External cavity high-power narrow-linewidth laser based on weak feedback

Abstract

The invention relates to an external cavity high-power narrow-linewidth laser based on weak feedback, and the laser comprises a sub-light source output part which is used for outputting a sub-light source; the laser output part is used for outputting narrow linewidth laser; the isolator is arranged between the sub light source output part and the laser output part; the multi-layer reflecting film assembly is plated at the input end of the isolator or the output end of the sub light source output part and is used for filtering the sub light sources to form transmission light and feedback light; the rear end of the isolator outputs the transmission light to the laser output part, so that the transmission light is output as narrow-linewidth laser; and the sub light source output part is also used for receiving the feedback light so as to realize self-injection locking, and the laser has the advantages of high-power narrow-linewidth laser output, simple structure, low cost, simple process, relatively small packaging size and convenience in laser packaging.

Description

Technical Field

[0001] The invention relates to the technical field of lasers, and in particular to an external cavity high-power narrow-linewidth laser based on weak feedback. Background Art

[0002] Lasers have broad application prospects in communications, military, medical treatment, and optical information processing. With the development of Internet communications, people's demand for communication capacity has increased dramatically, which has put forward more stringent requirements on the line width and frequency stability of lasers.

[0003] At present, there are two main methods to achieve line width narrowing: the internal cavity method and the external cavity method. The internal cavity method mainly achieves the purpose of line width narrowing by designing the structure of the internal resonant cavity of the semiconductor laser, such as the laser diode (DFB), but its narrowing effect is limited, and its line width is generally still in the order of hundreds of kHz. The external cavity method mainly uses an external cavity with a high quality factor, such as setting a grating reflector or multiple sets of grating structures in the external cavity of the laser, but its disadvantages are also obvious: the structure is relatively complex, which will increase the difficulty of processing and packaging to a certain extent, and the processing technology requirements are high and the cost is high.

[0004] Therefore, it is urgent for technicians in this field to provide an external cavity high-power narrow-linewidth laser based on weak feedback, which has the advantages of high-power narrow-linewidth laser output, simple structure, low cost, simple process, relatively small packaging volume, and convenient laser packaging. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defects in the prior art, thereby providing an external cavity high-power narrow-linewidth laser based on weak feedback.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] An external cavity high-power narrow-linewidth laser based on weak feedback, comprising:

[0008] A sub-light source output unit, used for outputting a sub-light source;

[0009] A laser output unit, used for outputting narrow line width laser;

[0010] An isolator, disposed between the sub-light source output portion and the laser output portion;

[0011] A multilayer reflective film assembly, plated on the input end of the isolator or plated on the output end of the sub-light source output part, used for filtering the sub-light source to form transmitted light and feedback light;

[0012] The rear end of the isolator outputs the transmitted light to the laser output part as narrow line width laser output;

[0013] The sub-light source output part is also used to receive the feedback light to achieve self-injection locking.

[0014] Preferably, the multilayer reflective film assembly comprises a spacer layer and two reflective films;

[0015] Along the optical path direction, the spacer layer is located between two reflective films, and the reflectivities of the two reflective films are equal.

[0016] Preferably, the optical thickness of the reflective film is 1 / 4 times the central wavelength.

[0017] Preferably, the reflective film comprises a plurality of first dielectric films and second dielectric films that are alternately stacked;

[0018] The first dielectric film and the second dielectric film have different refractive indices;

[0019] The first dielectric film and the second dielectric film are made of a substrate, and the refractive index of the substrate ranges from 1.38 to 2.6.

[0020] Preferably, the reflectivity of the multilayer reflective film assembly is less than 5%.

[0021] Preferably, the spacer layer is configured as a single-layer film, or the spacer layer is configured as two-layer films having the same refractive index.

[0022] Preferably, the sub-light source output unit comprises a laser diode and an output collimator;

[0023] The output collimator is disposed between the laser diode and the isolator to form the output end of the sub-light source output part and is used to collimate the output light of the laser diode;

[0024] The multi-layer reflective film assembly is plated on the front end face or the rear end face of the output collimating mirror;

[0025] The laser diode is arranged on the effective focal plane of the output collimating mirror.

[0026] Preferably, the laser diode is configured as a distributed feedback semiconductor laser;

[0027] The front end face of the distributed feedback semiconductor laser is plated with an AR anti-reflection film, and the rear end face is plated with a high-reflection film.

[0028] Preferably, the laser output unit comprises a focusing lens and an output optical fiber;

[0029] The focusing lens is used to focus the transmitted light onto the output optical fiber;

[0030] The output optical fiber is used to output narrow line width laser.

[0031] Preferably, it also includes a base, an aluminum nitride heat sink, a thermoelectric cooler and a thermistor;

[0032] The laser output part, the isolator and the aluminum nitride heat sink are all fixedly mounted on the base;

[0033] The sub-light source output part includes a laser diode, and the laser diode is mounted on the aluminum nitride heat sink;

[0034] The thermistor is arranged on one side of the laser diode to detect the real-time temperature of the laser diode;

[0035] The thermoelectric cooler is used to control the temperature of the laser according to the real-time temperature detected by the thermistor.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The external cavity high-power narrow linewidth laser based on weak feedback provided in the above technical scheme realizes FP filtering function by coating a multilayer reflective film component at the input end of the isolator or the output end of the sub-light source output part, so that the output light of the sub-light source output part can be filtered by the multilayer reflective film component, and weak feedback self-injection locking can be realized, and the laser output part can further output high-power, narrow linewidth laser; further, by coating a multilayer reflective film at the input end of the isolator or the output end of the sub-light source output part, a high degree of matching of the butterfly packaging form commonly used for lasers can be achieved, and weak feedback self-injection locking can be realized without increasing the volume and components of the laser diode butterfly packaging, and the laser output part can further output high-power, narrow linewidth laser. Compared with other existing types of narrow linewidth semiconductor lasers (such as grating structures set in the external cavity), the laser in this scheme has the advantages of realizing high-power narrow linewidth laser output, simple structure, low cost, simple process, and convenient laser packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 A schematic diagram of the structure of one example of the laser provided by the present invention.

[0040] Figure 2 for Figure 1A schematic diagram of the structure of one example of a multilayer reflective film assembly.

[0041] Figure 3 This is a schematic structural diagram of another example of the laser provided by the present invention.

[0042] Figure 4 This is a schematic structural diagram of a second example of the laser provided by the present invention.

[0043] Figure 5 This is a schematic structural diagram of a third example of the laser provided by the present invention.

[0044] Description of reference numerals:

[0045] 1. Sub-light source output unit; 11. Laser diode; 12. Output collimator; 2. Laser output unit; 21. Focusing lens; 22. Output optical fiber; 3. Isolator; 4. Multilayer reflective film assembly; 41. Spacer layer; 42. Reflective film; 421. First dielectric film; 422. Second dielectric film; 5. Base; 6. Aluminum nitride heat sink; 7. Thermoelectric cooler; 8. Thermistor. DETAILED DESCRIPTION

[0046] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0048] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0049] Embodiment 1

[0050] See also Figures 1 to 3 The embodiment of the present invention provides an external cavity high-power narrow linewidth laser based on weak feedback, including a sub-light source output part 1, a laser output part 2, an isolator 3 and a multilayer reflective film assembly 4. Among them, the sub-light source output part 1 is used to output a sub-light source; the laser output part 2 is used to output a narrow linewidth laser; the isolator 3 is arranged between the sub-light source output part 1 and the laser output part 2, the multilayer reflective film assembly 4 is plated on the input end of the isolator 3 or plated on the output end of the sub-light source output part 1, and the multilayer reflective film assembly 4 is used to filter the sub-light source to form transmitted light and feedback light. The rear end of the isolator 3 outputs the transmitted light to the laser output part 2 as a narrow linewidth laser output; the sub-light source output part 1 is also used to receive feedback light to achieve self-injection locking. When the laser is in use, the sub-light source output part 1 outputs a sub-light source, which is transmitted to the multilayer reflective film assembly 4 and the isolator 3. The multilayer reflective film assembly 4 filters and selects the frequency of the sub-light source. Part of the sub-light source passes through the multilayer reflective film assembly 4 to form transmitted light, which is output to the laser output part 2 through the rear end of the isolator 3 as a narrow linewidth laser output; part of the sub-light source is reflected by the multilayer reflective film assembly 4 to form reflected light, which is reflected back to the sub-light source output part 1 to achieve self-injection locking.

[0051] By coating the multilayer reflective film assembly 4 at the input end of the isolator 3 or the output end of the sub-light source output unit 1, the FP filtering function is realized, so that the output light of the sub-light source output unit 1 can be filtered by the multilayer reflective film assembly 4, and weak feedback self-injection locking can be realized, and the laser output unit 2 can further output high-power, narrow-linewidth laser; further, by setting the multilayer reflective film 42 at the input end of the isolator 3 or the output end of the sub-light source output unit 1, a high degree of matching of the butterfly packaging form commonly used for lasers can be achieved, and then weak feedback self-injection locking can be achieved without increasing the volume and components of the laser diode butterfly packaging, and the laser output unit 2 can further output high-power, narrow-linewidth laser. Compared with other types of existing narrow-linewidth semiconductor lasers (such as grating structures set in the external cavity), the laser in this solution has the advantages of realizing high-power narrow-linewidth laser output, simple structure, low cost, simple process, and convenient laser packaging.

[0052] Specifically, in this embodiment, the multilayer reflective film assembly 4 can be directly plated on the front end surface of the isolator 3, that is, plated on the output end of the isolator 3. This makes the solution completely match the existing laser butterfly packaging structure, and the step of aligning the external cavity and the laser during the packaging process can be omitted.

[0053] In order to achieve weak feedback, in this embodiment, the reflectivity of the multilayer reflective film assembly 4 is less than 5%.

[0054] See also Figure 2 In this embodiment, the multilayer reflective film assembly 4 includes a spacer layer 41 and two reflective films 42; along the optical path direction, the spacer layer 41 is located between the two reflective films 42, and the reflectivities of the two reflective films 42 are equal.

[0055] Specifically, the reflective film 42 includes a plurality of alternately stacked first dielectric films 421 and second dielectric films 422; the first dielectric film 421 and the second dielectric film 422 have different refractive indices; the first dielectric film 421 and the second dielectric film 422 are made of a substrate, and the refractive index of the substrate ranges from 1.38 to 2.6; and thus, the overall reflectivity of the reflective film 42 can be changed by changing the refractive index values ​​of the first dielectric film 421 and the second dielectric film 422.

[0056] Of course, in other embodiments, the reflective film 42 may also be configured as a non-uniform film whose refractive index changes continuously with increasing thickness.

[0057] Furthermore, the optical thickness of the reflective film 42 is 1 / 4 times the central wavelength.

[0058] Furthermore, in this embodiment, the spacer layer 41 is configured as a single-layer film. Of course, in other embodiments, the spacer layer 41 may also be configured as two layers of films having the same refractive index.

[0059] See also Figure 1 and Figure 3 In this embodiment, the sub-light source output unit 1 includes a laser diode 11 and an output collimator 12. The output collimator 12 is disposed between the laser diode 11 and the isolator 3 to form an output end of the sub-light source output unit 1, and is used to collimate the output light of the laser diode 11. Of course, in other embodiments, the sub-light source output unit 1 can also be configured as a combination structure of an SOA and an output collimator 12.

[0060] Specifically, the output collimator 12 is configured as an aspheric lens, and the laser diode 11 is disposed on an effective focal plane of the output collimator 12 .

[0061] Furthermore, the laser diode 11 is configured as a distributed feedback semiconductor laser; along the optical path, the front end face of the distributed feedback semiconductor laser is coated with an AR anti-reflection film, and the rear end face is coated with a high-reflection film.

[0062] See also Figure 1 and Figure 3 In this embodiment, the laser output unit 2 includes a focusing lens 21 and an output optical fiber 22; the focusing lens 21 is used to focus the transmitted light to the output optical fiber 22; the output optical fiber 22 is used to output narrow line width laser.

[0063] In order to achieve the stability of the entire laser and ensure that the position of the optical element is not affected by factors such as vibration and thus not shifted, thereby improving the stability of the output narrow linewidth laser, in this embodiment, a base 5 is also included, and the sub-light source output part 1, the laser output part 2, and the isolator 3 are all fixedly mounted on the base 5.

[0064] Specifically, the laser diode 11 of the sub-light source output part 1 is fixed on the base 5 through the aluminum nitride heat sink 6, wherein the laser diode 11 is fixedly mounted on the aluminum nitride heat sink 6 through the eutectic process, and the light-emitting surface of the laser diode 11 is flush with one side (one side end face along the optical path direction) of the aluminum nitride heat sink 6, and the aluminum nitride heat sink 6 is fixed on the base 5 through gold soldering. The output collimator 12 of the sub-light source output part 1, the focusing lens 21 of the laser output part 2, and the isolator 3 can all be fixed on the base 5 through the fixed seat arranged opposite thereto, and the corresponding fixed seat and the base 5 can also be fixed by laser welding.

[0065] It can be known that along the light path direction (i.e. Figure 1 As shown in the L direction, the laser diode 11, the output collimator 12, the multilayer reflective film assembly 4, the isolator 3, the focusing lens 21, and the output optical fiber 22 are arranged in sequence.

[0066] See also Figure 3 In order to reduce the deformation of the laser chip (such as the laser diode 11 or SOA) caused by temperature changes, and thus reduce the laser power jitter, in this embodiment, a thermoelectric cooler 7 and a thermistor 8 are also included, and active and tight temperature control of the laser chip (such as the laser diode 11 or SOA) is achieved through the thermistor 8 and the thermoelectric cooler 7.

[0067] Specifically, the thermistor 8 is disposed on one side of the laser diode 11 to detect the real-time temperature of the laser diode 11; the thermoelectric cooler 7 is placed below the base 5 to control the temperature of the entire laser according to the real-time temperature detected by the thermistor 8. That is, the real-time temperature detected by the thermistor 8 is fed back to the thermoelectric cooler 7, and the temperature of the entire laser is controlled in real time by the thermoelectric cooler 7.

[0068] Embodiment 2

[0069] See also Figure 4 Based on the above embodiment 1, the difference of this embodiment is that the multilayer reflective film assembly 4 is plated on the output end of the sub-light source output part 1. Specifically, in this embodiment, the multilayer reflective film assembly 4 is plated on the front end surface of the output collimator 12.

[0070] Embodiment 3

[0071] See also Figure 5Based on the above embodiment 1, the difference of this embodiment is that the multilayer reflective film assembly 4 is plated on the output end of the sub-light source output part 1. Specifically, in this embodiment, the multilayer reflective film assembly 4 is plated on the rear end surface of the output collimator 12.

[0072] It is worth noting that, although the multilayer reflective film assembly 4 has a certain thickness in the figure, it is only a schematic diagram, and the specific coating method and coating thickness can be set according to actual needs.

[0073] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. An external cavity high-power narrow-linewidth laser based on weak feedback, characterized in that: include: A sub-light source output unit (1), used for outputting a sub-light source; A laser output unit (2), used for outputting narrow line width laser; An isolator (3) is arranged between the sub-light source output part (1) and the laser output part (2); A multilayer reflective film component (4) is plated on the input end of the isolator (3) or the output end of the sub-light source output part (1), and is used to filter the sub-light source to form transmitted light and feedback light; The rear end of the isolator (3) outputs the transmitted light to the laser output part (2) as narrow line width laser output; The sub-light source output part (1) is also used to receive the feedback light to achieve self-injection locking.

2. The external cavity high-power narrow linewidth laser based on weak feedback according to claim 1, characterized in that: The multilayer reflective film assembly (4) comprises a spacer layer (41) and two reflective films (42); Along the optical path direction, the spacer layer (41) is located between two reflective films (42), and the reflectivities of the two reflective films (42) are equal.

3. The external cavity high-power narrow linewidth laser based on weak feedback according to claim 2, characterized in that: The optical thickness of the reflective film (42) is 1 / 4 times the central wavelength.

4. The external cavity high-power narrow linewidth laser based on weak feedback according to claim 2, characterized in that: The reflective film (42) comprises a plurality of alternately stacked first dielectric films (421) and second dielectric films (422); The first dielectric film (421) and the second dielectric film (422) have different refractive indices; The first dielectric film (421) and the second dielectric film (422) are made of a substrate, and the refractive index of the substrate ranges from 1.38 to 2.

6.

5. The external cavity high-power narrow linewidth laser based on weak feedback according to claim 1 or 2, characterized in that: The reflectivity of the multilayer reflective film assembly (4) is less than 5%.

6. The weak feedback external cavity high-power narrow linewidth laser according to claim 2, characterized in that: The spacer layer is configured as a single-layer film, or the spacer layer is configured as two-layer films with the same refractive index.

7. The external cavity high-power narrow linewidth laser based on weak feedback according to claim 1, characterized in that: The sub-light source output part (1) comprises a laser diode (11) and an output collimator (12); The output collimator (12) is arranged between the laser diode (11) and the isolator (3), forming the output end of the sub-light source output part (1), and is used to collimate the output light of the laser diode (11); The multilayer reflective film assembly (4) is plated on the front end face or the rear end face of the output collimating mirror (12); The laser diode (11) is arranged on the effective focal plane of the output collimating mirror (12).

8. The external cavity high-power narrow-linewidth laser based on weak feedback according to claim 7, characterized in that: The laser diode (11) is configured as a distributed feedback semiconductor laser; The front end face of the distributed feedback semiconductor laser is plated with an AR anti-reflection film, and the rear end face is plated with a high-reflection film.

9. The external cavity high-power narrow linewidth laser based on weak feedback according to claim 1, characterized in that: The laser output unit (2) comprises a focusing lens (21) and an output optical fiber (22); The focusing lens (21) is used to focus the transmitted light onto the output optical fiber (22); The output optical fiber (22) is used to output narrow line width laser.

10. The external cavity high-power narrow-linewidth laser based on weak feedback according to claim 1, characterized in that: It also includes a base (5), an aluminum nitride heat sink (6), a thermoelectric cooler (7) and a thermistor (8); The laser output unit (2), the isolator (3) and the aluminum nitride heat sink (6) are all fixedly mounted on the base (5); The sub-light source output part (1) comprises a laser diode (11), and the laser diode (11) is mounted on the aluminum nitride heat sink (6); The thermistor (8) is arranged on one side of the laser diode (11) to detect the real-time temperature of the laser diode (11); The thermoelectric cooler (7) is used to control the temperature of the laser according to the real-time temperature detected by the thermistor (8).

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