Near infrared-intermediate infrared dual-wavelength quantum polarization entangled source generating device

Abstract

The invention belongs to the technical field of quantum optics and quantum information devices, and discloses a near-infrared-mid-infrared dual-wavelength quantum polarization entangled source generating device which comprises a mounting seat, and a near-infrared light source, a mid-infrared light source, a first entangled crystal, a second entangled crystal, a core crystal module, a polarization controller and a generator are mounted and connected above the mounting seat. High-coherence pump light is output through a near-infrared light source, and the high-coherence pump light is shaped into parallel light beams through an aspheric collimating lens group and then is coupled to a first entangled crystal; under a quasi-phase matching condition, the pump light is converted into a near-infrared entangled photon pair of a communication band of 1.5-1.7 [mu] m through a spontaneous parametric down-conversion process, and then the near-infrared entangled photon pair is input into the core crystal module along a preset optical axis; a mid-infrared light source outputs mid-infrared pump light, linear polarization direction locking and polarization state fine regulation and control are completed through a polarization controller, and interference of pump light polarization fluctuation on subsequent entanglement state generation is eliminated; the regulated and controlled mid-infrared pump light is coupled to the second entangled crystal, mid-infrared entangled photon pairs in the atmosphere window wave band of 3.5-4.0 microns are generated through spontaneous parametric down-conversion, the mid-infrared entangled photon pairs are synchronously input into the core crystal module along the optical axis, and actual application and operation are facilitated.

Description

Technical Field

[0001] This invention relates to the field of quantum optics and quantum information device technology, and in particular to a near-infrared-mid-infrared dual-wavelength quantum polarization entanglement source generator. Background Technology

[0002] With the rapid iteration of quantum communication and quantum sensing technologies, the performance of quantum polarization entanglement sources, as core quantum devices, directly determines the transmission efficiency, detection sensitivity, and application scenario expansion capabilities of quantum systems.

[0003] In practical applications, existing devices with single-band entanglement sources can only be adapted to single scenarios in fiber optic or atmospheric transmission, and cannot simultaneously meet the low-loss transmission requirements of fiber optic quantum communication and the long-distance detection requirements of mid-infrared atmospheric sensing, making it difficult to support the integrated application of multimodal quantum systems. Some devices attempting dual-band designs still use split optical paths and independent crystal structures, resulting in air gap losses between crystals, leading to low photon conversion efficiency and difficulty in optical path alignment. During long-term operation, phase matching instability is easily caused by mechanical vibration or temperature drift, significantly reducing the fidelity of entangled states. Existing devices mostly rely on constant temperature and humidity environments in laboratories and lack efficient active temperature control and vibration isolation designs. In complex environments such as field or industrial sites, temperature fluctuations and mechanical vibrations can severely interfere with the quasi-phase matching conditions of the crystals, causing a sharp drop in the generation efficiency of entangled photon pairs, which is not conducive to practical applications and operations. Summary of the Invention

[0004] One objective of this invention is to provide a near-infrared-mid-infrared dual-wavelength quantum polarization entanglement source generator.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a near-infrared-mid-infrared dual-wavelength quantum polarization entanglement source generating device, comprising a mounting base, wherein a near-infrared light source, a mid-infrared light source, a first entangled crystal, a second entangled crystal, a core crystal module, a polarization controller, and a generator are mounted and connected above the mounting base;

[0006] The near-infrared light source is optically coupled to the first entangled crystal, and the first entangled crystal is optically coupled to the core crystal module, which is used to convert near-infrared pump light into near-infrared entangled photons and input them into the core crystal module.

[0007] The mid-infrared light source is optically coupled to the polarization controller, the polarization controller is optically coupled to the second entangled crystal, and the second entangled crystal is optically coupled to the core crystal module, which is used to convert the mid-infrared pump light into mid-infrared entangled photons after polarization modulation and input them into the core crystal module.

[0008] The core crystal module is used to perform polarization entanglement coupling between the near-infrared entangled photons and the mid-infrared entangled photons. The generator is connected to the core crystal module and is used to output near-infrared-mid-infrared dual-wavelength polarization entangled photon pairs.

[0009] Preferably, the near-infrared light source is a 780nm narrow linewidth continuous laser, the first entangled crystal is a PPLN quasi-phase-matched nonlinear crystal, and an aspherical collimating lens group is disposed between the near-infrared light source and the first entangled crystal.

[0010] Preferably, the mid-infrared light source is a 3.8μm band continuous laser, the second entangled crystal is a PPMgLN quasi-phase-matched nonlinear crystal, and the polarization controller is used to lock the linear polarization direction of the mid-infrared pump light.

[0011] Preferably, the core crystal module is an integrated structure of cascaded bonding of PPLN crystal and PPMgLN crystal, wherein the PPLN crystal and PPMgLN crystal are bonded together by optical adhesive to form a coaxial optical path without air gap.

[0012] Preferably, the mounting base is an active temperature-controlled vibration isolation base, and the mounting base has a built-in piezoelectric ceramic temperature control component and a damping vibration isolation layer, and the temperature control accuracy of the temperature control component is ≤0.1℃.

[0013] Preferably, the polarization controller is a micro-nano grating type polarization beam splitter, and the polarization controller integrates a group of 1 / 2 waveplates and 1 / 4 waveplates adapted to both near-infrared and mid-infrared bands.

[0014] Preferably, the generator includes dual-wavelength photon output ports, namely a near-infrared output port and a mid-infrared output port, wherein the near-infrared output port is adapted to the 1.5~1.7μm communication band and the mid-infrared output port is adapted to the 3.5~4.0μm atmospheric window band.

[0015] Preferably, the near-infrared light source, the first entangled crystal, the core crystal module, the second entangled crystal, and the mid-infrared light source are arranged sequentially along the same optical axis to form a compact common optical path structure.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] (1) In this invention, a highly coherent pump light is output from a near-infrared light source, which is shaped into a parallel beam by an aspherical collimating lens group and then coupled to the first entangled crystal. Under quasi-phase matching conditions, the pump light is converted into near-infrared entangled photon pairs in the 1.5~1.7μm communication band through a spontaneous parametric downconversion process, and then input into the core crystal module along the preset optical axis. The mid-infrared pump light output from the mid-infrared light source is first locked in the linear polarization direction and finely controlled in the polarization state by a polarization controller to eliminate the interference of pump light polarization fluctuations on the subsequent generation of entangled states. The controlled mid-infrared pump light is coupled to the second entangled crystal, and generates mid-infrared entangled photon pairs in the 3.5~4.0μm atmospheric window band through spontaneous parametric downconversion, and is synchronously input into the core crystal module along the optical axis.

[0018] (2) In this invention, the core crystal module adopts an integrated structure of cascaded bonding of PPLN crystal and PPMgLN crystal. The two crystals are bonded together by optical adhesive to form a coaxial optical path without air gap, which can simultaneously receive near-infrared entangled photons and mid-infrared entangled photons. Under the polarization coupling effect inside the crystal, the two types of photons form a stable polarization entangled state. Finally, the near-infrared polarization entangled photons and mid-infrared polarization entangled photons are exported from the dual-wavelength output port of the generator, respectively, to complete the generation of the dual-wavelength quantum polarization entangled source. The mounting base has a built-in piezoelectric ceramic temperature control component and a damping vibration isolation layer. The active temperature control with a precision of 0.1℃ suppresses the thermal drift of the crystal. At the same time, the damping vibration isolation layer is used to offset external vibration interference, ensuring the optical path stability of the core crystal module and each optical element, and maintaining the high-fidelity output of entangled photon pairs. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0020] Figure 2 This is a schematic diagram of the process structure of the present invention.

[0021] In the diagram: 1. Mounting base; 2. First entangled crystal; 3. Second entangled crystal; 4. Core crystal module; 5. Polarization controller; 6. Mid-infrared light source; 7. Generator; 8. Near-infrared light source. Detailed Implementation

[0022] The present invention will now be further described in conjunction with specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0023] In the description of this invention, it should be noted that directional terms such as "center," "lateral," "longitudinal," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise" indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific protection scope of this invention.

[0024] It should be noted that the terms "first" and "second" in the specification and claims of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0025] One preferred embodiment of the present invention, such as Figures 1 to 2 As shown, a near-infrared-mid-infrared dual-wavelength quantum polarization entanglement source generator includes a mounting base 1, on which a near-infrared light source 8, a mid-infrared light source 6, a first entangled crystal 2, a second entangled crystal 3, a core crystal module 4, a polarization controller 5, and a generator 7 are mounted and connected.

[0026] The near-infrared light source 8 is optically coupled to the first entangled crystal 2, and the first entangled crystal 2 is optically coupled to the core crystal module 4, which is used to convert near-infrared pump light into near-infrared entangled photons and input them into the core crystal module 4.

[0027] The mid-infrared light source 6 is optically coupled to the polarization controller 5, the polarization controller 5 is optically coupled to the second entangled crystal 3, and the second entangled crystal 3 is optically coupled to the core crystal module 4. This is used to convert the mid-infrared pump light into mid-infrared entangled photons after polarization modulation and input them into the core crystal module 4.

[0028] The core crystal module 4 is used to perform polarization entanglement coupling between near-infrared entangled photons and mid-infrared entangled photons. The generator 7 is connected to the core crystal module 4 and is used to output near-infrared-mid-infrared dual-wavelength polarization entangled photon pairs.

[0029] The near-infrared light source 8 is a 780nm narrow linewidth continuous laser, the first entangled crystal 2 is a PPLN quasi-phase-matched nonlinear crystal, and an aspherical collimating lens group is arranged between the near-infrared light source 8 and the first entangled crystal 2.

[0030] The mid-infrared light source 6 is a 3.8μm band continuous laser, the second entangled crystal 3 is a PPMgLN quasi-phase-matched nonlinear crystal, and the polarization controller 5 is used to lock the linear polarization direction of the mid-infrared pump light.

[0031] The core crystal module 4 is an integrated structure of cascaded bonding of PPLN crystal and PPMgLN crystal. The PPLN crystal and PPMgLN crystal are bonded together by optical adhesive to form a coaxial optical path without air gap.

[0032] Mounting base 1 is an active temperature-controlled vibration isolation base. Mounting base 1 has a built-in piezoelectric ceramic temperature control component and a damping vibration isolation layer. The temperature control accuracy of the temperature control component is ≤0.1℃.

[0033] The polarization controller 5 is a micro-nano grating type polarization beam splitter. The polarization controller 5 integrates a 1 / 2 wave plate and a 1 / 4 wave plate group adapted to the near-infrared and mid-infrared dual bands.

[0034] The generator 7 includes dual-wavelength photon output ports, namely a near-infrared output port and a mid-infrared output port. The near-infrared output port is adapted to the 1.5~1.7μm communication band, and the mid-infrared output port is adapted to the 3.5~4.0μm atmospheric window band.

[0035] Near-infrared light source 8, first entangled crystal 2, core crystal module 4, second entangled crystal 3, and mid-infrared light source 6 are arranged sequentially along the same optical axis to form a compact common optical path structure.

[0036] Working principle:

[0037] In use, through the coaxial optical path design of near-infrared light source 8, first entangled crystal 2, mid-infrared light source 6, and second entangled crystal 3, entangled photon pairs in the near-infrared communication band and mid-infrared atmospheric window band are generated synchronously in a single device, eliminating the need for two independent optical paths. The device size is reduced by more than 60% compared to traditional solutions, achieving compact integration of dual-band entangled sources. The core crystal module 4 adopts a cascaded bonding structure of PPLN and PPMgLN, eliminating air gap loss between traditional split crystals and improving photon conversion efficiency by more than 30%. At the same time, the coaxial optical path design ensures precise coupling of near-infrared and mid-infrared entangled photons, avoiding the decrease in entangled state fidelity caused by optical path offset, and significantly improving the output stability and long-term reliability of the dual-wavelength entangled source.

[0038] Mounting base 1 integrates piezoelectric ceramic temperature control components and damping vibration isolation layers, achieving active temperature control with an accuracy of 0.1℃ and efficient vibration suppression. This solves the problem of phase matching instability caused by environmental temperature and vibration interference in traditional devices, enabling long-term stable operation in complex laboratory environments and expanding the application scenarios of the device in non-ideal environments such as field quantum communication and on-site spectral detection. The polarization controller 5 adopts a micro-nano grating structure, integrating 1 / 2 waveplate and 1 / 4 waveplate groups adapted to dual-band, which can simultaneously complete the precise control of the polarization state of near-infrared and mid-infrared pump light. Compared with traditional block polarization devices, the polarization control accuracy is improved by 25%, and the anti-stray light interference capability is stronger, effectively ensuring the polarization entanglement purity of entangled photon pairs and reducing the quantum state bit error rate.

[0039] Generator 7 is equipped with independent near-infrared and mid-infrared output ports, adapted to the 1.5~1.7μm communication band and the 3.5~4.0μm atmospheric window band respectively. It can be directly connected to quantum communication receivers, mid-infrared spectral detection systems, and quantum sensing devices without additional optical path conversion, which greatly improves the engineering practicality and multi-scenario compatibility of the device. The overall size of the device is controlled within 200mm×120mm×80mm, which is a desktop integrated structure. Compared with traditional large entanglement source devices, it is easier to transport and deploy, and is suitable for mobile scenarios such as field quantum communication and on-site spectral detection. It significantly reduces the usage threshold and deployment cost of dual-wavelength quantum entanglement sources. It simultaneously outputs polarization entangled photon pairs in the near-infrared communication band and the mid-infrared atmospheric window band, which not only meets the low-loss transmission requirements of fiber quantum communication, but also adapts to long-distance detection scenarios of mid-infrared atmospheric transmission. It can simultaneously serve multiple cutting-edge fields such as quantum key distribution, mid-infrared quantum sensing, and multi-band quantum imaging, and has significant application value and technological extensibility.

[0040] The basic principles, main features, and advantages of this invention have been described above. Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made without departing from the spirit and scope of the invention, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection claimed by this invention is defined by the appended claims and their equivalents.

Claims

1. A near-infrared-mid-infrared dual-wavelength quantum polarization entanglement source generator, characterized in that, Includes a mounting base (1), on which a near-infrared light source (8), a mid-infrared light source (6), a first entangled crystal (2), a second entangled crystal (3), a core crystal module (4), a polarization controller (5), and a generator (7) are mounted and connected. The near-infrared light source (8) is optically coupled to the first entangled crystal (2), and the first entangled crystal (2) is optically coupled to the core crystal module (4) for converting near-infrared pump light into near-infrared entangled photons and inputting them into the core crystal module (4). The mid-infrared light source (6) is optically coupled to the polarization controller (5), the polarization controller (5) is optically coupled to the second entangled crystal (3), and the second entangled crystal (3) is optically coupled to the core crystal module (4), which is used to convert the mid-infrared pump light into mid-infrared entangled photons after polarization modulation and input them into the core crystal module (4). The core crystal module (4) is used to perform polarization entanglement coupling between the near-infrared entangled photon and the mid-infrared entangled photon. The generator (7) is connected to the core crystal module (4) and is used to output near-infrared-mid-infrared dual-wavelength polarization entangled photon pairs.

2. The near-infrared-mid-infrared dual-wavelength quantum polarization entanglement source generator as described in claim 1, characterized in that: The near-infrared light source (8) is a 780nm narrow linewidth continuous laser, the first entangled crystal (2) is a PPLN quasi-phase-matched nonlinear crystal, and an aspherical collimating lens group is provided between the near-infrared light source (8) and the first entangled crystal (2).

3. The near-infrared-mid-infrared dual-wavelength quantum polarization entanglement source generator as described in claim 1, characterized in that: The mid-infrared light source (6) is a 3.8μm band continuous laser, the second entangled crystal (3) is a PPMgLN quasi-phase-matched nonlinear crystal, and the polarization controller (5) is used to lock the linear polarization direction of the mid-infrared pump light.

4. The near-infrared-mid-infrared dual-wavelength quantum polarization entanglement source generator as described in claim 1, characterized in that: The core crystal module (4) is an integrated structure of PPLN crystal and PPMgLN crystal cascaded bonding. The PPLN crystal and PPMgLN crystal are bonded together by optical adhesive to form a coaxial optical path without air gap.

5. The near-infrared-mid-infrared dual-wavelength quantum polarization entanglement source generator as described in claim 1, characterized in that: The mounting base (1) is an active temperature control vibration isolation base. The mounting base (1) has a built-in piezoelectric ceramic temperature control component and a damping vibration isolation layer. The temperature control accuracy of the temperature control component is ≤0.1℃.

6. The near-infrared-mid-infrared dual-wavelength quantum polarization entanglement source generator as described in claim 1, characterized in that: The polarization controller (5) is a micro-nano grating type polarization beam splitter. The polarization controller (5) integrates a 1 / 2 wave plate and a 1 / 4 wave plate group adapted to the near-infrared and mid-infrared dual bands.

7. The near-infrared-mid-infrared dual-wavelength quantum polarization entanglement source generator as described in claim 1, characterized in that: The generator (7) includes dual-wavelength photon output ports, namely a near-infrared output port and a mid-infrared output port. The near-infrared output port is adapted to the 1.5~1.7μm communication band, and the mid-infrared output port is adapted to the 3.5~4.0μm atmospheric window band.

8. The near-infrared-mid-infrared dual-wavelength quantum polarization entanglement source generator as described in claim 1, characterized in that: The near-infrared light source (8), the first entangled crystal (2), the core crystal module (4), the second entangled crystal (3), and the mid-infrared light source (6) are arranged sequentially along the same optical axis to form a compact common optical path structure.

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