraction efficiency of the DBR laser 1.

[0062] The waveguide layer 128 is made of a waveguide material with an adjustable effective refractive index. In this embodiment, the effective refractive index of the waveguide layer 128 can be adjusted by injecting current. When the current injected into the waveguide layer 128 changes, the carriers injected into the waveguide layer 128 will change, thereby causing the effective refractive index of the waveguide layer 128 to change.

[0063] The waveguide layer 128 is provided with a Bragg grating 129 extending along the light propagation direction X. The Bragg grating 129 is provided in a portion of the waveguide layer 128 away from the substrate 100, and includes a plurality of grating grooves arranged along the light propagation direction X. The grating grooves can be formed by etching the waveguide layer 128. The Bragg grating 129 can be a uniform Bragg grating arranged along the light propagation direction X. Here, the uniform Bragg grating means that the grating grooves in the Bragg grating are the same, and can be arranged at equal intervals along the light propagation direction X, so that the grating period is uniformly arranged in the light propagation direction X. The use of a uniform Bragg grating is conducive to reducing the difficulty of regulating the grating reflection spectrum, and is conducive to the preparation of the Bragg grating 129. In some other embodiments, the Bragg grating 129 can be a non-uniform Bragg grating arranged along the light propagation direction X. Here, the non-uniform Bragg grating means that the grating grooves in the Bragg grating are different, or the grating grooves are the same, but are arranged at non-equal intervals along the light propagation direction X; so that the grating period is non-uniformly arranged in the light propagation direction X.

[0064] The product of the grating coupling coefficient of the Bragg grating 129 and the length of the Bragg grating 129 in the light propagation direction X is between 0.5 and 2. For example, when the grating coupling coefficient is 10 per centimeter, the length of the Bragg grating 129 in the light propagation direction X can be 500 micrometers to 2000 micrometers. For another example, when the grating coupling coefficient is 20 per centimeter, the length of the Bragg grating 129 in the light propagation direction X can be 250 micrometers to 1000 micrometers.

[0065] Such a design, on the one hand, can improve the transmission performance of the Bragg grating 129 by controlling the optical loss of the Bragg grating 129, thereby improving the light extraction efficiency of the DBR laser 1 and ensuring the working performance of the DBR laser 1. On the other hand, by controlling the relationship between the grating coupling coefficient of the Bragg grating 129 and the length in the light propagation direction X, it is helpful to form a grating reflection spectrum that meets the working requirements; thereby, it is helpful to improve the working performance of the DBR laser 1.

[0066] The second cladding layer 127 is disposed on a side of the waveguide layer 128 away from the substrate 100 , and a portion of the material of the second cladding layer 127 close to the waveguide layer 128 is filled into the grating grooves of the waveguide layer 128 .

[0067] In this embodiment, in the light propagation direction X, the lengths of the grating portion 120, the waveguide layer 128, the Bragg grating 129 and the second cladding 127 are equal, that is, the waveguide layer 128, the Bragg grating 129 and the second cladding 127 extend from one end of the grating portion 120 to the other end in the light propagation direction X.

[0068] The first electrode 122, the second electrode 124 and the third electrode 126 are all arranged on a side of the second cladding 127 away from the substrate 100 and opposite to different parts of the Bragg grating 129; that is, in the orthographic projection onto the substrate 100, the first electrode 122, the second electrode 124 and the third electrode 126 overlap with different parts of the Bragg grating 129.

[0069] Please continue to refer to Figure 1 , the first electrode 122, the second electrode 124 and the third electrode 126 are arranged in sequence in the light propagation direction X, and the first electrode 122 is closer to the active area electrode 112 relative to the third electrode 126; that is, in the light propagation direction X, the first electrode 122, the second electrode 124 and the third electrode 126 are arranged in sequence in the order away from the active part 110. The first electrode 122, the second electrode 124 and the third electrode 126 are electrically isolated by the isolation groove to reduce the interference between the first electrode 122, the second electrode 124 and the third electrode 126. An isolation groove for electrical isolation can also be set between the active area electrode 112 and the first electrode 122 to reduce the interference between the active area electrode 112 and the first electrode 122.

[0070] The first electrode 122, the second electrode 124 and the third electrode 126 are used to receive electrode signals and realize current injection into the waveguide layer 128. The first electrode 122, the second electrode 124 and the third electrode 126 can all be metal electrodes in square, circular or other shapes. The materials used to make the first electrode 122, the second electrode 124 and the third electrode 126 can be the same as or different from the material of the active area electrode 112. In this embodiment, the active area electrode 112, the first electrode 122, the second electrode 124 and the third electrode 126 are made of the same material to facilitate the above electrodes to be made and formed in the same process step.

[0071] As can be seen from the above description, the effective refractive index of the waveguide layer 128 can be regulated by injecting current. When the current injected into the waveguide layer 128 changes, the carriers injected into the waveguide layer 128 will change, thereby causing the effective refractive index of the waveguide layer 128 to change. Therefore, when the first electrode 122, the second electrode 124, and the third electrode 126 receive the electrode signal and inject current into the waveguide layer 128, they can change the refractive index of the waveguide layer 128 below them, that is, change the effective refractive index of the portion of the Bragg grating 129 corresponding to the first electrode 122, the second electrode 124, and the third electrode 126, thereby achieving control of the Bragg grating 129 and changing the grating reflection spectrum of the Bragg grating 129 to generate optical feedback to the active part 110 that meets the working requirements.

[0072] In this embodiment, the first electrode 122, the second electrode 124 and the third electrode 126 are all square electrodes, and in the light propagation direction X, the lengths of the first electrode 122 and the third electrode 126 are equal, and the length of the second electrode 124 is less than the first electrode 122. Exemplarily, the lengths of the first electrode 122 and the third electrode 126 are between 80 microns and 450 microns, and the length of the third grating is between 10 microns and 100 microns. With such a design, a grating reflection spectrum that meets the working requirements can be formed by controlling the first electrode 122, the second electrode 124 and the third electrode 126, and the control difficulty of adjusting the grating reflection spectrum can be reduced.

[0073] In some other embodiments, in the light propagation direction X, the length of the first electrode 122 is greater than the length of the third electrode 126, the length difference between the two is less than or equal to 30% of the length of the first electrode 122, and the lengths of the first electrode 122 and the third electrode 126 are both greater than the length of the second electrode 124.

[0074] For the convenience of description herein, the portions of the Bragg grating 129 that are respectively opposite to the first electrode 122, the second electrode 124, and the third electrode 126 are defined as the first grating portion, the second grating portion, and the third grating portion. That is, the portion of the Bragg grating 129 covered by the orthographic projection of the first electrode 122 is the first grating portion, and the first electrode 122 can control the effective refractive index of the first grating portion; the lengths of the first electrode 122 and the first grating portion in the light propagation direction X are equal. The portion of the Bragg grating 129 covered by the orthographic projection of the second electrode 124 is the second grating portion, and the second electrode 124 can control the effective refractive index of the second grating portion; the lengths of the second electrode 124 and the second grating portion in the light propagation direction X are equal. The portion of the Bragg grating 129 covered by the orthographic projection of the third electrode 126 is the third grating portion, and the third electrode 126 can control the effective refractive index of the third grating portion. The lengths of the third electrode 126 and the third grating portion in the light propagation direction X are equal.

[0075] When the first electrode signal 121, the second electrode signal 123 and the third electrode signal 125 with the same current density are loaded to the first electrode 122, the second electrode 124 and the third electrode 126 respectively, the Bragg grating 129 can form a grating reflection spectrum with a reflection peak, and the central wavelength of the reflection peak in the grating reflection spectrum is the Bragg wavelength.

[0076] When the first electrode signal 121, the second electrode signal 123 and the third electrode signal 125 with different current densities are applied to the first electrode 122, the second electrode 124 and the third electrode 126, the shape of the grating reflection spectrum of the Bragg grating 129 will change. For example, when the first electrode signal 121 and the third electrode signal 125 with a first current density are applied to the first electrode 122 and the third electrode 126, respectively, and the second electrode signal 123 with a second current density is applied to the second electrode 124, and the first current density is less than the second current density, the second grating portion can generate an equivalent phase shift under the control of the second electrode 124, such as Figure 2 As shown, by introducing the equivalent phase shift segment, a depression 210C and two reflection peaks located on both sides of the depression are formed on the grating reflection spectrum 210 of the DBR laser 1, wherein the main reflection peak 210A with a higher maximum reflectivity is located on the short-wavelength side of the depression 210C, and the secondary reflection peak 210B with the second highest maximum reflectivity is located on the long-wavelength side of the depression 210C.

[0077] It can be seen from this that the DBR laser 1 provided in the embodiment of the present application can realize the control of the effective refractive index of different parts of the Bragg grating 129 by loading electrode signals to the first electrode 122, the second electrode 124 and the third electrode 126, so that an equivalent phase shift can be generated in the middle position of the Bragg grating 129, so that a suitable grating reflection spectrum can be realized without separately making a phase shift segment; such a design is conducive to reducing the processing difficulty of the Bragg grating 129, thereby helping to improve processing efficiency and reduce manufacturing costs. In addition, the grating reflection spectrum 210 of the Bragg grating 129 can be adjusted by controlling and changing the equivalent phase shift amount, which is conducive to the control of the DBR laser 1.

[0078] Figure 2 A schematic diagram of a grating reflection spectrum 210 of the grating portion 120 provided in an embodiment of the present application, and a schematic diagram of an optical power spectrum 220 of a DBR laser in a stable lasing state, as shown in FIG. Figure 2 As shown, in the DBR laser 1 provided in the embodiment of the present application, by changing the electrode signals of the first electrode 122, the second electrode 124 and the third electrode 126, the wavelength of the main lasing mode 211 of the DBR laser 1 can be tuned so that the main lasing mode 211 falls on the left side of the depression 210C in the grating reflection spectrum 210, that is, on the long wavelength side of the main reflection peak 210A in the grating reflection spectrum 210.

[0079] With such a design, when the active part 110 of the DBR laser 1 is modulated, the current rises, the optical power rises, and the main lasing mode 211 moves toward the short wavelength direction (blue shift) due to the frequency chirp. In this case, the Bragg grating 129 increases the reflectivity of the main lasing mode 211, which plays a positive feedback role in the increase of the optical power. Therefore, when the main lasing mode 211 is tuned to the long wavelength side of the main reflection peak 210A in the grating reflection spectrum 210, the grating part 120 can equivalently convert the frequency chirp into an increase in differential gain, thereby effectively improving the modulation bandwidth of the DBR laser 1. When the main lasing mode 211 is aligned to the long wavelength edge of the main reflection peak 210A of the grating reflection spectrum 210 in the DBR laser 1, the effect that occurs under modulation is called the detuned loading effect, which can achieve the effects of effectively enhancing the differential gain, improving the response speed, and increasing the modulation bandwidth.

[0080] Based on the above description, it can be known that the strength of the detuned loading effect is related to the slope of the grating reflection spectrum 210 of the Bragg grating 129 near the main lasing mode 211. Therefore, by tuning the wavelength of the main lasing mode 211 and changing the alignment position of the main lasing mode 211 and the grating reflection spectrum 210, the strength of the detuned loading effect can be changed, and the strength of the relaxation oscillation peak of the DBR laser 1 can be changed.

[0081] Please continue to refer to Figure 2 The DBR laser 1 using the above structure can also utilize the photon-photon resonance (PPR) effect to increase the modulation bandwidth. Specifically, by utilizing the depression of the grating reflection spectrum 210 caused by the second electrode 124 loading the electrode signal, a phase jump can be brought about, so that the grating part 120 can select the main lasing mode 211 while making another adjacent sub-mode meet the lasing phase condition, thereby forming an additional PPR mode 212.

[0082] When the active part 110 of the DBR laser 1 is modulated, the modulation sideband will broaden the spectrum near the main lasing mode 211. When the spectrum is extended to the PPR mode 212, the corresponding frequency component is resonantly amplified. This is reflected in the modulation response curve of the DBR laser 1 as an additional resonance peak at the PPR frequency, i.e., the PPR peak. The PPR frequency is equal to the frequency difference between the main lasing mode 211 and the PPR mode 212.

[0083] In the DBR laser 1 provided in the embodiment of the present application, the length of the active part 110 in the light propagation direction X, the length of the grating part 120 in the light propagation direction X, and the selection of the grating coupling coefficient affect the PPR frequency. As described above, in the DBR laser 1 provided in the present embodiment, along the light propagation direction X, the length of the active part 110 is 50 microns to 150 microns, and the length of the grating part 120 is 300 microns to 1000 microns; the product of the length of the grating part 120 and the grating coupling coefficient is between 0.5 and 2; in this case, the DBR laser 1 can have a PPR frequency of 20 GHz to 60 GHz.

[0084] Exemplarily, the length of the active portion 110 is 90 microns, the length of the grating portion 120 is 450 microns, the coupling coefficient of the Bragg grating 129 is 30 per centimeter, and the corresponding PPR frequency is about 55 GHz.

[0085] By controlling the distance between the PPR peak and the carrier-photon resonance (CPR) peak (i.e., the relaxation oscillation peak), the signal response intensity between the PPR peak and the CPR peak can be increased to meet the 3dB requirement, thereby greatly improving the modulation bandwidth of the DBR laser 1. For example, in this embodiment, the modulation bandwidth of the DBR laser 1 can be increased to 60GHz through the PPR effect, thereby meeting the requirement for a large modulation bandwidth of the DBR laser 1.

[0086] For the DBR laser 1 adopting the above structure, the embodiment of the present application provides a current control method for the first electrode 122, the second electrode 124 and the third electrode 126. In the current control method, the first electrode signal 121 and the third electrode signal 125 of the first current density are respectively loaded to the first electrode 122 and the third electrode 126. When the structures of the first electrode 122 and the third electrode 126 are the same, the current magnitudes of the first electrode signal 121 and the third electrode signal 125 are equal. The second electrode signal of the second current density is loaded to the second electrode 124, and the second current density is slightly less than the first current density. For example, the second current density is 100% to 110% of the first current density.

[0087] For example, Figure 3 A relationship diagram of the control currents of the first electrode 122, the second electrode 124 and the third electrode 126 is provided in an embodiment of the present application, wherein the relationship line 311 is used to represent the current relationship between the first electrode signal 121 and the third electrode signal 125, and the relationship line 312 is used to represent the current relationship between the first electrode signal 121 and the second electrode signal 123.

[0088] Please combine Figure 2, in DBR laser 1 using Figure 3 When the current relationship shown is tuned, the effective refractive index of the Bragg grating 129 portion below the second electrode 124 is less than the effective refractive index of the Bragg grating 129 portion below the first electrode 122 and the third electrode 126, so that a depression 210C is generated in the grating reflection spectrum 210. During the current tuning process, the position of the depression 210C in the grating reflection spectrum 210 remains unchanged, but the depth of the depression 210C and the relative strength of the reflection main peak 210A and the reflection secondary peak 210B change; the main lasing mode 211 and the PPR mode 212 move on the grating reflection spectrum 210, playing a role in tuning the strength of the photon-photon resonance effect.

[0089] Figure 4 In accordance with Figure 3 When the current is tuned in the medium current tuning mode, the small signal response diagram of DBR laser 1 is shown in Figure 4 In FIG. 3 , the light-colored portion is the area where the small signal response is greater than 3dB, and its boundary is the dotted line 321. The dark-colored portion is the area where the small signal response is less than -3dB, and its boundary is the dotted line 322. Figure 4 As shown, when the main lasing mode 211 is tuned to the long wavelength side of the main reflection peak 210A in the grating reflection spectrum 210, and the PPR mode 212 is located at the short wavelength side of the secondary reflection peak 210B in the grating reflection spectrum 210, the DBR laser 1 produces a PPR effect, so that an additional PPR resonance peak appears near 37 GHz, and the -3dB bandwidth (dashed line 322) is extended to 45 GHz; thereby, the modulation bandwidth of the DBR laser 1 can be greatly improved. Moreover, as the first electrode signal 121 increases, the response intensity for the same PPR frequency increases.

[0090] Figure 5 FIG. 1 shows a DBR laser 1 according to Figure 3 When the current is gradually increased in the middle way, the three groups of small signal response curves 331, 332, and 333, wherein the current of the first electrode signal 121 corresponding to the three groups of small signal response curves 331, 332, and 333 increases in sequence, it can be seen that according to Figure 3 When current tuning is performed in the manner shown, the strength of the PPR peak can be increased or decreased while keeping the PPR frequency unchanged. When the DBR laser 1 is used, a set of control current values ​​corresponding to a flat PPR peak, such as the small signal response curve 332, can be selected as the static operating point of the DBR laser 1 to obtain better modulation characteristics.

[0091] It can be seen from the above description that in the DBR laser 1 provided in the embodiment of the present application, the relative strength of the reflection main peak 210A and the reflection secondary peak 210B in the grating reflection spectrum 210 can be changed by changing the size of the current (second electrode signal 123) applied to the second electrode 124, so the intensity of the PPR mode 212 can be increased by enhancing the reflection secondary peak 210B, thereby achieving the effect of enhancing the photon-photon resonance effect. In addition, it can also avoid the situation in the related art that when the main lasing mode 211 is enhanced, the PPR mode 212 will be weakened accordingly. The DBR laser 1 provided in the embodiment of the present application has a larger adjustment range for the PPR mode 212 and the PPR effect intensity, and is simpler and more flexible.

[0092] For the DBR laser 1 using the above structure, the embodiment of the present application provides another current control method for the first electrode 122, the second electrode 124 and the third electrode 126, in which a first electrode signal 121 of a first current density is loaded to the first electrode 122, a second electrode signal 123 of a second current density is loaded to the second electrode 124, and a third electrode signal 125 of a third current density is loaded to the third electrode; wherein the first current density is greater than the third current density, and both the first current density and the third current density are less than the second current density. By using this current control method, compensation for the grating waveguide loss coefficient can be achieved.

[0093] During the manufacturing process of the DBR laser 1, the different roughness of the grating etched surface will lead to different loss coefficients of the grating waveguide, thereby affecting the depth of the depression in the grating reflection spectrum. Figure 6 As shown, for example, when the grating waveguide loss is equal to 20 per centimeter, the grating reflection spectrum is Figure 6 The grating reflection spectrum of 410 is compared with the grating reflection spectrum of 10 cm loss (combined with Figure 1 , Figure 1 The grating reflection spectrum 210 in FIG. 2 is the case when the grating waveguide loss is 10 per centimeter).

[0094] At this time, the depression of the grating reflection spectrum can be deepened by gradually increasing the current difference between the first electrode 122 and the third electrode 126. For example, when the first electrode 122 and the third electrode 126 adopt the same structure, the first electrode signal 121 is greater than the second electrode signal 123, and the difference is 7.6mA and 16mA respectively, and the corresponding grating reflection spectra are 420 and 430. It can be seen that the current control method can adjust the depth of the depression in the grating reflection spectrum to compensate for the influence of different grating waveguide loss coefficients on optical feedback.

[0095] For example, Figure 6 and Figure 7As shown, when the grating waveguide loss is equal to 20 per centimeter, if the currents of the first electrode 122 and the third electrode 126 are kept equal, the PPR peak and the relaxation oscillation peak merge with each other due to the excessive loss (curve 411), resulting in the degradation of the modulation bandwidth of the DBR laser 1. By increasing the current difference between the first electrode 122 and the third electrode 126, the frequency of the PPR peak can be increased to separate it from the relaxation oscillation peak, compensating for the degradation of the modulation bandwidth caused by the excessive loss coefficient of the grating waveguide. For example, when the above current difference is 7.6mA and 16mA, the corresponding Figure 7 The small signal response curves in are 421 and 431 respectively. It can be seen that by adopting the current control method provided in the embodiment of the present application, the modulation bandwidth degradation caused by different grating waveguide loss coefficients can be compensated.

[0096] The present application embodiment provides a control method, which is used to control the DBR laser 1 in the above embodiment. Figure 8 As shown, the control method 2 includes:

[0097] Step S100: Obtain target modulation bandwidth.

[0098] In step S100 , the target modulation bandwidth refers to the modulation bandwidth that the DBR laser 1 is expected to obtain. Under different working conditions, the target modulation bandwidth is usually different.

[0099] Step S200 : Based on the target modulation bandwidth, the first electrode signal 121 , the second electrode signal 123 , and the third electrode signal 125 are input to the first electrode 122 , the second electrode 124 , and the third electrode 126 , respectively.

[0100] Among them, the current density of the first electrode signal 121 is the first current density; the current density of the second electrode signal 123 is the second current density; the current density of the third electrode signal 125 is the third current density; the first current density and the third current density are both smaller than the second current density.

[0101] In some embodiments, the first electrode 122 and the third electrode 126 have the same structure; in step S200, the current magnitudes of the first electrode signal 121 and the third electrode signal 125 are the same; and the ratio of the second current density to the first current density, and the ratio of the second current density to the second current density are both between 1 and 1.1.

[0102] In some embodiments, in step S200 , the first current density is greater than the third current density, and both the first current density and the third current density are less than the second current density.

[0103] In some embodiments, in step S200 , the first electrode 122 and the third electrode 126 have the same structure, and the first electrode signal 121 is greater than the third electrode signal 125 .

[0104] The working principle and technical effects of the above control method 2 can be referred to the relevant description of the DBR laser 1 above, which will not be repeated here.

[0105] In the above-mentioned DBR laser 1 and control method 2 embodiments, the scheme is explained by taking the first electrode 122, the second electrode 124 and the third electrode 126 changing the effective refractive index of different parts in the Bragg grating 129 by carrier injection as an example, but the embodiments of the present application are not limited to this.

[0106] In some embodiments, the regulation of the effective refractive index of different parts of the Bragg grating 129 can also be achieved by thermal tuning, that is, the first electrode 122, the second electrode 124 and the third electrode 126 are all electrically heated electrodes for adjusting the effective refractive index of different parts of the Bragg grating 129 by thermal tuning. The working principle and effect of the DBR laser 1 using thermal tuning can be referred to the above description and will not be repeated here.

[0107] In other embodiments, the adjustment of the effective refractive index of different parts in the Bragg grating 129 can also be achieved by a combination of carrier injection and thermal tuning; that is, part of the first electrode 122, the second electrode 124 and the third electrode 126 are electric heating electrodes, and the other part is a metal electrode.

[0108] The DBR laser 1 and control method 2 provided in the embodiment of the present application can be applied to the fields of optical communication, optical storage, optical computing, laser radar, spectral analysis and medical treatment. For example, the embodiment of the present application also provides an optical module, which is used to convert electrical signals into optical signals. It can be an optical transmission module or an integrated optical transceiver module. Fig. 9 As shown, the optical module 3 includes the DBR laser 1 in the above embodiment, and a driving circuit 31 electrically connected to the DBR laser 1, and the driving circuit 31 is configured to output a control signal for controlling the operation of the DBR laser, and the control signal includes an electrode signal loaded on the first electrode 122, the second electrode 124 and the third electrode 126.

[0109] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A distributed Bragg reflector laser, characterized in that: The distributed Bragg reflector laser comprises a substrate and an active part and a grating part arranged on the substrate, wherein the active part and the grating part are arranged on the substrate along a light propagation direction; The grating part is coupled to one end of the active part, and the grating part includes a waveguide layer, a first electrode, a second electrode and a third electrode; Wherein, the waveguide layer is arranged on one side of the substrate and is provided with a Bragg grating arranged along the light propagation direction; The first electrode, the second electrode and the third electrode are all arranged on the side of the Bragg grating away from the substrate and are arranged at intervals along the light propagation direction; the first electrode, the second electrode and the third electrode are used to control the effective refractive index of the Bragg grating below respectively based on the input electrode signal.

2. The distributed Bragg reflector laser according to claim 1, characterized in that: The Bragg grating is a uniform Bragg grating arranged along the light propagation direction.

3. The distributed Bragg reflector laser according to claim 1 or 2, characterized in that: The product of the length of the Bragg grating in the light propagation direction and the grating coupling coefficient is between 0.5 and 2.

4. The distributed Bragg reflector laser according to any one of claims 1 to 3, characterized in that: In the light propagation direction, the length of the active part is 50 micrometers to 150 micrometers; the length of the Bragg grating is equal to the length of the grating part, and the length of the grating part is 300 micrometers to 1000 micrometers.

5. The distributed Bragg reflector laser according to claim 4, characterized in that: In the light propagation direction, the length of the active part is 90 micrometers, the length of the grating part is 450 micrometers, and the coupling coefficient of the Bragg grating is 30 per centimeter.

6. The distributed Bragg reflector laser according to any one of claims 1 to 5, characterized in that: The first electrode, the second electrode and the third electrode are all electrically heated electrodes for adjusting the effective refractive index of the Bragg grating by thermal tuning; Alternatively, the first electrode, the second electrode and the third electrode are all metal electrodes for adjusting the effective refractive index of the Bragg grating by carrier injection; Alternatively, some of the first electrode, the second electrode and the third electrode are electric heating electrodes, and some are metal electrodes.

7. The distributed Bragg reflector laser according to claim 6, characterized in that: In the light propagation direction, the lengths of the first electrode and the third electrode are equal and both are greater than the length of the second electrode; Alternatively, in the light propagation direction, the length of the first electrode is greater than the length of the third electrode, and the difference is less than or equal to 30% of the length of the first electrode; the length of the first electrode and the length of the third electrode are both greater than the length of the second electrode.

8. The distributed Bragg reflector laser according to claim 7, characterized in that: In the light propagation direction, the length of the second electrode is 10 micrometers to 100 micrometers.

9. The distributed Bragg reflector laser according to any one of claims 1 to 8, characterized in that: The first electrode, the second electrode and the third electrode have the same shape.

10. The distributed Bragg reflector laser according to any one of claims 1 to 9, characterized in that: The end face of the active part away from the grating part in the light propagation direction is a light output end face; the light output end face is a natural cleavage face, or is coated with a first anti-reflection film.

11. The distributed Bragg reflector laser according to any one of claims 1 to 10, characterized in that: The end face of the active part away from the grating part in the light propagation direction is a light output end face; the end face of the grating part away from the active part in the light propagation direction is provided with a second anti-reflection film, and the reflectivity of the second anti-reflection film is less than 1%.

12. A control method, applied to the distributed Bragg reflector laser according to any one of claims 1 to 11; It is characterized in that The control method comprises: Obtain target modulation bandwidth; Based on the target modulation bandwidth, inputting a first electrode signal, a second electrode signal and a third electrode signal to the first electrode, the second electrode and the third electrode respectively; Wherein, the current density of the first electrode signal and the current density of the third electrode signal are both smaller than the current density of the second electrode signal.

13. The control method according to claim 12, characterized in that: The first electrode and the third electrode have the same structure, and the first electrode signal and the third electrode signal have the same current magnitude; A ratio of the current density of the second electrode signal to the current density of the first electrode signal, and a ratio of the current density of the second electrode signal to the current density of the third electrode signal are both between 1 and 1.

1.

14. The control method according to claim 12, characterized in that: The current density of the first electrode signal is greater than the current density of the third electrode signal, and the current density of the first electrode signal and the current density of the third electrode signal are both less than the current density of the second electrode signal.

15. The control method according to claim 12, characterized in that: The first electrode and the third electrode have the same structure, and the first electrode signal is greater than the third electrode signal.

Images