All-fiber broadband high-compression-degree vacuum compression state light source based on two-way amplification
By employing a two-way amplification structure in an all-fiber broadband vacuum compressed light source and utilizing nonlinear waveguide crystal coating technology to achieve efficient separation of pump light and compressed light, the problems of low nonlinear conversion efficiency and filter device loss are solved, resulting in a higher compression ratio and a smaller light source.
Patent Information
- Application Number
- CN202511172966.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-21
- Publication Date
- 2025-10-28
AI Technical Summary
Existing all-fiber solutions suffer from low nonlinear conversion efficiency and high insertion loss of filtering devices, resulting in low compression of the compressed light source and the introduction of additional noise during the filtering process.
A double-pass amplification all-fiber structure is adopted. Pump light and compression light are separated by coating on a nonlinear waveguide crystal. The pump light passes through the nonlinear waveguide crystal twice. Combined with a circulator, the pump light and compression light are separated efficiently, avoiding the use of filtering devices.
It improves nonlinear conversion efficiency, achieves higher compression output, and avoids additional losses and noise caused by filtering devices. Its compact structure makes it suitable for miniaturization and practical application.
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Figure CN120848089A_ABST
Abstract
Description
Technical Field
[0001] This invention proposes a full-fiber broadband high-compressibility vacuum compressed state light source based on two-way amplification, which relates to the field of quantum optics technology. Background Technology
[0002] Compressed light sources, as an important non-classical light source, play an irreplaceable role in many fields such as quantum communication, quantum computing, quantum precision measurement, and quantum radar. Currently, the main methods for fabricating compressed light sources fall into two categories: free-space schemes and all-fiber schemes. Free-space schemes often employ a combination of cavity-locked and phase-locked technologies, using precise calibration and multi-channel locking control to achieve the output of the compressed light source. Its advantage is high output compression, but its disadvantages include a large and complex system, making it difficult to apply outside of laboratory environments. Furthermore, the design of the resonant cavity limits the bandwidth of the compressed light source, typically in the MHz range, which to some extent affects its application. All-fiber schemes, on the other hand, often use waveguide structures to obtain the output of the compressed light source through a single pass through a nonlinear crystal. Its advantages include a simple structure, eliminating the need for complex mode matching processes, which is beneficial for the miniaturization and industrialization of compressed light sources. Simultaneously, the single pass through the nonlinear crystal can fully utilize the bandwidth of the nonlinear process to achieve broadband compressed light source output, with bandwidth reaching the THz level. Its disadvantages include low nonlinear conversion efficiency and high output loss, resulting in a relatively low output compression.
[0003] This invention employs an all-fiber solution, utilizing a waveguide structure to achieve broadband vacuum compressed light source output. The technical problems this invention aims to solve are: first, the low nonlinear conversion efficiency caused by a single-pass nonlinear crystal, which limits the improvement of the compressed light source's compression ratio; and second, the significant insertion loss of conventional filtering devices during the filtering of residual pump light after compressed light generation, which introduces additional noise and reduces the actual compression ratio. Summary of the Invention
[0004] This invention proposes a two-way amplified all-fiber broadband high-compressibility vacuum compressed state light source, comprising the following optical components: laser, isolator, beam splitter, frequency doubling module, circulator, and compressed light generation module; all optical components are connected by optical fibers.
[0005] The laser emitted by the laser is linearly polarized light, and the laser light enters the beam splitter after passing through the isolator;
[0006] Most of the laser beam after passing through the beam splitter enters the frequency doubling module to generate pump light; a small portion of the laser beam is used as the background light for subsequent detection.
[0007] The pump light is input from the first port of the circulator and output from the second port, entering the compressed light generation module. The compressed light generation module is a nonlinear waveguide crystal. The incident end face of the nonlinear waveguide crystal is coated with a high-transmittance film for pump light, with a transmittance > 99%; the output end face is coated with a high-transmittance film for compressed light and a high-reflectance film for pump light. The transmittance of the high-transmittance film is > 99%, and the reflectance of the high-reflectance film is > 99%. The pump light reflected back from the output end face re-enters the nonlinear waveguide crystal, exits from the incident end face, enters the second port of the circulator, and is output from the third port, thus achieving the separation of pump light and compressed light.
[0008] In a preferred embodiment, the material of the nonlinear waveguide crystal is a periodic polarization medium.
[0009] In a preferred embodiment, the frequency doubling module is an optical fiber medium, an optical fiber coupling medium, or a periodically polarized frequency doubling medium.
[0010] In a preferred embodiment, all optical fibers are polarization-maintaining fibers.
[0011] In a preferred embodiment, the beam splitter is a proportional beam splitter corresponding to the laser wavelength; the isolator is an optical fiber isolator corresponding to the laser wavelength.
[0012] In a preferred embodiment, the laser is a low-noise single-frequency fiber laser or a low-noise single-frequency semiconductor laser.
[0013] In a preferred embodiment, the all-fiber broadband high-compressibility vacuum compressed state light source further includes an amplifier. The laser emitted by the laser enters the amplifier after passing through an isolator, where it is amplified in power before entering the beam splitter.
[0014] Compared with the prior art, the present invention has the following beneficial technical effects:
[0015] This invention relates to a two-way amplified all-fiber broadband high-compressibility vacuum compressed state light source. Based on current all-fiber broadband vacuum compressed state light source schemes, it proposes a method to optimize the output compression of the compressed state light source. This method not only improves the nonlinear conversion efficiency of the compressed light generation process, thereby achieving higher compression, but also efficiently separates the residual pump light and compressed light, solving the problem of additional losses caused by conventional fiber optic filtering devices and improving the actual output compression of the compressed state light source.
[0016] The present invention provides a high-compressibility vacuum compressed state light source based on two-way amplification and full-fiber broadband. Compared with the free space scheme, the present invention avoids complex mode matching problems, has a more compact structure, stronger resistance to environmental interference, and better compatibility with back-end application systems, thereby accelerating the practical application of compressed state light fields.
[0017] The present invention provides a full-fiber broadband high-compressibility vacuum compressed state light source based on double-pass amplification that does not require a resonant cavity. By coating a nonlinear waveguide crystal, the pump light passes through the waveguide crystal twice, thereby achieving the separation of the pump light and the compressed light. Attached Figure Description
[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1 This is a schematic diagram of the all-fiber broadband high-compressibility vacuum compressed state light source based on two-way amplification in Example 1;
[0020] Figure 2 This is a schematic diagram of the all-fiber broadband high-compressibility vacuum compressed state light source based on two-way amplification in Example 2;
[0021] Figure 3 A theoretical comparison of the nonlinear conversion efficiency of existing compressed light sources and the compressed light source of this invention is presented. Detailed Implementation
[0022] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0023] In the accompanying drawings of specific embodiments of the present invention, in order to better and more clearly describe the working principle of each component in the system and show the connection relationship of each part in the device, only the relative positional relationship between each component is clearly distinguished. It does not constitute a limitation on the signal transmission direction, connection sequence, or size and shape of each part within the component or structure.
[0024] A high-compressibility vacuum compressed state light source based on two-way amplification and full-fiber broadband, comprising: a laser, an isolator, a beam splitter, a frequency doubling module, a circulator, and a compressed light generation module.
[0025] The laser is a low-noise, single-frequency laser, which can be either a fiber laser or a semiconductor laser. The laser outputs linearly polarized light, which is transmitted through a polarization-maintaining fiber.
[0026] The isolator is a conventional fiber optic isolator corresponding to the laser wavelength, used to prevent backlight in the optical path from returning to the laser and causing damage to the laser or interference to the entire system.
[0027] A beam splitter is a proportional beam splitter corresponding to the wavelength of the laser, such as a 99 / 1 beam splitter. Its purpose is to split the fundamental frequency laser into two paths: one (most of the light) is used for frequency doubling to generate pump light, and the other (a small part of the light) is used for the background light required for subsequent detection.
[0028] The frequency doubling module can be an optical fiber medium or an optical fiber coupling medium. It can be a common frequency doubling medium or a periodically polarized frequency doubling medium. The higher the second-order nonlinear coefficient of the frequency doubling medium, the higher the pump light generated by frequency doubling, or the lower the fundamental frequency power required to obtain the same pump light power.
[0029] The circulator is a circulator corresponding to the pump light wavelength of the system. The pump light is input from the first port 1 of the circulator and output from the second port 2. The residual pump light returned by the compressed light generation module is input from the second port 2 and output from the third port 3.
[0030] The compressed light generation module is a nonlinear waveguide crystal. The nonlinear waveguide crystal material is a periodically polarized medium with high nonlinear conversion efficiency, such as PPLN or PPKTP. By coating the nonlinear waveguide crystal, the pump light passes through the waveguide crystal twice, simultaneously achieving separation of the pump light and the compressed light. The incident end face of the crystal is coated with a high-transmittance film for the pump light, with a transmittance >99%; the output end face is coated with a high-transmittance film for the compressed light, with a transmittance >99%; and the pump light is coated with a high-reflectance film, with a reflectance >99%.
[0031] Preferably, all optical fibers are polarization-maintaining fibers.
[0032] Example 1
[0033] like Figure 1 As shown, the all-fiber broadband high-compressibility vacuum compressed state light source based on two-way amplification in this embodiment includes a 1550nm low-noise single-frequency laser, a 1550nm isolator, a 1550nm 99 / 1 beam splitter, a frequency doubling module, a 775nm circulator, and a compressed light generation module.
[0034] A 1550nm low-noise single-frequency laser beam passes through a 1550nm isolator and then enters a 1550nm 99 / 1 beam splitter. The isolator prevents reflected light from subsequent components from entering the laser and affecting its stability. After passing through the 1550nm 99 / 1 beam splitter, most of the 1550nm laser light enters the frequency doubling module to generate 775nm pump light. A small portion of the 1550nm laser light serves as the background light for subsequent detection. The frequency doubling module is a periodically polarized lithium niobate (PPLN) fiber waveguide device. The pump light enters from port 1 of the 775nm circulator and exits from port 2, entering the compressed light generation module. The compressed light generation module is also a PPLN fiber waveguide device, with a high-transmittance coating for 775nm light (transmittance > 99%) on the crystal incident end face and a high-transmittance coating for 1550nm light (transmittance > 99%) and a high-reflectance coating for 775nm light (reflectance > 99%) on the output end face. After passing through the output end face of the crystal, the 775nm pump light is returned to the compressed light generation module. This two-stage passage through the nonlinear crystal improves the nonlinear conversion efficiency of the compressed light generation, which is beneficial for achieving higher compression ratios. The reflected pump light is input through port 2 of the circulator and output through port 3. Simultaneously, efficient separation of the 775nm pump light and the 1550nm compressed light is achieved at the output end, eliminating the need for subsequent filtering and avoiding the introduction of filtering noise that could reduce the output compression ratio.
[0035] Example 2
[0036] like Figure 2 As shown, a high-compressibility vacuum compressed state light source based on two-way amplification and full-fiber broadband comprises a 1064nm low-noise single-frequency laser, a 1064nm isolator, a 1064nm amplifier, a 1064nm 99 / 1 beam splitter, a frequency doubling module, a 532nm circulator, and a compressed light generation module.
[0037] A 1064nm low-noise single-frequency laser beam passes through a 1064nm isolator before entering a 1064nm amplifier. The isolator prevents reflected light from subsequent components from entering the laser and affecting its stability. The 1064nm amplifier increases the output power of the 1064nm laser, suitable for situations where the laser's output power is low. The light output from the 1064nm amplifier then enters a 1064nm 99 / 1 beam splitter. Most of the 1064nm laser light enters the frequency doubling module to generate 532nm pump light. A small portion of the 1064nm laser light serves as the background light for subsequent detection. The frequency doubling module is a periodically polarized potassium titanium phosphate (PPKTP) fiber waveguide device. The pump light enters from port 1 of the 532nm circulator and exits from port 2, entering the compressed light generation module. The compressed light generation module also uses PPKTP fiber waveguide devices. The crystal's incident end face is coated with a high-transmittance film for 532nm light (transmittance > 99%), while the output end face is coated with a high-transmittance film for 1064nm light (transmittance > 99%) and a high-reflectance film for 532nm light (reflectance > 99%). After passing through the crystal's output end face, the 532nm pump light is returned to the compressed light generation module. This two-stage passage through the nonlinear crystal improves the nonlinear conversion efficiency of the compressed light generation, facilitating higher compression output. The reflected pump light is input through port 2 of the circulator and output through port 3. Simultaneously, efficient separation of the 532nm pump light and the 1064nm compressed light is achieved at the output end, eliminating the need for subsequent filtering and avoiding the introduction of filtering noise that could reduce output compression.
[0038] Example 3
[0039] like Figure 3 The figure shows a theoretical comparison of the nonlinear conversion efficiency of the pump light passing through the nonlinear crystal once in the traditional scheme and the pump light passing through the nonlinear crystal twice in the present invention. Figure 3 This is a small-signal gain state simulation using a 20mm nonlinear PPLN crystal as an example.
[0040] Table 1 compares the effects of the compressed light filtering method of this invention with those of conventional compressed light filtering methods: The nonlinear crystal end face that generates compressed light is itself coated with an antireflection film corresponding to the wavelength of compressed light. Adding a high-reflection film for pump light to the output end face does not cause additional loss to the compressed light, thus not introducing additional noise and preventing a reduction in output compression. In conventional methods, both fiber filters and wavelength division multiplexers (WDM) have insertion loss, which introduces additional noise and leads to a reduction in output compression.
[0041] Table 1 Comparison of the filtering method in this scheme with the traditional filtering method
[0042]
[0043] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.
[0044] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0045] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.
Claims
1. A high-compressibility vacuum compressed state light source based on two-way amplification and all-fiber broadband, characterized in that, It includes the following optical components: laser, isolator, beam splitter, frequency multiplier module, circulator, and compressed light generation module; all optical components are connected by optical fiber. The laser emitted by the laser is linearly polarized light, and the laser light enters the beam splitter after passing through the isolator; Most of the laser beam after passing through the beam splitter enters the frequency doubling module to generate pump light; a small portion of the laser beam is used as the background light for subsequent detection. The pump light is input from the first port of the circulator and output from the second port, entering the compressed light generation module. The compressed light generation module is a nonlinear waveguide crystal. The incident end face of the nonlinear waveguide crystal is coated with a high-transmittance film for pump light, with a transmittance > 99%; the output end face is coated with a high-transmittance film for compressed light and a high-reflectance film for pump light. The transmittance of the high-transmittance film is > 99%, and the reflectance of the high-reflectance film is > 99%. The pump light reflected back from the output end face re-enters the nonlinear waveguide crystal, exits from the incident end face, enters the second port of the circulator, and is output from the third port, thus achieving the separation of pump light and compressed light.
2. The all-fiber broadband high-compressibility vacuum compressed state light source based on two-way amplification according to claim 1, characterized in that, The material of the nonlinear waveguide crystal is a periodic polarization medium.
3. The all-fiber broadband high-compressibility vacuum compressed state light source based on two-way amplification according to claim 1, characterized in that, The frequency doubling module is an optical fiber medium, an optical fiber coupling medium, or a periodically polarized frequency doubling medium.
4. The all-fiber broadband high-compressibility vacuum compressed state light source based on two-way amplification according to claim 1, characterized in that, All optical fibers are polarization-maintaining fibers.
5. The all-fiber broadband high-compressibility vacuum compressed state light source based on two-way amplification according to claim 1, characterized in that, The beam splitter is a proportional beam splitter corresponding to the laser wavelength; the isolator is an optical fiber isolator corresponding to the laser wavelength.
6. The all-fiber broadband high-compressibility vacuum compressed state light source based on two-way amplification according to claim 1, characterized in that, The laser is a low-noise single-frequency fiber laser or a low-noise single-frequency semiconductor laser.
7. The all-fiber broadband high-compressibility vacuum compressed state light source based on two-way amplification according to claim 1, characterized in that, The all-fiber broadband high-compressibility vacuum compressed state light source also includes an amplifier. The laser emitted by the laser enters the amplifier after passing through an isolator, where it is amplified in power before entering the beam splitter.