CN115912031A - Integrated external cavity laser and use method - Google Patents

Abstract

The invention discloses an integrated external cavity laser and a using method thereof, relating to the technical field of optical communication and photonic integrated devices, wherein the integrated external cavity laser comprises a pumping light source, a coupling module and an external cavity module; the coupling module is used for coupling the pump light signal output by the pump light source into the external cavity module; the external cavity module is used for gaining the pump light signals, dividing the gained light signals into two paths to respectively adjust the splitting ratio between the two paths of light, combining the two paths of light signals, and outputting the combined light signals and returning the combined light signals to gain again. The invention can provide on-chip gain and improve the emergent power of the external cavity laser under the condition that the performance of the existing integrated device is limited.

Description

Integrated external cavity laser and use method

Technical Field

The invention relates to the technical field of optical communication and photonic integrated devices, in particular to an integrated external cavity laser and a using method thereof.

Background

Tunable lasers have important applications in wavelength division multiplexing systems of optical communication networks as well as coherent optical communication systems. As an important implementation method of a tunable laser, the external cavity laser has the advantages of a large wavelength tunable range, a high side mode suppression ratio, a narrow line width, high temperature stability and the like, and has been applied in a relatively large scale.

Besides the advantages, the integrated external cavity laser also has the advantages of low power consumption, small size and the like of an integrated device, can be integrated into a complex photoelectric chip as an on-chip light source, and has great scientific research and commercial application values.

However, limited by the performance of the on-chip device, the performance of the current integrated external cavity laser, such as the line width and the side mode suppression ratio, is difficult to be greatly improved.

Disclosure of Invention

In view of the defects in the prior art, a first aspect of the present invention provides a method for increasing the on-chip gain and the output power of an external cavity laser under the condition that the performance of the existing integrated device is limited.

In order to achieve the purpose, the invention adopts the technical scheme that:

an integrated external cavity laser comprising: the device comprises a pumping light source, a coupling module and an external cavity module;

the coupling module is used for coupling the pump light signal output by the pump light source into the external cavity module;

the external cavity module is used for gaining the pump light signal, dividing the gained light signal into two paths to respectively adjust the splitting ratio between the two paths of light, combining the two paths of light signals, and using part of the combined light signal for output and part of the combined light signal for returning to gain again.

In some embodiments, the external cavity module comprises:

the coupling unit is connected with the coupling module;

the gain module is connected with the coupling unit and is used for gaining the pump light signal;

the high-Q resonant cavity module is connected with the gain module and used for filtering the pumping optical signal, outputting a gained optical signal and selecting a laser mode;

the adjustable light splitting module is connected with the high Q resonant cavity module and is used for splitting the gained optical signal into two paths and adjusting the light splitting ratio between the two paths of light;

and the beam combining module is connected with the adjustable light splitting module and the gain module and is used for combining two paths of light split by the adjustable light splitting module into one path, inputting one part of the combined optical signal back to the gain module and outputting the other part of the combined optical signal.

In some embodiments, the high-Q cavity module comprises:

the uploading and downloading micro-ring is provided with a hot electrode;

the first waveguide is connected with the gain module and used for coupling the output of the gain module into the uploading and downloading micro-ring, and the uploading and downloading micro-ring adjusts the resonant wavelength through a thermode to filter the pumping optical signal;

and the second waveguide is matched with the first waveguide to enclose the uploading and downloading micro-ring, and is connected with the adjustable light splitting module and used for coupling the gained optical signal into the adjustable light splitting module.

In some embodiments, the tail ends of the first waveguide and the second waveguide are provided with an anti-reflection structure.

In some embodiments, the tunable optical splitting module comprises:

the first multimode interferometer is used for dividing the gained optical signals transmitted by the second waveguide into two paths;

the third waveguide is connected with one path of the first multimode interferometer, and a hot electrode is arranged on the first waveguide;

the fourth waveguide is connected with the other path of the first multimode interferometer, a hot electrode is arranged on the fourth waveguide, and the fourth waveguide and the third waveguide are equal in length;

the second multimode interferometer is connected with the third waveguide and the fourth waveguide and divides the optical signals transmitted by the third waveguide and the fourth waveguide into two paths again;

the fifth waveguide is connected with one path of the second multimode interferometer, and a hot electrode is arranged on the fifth waveguide;

and the sixth waveguide is connected with the other path of the second multimode interferometer, a thermode is arranged on the sixth waveguide, and the fifth waveguide and the sixth waveguide are equal in length.

In some embodiments, the beam combining module comprises a third multimode interferometer and a fourth multimode interferometer;

the third multimode interferometer is connected with the fifth waveguide and the sixth waveguide and is used for combining the optical signals output by the fifth waveguide and the sixth waveguide, and part of the combined optical signals are used for output and part of the combined optical signals are input to the fourth multimode interferometer;

one input port of the fourth multimode interferometer is connected with the third multimode interferometer, the other input port of the fourth multimode interferometer is connected with the coupling unit, and an output port of the fourth multimode interferometer is connected with the gain module.

In some embodiments, the coupling unit is a spot-size converter.

In some embodiments, the gain module is an erbium doped waveguide amplifier.

In some embodiments, the coupling module is a lens.

The second aspect of the present invention provides a method for using the integrated external cavity laser, which can provide on-chip gain and improve the output power of the external cavity laser under the condition that the performance of the existing integrated device is limited.

In order to achieve the purpose, the invention adopts the technical scheme that:

a method of using an integrated external cavity laser as described above, the method comprising the steps of:

the external cavity module is used for gaining the pump light signals, the gained light signals are divided into two paths, and the splitting ratio between the two paths of light is adjusted to form a PT symmetry broken state;

controlling conditions to enable only one selected mode to meet a PT symmetry breaking state so as to concentrate energy to the selected mode;

and changing the mode selected in the PT symmetry deficiency state by changing the resonance frequency of the external cavity module, and then changing the wavelength of emergent light.

Compared with the prior art, the invention has the advantages that:

the integrated external cavity laser comprises a pumping light source, a coupling module and an external cavity module. The pump light signal generated by the pump light source is coupled into the external cavity module through the coupling module and the coupling unit, and enters the gain module to generate a gain effect on the optical signal with the corresponding wavelength. The gained optical signal and the pump optical signal pass through the high Q resonant cavity module at the same time, the pump optical signal is filtered, and the mode of the laser is selected. The optical signal after gain enters the adjustable light splitting module, the optical signal is divided into two paths with equal length, the two paths of signals are combined into one path through the beam combining module, and the path returns to the gain module, so that two loops with equal physical length are formed. By adjusting the splitting ratio when the two loops are divided into two paths, the two loops meet PT symmetrical breaking conditions, a single mode can be further excited, and a side touch is inhibited. By adjusting the resonant wavelength of the high-Q resonant cavity to align with the characteristic wavelength of the gain module, PT symmetry breaking can be selectively controlled, and an excited mode can be aligned with the resonant wavelength of the high-Q resonant cavity, so that laser with high emergent power, narrow line width and high side mode suppression ratio can be excited.

Drawings

FIG. 1 is a block diagram of an integrated external cavity laser according to an embodiment of the present invention;

FIG. 2 is a block diagram of an outer chamber module according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of an external chamber module according to an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of an integrated external cavity laser in one embodiment of the present invention;

fig. 5 is a flow chart of a method of using an integrated external cavity laser in an embodiment of the present invention.

In the figure: 1. a pump light source; 2. a coupling module; 3. an outer cavity module; 31. a coupling unit; 32. a gain module; 33. a high Q resonant cavity module; 331. uploading and downloading micro-rings; 332. a first waveguide; 333. a second waveguide; 334. an anti-reflection structure; 34. an adjustable light splitting module; 341. a first multimode interferometer; 342. a third waveguide; 343. a fourth waveguide; 344. a second multimode interferometer; 345. a fifth waveguide; 346. a sixth waveguide; 35. a beam combining module; 351. a third multimode interferometer; 352. a fourth multimode interferometer; 36. an exit port; 4. a thermode.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Referring to fig. 1, an embodiment of the present invention discloses an integrated external cavity laser, which includes a pump light source 1, a coupling module 2, and an external cavity module 3.

The coupling module 2 is configured to couple a pump light signal output by the pump light source 1 into the external cavity module 3; the external cavity module 3 is configured to gain the pump light signal, divide the gained light signal into two paths, and adjust the splitting ratio between the two paths of light, and the external cavity module 3 is further configured to combine the light signals divided into two paths, and use part of the combined light signal for output and part of the combined light signal for returning to gain again.

Specifically, the pump light source 1 is connected to the coupling module 2, and the coupling module 2 is connected to the external cavity module 3. The external cavity module 3 is a monolithically integrated system on chip, which may be based on a silicon nitride material system, or may be silicon, silicon oxide, or other material systems commonly used in the art.

The pump light source 1, the coupling module 2 and the external cavity module 3 may be monolithically integrated by a heterogeneous integration technology, a hybrid integration technology or other integration technologies commonly used in the art.

The light emitted by the pump light source 1 in the embodiment of the present invention is input into the external cavity module 3 through the coupling module 2, and the generated laser light exits from the external cavity module 3. The external cavity module 3 can realize optical amplification, can select a laser mode by utilizing PT (space symmetry-time) symmetry break, greatly optimizes a mode selection effect by combining a mode selection effect of a high-Q resonant cavity, and realizes a laser signal with high power, narrow bandwidth and high side mode suppression ratio.

In a specific implementation, the pump light source 1 may be a laser, and the coupling module 2 is a lens.

Referring to fig. 2, the external cavity module 3 includes a coupling unit 31, a gain module 32, a high-Q cavity module 33, a tunable light splitting module 34, a beam combining module 35, and an exit port 36.

Wherein, the coupling unit 31 is connected with the coupling module 2; the gain module 32 is connected to the coupling unit 31 and is configured to gain the pump light signal; the high-Q resonant cavity module 33 is connected to the gain module 32, and is configured to filter the pump light signal, output a gained light signal, and select a laser mode; the adjustable light splitting module 34 is connected with the high-Q resonant cavity module 33, and is configured to split the gained optical signal into two paths and adjust a splitting ratio between the two paths of light; the beam combining module 35 is connected to the tunable optical splitting module 34, the gain module 32 and the exit port 36, and is configured to combine two paths of light split by the tunable optical splitting module 34 into one path, input a part of the combined optical signal back to the gain module 32, and output the other part of the combined optical signal from the exit port 36. Thus, the gain module 32, the high-Q cavity module 33, the tunable splitting module 34, and the beam combining module 35 are connected in a ring shape to form the main body of the external cavity laser cavity.

The coupling unit 31 is used for coupling the light input by the coupling module 2 into the system on chip and transmitting the light to the gain module 32. The coupling unit 31 may be implemented using a spot-size converter or other techniques commonly used in the art. The gain block 32 is used to generate on-chip gain and may be implemented based on erbium doped waveguide amplifier technology or other techniques commonly used in the art.

The high-Q cavity module 33 includes an up-down loading type micro-ring 331, a first waveguide 332, a second waveguide 333, and an anti-reflection structure 334.

Wherein, the upload and download micro-ring 331 is provided with a thermode 4; the first waveguide 332 is connected to the gain module 32 and is configured to couple the output of the gain module 32 into the upload and download microring 331, and the upload and download microring 331 adjusts the resonant wavelength through the thermode 4 to filter the pump light signal; the second waveguide 333 is matched with the first waveguide 332 to enclose the upload and download microring 331, and the second waveguide 333 is connected to the tunable optical splitting module 34, and is configured to couple the gained optical signal into the tunable optical splitting module 34. The tail ends of the first waveguide 332 and the second waveguide 333 are each provided with an antireflection structure.

The adjustable light splitting module 34 splits the light output by the high-Q resonant cavity module 33 into two paths, and can arbitrarily adjust the splitting ratio between the two paths of light, and the effect can be achieved by using an adjustable mach-zehnder interferometer (MZI), an adjustable directional coupler, or other methods commonly used in the art. In the present embodiment, the tunable optical splitting module 34 includes a first multi-mode interferometer 341, a third waveguide 342, a fourth waveguide 343, a second multi-mode interferometer 344, a fifth waveguide 345, and a sixth waveguide 346.

The first multimode interferometer 341 is configured to divide the gained optical signal transmitted by the second waveguide 333 into two paths; the third waveguide 342 is connected to one path of the first multimode interferometer 341, and the third waveguide 342 is provided with a hot electrode 4; the fourth waveguide 343 is connected to the other path of the first multimode interferometer 341, the hot electrode 4 is disposed on the fourth waveguide 343, and the fourth waveguide 343 and the third waveguide 342 have equal length; the second multimode interferometer 344 is connected to the third waveguide 342 and the fourth waveguide 343, and splits the optical signals transmitted by the third waveguide 342 and the fourth waveguide 343 into two paths again; the fifth waveguide 345 is connected with one path of the second multimode interferometer 344, and the fifth waveguide 345 is provided with a hot electrode 4; the sixth waveguide 346 is connected to the other path of the second multi-mode interferometer 344, the hot electrode 4 is disposed on the sixth waveguide 346, and the fifth waveguide 345 and the sixth waveguide 346 have the same length.

The beam combining module 35 is configured to combine the two paths of light split by the tunable light splitting module 34 into one path, and input a part of the one path of light back to the gain module 32 and input another part of the one path of light to the exit port 36. In the present embodiment, the beam combining module 35 includes a third multimode interferometer 351 and a fourth multimode interferometer 352.

The third multimode interferometer 351 is connected to the fifth waveguide 345 and the sixth waveguide 346, and is configured to combine the optical signals output by the fifth waveguide 345 and the sixth waveguide 346, and use part of the combined optical signal for output and input part of the combined optical signal to the fourth multimode interferometer 352; one input port of the fourth multimode interferometer 352 is connected to the third multimode interferometer 351, the other input port is connected to the coupling unit 31, and an output port of the fourth multimode interferometer 352 is connected to the gain block 32.

The exit port 36 is used to emit the generated laser signal out of the chip. May be implemented using a spot-size converter, grating, or other methods commonly used by those skilled in the art.

In some embodiments, referring to fig. 3, the specific structure of the external cavity module 3 includes: a spot-size converter (coupling unit) 31, a 2 × 1 fourth multimode interferometer 352, an erbium-doped waveguide amplifier (gain module) 32, an up-loading and down-loading microring 331, an anti-reflection structure 334, a 1 × 2 first multimode interferometer (MMI) 341, a 2 × 2 second multimode interferometer 344, a 2 × 2 third multimode interferometer 351, a spot-size converter (exit port) 36, and a hot electrode 4.

The working principle of an embodiment of the invention is described below with reference to fig. 4:

laser (pump light source) 1 emits light with wavelength lambda ₁ The light is converged on a spot-size converter (coupling unit) 31 through a lens (coupling module) 2, and is input into an erbium-doped waveguide amplifier (gain module) 32 through one input port of a fourth multimode interferometer 352, so as to excite the light with a wavelength of lambda ₂ Of optical signal of wavelength lambda ₁ And λ ₂ The light passes through the upload/download micro-ring 331, and the resonance wavelength of the upload/download micro-ring 331 is adjusted by the hot electrode 4 thereon to be equal to λ ₂ Align and will lambda ₁ Filtered out and other light is absorbed by the anti-reflective structure 334. Wavelength of λ ₂ The optical signal of (1) is divided into two paths with equal length by the first multimode interferometer 341, the phase difference between the two paths is changed by the hot electrode 4 on the third waveguide 342 and the fourth waveguide 343, and the optical signal of (2) is divided into two paths by the second multimode interferometer 344, and the splitting ratio between the two paths is related to the phase difference caused by the hot electrode 4 on the third waveguide 342 and the fourth waveguide 343. After the tunable light splitting, a part of the two optical signals pass through the third multimode interferometer 351 and are input to the exit port 36, and a part of the two optical signals pass through the fourth multimode interferometer 352, so that the optical paths form a complete resonant cavity.

After passing through the second multimode interferometer 344, the resonant cavity splits into two loops with the same physical length but different optical powers and coupled to each other, and when one loop generates gain and the other loop generates loss by adjusting the splitting ratio, the mode in the loop can be expressed as follows according to the PT symmetry principle:

wherein ω is _n Is the eigenfrequency of the nth mode, g _n And alpha _n The gain and loss in the two loops, κ, of the nth mode, respectively _n Is the coupling coefficient between the two loops. When the splitting ratio is adjusted to make the gain and loss satisfy g _n ＝-α _n When, the above formula can be rewritten as:

the PT symmetry condition is satisfied at this time. When the loop gain is larger than the coupling coefficient, i.e. g _n >κ _n During the process, PT symmetry is broken, a pair of conjugate amplification and attenuation eigenmodes are generated, the gain obtained by the amplification mode is far larger than that of other modes, single-mode lasing is achieved, and the line width of the laser can be further narrowed on the basis of uploading and downloading mode selection of the micro-ring 331. When the control condition makes only one selected mode meet PT symmetrical defect state, the energy is concentrated to the selected modeSince the other modes are suppressed by the conservation of energy in the modes, the edge-mode suppression ratio of the emitted laser beam can be improved. The resonant wavelength of the uploading and downloading micro-ring 331 is changed by adjusting the voltage of the hot electrode 4 applied to the uploading and downloading micro-ring 331, so that the mode selected in the PT symmetrical defect state can be changed, the emergent light wavelength of the laser is changed, and the wavelength can be adjusted. When the wavelength is adjusted to the gain wavelength lambda of the erbium-doped waveguide amplifier (gain block) 32 ₂ During alignment, the power of the emitted laser can be further increased.

In summary, the integrated external cavity laser in the present invention includes a pumping light source 1, a coupling module 2 and an external cavity module 3. The pump light signal generated by the pump light source 1 is coupled into the external cavity module 3 through the coupling module 2 and the coupling unit 31, and the pump light signal enters the gain module 32 to generate a gain effect on the light signal with a corresponding wavelength. The gained optical signal and the pump optical signal pass through the high-Q cavity module 33 at the same time, the pump optical signal is filtered, and the mode of the laser is selected. The optical signal after gain enters the adjustable optical splitting module 34, and the optical signal is split into two equal paths, and then the two paths of signals are combined into one path by the beam combining module 35, and the path returns to the gain module 32, so that two loops with the same physical length are formed. By adjusting the splitting ratio when the two loops are divided into two paths, the two loops meet PT symmetrical breaking conditions, single mode can be further excited, and side touch is inhibited. By adjusting the resonant wavelength of the high-Q resonant cavity to align the resonant wavelength of the high-Q resonant cavity with the characteristic wavelength of the gain module, PT symmetry breaking can be selectively controlled, and an excited mode is aligned with the resonant wavelength of the high-Q resonant cavity, so that laser with high emergent power, narrow line width and high side mode rejection ratio is excited.

Referring to fig. 5, an embodiment of the present invention further discloses a method for using the integrated external cavity laser, where the method includes the following steps:

s1, the external cavity module is used for gaining the pump light signal, the gained light signal is divided into two paths, and the splitting ratio between the two paths of light is adjusted to form a PT symmetrical defect state.

And S2, controlling conditions to enable only one selected mode to meet the PT symmetry deficiency state so as to concentrate energy to the selected mode.

And S3, changing the mode selected in the PT symmetry deficiency state by changing the resonance frequency of the external cavity module, and then changing the wavelength of emergent light.

Specifically, the specific structure of the external cavity module 3 includes: a spot size converter (coupling unit) 31, a 2 × 1 fourth multimode interferometer (MMI) 352, an erbium-doped waveguide amplifier (gain module) 32, an upload-download microring 331, an anti-reflection structure 334, a 1 × 2 first multimode interferometer 341, a 2 × 2 second multimode interferometer 344, a 2 × 2 third multimode interferometer 351, a spot size converter (exit port) 36, and a hot electrode 4.

Laser (pump light source) 1 emits light with wavelength lambda ₁ The light is converged on a spot size converter (coupling unit) 31 through a lens (coupling module) 2, and is input into an erbium-doped waveguide amplifier (gain module) 32 through an input port of a fourth multimode interferometer 352, so as to excite the wavelength of lambda ₂ Of optical signal of wavelength lambda ₁ And λ ₂ The light passes through the upload/download micro-ring 331, and the resonance wavelength of the upload/download micro-ring 331 is adjusted by the hot electrode 4 thereon to be equal to λ ₂ Align and will lambda ₁ Filtered out and the other light is absorbed by the anti-reflective structure 334. Wavelength of λ ₂ The optical signal is divided into two equal-length paths by the first multimode interferometer 341, the phase difference between the two paths is changed by the hot electrode 4 on the third waveguide 342 and the fourth waveguide 343, and the optical signal is divided into two paths by the second multimode interferometer 344, and the splitting ratio between the two paths is related to the phase difference caused by the hot electrode 4 on the third waveguide 342 and the fourth waveguide 343. After the tunable light splitting, a part of the two optical signals pass through the third multi-mode interferometer 351 and are input to the exit port 36, and a part of the two optical signals pass through the fourth multi-mode interferometer 352, so that the optical paths form a complete resonant cavity.

After passing through the second multimode interferometer 344, the resonant cavity splits into two loops with the same physical length but different optical powers and coupled to each other, and when one loop generates gain and the other loop generates loss by adjusting the splitting ratio, the mode in the loop can be expressed as follows according to the PT symmetry principle:

wherein ω is _n Is the eigenfrequency of the nth mode, g _n And alpha _n The gain and loss in the two loops, κ, of the nth mode, respectively _n Is the coupling coefficient between the two loops. When the splitting ratio is adjusted to make the gain and loss satisfy g _n ＝-α _n When, the above formula can be rewritten as:

the PT symmetry condition is satisfied at this time. When the loop gain is greater than the coupling coefficient, i.e. g _n >κ _n During the process, PT symmetry is broken, a pair of conjugate amplification and attenuation eigenmodes is generated, the gain obtained by the amplification mode is far larger than that of other modes, so that single-mode lasing is realized, and the line width of the laser can be further narrowed on the basis of mode selection of the uploading and downloading micro-ring 331. When only one selected mode meets the PT symmetrical breaking state under the control condition, the energy is concentrated in the selected mode, and other modes are inhibited according to energy conservation, so that the side-touch inhibition ratio of the emitted laser can be improved. The resonant wavelength of the uploading and downloading micro-ring 331 is changed by adjusting the voltage of the thermode 4 applied to the uploading and downloading micro-ring 331, so that the mode selected in the PT symmetrical breaking state can be changed, the emergent light wavelength of the laser is changed, and wavelength adjustment is realized. When the wavelength is adjusted to the gain wavelength lambda of the erbium-doped waveguide amplifier (gain block) 32 ₂ During alignment, the power of the emitted laser can be further increased.

The above description is merely exemplary of the present application and is presented to enable those skilled in the art to understand and practice the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. An integrated external cavity laser, comprising: the device comprises a pumping light source, a coupling module and an external cavity module;

the coupling module is used for coupling the pump light signal output by the pump light source into the external cavity module;

the external cavity module is used for gaining the pump light signals, dividing the gained light signals into two paths to respectively adjust the splitting ratio between the two paths of light, combining the light signals divided into the two paths, and using part of the combined light signals for output and part of the combined light signals for returning to gain again.

2. An integrated external cavity laser as claimed in claim 1, wherein said external cavity module comprises:

the coupling unit is connected with the coupling module;

the gain module is connected with the coupling unit and is used for gaining the pump light signal;

the high-Q resonant cavity module is connected with the gain module and used for filtering the pumping optical signal, outputting a gained optical signal and selecting a laser mode;

the adjustable light splitting module is connected with the high Q resonant cavity module and is used for splitting the gained optical signal into two paths and adjusting the light splitting ratio between the two paths of light;

and the beam combining module is connected with the adjustable light splitting module and the gain module and is used for combining two paths of light split by the adjustable light splitting module into one path, inputting one part of the combined optical signal back to the gain module and outputting the other part of the combined optical signal.

3. An integrated external cavity laser as claimed in claim 2, wherein said high Q cavity module comprises:

the uploading and downloading micro-ring is provided with a hot electrode;

the first waveguide is connected with the gain module and used for coupling the output of the gain module into the uploading and downloading micro-ring, and the uploading and downloading micro-ring adjusts the resonance wavelength through a thermode to filter the pump light signal;

and the second waveguide is matched with the first waveguide to enclose the uploading and downloading micro-ring, and is connected with the adjustable light splitting module and used for coupling the gained optical signal into the adjustable light splitting module.

4. An integrated external cavity laser as claimed in claim 3, wherein: and the tail ends of the first waveguide and the second waveguide are provided with anti-reflection structures.

5. An integrated external cavity laser as claimed in claim 3, wherein said tunable splitting module comprises:

the first multimode interferometer is used for dividing the gained optical signals transmitted by the second waveguide into two paths;

the third waveguide is connected with one path of the first multimode interferometer, and a hot electrode is arranged on the first waveguide;

a fourth waveguide connected to the other path of the first multimode interferometer, the fourth waveguide having a hot electrode thereon, and the fourth waveguide being equal in length to the third waveguide;

the second multimode interferometer is connected with the third waveguide and the fourth waveguide and divides the optical signals transmitted by the third waveguide and the fourth waveguide into two paths again;

the fifth waveguide is connected with one path of the second multimode interferometer, and a hot electrode is arranged on the fifth waveguide;

and the sixth waveguide is connected with the other path of the second multimode interferometer, a thermode is arranged on the sixth waveguide, and the fifth waveguide and the sixth waveguide are equal in length.

6. An integrated external cavity laser as claimed in claim 4 wherein said beam combining module comprises a third and a fourth multimode interferometer;

the third multimode interferometer is connected with the fifth waveguide and the sixth waveguide and used for combining the optical signals output by the fifth waveguide and the sixth waveguide, and part of the combined optical signals are used for output and part of the combined optical signals are input to the fourth multimode interferometer;

one input port of the fourth multi-mode interferometer is connected with the third multi-mode interferometer, the other input port of the fourth multi-mode interferometer is connected with the coupling unit, and the output port of the fourth multi-mode interferometer is connected with the gain module.

7. An integrated external cavity laser as claimed in claim 2 wherein the coupling element is a spot-size converter.

8. An integrated external cavity laser as claimed in claim 1, wherein: the gain module is an erbium-doped waveguide amplifier.

9. An integrated external cavity laser as claimed in claim 1, wherein: the coupling module is a lens.

10. A method of using the integrated external cavity laser of claim 1, comprising the steps of:

the external cavity module is used for gaining the pump light signal, the gained light signal is divided into two paths, and the splitting ratio between the two paths of light is adjusted to form a PT symmetrical defect state;

controlling conditions to enable only one selected mode to meet a PT symmetry breaking state so as to concentrate energy to the selected mode;

and changing the mode selected in the PT symmetry deficiency state by changing the resonance frequency of the external cavity module, and then changing the wavelength of emergent light.

Images