Injection-locked semiconductor seed source based self-harmonic frequency-doubled laser

Abstract

The application provides an automatic resonant frequency-doubled laser based on an injection-locked semiconductor seed source, which forms injection locking by injecting the fundamental frequency light transmitted when the resonant frequency-doubled cavity resonates into the semiconductor seed source through the coupling light path, so that the seed light emitted by the semiconductor seed source and the resonant frequency-doubled cavity are always in a resonant state, and automatic resonant frequency doubling is realized. Compared with a traditional resonant frequency-doubled laser, the laser of the application can realize automatic resonance of the seed light and the resonant frequency-doubled cavity without an additional active optical and electrical control link, realize continuous and efficient transmission laser output, has a simple structure, and in the traditional resonant frequency-doubled laser scheme which needs active locking, the fundamental frequency light is required to be single-frequency laser, and the application does not have this requirement, and the fundamental frequency light transmitted by the resonant frequency-doubled cavity can also operate in multiple modes which are resonant with the resonant frequency-doubled cavity by injection locking in the semiconductor seed source.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic technology, and in particular to an autoresonant frequency doubling laser based on an injection-locked semiconductor seed source. Background Technology

[0002] Resonant frequency doubling is a technique that uses multi-beam interference to enhance the intensity of the fundamental frequency photoelectric field to achieve high frequency doubling efficiency. This technique can generate high-power green light, ultraviolet lasers, and blue light, expanding the wavelength range of lasers. However, traditional resonant frequency-doubled lasers require HC frequency stabilization and PDH frequency stabilization techniques to generate an error signal between the laser frequency and the resonance peak of the resonant frequency doubling cavity. Then, PID control is used to lock the fundamental frequency laser and the resonant frequency doubling cavity together to achieve continuous high-efficiency frequency doubling. This significantly increases the complexity of the system. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides an autoresonant frequency doubling laser based on an injection-locked semiconductor seed source. This laser achieves automatic resonant frequency doubling by injecting and locking the fundamental frequency light transmitted through the frequency doubling cavity into the semiconductor seed source, without the need for active locking.

[0004] The present invention relates to an auto-resonant frequency-doubled laser based on an injection-locked semiconductor seed source, comprising a semiconductor seed source, an injection-locked coupling optical path, a resonant frequency-doubled cavity, and a frequency-doubled crystal. The semiconductor seed source is used to emit seed light. The frequency-doubled crystal is located inside the resonant frequency-doubled cavity. The seed light is incident into the resonant frequency-doubled cavity, oscillates within the cavity, and is frequency-doubled by the crystal. The fundamental frequency light transmitted from the resonant frequency-doubled cavity is then incident into the semiconductor seed source via the injection-locked coupling optical path to form an injection lock.

[0005] Preferably, the injection-locked coupling optical path includes a backward coupling optical path, through which the fundamental frequency light transmitted from the resonant frequency doubling cavity is incident into the semiconductor seed source.

[0006] Furthermore, the backward coupling optical path includes a first backward coupling lens, through which the fundamental frequency light transmitted from the resonant frequency doubling cavity is incident into the semiconductor seed source; the backward coupling optical path includes a second backward coupling lens and a backward transmission fiber, which is connected to the semiconductor seed source, through which the fundamental frequency light transmitted from the resonant frequency doubling cavity is incident into the semiconductor seed source.

[0007] Furthermore, the laser also includes a first amplifier located between the semiconductor seed source and the resonant frequency doubling cavity, through which the seed light is incident into the resonant frequency doubling cavity.

[0008] Furthermore, the injection-locked coupling optical path also includes a forward coupling optical path, and a backward coupling optical path is connected to the forward coupling optical path. The seed light is incident into the resonant frequency doubling cavity through the forward coupling optical path, and the fundamental frequency light transmitted and output by the resonant frequency doubling cavity is incident into the semiconductor seed source after passing through the backward coupling optical path and the forward coupling optical path.

[0009] Furthermore, the forward coupling optical path includes a partially transmissive mirror located between the semiconductor seed source and the resonant frequency doubling cavity. The seed light is incident into the resonant frequency doubling cavity through the partially transmissive mirror. The fundamental frequency light transmitted and output from the resonant frequency doubling cavity passes through the backward coupling optical path and the partially transmissive mirror in sequence before being incident into the semiconductor seed source. The forward coupling optical path also includes an optical fiber circulator located between the semiconductor seed source and the resonant frequency doubling cavity. The backward coupling optical path is connected to the optical fiber circulator. The seed light is incident into the resonant frequency doubling cavity through the optical fiber circulator. The fundamental frequency light transmitted and output from the resonant frequency doubling cavity passes through the backward coupling optical path and the optical fiber circulator in sequence before being incident into the semiconductor seed source.

[0010] Furthermore, the laser also includes a second amplifier located between the fiber optic circulator and the resonant frequency doubling cavity. The seed light passes through the fiber optic circulator and the second amplifier before entering the resonant frequency doubling cavity.

[0011] Furthermore, the laser also includes a seed light coupling lens located between the second amplifier and the resonant frequency doubling cavity. The seed light passes through the fiber optic circulator, the second amplifier, and the seed light coupling lens before entering the resonant frequency doubling cavity.

[0012] Compared with existing technologies, the autoresonant frequency doubling laser based on an injection-locked semiconductor seed source of the present invention achieves automatic resonant frequency doubling by injecting the fundamental frequency light transmitted from the resonant frequency doubling cavity into the semiconductor seed source through an injection-locked coupling optical path. This ensures that the seed light emitted from the semiconductor seed source and the resonant frequency doubling cavity are always in a resonant state, thus achieving automatic resonant frequency doubling. Compared with traditional resonant frequency doubling lasers, the laser of the present invention can achieve automatic resonance between the seed light and the resonant frequency doubling cavity without additional active optical and electrical control links, achieving continuous high-efficiency transmitted laser output. The structure is simple, and traditional resonant frequency doubling laser schemes that require active locking require the fundamental frequency light to be a single-frequency laser, which is not required in the present invention. The fundamental frequency light transmitted from the resonant frequency doubling cavity can also operate by injecting and locking it in the semiconductor seed source to form multiple modes resonating with the resonant frequency doubling cavity. Attached Figure Description

[0013] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of a traditional resonant frequency-doubled laser.

[0015] Figure 2 This is a schematic diagram of an autoresonant frequency doubling laser based on an injection-locked semiconductor seed source according to an embodiment of the present invention.

[0016] Figure 3 This is a schematic diagram of an autoresonant frequency doubling laser based on an injection-locked semiconductor seed source, according to another embodiment of the present invention.

[0017] Figure 4 This is a schematic diagram of the structure of an autoresonant frequency doubling laser based on an injection-locked semiconductor seed source according to the third embodiment of the present invention.

[0018] Figure 5 This is a schematic diagram of the structure of an autoresonant frequency doubling laser based on an injection-locked semiconductor seed source according to the fourth embodiment of the present invention.

[0019] Figure 6 This is a schematic diagram of the structure of an autoresonant frequency doubling laser based on an injection-locked semiconductor seed source according to the fifth embodiment of the present invention. Detailed Implementation

[0020] To provide a further understanding of the purpose, structure, features, and functions of the present invention, detailed descriptions are provided below with reference to specific embodiments.

[0021] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0022] Please see Figure 1 , Figure 1This is a schematic diagram of a traditional resonant frequency-doubled laser. In this diagram, the resonant frequency-doubled laser includes a semiconductor seed source 1', an amplifier 2', a resonant frequency-doubled cavity 3', and a frequency-doubled crystal 4', with the crystal 4' located within the cavity 3'. Seed light emitted from the semiconductor seed source 1' is amplified by the amplifier 2' and then incident into the resonant frequency-doubled cavity 3'. The frequency-doubled crystal 4' performs a nonlinear frequency transformation to generate a frequency-doubled laser. The resonant frequency-doubled cavity 3' consists of several cavity mirrors that highly reflect the seed light. Utilizing the principle of multi-beam interference, the seed light can only be incident into the cavity 3' when it resonates with it. After multiple reflections within the cavity, the electric field intensity is multiplied, and the efficiency is greatly increased through the frequency-doubled conversion by the crystal 4'.

[0023] However, due to the drift of the seed light and the resonant frequency doubling cavity, the laser cannot resonate with the resonant frequency doubling cavity at all times. In order to continuously obtain high frequency doubling efficiency, additional methods are required, such as locking the resonant frequency doubling cavity to the laser based on HC frequency doubling and PDH frequency doubling, or locking the laser to the resonant frequency doubling cavity. This requires additional complex optical and electrical control links, which increases the complexity.

[0024] Please see Figure 2 , Figure 2 This is a schematic diagram of an autoresonant frequency-doubled laser based on an injection-locked semiconductor seed source according to an embodiment of the present invention. In this embodiment, the resonant frequency-doubled laser includes a semiconductor seed source 1, an injection-locked coupling optical path 2, a resonant frequency-doubled cavity 3, and a frequency-doubled crystal 4.

[0025] Semiconductor seed source 1 is used to emit seed light.

[0026] The frequency doubling crystal 4 is located inside the resonant frequency doubling cavity 3.

[0027] The seed light is incident into the resonant frequency doubling cavity 3, oscillates within the resonant frequency doubling cavity 3, and after being frequency doubled by the frequency doubling crystal 4, the fundamental frequency light transmitted from the resonant frequency doubling cavity 3 is incident into the semiconductor seed source 1 through the injection-lock coupling optical path 2 to form an injection lock.

[0028] In this embodiment, the fundamental frequency light transmitted from the resonant frequency doubling cavity 3 is injected into the semiconductor seed source 1 via the injection-lock coupling optical path 2 to form injection lock. This ensures that the seed light emitted from the semiconductor seed source 1 and the resonant frequency doubling cavity 3 are always in a resonant state, achieving automatic resonant frequency doubling. Compared to traditional resonant frequency doubling lasers, the laser in this embodiment does not require additional active optical and electrical control links to achieve automatic resonance between the seed light and the resonant frequency doubling cavity, achieving continuous high-efficiency transmitted laser output. The structure is simple, and traditional resonant frequency doubling laser schemes that require active locking require the fundamental frequency light to be a single-frequency laser. This embodiment does not have this requirement. The fundamental frequency light transmitted from the resonant frequency doubling cavity 3 can also operate by injecting and locking it in the semiconductor seed source 1 to form multiple modes resonating with the resonant frequency doubling cavity.

[0029] Please see Figure 3 and Figure 4 , Figure 3 This is a schematic diagram of an autoresonant frequency doubling laser based on an injection-locked semiconductor seed source, according to another embodiment of the present invention. Figure 4 This is a schematic diagram of the structure of an autoresonant frequency-doubling laser based on an injection-locked semiconductor seed source according to the third embodiment of the present invention. Figure 2 Compared to the Chinese embodiment, in Figure 3 and Figure 4 In one embodiment, the injection-locked coupling optical path 2 includes a backward coupling optical path 21, through which the fundamental frequency light transmitted from the resonant frequency doubling cavity 3 is incident on the semiconductor seed source.

[0030] Please see Figure 3 ,exist Figure 3 In this embodiment, the backward coupling optical path 21 includes a first backward coupling lens 211. The fundamental frequency light transmitted from the resonant frequency doubling cavity 3 is incident into the semiconductor seed source 1 through the first backward coupling lens 211. The fundamental frequency light transmitted from the resonant frequency doubling cavity 3 when it resonates is incident into the semiconductor seed source 1 through the spatial optical path to form an injection lock.

[0031] Please see Figure 4 ,exist Figure 4 In this embodiment, the backward coupling optical path 21 includes a second backward coupling lens 212 and a backward transmission optical fiber 213. The backward transmission optical fiber 213 is connected to the semiconductor seed source 1. The second backward coupling lens 212 is used to focus the fundamental frequency light transmitted and output when the resonant frequency doubling cavity 3 resonates into the backward transmission optical fiber 213. The fundamental frequency light transmitted and output by the resonant frequency doubling cavity 3 is incident into the semiconductor seed source 1 after passing through the second backward coupling lens 212 and the backward transmission optical fiber 213.

[0032] Please continue reading Figure 3 and Figure 4In a preferred embodiment, the resonant frequency doubling cavity 3 is a four-cavity mirror folded ring cavity. The resonant frequency doubling cavity 3 includes a first cavity mirror 31, a second cavity mirror 32, a third cavity mirror 33, and a fourth cavity mirror 34. The frequency doubling crystal 4 is located between the third cavity mirror 33 and the fourth cavity mirror 34. The seed light is transmitted and input from the first cavity mirror 31, oscillates in the resonant frequency doubling cavity 3, and is frequency doubled by the frequency doubling crystal 4. The fundamental frequency light transmitted and output from the first cavity mirror 31, the second cavity mirror 32, the third cavity mirror 33, or the fourth cavity mirror 34 is incident into the semiconductor seed source 1 through the backward coupling optical path 21. The target laser is transmitted and output from the fourth cavity mirror 34.

[0033] Preferably, the backward coupling optical path 21 is located between the third cavity mirror 33 and the semiconductor seed source 1, so that the path of the backward coupling optical path 21 is shorter.

[0034] Please continue reading Figure 3 and Figure 4 The laser also includes a first amplifier 51, which is used to amplify the laser light entering it by stimulated emission and increase the output power. The first amplifier 51 is located between the semiconductor seed source 1 and the resonant frequency doubling cavity 3. The seed light is incident into the resonant frequency doubling cavity 3 through the first amplifier 51.

[0035] exist Figure 3 In this embodiment, a spatial optical path exists between the semiconductor seed source 1 and the first amplifier 51. Figure 4 In this embodiment, the semiconductor seed source 1 and the first amplifier 51 are connected by a transmission optical fiber.

[0036] In practical applications, the backward coupling optical path 21 can also adopt other structures, as long as the fundamental frequency light transmitted from the resonant frequency doubling cavity 3 can be partially incident into the semiconductor seed source 1 through the backward coupling optical path 21. The resonant frequency doubling cavity 3 is not limited to a four-cavity mirror folded ring cavity, but can also be a resonant frequency doubling cavity of other structures. The fundamental frequency light transmitted from any cavity mirror of the resonant frequency doubling cavity is partially incident into the semiconductor seed source 1 through the backward coupling optical path 21 to form injection lock. The first amplifier 51 can be an amplifier with semiconductor material as the gain medium, an amplifier with optical fiber as the gain medium, an amplifier with solid crystal as the gain medium, etc.

[0037] Please see Figure 5 and Figure 6 , Figure 5 This is a schematic diagram of the structure of the autoresonant frequency doubling laser based on an injection-locked semiconductor seed source according to the fourth embodiment of the present invention. Figure 6 This is a schematic diagram of the structure of an autoresonant frequency-doubling laser based on an injection-locked semiconductor seed source according to the fifth embodiment of the present invention. Figure 1 Compared to the Chinese embodiment, in Figure 5 and Figure 6In the embodiment, the injection-locked coupling optical path 2 includes a backward coupling optical path 21' and a forward coupling optical path 22'. The backward coupling optical path 21' and the forward coupling optical path 22' are connected. The seed light is incident into the resonant frequency doubling cavity 3 through the forward coupling optical path 22'. The fundamental frequency light transmitted and output from the resonant frequency doubling cavity 3 is incident into the semiconductor seed source 1 after passing through the backward coupling optical path 21' and the forward coupling optical path 22'.

[0038] Please see Figure 5 ,exist Figure 5 In this embodiment, the forward coupling optical path 22' includes a partial transmission reflector 221', which is located between the semiconductor seed source 1 and the resonant frequency doubling cavity 3. The seed light is incident into the resonant frequency doubling cavity 3 through the partial transmission reflector 221'. The fundamental frequency light transmitted and output from the resonant frequency doubling cavity 3 passes through the backward coupling optical path 21' and the partial transmission reflector 221' in sequence before being incident into the semiconductor seed source 1.

[0039] The backward coupling optical path 21' can be adopted with Figure 3 The same structure as in the embodiment, namely the backward coupling optical path 21' includes a first backward coupling lens 211'. The fundamental frequency light transmitted and output from the resonant frequency doubling cavity 3 passes through the first backward coupling lens 211' and the partial transmission and reflection mirror 221' in sequence before being incident into the semiconductor seed source 1. The fundamental frequency light transmitted and output when the resonant frequency doubling cavity 3 resonates is incident into the semiconductor seed source 1 through the spatial optical path to form an injection lock.

[0040] Please continue reading Figure 5 The laser also includes a second amplifier 52, which is used to amplify the laser light entering it by stimulated emission and increase the output power. The second amplifier 52 is located between the partial transmission mirror 221' and the resonant frequency doubling cavity 3. The seed light passes through the partial transmission mirror 221' and the second amplifier 52 and then enters the resonant frequency doubling cavity 3.

[0041] Please see Figure 6 ,exist Figure 6 In this embodiment, the forward coupling optical path 22' includes an optical fiber circulator 222', which is located between the semiconductor seed source 1 and the resonant frequency doubling cavity 3. The backward coupling optical path 21' is connected to the optical fiber circulator 222'. The seed light is incident into the resonant frequency doubling cavity 3 through the optical fiber circulator 222'. The fundamental frequency light transmitted and output from the resonant frequency doubling cavity 3 passes through the backward coupling optical path 21' and the optical fiber circulator 222' in sequence before being incident into the semiconductor seed source 1.

[0042] The backward coupling optical path 21' can be adopted with Figure 4The same structure as in the embodiment, namely the backward coupling optical path 21' includes a second backward coupling lens 212' and a backward transmission optical fiber 213'. The backward transmission optical fiber 213' is connected to the optical fiber circulator 222'. The fundamental frequency light transmitted and output from the resonant frequency doubling cavity 3 passes through the second backward coupling lens 212', the backward transmission optical fiber 213', and the optical fiber circulator 222' in sequence before being incident on the semiconductor seed source 1.

[0043] Please continue reading Figure 6 The laser also includes a third amplifier 53, which is used to amplify the laser light entering it by stimulated emission and increase the output power. The third amplifier 53 is located between the fiber optic circulator 222' and the resonant frequency doubling cavity 3. The seed light is incident into the resonant frequency doubling cavity 3 through the fiber optic circulator 222' and the third amplifier 53.

[0044] Furthermore, the laser also includes a seed light coupling lens 6, which is used to shape the seed light. The seed light coupling lens 6 is located between the third amplifier 53 and the resonant frequency doubling cavity 3. The seed light is incident into the resonant frequency doubling cavity 3 through the fiber optic circulator 222', the third amplifier 53, and the seed light coupling lens 6.

[0045] exist Figure 5 In this embodiment, the spaces between the semiconductor seed source 1 and the partial transmission mirror 221', between the first rearward coupling lens 211' and the partial transmission mirror 221', and between the partial transmission mirror 221' and the second amplifier 52 are all spatial optical paths. Figure 6 In this embodiment, the semiconductor seed source 1 and the fiber optic circulator 222', the fiber optic circulator 222' and the third amplifier 53, and the fiber optic circulator 222' and the second backward coupling lens 212' are all connected by transmission optical fibers.

[0046] In practical use, regardless of whether injection lock is formed, the semiconductor seed source always has an output and will not damage the amplifier that depends on the input laser power; the forward coupling optical path 22' can also adopt other structures, as long as it can enable part of the fundamental frequency light to be incident on the semiconductor seed source 1 and output part of the laser at the same time.

[0047] Please continue reading Figure 5 or Figure 6 The resonant frequency doubling cavity 3 can be adopted with... Figure 3The same structure as in the embodiment is used, namely, the resonant frequency doubling cavity 3 is a four-cavity mirror folded ring cavity. The resonant frequency doubling cavity 3 includes a first cavity mirror 31', a second cavity mirror 32', a third cavity mirror 33', and a fourth cavity mirror 34'. The frequency doubling crystal 4 is located between the third cavity mirror 33' and the fourth cavity mirror 34'. The seed light is transmitted and input from the first cavity mirror 31', oscillates in the resonant frequency doubling cavity 3, and after being frequency doubled by the frequency doubling crystal 4, the fundamental frequency light transmitted and output from the third cavity mirror 33' passes through the backward coupling optical path 21' and the forward coupling optical path 22' in sequence before being incident on the semiconductor seed source 1. The target laser is transmitted and output from the fourth cavity mirror 34'.

[0048] The resonant frequency doubling cavity 3 can also be a resonant frequency doubling cavity of other structures. The fundamental frequency light portion transmitted and output by any cavity mirror of the resonant frequency doubling cavity is incident into the semiconductor seed source 1 through the backward coupling optical path 21' and the forward coupling optical path 22' to form injection lock.

[0049] This invention relates to an autoresonant frequency-doubled laser based on an injection-locked semiconductor seed source. By injecting the fundamental frequency light transmitted from the resonant frequency-doubled cavity into the semiconductor seed source via an injection-locked coupling optical path, injection locking is achieved. This ensures that the seed light emitted from the semiconductor seed source and the resonant frequency-doubled cavity remain in a resonant state, thus realizing automatic resonant frequency doubling. Compared to traditional resonant frequency-doubled lasers, this invention eliminates the need for additional active optical and electrical control links to achieve automatic resonance between the seed light and the resonant frequency-doubled cavity, resulting in continuous high-efficiency transmitted laser output. The structure is simple, and unlike traditional resonant frequency-doubled laser schemes that require active locking, which demand a single-frequency laser, this invention does not. The fundamental frequency light transmitted from the resonant frequency-doubled cavity can also operate by injecting and locking it in the semiconductor seed source to form multiple resonant modes with the resonant frequency-doubled cavity.

[0050] The present invention has been described by the above-described embodiments; however, these embodiments are merely examples for implementing the present invention. Furthermore, the technical features involved in the different embodiments of the present invention described above can be combined with each other as long as they do not conflict with each other. It must be pointed out that the disclosed embodiments do not limit the scope of the present invention. On the contrary, any modifications and refinements made without departing from the spirit and scope of the present invention are within the scope of patent protection of the present invention.

Claims

1. An automatic resonant frequency-doubled laser based on an injection-locked semiconductor seed source, characterized in that, The semiconductor seed source, the injection locking coupling light path, the resonant frequency doubling cavity and the frequency doubling crystal are included. The semiconductor seed source is used for emitting seed light. The frequency doubling crystal is located in the resonant frequency doubling cavity. The seed light is incident into the resonant frequency doubling cavity, oscillates in the resonant frequency doubling cavity, and after frequency doubling processing of the frequency doubling crystal, the fundamental frequency light transmitted from the resonant frequency doubling cavity is incident into the semiconductor seed source through the injection locking coupling light path to form injection locking.

2. The injection-locked semiconductor seed source based automatic frequency multiplication laser of claim 1, wherein, The injection locking coupling light path includes a backward coupling light path, and the fundamental frequency light transmitted from the resonant frequency doubling cavity is incident into the semiconductor seed source through the backward coupling light path.

3. The injection-locked semiconductor seed source based automatic frequency multiplication laser of claim 2, wherein, The backward coupling light path includes a first backward coupling lens, and the fundamental frequency light transmitted from the resonant frequency doubling cavity is incident into the semiconductor seed source through the first backward coupling lens.

4. The injection-locked semiconductor seed source based automatic frequency multiplication laser of claim 2, wherein, The backward coupling light path includes a second backward coupling lens and a backward transmission optical fiber, the backward transmission optical fiber is connected with the semiconductor seed source, and the fundamental frequency light transmitted from the resonant frequency doubling cavity is incident into the semiconductor seed source through the second backward coupling lens and the backward transmission optical fiber.

5. The injection-locked semiconductor seed source based automatic frequency multiplication laser of claim 2, wherein, A first amplifier is further included, the first amplifier is located between the semiconductor seed source and the resonant frequency doubling cavity, and the seed light is incident into the resonant frequency doubling cavity through the first amplifier.

6. The injection-locked semiconductor seed source based automatic frequency multiplication laser of claim 2, wherein, The injection locking coupling light path further includes a forward coupling light path, the backward coupling light path is connected with the forward coupling light path, the seed light is incident into the resonant frequency doubling cavity through the forward coupling light path, and the fundamental frequency light transmitted from the resonant frequency doubling cavity is incident into the semiconductor seed source through the backward coupling light path and the forward coupling light path. The forward coupling light path includes a partially transmitting mirror, the partially transmitting mirror is located between the semiconductor seed source and the resonant frequency doubling cavity, the seed light is incident into the resonant frequency doubling cavity through the partially transmitting mirror, and the fundamental frequency light transmitted from the resonant frequency doubling cavity is incident into the semiconductor seed source in sequence through the backward coupling light path and the partially transmitting mirror.

7. The injection-locked semiconductor seed source based automatic frequency multiplication laser of claim 2, wherein, The injection locking coupling light path further includes a forward coupling light path, the backward coupling light path is connected with the forward coupling light path, the seed light is incident into the resonant frequency doubling cavity through the forward coupling light path, and the fundamental frequency light transmitted from the resonant frequency doubling cavity is incident into the semiconductor seed source through the backward coupling light path and the forward coupling light path. The forward coupling light path includes a fiber loop, the fiber loop is located between the semiconductor seed source and the resonant frequency doubling cavity, the backward coupling light path is connected with the fiber loop, the seed light is incident into the resonant frequency doubling cavity through the fiber loop, and the fundamental frequency light transmitted from the resonant frequency doubling cavity is incident into the semiconductor seed source in sequence through the backward coupling light path and the fiber loop.

8. The injection-locked semiconductor seed source based automatic frequency multiplication laser of claim 7, wherein, A second amplifier is further included, the second amplifier is located between the fiber loop and the resonant frequency doubling cavity, and the seed light is incident into the resonant frequency doubling cavity through the fiber loop and the second amplifier.

9. The injection-locked semiconductor seed source based automatic frequency multiplication laser of claim 8, wherein, A seed light coupling lens is further included between the second amplifier and the resonant frequency-doubling cavity, and the seed light is incident into the resonant frequency-doubling cavity through the optical fiber circulator, the second amplifier and the seed light coupling lens.

Images