A DR laser

Abstract

A DR laser includes a substrate (301), an active layer (302), a diffraction grating layer (303), a cladding layer (304), and an electrode (305); the active layer (302) and the diffraction grating layer (303) are stacked on top of each other and are disposed between the substrate (301) and the cladding layer (304); the electrode (305) is disposed on top of the cladding layer (304); the diffraction grating layer (303) includes a first region and a second region, wherein the thickness of the diffraction grating layer (303) is determined according to the coupling coefficient of the first region, and the grating period retention coefficient of the second region is determined according to the coupling coefficient of the second region, the grating period retention coefficient is used to indicate the ratio of the grating period retained in the second region to the grating period of the diffraction grating layer (303), and the coupling coefficient of the first region is greater than the coupling coefficient of the second region; antireflection AR films (306) are respectively coated on both ends of the laser. Flexible adjustment of the coupling coefficient can be achieved.

Description

Technical Field

[0001] Embodiments of the present application relate to the field of lasers, and in particular, to a DR laser. Background Art

[0002] Distributed Feedback (DFB) lasers have the advantages of small size, low power consumption, high electro-optical conversion efficiency, long life, wide wavelength coverage, and easy photon integration, and are widely used in optical communication systems. For DFB lasers, the light output efficiency and single-mode yield are the most concerned performance. Achieving a DFB laser with high light output efficiency and high single-mode yield has always been the pursuit of people.

[0003] In order to achieve a DFB laser with high light output efficiency and high single-mode yield, a Distributed Reflector (DR) laser scheme has been proposed. A DR laser can be equivalent to a combination of a Distributed Bragg Reflector (DBR) mirror and a DFB laser, and an anti-reflection (AR) film is coated during coating. One end is a high coupling coefficient region, and the other end is a low coupling coefficient region. The high coupling coefficient region acts as a DBR mirror with a high reflectivity, and the low coupling coefficient region is where the DFB works with a low reflectivity, acting as the laser body and the light output end.

[0004] Current DR lasers usually achieve the high coupling coefficient region by etching through the active layer to generate a grating or by using the length of the passive region to achieve the high coupling coefficient region. This results in relatively high process requirements for DR lasers and limited adjustment capabilities. Summary of the Invention

[0005] Embodiments of the present application provide a DR laser for flexibly adjusting the coupling coefficient.

[0006] A first aspect of an embodiment of the present application provides a DR laser, including: a substrate, an active layer, a diffraction grating layer, a cladding layer, and an electrode; the active layer and the diffraction grating layer are stacked on top of each other and are disposed between the substrate and the cladding layer; the electrode is disposed on the cladding layer; the diffraction grating layer includes a first region and a second region, wherein the thickness of the diffraction grating layer is determined according to the required coupling coefficient of the first region, and the grating period retention coefficient of the second region is determined according to the coupling coefficient of the second region, and the grating period retention coefficient is used to indicate the ratio of the grating period retained in the second region to the grating period of the diffraction grating layer, and the coupling coefficient of the first region is greater than the coupling coefficient of the second region; anti-reflection AR films are respectively coated on both ends of the laser.

[0007] In this embodiment, the substrate may be a semiconductor substrate. The cladding layer and the substrate may be of the same material system or different material systems, and the specific situation is not limited here.

[0008] In this embodiment, the thickness of the diffraction grating layer in the DR laser is determined according to the coupling coefficient of the first region, and the coupling coefficient of the second region is determined by the grating period retained in the second region. That is, the coupling coefficient of the first region is a fixed value, while the coupling coefficient of the second region is adjusted according to the grating period retention coefficient. Since the grating period retention coefficient is adjustable and does not affect the structure of the DR laser, flexible adjustment of the coupling coefficient can be achieved without changing the structure of the DR laser.

[0009] Optionally, the electrodes in the DR laser cover the first region and the second region. In this way, the first region and the second region are powered on simultaneously, so as to ensure that when operating with a large current, the stop bands of the first region and the second region move in the same direction, improving the anti-hop mode ability of the laser.

[0010] Optionally, the coupling coefficient of the second region can be adjusted according to the actually required coupling coefficient, mainly by using the grating period retention coefficient. In this embodiment, the grating period retention coefficient is used to indicate the ratio of the grating period retained in the second region to the grating period of the diffraction grating layer. At the same time, since all the grating periods of the diffraction grating layer are retained in the first region of the diffraction grating layer, the grating period retention coefficient can be calculated according to the following first formula, and the first formula is: Where S is the grating period retention coefficient, X is the coupling coefficient of the second region, and Y is the coupling coefficient of the first region. For example, when the coupling coefficient of the first coupling coefficient is 100 cm-1 and the coupling coefficient required for the second region is 50 cm-1, the grating period retention coefficient of the second region is one-half, that is, only 1 grating period is retained out of 2 grating periods; if the coupling coefficient required for the second region is 33.3 cm-1, the grating period retention coefficient of the second region is one-third, that is, only 1 grating period is retained out of 3 grating periods.

[0011] Optionally, the first region grating and the second region grating are adjustable, that is, the grating period of the diffraction grating layer is adjustable.

[0012] Optionally, the materials of the substrate and the cladding layer are indium phosphide InP or gallium arsenide GaAs system. That is, the DR laser can be fabricated using various materials under the InP / GaAs system, reducing the fabrication difficulty.

[0013] Optionally, since the manufacturing process of the grating layer is not limited, the positions of the active layer and the diffraction grating layer in the DR laser can be implemented in the following possible ways:

[0014] In an exemplary structure, the structures of the substrate, the active layer, the grating layer, and the cladding layer can be set as follows: the active layer is disposed on the substrate, the grating layer is disposed on the active layer, and the cladding layer is disposed on the grating layer (i.e., the overall structure is a P-type grating).

[0015] In another exemplary structure, the structures of the substrate, the active layer, the grating layer, and the cladding layer can be set as follows: the grating layer is disposed on the substrate, the active layer is disposed on the grating layer, and the cladding layer is disposed on the active layer (i.e., the overall structure is an N-type grating). By not limiting the positions of the active layer and the diffraction grating layer in this way, the processing limitations of the DR laser can be reduced.

[0016] In a second aspect, an embodiment of the present application provides a diffraction grating. The diffraction grating includes a first region and a second region. The thickness of the diffraction grating layer is determined according to the required coupling coefficient of the first region, and the grating period retention coefficient of the second region is determined according to the coupling coefficient of the second region. The coupling coefficient of the first region is greater than the coupling coefficient of the second region.

[0017] In this embodiment, the thickness of the diffraction grating layer is determined according to the coupling coefficient of the first region, and the coupling coefficient of the second region is determined by the grating period retained in the second region. That is, the coupling coefficient of the first region is a fixed value, and the coupling coefficient of the second region is adjusted according to the grating period retention coefficient. Since the grating period retention coefficient can be adjusted and does not affect the structure of the diffraction grating, flexible adjustment of the coupling coefficient can be achieved without changing the structure of the diffraction grating.

[0018] Optionally, the coupling coefficient of the second region can be adjusted according to the actually required coupling coefficient, mainly by using the grating period retention coefficient. In this embodiment, the grating period retention coefficient is used to indicate the ratio of the grating period retained in the second region to the grating period of the diffraction grating layer. At the same time, since all the grating periods of the diffraction grating layer are retained in the first region of the diffraction grating layer, the grating period retention coefficient can be calculated according to the following first formula, and the first formula is: Where S is the grating period retention coefficient, X is the coupling coefficient of the second region, and Y is the coupling coefficient of the first region. For example, when the coupling coefficient of the first coupling coefficient is 100 cm-1 and the coupling coefficient required for the second region is 50 cm-1, the grating period retention coefficient of the second region is one-half, that is, only 1 grating period needs to be retained within 2 grating periods; if the coupling coefficient required for the second region is 33.3 cm-1, the grating period retention coefficient of the second region is one-third, that is, only one grating period needs to be retained within 3 grating periods.

[0019] Optionally, the first region grating and the second region grating are controlled by a grating control device (such as an electron beam exposure system). Since the grating control device can achieve precise phase control, the DR laser can achieve a 100% single-mode yield and high light output.

[0020] In a third aspect, an embodiment of the present application provides an optical transmitter, which is characterized by including a grating control device, an optical modulation module, and the DR laser of the first aspect; wherein, the grating control device controls the grating period of the diffraction grating layer in the DR laser, the DR laser emits a light source signal and outputs it to the optical modulation module; the optical modulation module modulates the light source signal to generate an optical signal and outputs it.

[0021] Among them, in order to more precisely achieve the phase control of the diffraction grating layer, the grating control device can be an electron beam exposure system.

[0022] In a fourth aspect, an embodiment of the present application provides an optical communication system, which includes an optical switching device, a receiving device, and the optical transmitter of the third aspect; the optical transmitter sends an optical signal to the optical switching device; the optical switching device exchanges the optical signal and sends it to the receiving device; the receiving device receives the optical signal. Description of the Drawings

[0023] Figure 1 It is a schematic diagram of the active layer penetration scheme;

[0024] Figure 2 It is a schematic diagram of the active layer plus passive region working together scheme;

[0025] Figure 3 It is a schematic diagram of an embodiment of the DR laser in the embodiment of the present application;

[0026] Figure 4 It is a schematic diagram of another embodiment of the DR laser in the embodiment of the present application;

[0027] Figure 5 It is a schematic diagram of another embodiment of the DR laser in the embodiment of the present application;

[0028] Figure 6 A schematic diagram of grating period retention control in an embodiment of the present application;

[0029] Figure 7 A schematic diagram of an embodiment of an optical switching device in an embodiment of the present application;

[0030] Figure 8 A schematic diagram of an embodiment of an optical communication system in an embodiment of the present application. Detailed implementation manners

[0031] The embodiment of the present application provides a DR laser, which is used to flexibly adjust the coupling coefficient of the DR laser.

[0032] Terms such as "first", "second", "third", "fourth", etc. (if any) in the specification, claims and the above-mentioned drawings of the present application are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments described here can be implemented in an order other than that illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0033] DFB lasers have the advantages of small size, low power consumption, high electro-optical conversion efficiency, long life, wide wavelength coverage, easy photon integration, etc., and are widely used in optical communication systems. For DFB lasers, the light output efficiency and single-mode yield are the most important performance indicators to be concerned about. Achieving high light output efficiency and high single-mode yield DFB lasers has always been the pursuit of people. In order to achieve high light output efficiency and high single-mode yield DFB lasers, a DR laser scheme has been proposed. A DR laser can be equivalent to a combination of a DBR mirror and a DFB laser, and an AR film is coated during the coating process. One end is a high coupling coefficient region, and the other end is a low coupling coefficient region. The high coupling coefficient region acts as a DBR mirror with a high reflectivity, and the low coupling coefficient region is where the DFB operates with a low reflectivity, acting as the laser body and the light output end. Currently, the DR laser usually realizes the high coupling coefficient region by etching through the active layer to generate a grating or by using the length of the passive region to realize the high coupling coefficient region. As Figure 1 shown in the schematic diagram of the active layer etching-through scheme, the active layer of the DR laser generates photons through power supply and thus emits light; the diffraction grating layer is used to feedback the optical signal generated by the active layer to realize single-mode operation; the electrode represents the power supply region. And since the DR laser requires a high coupling coefficient region and a low coupling coefficient region, soFigure 1 The left - hand active layer shown is etched into a grating to achieve a high - coupling - coefficient region. In this solution, since the active layer in the left - hand high - coupling - coefficient region is etched through, the etched - through region will be covered by P - doped InP, and thus P - doped InP is connected to N - doped InP to form a leakage channel. Therefore, the left - hand high - coupling - coefficient region cannot be powered; the right - hand low - coupling - coefficient region needs to be powered to emit light. Therefore, good electrical isolation must be achieved between the left and the right. At the same time, when the low - coupling - coefficient region operates at a large current, due to the injected current, the active layer will heat up, resulting in the Bragg wavelength of the low - coupling - coefficient region shifting towards the long - wavelength direction. While the high - coupling - coefficient region is not powered and the Bragg wavelength remains unchanged, which causes the Bragg wavelengths of the low - coupling - coefficient region and the high - coupling - coefficient region to gradually shift from the original aligned state, and the chip has a risk of changing from a single - mode state to a multi - mode state, there is a risk of mode hopping. As Figure 2 In the DR laser solution shown, the DR laser includes a forward DBR1 region, a DFB region, and a backward DBR2 region. Among them, the forward and backward DBR regions are passive regions with the same grating. The length of DBR2 is greater than the length of DBR1, resulting in different reflectivities before and after. The DBR2 region forms a high - coupling region, and DBR1 forms a low - coupling region; the DFB region operates with normal power supply. The Figure 2 DR laser shown solves the Figure 1 electrical isolation problem and the mode - hopping problem of the DR laser shown, but Figure 2 the front - to - back light - output ratio of the DR laser shown needs to be adjusted by the DBR length, and the adjustment ability is limited, which will lead to an overly long chip length.

[0034] To solve this problem and achieve the function of flexibly adjusting the coupling coefficient of the DR laser without changing its size, the embodiments of the present application provide the following DR laser. As Figure 3 shown, the DR laser includes: a substrate 301, an active layer 302, a diffraction grating layer 303, a cladding layer 304, and an electrode 305; the active layer 302 and the diffraction grating layer 303 are disposed between the substrate 301 and the cladding layer 304; the electrode 305 is disposed on the cladding layer 304; the diffraction grating layer 303 includes a first region and a second region. Among them, the thickness of the diffraction grating layer 303 is determined according to the required coupling coefficient of the first region, and the grating - period retention coefficient of the second region is determined according to the coupling coefficient of the second region. The grating - period retention coefficient is used to indicate the ratio of the grating period retained in the second region to the grating period of the diffraction grating layer 303. The coupling coefficient of the first region is greater than the coupling coefficient of the second region; anti - reflection AR films 306 are respectively coated on both ends of the laser.

[0035] Optionally, since the manufacturing process of the diffraction grating layer in the DR laser is not limited, the positions of the active layer 302 and the diffraction grating layer 303 in the DR laser are not limited.

[0036] In an exemplary structure, as Figure 4 shown: The structures of the substrate 301, the active layer 302, the diffraction grating layer 303, and the cladding layer 304 are, in sequence, the active layer 302 is disposed on the substrate 301, the diffraction grating layer 303 is disposed on the active layer 302, and the cladding layer 304 is disposed on the diffraction grating layer 303 (i.e., the overall structure is a P-type grating). Its manufacturing process is: First, the active layer 302 is formed on the substrate 301, and then the diffraction grating layer 303 is formed according to the coupling coefficient of the first region; finally, the cladding layer 304 is formed on the diffraction grating layer 303.

[0037] In another exemplary structure, as Figure 5 shown: The structures of the substrate 301, the active layer 302, the diffraction grating layer 303, and the cladding layer 304 are, in sequence, the diffraction grating layer 303 is disposed on the substrate 301, the active layer 302 is disposed on the diffraction grating layer 303, and the cladding layer 304 is disposed on the active layer 302 (i.e., the overall structure is an N-type grating). Its manufacturing process is: First, the diffraction grating layer 303 is formed on the substrate 301 according to the coupling coefficient of the first region; then the active layer 302 is grown; finally, the cladding layer 304 is formed on the active layer 302.

[0038] Not limiting the positions of the active layer and the diffraction grating layer in this way can reduce the processing limitations of the DR laser.

[0039] Optionally, the electrode 305 in the DR laser can be designed to cover both the first region and the second region simultaneously. An exemplary solution can be as Figure 4 and Figure 5 shown. In this way, the first region and the second region can be powered on and operate simultaneously, and it is ensured that when operating under a large current, the Bragg wavelengths of the first region and the second region move in the same direction, improving the anti-hop mode ability of the DR laser.

[0040] Based on the DR laser in the above solution, the coupling coefficient of the second region of the diffraction grating layer in the DR laser can be adjusted according to the actually required coupling coefficient, mainly by using the grating period retention coefficient for adjustment. In this embodiment, the grating period retention coefficient is used to indicate the ratio of the grating period retained in the second region to the grating period of the diffraction grating layer. At the same time, since all the grating periods of the diffraction grating layer are retained in the first region of the diffraction grating layer, the grating period retention coefficient can be calculated according to the following first formula, and the first formula is: Where S is the grating period retention coefficient, X is the coupling coefficient of the second region, and Y is the coupling coefficient of the first region. For example, when the coupling coefficient of the first coupling coefficient is 100 cm-1 and the coupling coefficient required for the second region is 50 cm-1, the grating period retention coefficient of the second region is one-half, that is, only 1 grating period needs to be retained within 2 grating periods; if the coupling coefficient required for the second region is 33.3 cm-1, the grating period retention coefficient of the second region is one-third, that is, only one grating period needs to be retained within 3 grating periods. An exemplary solution can be as follows Figure 6 shown: when the coupling coefficient is 100 cm-1, all grating periods are retained; when the coupling coefficient is 50 cm-1, one grating period is retained every two grating periods; when the coupling coefficient is 33.3 cm-1, one grating period is retained every three grating periods.

[0041] Optionally, the materials of the substrate 301 and the cladding 304 are InP or GaAs systems. That is, the DR laser can be fabricated using various materials in the InP or GaAs systems, reducing the fabrication difficulty.

[0042] In this embodiment, since only the number of retained grating periods in the first region or the second region is controlled when adjusting the coupling coefficient, and the size of the grating period is not limited, the DR laser can be applied to the 1310 nm band (also known as the O band) and the 1550 nm band (also known as the C band) of optical communication.

[0043] For details, please refer to Figure 7 shown, the present application provides an optical transmitter 700, where the optical transmitter 700 includes a DR laser 701, a grating control device 702, and an optical modulation module 703. Among them, the DR laser 701 has the structure and function of the DR laser described in any one of the above Figures 3 to 6 ;

[0044] The grating control device 702 is used to control the grating period of the diffraction grating layer in the DR laser 701;

[0045] The DR laser 701 emits a light source signal and outputs it to the optical modulation module 703;

[0046] The optical modulation module 703 modulates the light source signal to generate an optical signal and outputs it.

[0047] Optionally, the first region grating and the second region grating are controlled by a grating control device (such as an electron beam exposure system). Because the grating control device can achieve precise phase control, the DR laser can achieve a 100% single-mode yield and high light output.

[0048] For details, please refer to Figure 8 As shown, the present application provides an optical communication system 800. Among them, the optical communication system 800 includes an optical transmitter 801, an optical switching device 802, and a receiving device 803. Among them, the optical transmitter 801 has Figure 7 the structure and functions of the described optical transmitter;

[0049] Among them, the optical transmitter 801 sends an optical signal to the optical switching device 802; the optical switching device 802 exchanges the optical signal and sends it to the receiving device 803; the receiving device 803 receives the optical signal, thereby realizing the interaction of optical signals.

[0050] Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the above-described systems, devices, and units can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0051] In several embodiments provided by the present application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces, indirect couplings or communication connections of devices or units, and can be in electrical, mechanical or other forms.

[0052] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0053] In addition, the functional units in each embodiment of the present application can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units.

[0054] When the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of this application. The foregoing storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs.

[0055] As described above, the above embodiments are only used to illustrate the technical solutions of this application, rather than to limit them; although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of various embodiments of this application.

Claims

1. A distributed feedback DR laser, characterized in that, Comprising: a substrate, an active layer, a diffraction grating layer, a cladding layer, and electrodes; The active layer and the diffraction grating layer are stacked on each other and are disposed between the substrate and the cladding layer; The electrodes are disposed on the cladding layer; The diffraction grating layer includes a first region and a second region, wherein the thickness of the diffraction grating layer is determined according to the coupling coefficient of the first region, and the grating period retention coefficient of the second region is determined according to the coupling coefficient of the second region and the coupling coefficient of the first region, and the grating period retention coefficient is used to indicate the ratio of the grating period retained in the second region to the grating period of the diffraction grating layer, and the coupling coefficient of the first region is greater than the coupling coefficient of the second region; Anti-reflection AR films are respectively coated on both ends of the laser.

2. The laser according to claim 1, characterized in that, The electrodes cover the first region and the second region.

3. The laser according to any one of claims 1 or 2, characterized in that The grating period retention coefficient is determined by a first formula, and the first formula is: , where the is the grating period retention coefficient, the is the coupling coefficient of the second region, and the is the coupling coefficient of the first region.

4. The laser according to any one of claims 1 to 3, characterized in that, The grating period of the diffraction grating layer is adjustable.

5. The laser according to any one of claims 1 to 4, characterized in that, The materials of the substrate and the cladding layer are indium phosphide InP system; Or, The materials of the substrate and the cladding layer are gallium arsenide GaAs system.

6. The laser according to any one of claims 1 to 5, characterized in that, The diffraction grating layer is disposed on the substrate, the active layer is disposed on the diffraction grating layer, and the cladding layer is disposed on the active layer.

7. The laser according to any one of claims 1 to 5, characterized in that, The active layer is disposed on the substrate, the diffraction grating layer is disposed on the active layer, and the cladding layer is disposed on the diffraction grating layer.

8. A diffraction grating, characterized in that, Comprising: a first region and a second region, wherein the thickness of the diffraction grating is determined according to the coupling coefficient of the first region, and the grating period retention coefficient of the second region is determined according to the coupling coefficient of the second region and the coupling coefficient of the first region, and the grating period retention coefficient is used to indicate the ratio of the grating period retained in the second region to the grating period of the diffraction grating, and the coupling coefficient of the first region is greater than the coupling coefficient of the second region.

9. The diffraction grating according to claim 8, characterized in that, The grating period retention coefficient is determined by a first formula, and the first formula is: , where the is the grating period retention coefficient, and the is the coupling coefficient of the second region, and the is the coupling coefficient of the first region.

10. The diffraction grating according to any one of claims 8 or 9, characterized in that The grating period of the diffraction grating is adjustable.

11. An optical transmitter, characterized in that, Comprising an optical modulation module, a grating control device, and a DR laser as described in any one of claims 1 to 7; The grating control device controls the grating period of the diffraction grating layer in the DR laser; The DR laser emits a light source signal and outputs it to the optical modulation module; The optical modulation module modulates the light source signal to generate an optical signal and outputs it.

12. The optical transmitter according to claim 11, wherein, The grating control device is an electron beam exposure system.

13. An optical communication system, characterized in that, Comprising an optical switching device, a receiving device, and an optical transmitter as described in any one of claims 11 to 12; The optical transmitter sends an optical signal to the optical switching device; The optical switching device exchanges the optical signal and sends it to the receiving device; The receiving device receives the optical signal.

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