A high frequency high energy pulse single frequency laser

Abstract

The application provides a high-frequency high-energy pulse single-frequency laser, a seed source unit, a semiconductor optical amplification unit arranged on an output light path and a passive modulation device unit arranged on a modulation light path, and the passive modulation device unit comprises a semiconductor saturable absorber mirror. The application adopts a single-frequency semiconductor seed source and MOPA amplification, and then utilizes a saturable absorber to realize a hybrid high-energy pulse single-frequency laser of passive self-mode locking, and is particularly applicable to quantum navigation and high-spectral resolution radar.

Description

Technical Field

[0001] This invention relates to the field of laser technology, and more specifically, to a high-frequency, high-energy pulsed single-frequency laser. Background Technology

[0002] Single-frequency lasers play an irreplaceable role in quantum navigation. However, while semiconductor lasers possess excellent single-frequency performance, they struggle to achieve high power output. Therefore, power amplification modules are essential. MOPA amplification is a relatively mature and effective solution, achieving watt-level power output with a single-stage amplification. (See [reference needed]). Figure 1 This method requires only two active optical devices and a few passive optical devices, resulting in low system complexity. Furthermore, it directly employs electro-optical conversion for power amplification, leading to low system power consumption. However, it is difficult for this type of high-power single-frequency fiber laser to achieve high-energy pulse output. Summary of the Invention

[0003] This invention addresses the technical problems existing in the prior art by providing a high-frequency, high-energy pulsed single-frequency laser, comprising a seed source unit, a semiconductor optical amplification unit arranged in the output optical path, and a passive modulation device unit arranged in the modulation optical path, wherein the passive modulation device unit comprises a semiconductor saturable absorber mirror.

[0004] The seed source unit outputs a single-frequency seed laser. After the power of the single-frequency seed laser is amplified by the semiconductor optical amplification unit, the first seed laser is directly output through the output optical path. The second seed laser is focused on the semiconductor saturable absorber mirror through the modulation optical path. The semiconductor saturable absorber mirror generates a pulse, and the pulse is reflected by the semiconductor saturable absorber mirror to modulate the first seed laser, so that all seed laser outputs are pulsed single-frequency lasers.

[0005] Based on the above technical solution, the present invention can also be improved as follows.

[0006] Optionally, the output optical path is further provided with a first half-wave plate, a rectangular lens, a second half-wave plate, a polarizing beam splitter, and a third half-wave plate in sequence. A first optical isolator is provided between the seed source unit and the first half-wave plate, and a second optical isolator is provided after each of the third half-wave plates. The semiconductor optical amplification unit is provided between the first half-wave plate and the rectangular lens.

[0007] The single-frequency distributed feedback semiconductor laser seed source is used to output seed laser;

[0008] The first optical isolator is used to isolate the backscattered light of the seed laser;

[0009] The first half-wave plate is used to control the polarization direction of the laser injected into the semiconductor optical amplification unit;

[0010] The semiconductor optical amplification unit is used to amplify the power of the seed laser to the watt level;

[0011] The rectangular lens is used to shape the magnified linear beam into a point shape;

[0012] The polarizing beam splitter, the second half-wave plate, and the third half-wave plate are used to split the laser beam into two paths. The first path is output through the second optical isolator, and the second path is output through the modulation optical path.

[0013] Optionally, an aspherical focusing mirror is further disposed between the semiconductor saturable absorber mirrors in the modulation optical path. The aspherical focusing mirror is used to focus parallel light, and the semiconductor saturable absorber mirror is a total reflection mirror used to achieve passive mode-locked output and modulate the laser in the output optical path.

[0014] Optionally, the seed source unit is a single-frequency distributed feedback semiconductor laser seed source.

[0015] Optionally, the seed source unit is a DFB / DBR single-frequency fiber laser seed source, which outputs a single-frequency laser in the range of 10mW.

[0016] Optionally, the seed source unit, the first optical isolator, the first half-wave plate, the second half-wave plate, the polarizing beam splitter, the third half-wave plate, and the second optical isolator have the same frequency.

[0017] This invention provides a high-frequency, high-energy pulsed single-frequency laser, which is a hybrid high-power, high-energy single-frequency laser that combines a high-power amplifier, a semiconductor laser, and a saturable absorber. It combines the advantages of single-frequency semiconductor lasers and passively mode-locked pulsed lasers. Without affecting the single-frequency performance of the laser, it simplifies the optical path structure, reduces the number of active optical devices, and reduces system power consumption and system complexity, thus better meeting the needs of practical applications. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a high-power single-frequency semiconductor laser in the prior art;

[0019] Figure 2 This is a schematic diagram of the composition and structure of a high-frequency, high-energy pulsed single-frequency laser provided by the present invention.

[0020] In the attached diagram, the component names represented by each number are as follows:

[0021] 1. Seed source for a 780nm single-frequency distributed feedback semiconductor laser; 2. First 780nm optical isolator; 3. First 780nm half-wave plate; 4. Conical optical amplifier; 5. Rectangular lens; 6. Second 780nm half-wave plate; 7. 780nm polarizing beam splitter; 8. Third 780nm half-wave plate; 9. Second 780nm optical isolator; 10. Aspherical focusing mirror; 11. Semiconductor saturable absorber mirror. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In addition, the technical features of the various embodiments or individual embodiments provided by the present invention can be arbitrarily combined with each other to form feasible technical solutions. Such combinations are not constrained by the order of steps and / or structural composition patterns, but must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0023] Since existing high-power single-frequency fiber lasers are difficult to achieve high-energy pulse output, this invention utilizes a saturable absorber to achieve high-energy, high-power, and high-quality laser output with good single-frequency characteristics.

[0024] Using saturable absorbers to achieve passive modulation and output Q-switched or mode-locked pulsed lasers has always been a good solution for pulsed lasers. Saturable absorbers are relatively cheaper than the devices required for active modulation, and their optical path is simpler.

[0025] See Figure 2 The present invention provides a high-frequency, high-energy pulsed single-frequency laser, which mainly includes a seed source unit, a semiconductor optical amplification unit arranged in the output optical path, and a passive modulation device unit arranged in the modulation optical path. The passive modulation device unit includes a semiconductor saturable absorber mirror.

[0026] The seed source unit outputs a single-frequency seed laser. After the semiconductor optical amplification unit amplifies the power of the single-frequency seed laser, the first seed laser is directly output through the output optical path. The second seed laser is focused onto a semiconductor saturable absorber mirror through a modulation optical path. The semiconductor saturable absorber mirror generates a pulse, and the pulse is reflected by the semiconductor saturable absorber mirror to modulate the first seed laser, so that all seed laser outputs are pulsed single-frequency lasers.

[0027] Understandably, the laser provided by this invention mainly comprises three parts: a seed source unit, a semiconductor optical amplifier unit, and a passive modulation device unit, all of which are spatial optical structures. A seed laser is output from the seed source, the semiconductor optical amplifier amplifies the power, and finally the laser is focused onto a semiconductor saturable absorber mirror (SESAM). Mode-locked pulse output is achieved by utilizing the nonlinear effect of the saturable absorber.

[0028] The output optical path is further provided with a first half-wave plate, a rectangular lens, a second half-wave plate, a polarizing beam splitter, and a third half-wave plate in sequence. A first optical isolator is provided between the seed source unit and the first half-wave plate, and a second optical isolator is provided after each of the third half-wave plates. The semiconductor optical amplification unit is located between the first half-wave plate and the rectangular lens.

[0029] A single-frequency distributed feedback semiconductor laser seed source is used to output a seed laser; a first optical isolator is used to isolate the backscattered light of the seed laser; a first half-wave plate is used to control the polarization direction of the laser injected into the semiconductor optical amplification unit; the semiconductor optical amplification unit is used to amplify the power of the seed laser to the watt level; a rectangular lens is used to shape the amplified linear beam into a point shape; a polarizing beam splitter, as well as the second and third half-wave plates, are used to split the laser beam into two paths, the first path being output through the second optical isolator and the second path being output through a modulation optical path.

[0030] An aspherical focusing mirror is also provided between the semiconductor saturable absorber mirrors in the modulation optical path. The aspherical focusing mirror is used to focus parallel light, and the semiconductor saturable absorber mirror is a total reflection mirror used to achieve passive mode-locked output and modulate the laser in the output optical path.

[0031] It should be noted that the seed source unit, the first optical isolator, the first half-wave plate, the second half-wave plate, the polarizing beam splitter, the third half-wave plate, and the second optical isolator all have the same frequency. For example, taking a pulsed laser outputting 780nm as an example... Figure 2The overall structure of the high-frequency, high-energy pulsed single-frequency laser includes a 780nm single-frequency distributed feedback semiconductor laser seed source 1, a first 780nm optical isolator 2, a first 780nm half-wave plate 3, a conical optical amplifier 4, a rectangular lens 5, a second 780nm half-wave plate 6, a 780nm polarizing beam splitter 7, a third 80nm half-wave plate 8, and a second 780nm optical isolator 9, as well as an aspherical focusing mirror 10 and a semiconductor saturable absorber mirror 11 disposed on the modulation optical path.

[0032] The seed source 1 of the 780nm single-frequency distributed feedback semiconductor laser is used to output seed laser, the first 780nm optical isolator 2 is used to isolate 780nm backscattered light, and the first 780nm half-wave plate 3 controls the polarization direction of the laser injected into the conical optical amplifier 4.

[0033] The cone-shaped light amplifier 4 is used to amplify the seed light power to the watt level. The rectangular lens 5 is used to shape the amplified linear beam into a point shape. The 780nm polarizing beam splitter 7, the second 780nm half-wave plate 6, and the third 780nm half-wave plate 8 are used for beam splitting. The aspherical focusing mirror 10 is used to focus parallel light. The semiconductor saturable absorber mirror 11 is used to achieve passive mode-locked output. The second 780nm isolator 9 is used to isolate backscattered light.

[0034] Compared with existing 780nm high-power single-frequency lasers, this invention has the characteristic of high-energy pulse output, and does not add too many components to the structure.

[0035] Figure 2 The working principle of the high-frequency, high-energy pulsed single-frequency laser is as follows: The seed source 1 of the 780nm single-frequency distributed feedback semiconductor laser can be a commonly used DFB / DBR single-frequency fiber laser seed source, which outputs a single-frequency 780nm laser in the order of 10mW. The laser passes through a first 780nm optical isolator 2 with an isolation of more than 60dB to suppress backscattered light, and then passes through a first 780nm half-wave plate 3 to control the polarization direction of the laser.

[0036] The laser, with its polarization ensured, is then injected into a conical optical amplifier 4 to amplify the 10mW-level laser power to the watt level. The amplified laser output is then shaped into a circle by a rectangular shaping lens 5, which reshapes the amplified, strip-shaped light spot.

[0037] After being shaped, the laser beam is split into two parts in a 1:1 ratio by a combination of a second 780nm half-wave plate 6 and a 780nm polarizing beam splitter 7. One part is output through a second 780nm optical isolator 9, and the other part is focused into an aspherical focusing lens 10, which focuses the parallel light onto a semiconductor saturable absorber 11. By finely adjusting the angle of the semiconductor saturable absorber 11 and adjusting the third 780nm half-wave plate 8, the reflected light is reflected back to the left into the optical path to achieve modulation and output pulsed laser.

[0038] This invention provides a high-frequency, high-energy pulsed single-frequency laser that combines a semiconductor laser, a power amplification unit, and a saturable absorber to achieve high-power, high-energy pulsed laser output. It leverages the advantages of a single-frequency semiconductor laser, ensuring high power while also achieving high-energy, high-repetition-rate pulses. Without compromising the single-frequency performance of the laser, the optical path structure is simple and does not increase the number of active optical devices, thus well meeting the needs of practical applications.

[0039] It should be noted that the descriptions of each embodiment in the above embodiments have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0040] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0041] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A high-frequency, high-energy pulsed single-frequency laser, characterized in that, It includes a seed source unit, a semiconductor optical amplification unit arranged in the output optical path, and a passive modulation device unit arranged in the modulation optical path, wherein the passive modulation device unit includes a semiconductor saturable absorber mirror; The seed source unit outputs a single-frequency seed laser. After the power of the single-frequency seed laser is amplified by the semiconductor optical amplification unit, the first seed laser is directly output through the output optical path. The second seed laser is focused on the semiconductor saturable absorber mirror through the modulation optical path. The semiconductor saturable absorber mirror generates a pulse. The pulse is reflected by the semiconductor saturable absorber mirror to modulate the first seed laser, so that all seed laser outputs are pulsed single-frequency lasers. The output optical path is also provided with a first half-wave plate, a rectangular lens, a second half-wave plate, a polarizing beam splitter, and a third half-wave plate in sequence. A first optical isolator is provided between the seed source unit and the first half-wave plate. A second optical isolator is provided after each third half-wave plate. The semiconductor optical amplification unit is provided between the first half-wave plate and the rectangular lens. The seed source unit is used to output seed laser; The first optical isolator is used to isolate the backscattered light of the seed laser; The first half-wave plate is used to control the polarization direction of the laser injected into the semiconductor optical amplification unit; The semiconductor optical amplification unit is used to amplify the power of the seed laser to the watt level; The rectangular lens is used to shape the magnified linear beam into a point shape; The polarizing beam splitter, the second half-wave plate, and the third half-wave plate are used to split the laser beam into two paths. The first path is output through the second optical isolator, and the second path is output through the modulation optical path.

2. The high-frequency, high-energy pulsed single-frequency laser according to claim 1, characterized in that, An aspherical focusing mirror is also provided between the semiconductor saturable absorber mirrors in the modulation optical path. The aspherical focusing mirror is used to focus parallel light. The semiconductor saturable absorber mirror is a total reflection mirror, which is used to achieve passive mode-locked output and modulate the laser in the output optical path.

3. The high-frequency, high-energy pulsed single-frequency laser according to claim 1, characterized in that, The seed source unit is a single-frequency distributed feedback semiconductor laser seed source.

4. The high-frequency, high-energy pulsed single-frequency laser according to claim 3, characterized in that, The seed source unit is a DFB / DBR single-frequency fiber laser seed source, which outputs a single-frequency laser in the range of 10mW.

5. The high-frequency, high-energy pulsed single-frequency laser according to claim 1, characterized in that, The seed source unit, the first optical isolator, the first half-wave plate, the second half-wave plate, the polarizing beam splitter, the third half-wave plate, and the second optical isolator have the same frequency.

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