Array single-frequency laser for atomic radar

Abstract

The invention discloses an array single-frequency laser for an atomic radar. The array single-frequency laser comprises a 1018nm single-frequency laser seed source, a 1018nm low-power optical fiber amplification unit, a 1018nm optical fiber beam splitting unit, a 1018nm high-power optical fiber amplification unit, a frequency doubling conversion unit, a 509nm optical fiber beam splitting unit, a 509nm semiconductor optical amplifier and a 509nm optical isolation unit. According to the array single-frequency laser, the means of optical fiber amplification, frequency conversion, semiconductor light amplification and the like can be comprehensively utilized, and a same-frequency seed array which is narrow in line width, free of mode hopping, wide in tuning range and low in output power is provided through optical fiber amplification and frequency conversion; by combining the advantages of wide gain spectrum line, wide wavelength adaptability range, high electro-optical efficiency and convenience in miniaturization and integration of semiconductor light amplification, an integratable array laser solution with low power consumption and low cost is provided for a Rydberg atomic radar array.

Description

Technical Field

[0001] The invention relates to the field of laser technology, and in particular to an array single-frequency laser for atomic radar. Background Art

[0002] The full name of atomic radar is Rydberg atomic radar. Rydberg atoms, also known as highly excited atoms, have large electric dipole moments and polarizability. Using Rydberg atoms to measure microwave electric fields is an important direction in the field of quantum precision measurement. Based on Rydberg atom microwave measurement technology, it can be expanded into atomic receivers, which can be used in the fields of microwave field intensity traceability and absolute measurement, high-sensitivity radar receivers, and wireless communication antennas. The sensitivity of microwave detectors based on Rydberg atoms can reach 300 times that of traditional radars, and they only respond quickly to target frequencies and have no response to clutter. They can detect extremely weak signals and have great potential for capturing ultra-long-distance targets.

[0003] The existing Rydberg atom microwave electric field measurement has a higher measurement accuracy than similar sensors in traditional systems, fully demonstrating its high-precision measurement capability. Rydberg atom microwave electric field measurement relies on single-frequency laser atoms for manipulation and detection, such as Figure 2 As shown, the single-frequency laser used in the Rydberg atomic detector can be divided into lower-power detection light and higher-power coupling light.

[0004] For Cs Rydberg atoms, single-channel high-power 509nm lasers are usually achieved in two ways: Figure 3 As shown, by using a ~1μm low-power narrow-linewidth seed source combined with a fiber amplifier to generate high-power ~1μm fundamental frequency light, and then obtaining a 509nm watt-level single-frequency laser output through a frequency doubling process; Figure 4 As shown, a GaN-based semiconductor chip is used to realize the direct output of a 509nm laser. A GaN semiconductor chip is usually used to provide gain, and an optical feedback unit is used to construct an external cavity mechanism to realize a 509nm narrow linewidth output.

[0005] Since the operation of the Rydberg atomic radar array requires an array laser that provides high power, high electro-optical efficiency, synchronously tuned output frequency, and can be miniaturized and integrated, it is urgent to design an array single-frequency laser for atomic radar to solve the above problems. Summary of the invention

[0006] The object of the present invention is to provide an array single-frequency laser for atomic radar to solve the above-mentioned deficiencies in the prior art.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] Including 1018nm single-frequency laser seed source, 1018nm low-power fiber amplification unit, 1018nm fiber splitting unit, 1018nm high-power fiber amplification unit, frequency doubling conversion unit, 509nm fiber splitting unit, 509nm semiconductor optical amplifier, 509nm optical isolation unit;

[0009] The 1018nm single-frequency laser seed source, the 1018nm low-power optical fiber amplification unit and the 1018nm optical fiber beam splitting unit are used to output a single-frequency, same-output-frequency and synchronously tunable low-power 1018nm laser array, and the low-power 1018nm laser array has M branches.

[0010] The array single-frequency laser makes comprehensive use of fiber amplification, frequency conversion and semiconductor optical amplification. It uses fiber amplification + frequency conversion to provide a same-frequency seed array with narrow linewidth, wide mode-hop-free tuning range and relatively low output power. It combines the advantages of semiconductor optical amplification gain spectrum linewidth, wide wavelength adaptability range, high electro-optical efficiency and easy miniaturization and integration, thus providing a low-power, low-cost, integrable array laser solution for the Rydberg atomic radar array.

[0011] Array single-frequency lasers can effectively reduce system power consumption and system complexity, and can perform topological expansion of more array elements as needed, thereby achieving an electro-optical efficiency better than 25%. This is extremely beneficial for the application of atomic radar in vehicle-mounted platforms with low load power and high mobility.

[0012] The 1018nm high-power fiber amplification unit, the frequency doubling conversion unit and the 509nm fiber splitting unit are used to achieve fiber amplification, frequency doubling conversion and 509nm uniform fiber splitting of a single-branch low-power 1018nm laser. The uniform fiber splitting has N branches and can output M*N single-frequency, same output frequency, synchronously tunable low-power 509nm laser arrays.

[0013] The 509nm semiconductor optical amplifier and the 509nm optical isolation unit are used to achieve polarization-maintaining power amplification and optical isolation of a single-channel low-power 509nm laser, and finally output M*N channels of high-power polarization-maintaining 509nm lasers.

[0014] The 1018nm single-frequency laser seed source is used to provide 1018nm low-power narrow-linewidth laser. The 1018nm single-frequency laser seed source generally uses a fiber-in-fiber-out fiber DFB or DBR seed source. It can also be connected in series with a fiber AOM or other frequency shifting device to increase the feedback bandwidth according to usage requirements.

[0015] The 1018nm low-power fiber amplifier unit is used to perform polarization-maintaining power amplification on the seed laser to meet the power requirement of the 1018nm beam splitting array. The 1018nm low-power fiber amplifier unit includes components required for amplification, such as an isolator, a splitter, a pump source, a pump combiner, a gain fiber, a pump stripper, and a monitoring PD.

[0016] The 1018nm optical fiber splitting unit is used to achieve uniform power splitting of the laser output by the 1018nm low-power optical fiber amplification unit.

[0017] The 1018nm high-power fiber amplifier unit is used to achieve polarization-maintaining power amplification of the 1018nm laser after splitting. The 1018nm high-power fiber amplifier unit includes components required for amplification, such as an isolator, a splitter, a pump source, a pump combiner, a gain fiber, a pump stripper, and a monitoring PD.

[0018] The frequency doubling conversion unit is used to achieve high-efficiency frequency doubling conversion of input high-power 1018nm fundamental frequency light, and achieve green high-power coupling output through high-efficiency coupling.

[0019] The 509nm fiber splitting unit is used to achieve uniform splitting of high-power 509nm, the 509nm semiconductor optical amplifier is used to achieve power amplification of the incident low-power narrow-linewidth 509nm laser, and the 509nm optical isolation unit is used to improve the polarization characteristics of the 509nm laser while performing optical isolation.

[0020] The 1018nm single-frequency laser seed source, the 1018nm low-power optical fiber amplification unit, the 1018nm optical fiber splitting unit, the 1018nm high-power optical fiber amplification unit, the frequency doubling conversion unit, the 509nm optical fiber splitting unit and the 509nm semiconductor optical amplifier are all connected in series by optical fiber fusion splicing, and the 509nm semiconductor optical amplifier, the 509nm optical isolation unit and the atomic array unit are all spatially coupled.

[0021] In the above technical solution, the present invention provides an array single-frequency laser for atomic radar, which has the following beneficial effects:

[0022] Array single-frequency lasers can use a variety of methods such as fiber amplification, frequency conversion and semiconductor optical amplification: using fiber amplification + frequency conversion to provide a same-frequency seed array with narrow linewidth, wide mode-hop-free tuning range and relatively low output power, combined with the advantages of semiconductor optical amplification gain spectrum linewidth, wide wavelength adaptability range, high electro-optical efficiency and easy miniaturization and integration, thus providing a low-power, low-cost, integrable array laser solution for the Rydberg atomic radar array. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0024] Figure 1 A schematic diagram of an array single-frequency laser provided for an embodiment of an array single-frequency laser for an atomic radar according to the present invention.

[0025] Figure 2 A schematic diagram of cesium Rydberg atom detection energy levels provided for an array single-frequency laser embodiment of the present invention for use in an atomic radar.

[0026] Figure 3 A schematic diagram of a single-frequency laser amplification and frequency doubling system provided for an array single-frequency laser embodiment of the present invention for use in an atomic radar.

[0027] Figure 4 A block diagram of a single-frequency semiconductor laser composition provided for an array single-frequency laser embodiment of the present invention for use in an atomic radar.

[0028] Description of reference numerals:

[0029] 1. 1018nm single-frequency laser seed source; 2. 1018nm low-power fiber amplification unit; 3. 1018nm fiber splitting unit; 4. 1018nm high-power fiber amplification unit; 5. Frequency doubling conversion unit; 6. 509nm fiber splitting unit; 7. 509nm semiconductor optical amplifier; 8. 509nm optical isolation unit. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0031] like Figure 1-4 As shown, an array single-frequency laser for atomic radar is provided in an embodiment of the present invention.

[0032] It includes a 1018nm single-frequency laser seed source 1, a 1018nm low-power optical fiber amplification unit 2, a 1018nm optical fiber splitting unit 3, a 1018nm high-power optical fiber amplification unit 4, a frequency doubling conversion unit 5, a 509nm optical fiber splitting unit 6, a 509nm semiconductor optical amplifier 7, and a 509nm optical isolation unit 8;

[0033] The 1018nm single-frequency laser seed source 1, the 1018nm low-power fiber amplification unit 2 and the 1018nm fiber splitting unit 3 are used to output a single-frequency, same-output-frequency and synchronously tunable low-power 1018nm laser array, which has M branches.

[0034] The 1018nm high-power fiber amplification unit 4, the frequency doubling conversion unit 5 and the 509nm fiber splitting unit 6 are used to realize the fiber amplification, frequency doubling conversion and 509nm uniform fiber splitting of a single-branch low-power 1018nm laser. The uniform fiber splitting is N branches, which can output M*N single-frequency, same output frequency, synchronously tunable low-power 509nm laser arrays.

[0035] The 509nm semiconductor optical amplifier 7 and the 509nm optical isolation unit 8 are used to achieve polarization-maintaining power amplification and optical isolation of a single-channel low-power 509nm laser, and finally output M*N channels of high-power polarization-maintaining 509nm lasers.

[0036] Array single-frequency lasers can use fiber amplification, frequency conversion and semiconductor optical amplification and other means: using fiber amplification + frequency conversion to provide a same-frequency seed array with narrow linewidth, wide mode-hop-free tuning range and relatively low output power, combined with the advantages of semiconductor optical amplification gain spectrum linewidth, wide wavelength adaptability range, high electro-optical efficiency and easy miniaturization and integration, thus providing a low-power, low-cost, integrable array laser solution for the Rydberg atomic radar array.

[0037] Array single-frequency lasers can effectively reduce system power consumption and system complexity, and can perform topological expansion of more array elements as needed, thereby achieving an electro-optical efficiency better than 25%. This is extremely beneficial for the application of atomic radar in vehicle-mounted platforms with low load power and high mobility.

[0038] The 1018nm single-frequency laser seed source 1 is used to provide 1018nm low-power narrow-linewidth laser. The 1018nm single-frequency laser seed source 1 generally uses a fiber-in-fiber-out fiber DFB or DBR seed source. It can also be connected in series with a fiber AOM or other frequency shifting device to increase the feedback bandwidth according to usage requirements.

[0039] The 1018nm single-frequency laser seed source 1 can be a commonly used DFB / DBR single-frequency fiber laser seed source, or a narrow-linewidth seed source such as a 1018nm semiconductor grating external cavity seed source. To meet the possible demand for high feedback bandwidth, the 1018nm single-frequency laser seed source 1 can also be connected in series with frequency shifting devices such as optical fiber AOM to increase the feedback bandwidth. To avoid the influence of return light from the back-end unit or component, the 1018nm single-frequency laser seed source 1 is equipped with an optical isolation unit.

[0040] The 1018nm low-power fiber amplifier unit 2 is used to perform polarization-maintaining power amplification on the seed laser to meet the power requirement of the 1018nm beam splitting array. The 1018nm low-power fiber amplifier unit 2 includes the isolator, splitter, pump source, pump combiner, gain fiber, pump stripper, monitoring PD and other components required for amplification.

[0041] The pump source can be a 940nm or 976nm semiconductor pump source. At the same time, in order to improve system stability and reduce relative intensity noise, the detection PD is used to achieve functions such as power stability and relative intensity noise suppression.

[0042] The 1018 nm optical fiber splitting unit 3 is used to achieve uniform power splitting of the laser output by the 1018 nm low-power optical fiber amplification unit 2 .

[0043] The 1018nm fiber splitter unit 3 is used to equally split the power of M=32 branches according to the array unit, such as 1024 array elements. According to the power after equally splitting and the additional loss of the 1018nm fiber splitter unit 3, an additional fiber power amplifier unit can be added between the 1018nm low-power fiber amplifier unit 2 and the 1018nm fiber splitter unit 3 as appropriate.

[0044] The 1018nm high-power fiber amplifier unit 4 is used to achieve polarization-maintaining power amplification of the 1018nm laser after splitting. The 1018nm high-power fiber amplifier unit 4 includes the components required for amplification, such as an isolator, a splitter, a pump source, a pump combiner, a gain fiber, a pump stripper, and a monitoring PD.

[0045] The 1018nm high-power optical fiber amplifier unit 4 is used to meet the demand of the frequency doubling conversion unit 5 for the fundamental frequency optical power. The 1018nm high-power optical fiber amplifier unit 4 reserves functions such as power stabilization and relative intensity noise suppression.

[0046] The frequency doubling conversion unit 5 is used to achieve high-efficiency frequency doubling conversion of input high-power 1018nm fundamental frequency light, and to achieve green high-power coupling output through high-efficiency coupling.

[0047] Taking into account the differences in uniform beam splitting effect, frequency doubling conversion process, green light coupling and other factors of the 1018nm high-power fiber amplifier unit 4, the 1018nm high-power fiber amplifier unit 4 can be used to achieve power leveling of M branches, and the frequency doubling conversion unit 5 adopts the fiber-in and fiber-out method. The input fiber adopts 1um single-mode polarization-maintaining fiber for injection, and is focused in the PPLN crystal through mode conversion to achieve high-efficiency conversion from 1018nm to 509nm, and then the single-mode polarization-maintaining high-power output of the 509nm laser is achieved through dichroic mirror filtering, mode conversion, etc.

[0048] The 509nm optical fiber splitting unit 6 is used to achieve uniform splitting of high-power 509nm, the 509nm semiconductor optical amplifier 7 is used to achieve power amplification of the incident low-power narrow-linewidth 509nm laser, and the 509nm optical isolation unit 8 can also be used to improve the polarization characteristics of the 509nm laser.

[0049] Considering the influence of subsequent returned light, a 509nm optical isolation unit 8 is added to suppress back reflection or scattering. Taking into account the power loss caused by fiber coupling and the spatial application properties of the back-end atomic array unit, the 509nm semiconductor optical amplifier 7 and the 509nm optical isolation unit 8 are coupled in the form of spatial light, and the 509nm fiber splitting unit 6 is used to achieve equal power division of N=32 branches.

[0050] The 1018nm single-frequency laser seed source 1, the 1018nm low-power fiber amplification unit 2, the 1018nm fiber splitting unit 3, the 1018nm high-power fiber amplification unit 4, the frequency doubling conversion unit 5, the 509nm fiber splitting unit 6 and the 509nm semiconductor optical amplifier 7 are all connected in series by fiber fusion splicing, and the 509nm semiconductor optical amplifier 7, the 509nm optical isolation unit 8 and the atomic array unit are all spatially coupled.

[0051] The spatial coupling method can reduce power loss while improving the polarization degree of the 509nm laser through the optical isolation unit, making it easier to integrate with the atomic array unit, and by utilizing the gain saturation effect of the semiconductor optical amplifier, it can also improve the power stability of the 509nm laser output light.

[0052] The 509nm semiconductor optical amplifier 7 adopts the method of optical fiber input and space output to amplify the incident low power.

[0053] Single-mode polarization-maintaining fibers are used between the 1018nm single-frequency laser seed source 1 and the 1018nm low-power fiber amplification unit 2, between the 1018nm low-power fiber amplification unit 2 and the 1018nm fiber splitting unit 3, between the 1018nm fiber splitting unit 3 and the 1018nm high-power fiber amplification unit 4, between the 1018nm high-power fiber amplification unit 4 and the frequency doubling conversion unit 5, between the frequency doubling conversion unit 5 and the 509nm fiber splitting unit 6, and between the 509nm fiber splitting unit 6 and the 509nm semiconductor optical amplifier 7.

[0054] The 1018nm single-frequency laser seed source 1, the 1018nm low-power fiber amplifier unit 2, the 1018nm fiber splitting unit 3, the 1018nm high-power fiber amplifier unit 4, and the frequency doubling conversion unit 5 are fused through a polarization-maintaining fiber. The frequency doubling conversion unit 5 and the 509nm fiber splitting unit 6 are fused through a green light band polarization-maintaining fiber. The 509nm fiber splitting unit 6 and the 509nm semiconductor optical amplifier 7 are also fused through a polarization-maintaining fiber. The internal output light of the 509nm semiconductor optical amplifier 7 uses an optical shaping element to perform beam circularization and collimation output, and is isolated and output through a small-volume 509nm optical isolation unit 8.

[0055] Taking into account the integration requirements of the atomic radar array, the atomic radar array can integrate the 509nm semiconductor optical amplifier 7, the 509nm optical isolation unit 8 and the atomic array unit.

[0056] In outdoor high temperature application scenarios, considering the impact of high temperature demagnetization on isolation performance, a combination of PBS and a quarter can be used to achieve isolation. If more array elements are needed, limited by the output power of the frequency doubling conversion unit 5, a 509nm fiber splitter unit 6 and a 509nm semiconductor optical amplifier 7 can be connected in series after the 509nm semiconductor optical amplifier 7 to achieve more levels of expansion.

[0057] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. An array single-frequency laser for atomic radar, characterized in that: It comprises a 1018nm single-frequency laser seed source (1), a 1018nm low-power optical fiber amplification unit (2), a 1018nm optical fiber splitting unit (3), a 1018nm high-power optical fiber amplification unit (4), a frequency doubling conversion unit (5), a 509nm optical fiber splitting unit (6), a 509nm semiconductor optical amplifier (7), and a 509nm optical isolation unit (8); The 1018nm single-frequency laser seed source (1), the 1018nm low-power optical fiber amplification unit (2) and the 1018nm optical fiber beam splitting unit (3) are used to output a single-frequency, same-output-frequency and synchronously tunable low-power 1018nm laser array, wherein the low-power 1018nm laser array has M branches.

2. The array single-frequency laser for atomic radar according to claim 1, characterized in that: The 1018nm high-power optical fiber amplification unit (4), the frequency doubling conversion unit (5) and the 509nm optical fiber splitting unit (6) are used to realize optical fiber amplification, frequency doubling conversion and 509nm uniform optical fiber splitting of a single-branch low-power 1018nm laser, wherein the uniform optical fiber splitting has N branches and can output M*N single-frequency, same output frequency, synchronously tunable low-power 509nm laser arrays.

3. The array single-frequency laser for atomic radar according to claim 1, characterized in that: The 509nm semiconductor optical amplifier (7) and the 509nm optical isolation unit (8) are used to achieve polarization-maintaining power amplification, optical isolation, etc. of a single-channel low-power 509nm laser, and ultimately output M*N channels of high-power polarization-maintaining 509nm lasers.

4. The array single-frequency laser for atomic radar according to claim 1, characterized in that: The 1018nm single-frequency laser seed source (1) is used to provide 1018nm low-power narrow-linewidth laser. The 1018nm single-frequency laser seed source (1) generally uses a fiber-in-fiber-out fiber DFB or DBR seed source, and can also be connected in series with a fiber AOM or other frequency shifting device according to usage requirements to increase the feedback bandwidth.

5. The array single-frequency laser for atomic radar according to claim 1, characterized in that: The 1018nm low-power optical fiber amplification unit (2) is used to perform polarization-maintaining power amplification on the seed laser to meet the power requirement of the 1018nm beam splitting array. The 1018nm low-power optical fiber amplification unit (2) internally comprises an isolator, a splitter, a pump source, a pump combiner, a gain optical fiber, a pump stripper, a monitoring PD and other components required for amplification.

6. The array single-frequency laser for atomic radar according to claim 1, characterized in that: The 1018 nm optical fiber splitting unit (3) is used to achieve uniform power splitting of the laser output by the 1018 nm low-power optical fiber amplification unit (2).

7. The array single-frequency laser for atomic radar according to claim 1, characterized in that: The 1018nm high-power optical fiber amplification unit (4) is used to achieve polarization-maintaining power amplification of the 1018nm laser after beam splitting. The 1018nm high-power optical fiber amplification unit (4) internally comprises an isolator, a beam splitter, a pump source, a pump combiner, a gain optical fiber, a pump stripper, a monitoring PD and other components required for amplification. The 1018nm high-power optical fiber amplification unit (4) is used to meet the demand of the frequency doubling conversion unit (5) for fundamental frequency optical power.

8. The array single-frequency laser for atomic radar according to claim 1, characterized in that: The frequency doubling conversion unit (5) is used to achieve high-efficiency frequency doubling conversion of input high-power 1018nm fundamental frequency light, and to achieve green high-power coupled output through high-efficiency coupling.

9. The array single-frequency laser for atomic radar according to claim 1, characterized in that: The 509nm optical fiber beam splitting unit (6) is used to realize uniform beam splitting of high-power 509nm, the 509nm semiconductor optical amplifier (7) is used to realize power amplification of an incident low-power narrow-linewidth 509nm laser, and the 509nm optical isolation unit (8) can be used to improve the polarization characteristics of the 509nm laser while isolating the light.

10. The array single-frequency laser for atomic radar according to claim 1, characterized in that: The 1018nm single-frequency laser seed source (1), the 1018nm low-power optical fiber amplification unit (2), the 1018nm optical fiber splitting unit (3), the 1018nm high-power optical fiber amplification unit (4), the frequency doubling conversion unit (5), the 509nm optical fiber splitting unit (6) and the 509nm semiconductor optical amplifier (7) are all connected in series by means of optical fiber fusion splicing; the 509nm semiconductor optical amplifier (7), the 509nm optical isolation unit (8) and the atomic array unit are all connected by means of spatial coupling; the 509nm semiconductor optical amplifier (7) adopts an optical fiber in-and-space out method for power amplification of incident low power.

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