All-fiber integrated quantum frequency conversion module and up-conversion single-photon detector

Abstract

The utility model relates to an all-fiber integrated quantum frequency conversion module and an up-conversion single-photon detector, and belongs to the field of single-photon detectors. According to the all-fiber integrated quantum frequency conversion module of the utility model, the wavelength division multiplexer and the waveguide are coupled by the coupling fiber and then are fixed inside the hollow packaging body together, so that the external interference degree of transmission of optical signals obtained by combination of the wavelength division multiplexer between the wavelength division multiplexer and the waveguide can be reduced, and the multimode components of pump light in the fiber can be reduced; therefore, the transmission loss of optical signals in the up-conversion detection system is reduced, and the transmission power is stabilized.

Description

TECHNICAL FIELD

[0001] The utility model relates to single photon detector technical field especially relates to a full optical fiber integrated quantum frequency conversion module and upconversion single photon detector. BACKGROUND

[0002] Single photon detector as the core device in quantum communication field has important application in single photon radar, quantum precision measurement and other scenes. Taking 1550nm communication waveband as an example, the single photon detector working at 1550nm communication waveband mainly has superconductive nanowire single photon detector, indium gallium arsenide single photon detector and upconversion single photon detector.

[0003] The upconversion single photon detection system based on 1064nm pumping has higher saturation counting rate and narrower overall optical path conversion bandwidth than indium gallium arsenide single photon detector in 1550nm waveband, and the commercial butterfly package 1064nm laser has developed maturely at present, can stably output larger power 1064nm pumping light, and the 1064nm pumping light is used as the pumping light source of the upconversion single photon detector system, can effectively simplify the optical path structure and the overall structure of system, so the upconversion single photon detection system based on 1064nm pumping light has practical application significance.

[0004] In the upconversion single photon detection system based on 1064nm pumping, the input end optical fiber of the upconversion period polarization lithium niobate (PPLN) waveguide that realizes frequency conversion, that is, the coupling optical fiber between the upconversion period polarization lithium niobate (PPLN) waveguide and wavelength division multiplexer, usually adopts polarization maintaining (PM) 1550nm gyro optical fiber, and 1064nm light, 1550nm light, especially 1064nm light is easily interfered by bending, external environmental vibration or temperature change in the transmission in this optical fiber, so that the transmission loss of the upconversion detection system increases and the transmission power is unstable. UTILITY MODEL CONTENTS

[0005] In view of the above technical problems, the utility model provides a full optical fiber integrated quantum frequency conversion module and upconversion single photon detection system to solve the technical problems that the transmission loss exists and the transmission power is unstable in the existing upconversion detection system.

[0006] In the first aspect, the utility model provides a full optical fiber integrated quantum frequency conversion module, which comprises wavelength division multiplexer, waveguide, coupling optical fiber, signal end optical fiber, pumping end optical fiber, exit optical fiber and hollow encapsulation body.

[0007] The wavelength division multiplexer and the waveguide are fixed inside the hollow package body, a common end of the wavelength division multiplexer is connected with an incident end of the waveguide through the coupling optical fiber, one end of the signal end optical fiber is connected with a signal end of the wavelength division multiplexer, and the other end of the signal end optical fiber is arranged outside the hollow package body, one end of the pump end optical fiber is connected with a pump end of the wavelength division multiplexer, and the other end of the pump end optical fiber is arranged outside the hollow package body, and one end of the outgoing optical fiber is coupled with an outgoing end of the waveguide, and the other end of the outgoing optical fiber is arranged outside the hollow package body.

[0008] Optionally, in order to further improve the stability of the coupling optical fiber, the wavelength division multiplexer and the waveguide are on the same straight line, and the straight line distance between the common end of the wavelength division multiplexer and the incident end of the waveguide is equal to the length of the coupling optical fiber.

[0009] Optionally, in order to further improve the stability of the coupling optical fiber, the length of the coupling optical fiber is less than 5 cm.

[0010] Optionally, in order to reduce transmission loss, the waveguide is a ridge waveguide.

[0011] Optionally, in order to improve the sum frequency effect, the waveguide is an up-conversion periodically poled lithium niobate thin film.

[0012] Optionally, the coupling optical fiber is a PM1550 gyro optical fiber, the signal end optical fiber is a PM1550 optical fiber, the pump end optical fiber is a PM980 optical fiber, the signal end optical fiber is used for accessing 1550nm signal light, and the pump end optical fiber is used for accessing 1064nm pump light; or the signal end optical fiber is a PM980 optical fiber, the pump end optical fiber is a PM1550 optical fiber, the signal end optical fiber is used for accessing 1064nm signal light, and the pump end optical fiber is used for accessing 1550nm pump light.

[0013] Optionally, in order to facilitate temperature control, the hollow package body is made of copper.

[0014] In a second aspect, the utility model also provides a kind of up-conversion single photon detector, including any one of the foregoing full-fiber integrated quantum frequency conversion module, and the up-conversion single photon detector further includes single photon counter;

[0015] The signal end optical fiber in the full-fiber integrated quantum frequency conversion module is used for accessing signal light, the pump end optical fiber in the full-fiber integrated quantum frequency conversion module is used for accessing pump light, and the outgoing optical fiber in the full-fiber integrated quantum frequency conversion module is connected with the single photon counter.

[0016] The above scheme has the following beneficial effects:

[0017] The all-fiber integrated quantum frequency conversion module of the utility model, after coupling wave division multiplexer and waveguide through coupling optical fiber, fixes them in the hollow packaging body, reduces the external interference degree of the optical signal after merging through the wave division multiplexer when transmitting between the wave division multiplexer and the waveguide, reduces the multimode component of the pump light in the optical fiber, thereby reducing the transmission loss of the optical signal in the up-conversion detection system and stabilizing the transmission power. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is the structure schematic view of the all-fiber integrated quantum frequency conversion module provided in the embodiment one of the utility model;

[0019] Figure 2 is the real object schematic view of the all-fiber integrated quantum frequency conversion module provided in the preferred embodiment of the utility model;

[0020] The symbols are explained as follows:

[0021] 1, signal end optical fiber and pump end optical fiber;2, TEC temperature control wire;3, emergent optical fiber. DETAILED DESCRIPTION

[0022] In order to make the technical problems, technical schemes and beneficial effects solved by the utility model more clearly understood, the following will be further described in detail in combination with the drawings and embodiments.

[0023] It should be understood that the embodiments set forth below represent the necessary information to enable those skilled in the art to practice the embodiments and illustrate the best mode contemplated for practicing the embodiments. Upon reading the following description, those skilled in the art will understand how to implement the concepts of the present disclosure and will recognize the applicability of these concepts to other applications. It will be appreciated that these concepts and applications fall within the scope of the present disclosure and the following claims.

[0024] It should also be understood that although the terms first, second, etc. can be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present disclosure. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0025] It should also be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or intervening elements can be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present.

[0026] It should also be understood that the terms "upper", "lower", "left", "right", "front", "back", "bottom", "intermediate", "middle", "top", and the like can be used herein to describe various elements as they are oriented in the drawings under discussion, and are merely for convenience in describing the present application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must be in a particular orientation, constructed and operated in a particular orientation, and therefore should not be limited to the terms so used.

[0027] These terms are used only to distinguish one element from another. For example, a first element can be termed an "upper" element, and a second element can be termed an "upper" element, similarly, according to the relative orientation of these elements, without departing from the scope of the present disclosure.

[0028] It is further understood that the terms "including", "including", "including" and / or "including" as used herein specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0029] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning consistent with their meaning in the context of the specification and relevant art, and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0030] In Embodiment One, a full-fiber integrated quantum frequency conversion module is provided, as shown in the structure Figure 1 The full-fiber integrated quantum frequency conversion module comprises a wavelength division multiplexer, a waveguide, a coupling fiber, a signal end fiber, a pump end fiber, an exit fiber, and a hollow package.

[0031] The wavelength division multiplexer and the waveguide are fixed inside the hollow package, the common end of the wavelength division multiplexer is connected to the incident end of the waveguide through the coupling fiber, one end of the signal end fiber is connected to the signal end of the wavelength division multiplexer, and the other end is arranged outside the hollow package. The other end of the pump end fiber is arranged outside the hollow package after being connected to the pump end of the wavelength division multiplexer, and the other end of the exit fiber is arranged outside the hollow package after being coupled to the exit end of the waveguide.

[0032] In practical applications, as Figure 1The wave division multiplexer (WDM) is arranged in line with the waveguide, and the linear distance between the common end (COM end) of the wave division multiplexer and the incident end of the waveguide is equal to the length of the coupling optical fiber. The reason for such arrangement is that, based on the premise that the wave division multiplexer and the waveguide are fixed inside the hollow package, by limiting the length of the coupling optical fiber to be equal to the linear distance between the common end of the wave division multiplexer and the incident end of the waveguide, the coupling optical fiber can be in a linear state with sufficient tension, thereby better resisting the bending caused by gravity and external vibration, more effectively reducing the optical signal transmission loss and improving the transmission power stability.

[0033] In order to further improve the tension of the coupling optical fiber and thus improve its effect of resisting the interference caused by gravity and external vibration, the length of the coupling optical fiber is preferably less than 5 cm, so that the length of the entire structure of the wave division multiplexer, the waveguide and the optical fiber therebetween can be kept below 12 cm, thereby reducing the volume of the all-fiber integrated quantum frequency conversion module.

[0034] In actual application, in order to reduce the transmission loss and improve the frequency doubling effect, the waveguide is preferably an up-conversion periodically poled lithium niobate ridge waveguide, specifically an up-conversion periodically poled lithium niobate crystal (PPLN) film with a thickness of 7 mm.

[0035] In actual application, 1064 nm light is used as pump light, thereby forming an up-conversion single-photon detection system based on 1064 nm pump and operating in the 1550 nm communication waveband. The up-conversion single-photon detection system includes the all-fiber integrated quantum frequency conversion module of the embodiment. In the all-fiber integrated quantum frequency conversion module, the signal end optical fiber connected to the wave division multiplexer is used to access 1550 nm signal light, and the pump end optical fiber connected to the wave division multiplexer is used to access 1064 nm pump light. The signal end optical fiber is a PM1550 optical fiber with a mode field diameter of 10 mm at 1550 nm, and the pump end optical fiber is a PM980 optical fiber with a mode field diameter of 6.5 mm at 1064 nm.

[0036] It should be noted that when the all-fiber integrated quantum frequency conversion module of the embodiment is used alone without being used in the above-mentioned up-conversion single-photon detection system based on 1064 nm pump and operating in the 1550 nm communication waveband, the signal end optical fiber and the pump end optical fiber of the wave division multiplexer in the all-fiber integrated quantum frequency conversion module can be interchangeable, i.e., the pump end optical fiber can be a PM1550 optical fiber with a mode field diameter of 10 mm at 1550 nm, used to access 1550 nm pump light, and the signal end optical fiber can be a PM980 optical fiber with a mode field diameter of 6.5 mm at 1064 nm, used to access 1064 nm signal light.

[0037] Back to the up-conversion single photon detection system based on 1064nm pump working in 1550nm communication band, the coupling efficiency is improved by mode field adaptation, and the coupling fiber uses PM1550 gyro fiber. It should be noted that the 1550nm signal light and the 1064nm pump light are input by the signal end and the pump end of the wavelength division multiplexer respectively, and then output to the waveguide through the coupling fiber by the common end of the wavelength division multiplexer. In this process, the coupling fiber contains both 1064nm light and 1550nm light, but the cutoff wavelength of the PM1550 gyro fiber is 1290-1520nm, so the 1064nm light is in a multimode transmission in the coupling fiber. Due to this form of multimode transmission, it is more susceptible to factors such as bending, vibration, and environmental temperature, which will increase the transmission loss and make the transmission power unstable.

[0038] With the structure of the all-fiber integrated quantum frequency conversion module described above in this embodiment, the degree of interference of 1064nm light in the coupling fiber during transmission due to factors such as bending, vibration, and environmental temperature can be significantly reduced, thereby reducing the impact of the transmission mode of 1064nm light in the coupling fiber on the up-conversion detection system, and achieving the effect of reducing the transmission loss and maintaining the transmission power stability of the up-conversion detection system even in the case of multimode transmission.

[0039] In a preferred embodiment, the all-fiber integrated quantum frequency conversion module is as shown in Figure 2 which includes a signal end fiber and a pump end fiber (1), a TEC temperature control line (2), and an exit fiber (3). The TEC temperature control line (2) is the temperature control line of a semiconductor cooler (TEC), which is attached to the waveguide inside the hollow packaging body to control the temperature of the waveguide.

[0040] In order to distinguish the signal end fiber and the pump end fiber (1), the TEC temperature control line (2), and the exit fiber (3), and improve the efficiency of building the up-conversion detection system, the signal end fiber and the pump end fiber (1), the TEC temperature control line (2), and the exit fiber (3) are arranged on different faces of the hollow packaging body.

[0041] At the same time, in order to improve the convenience of temperature control of the waveguide in the all-fiber integrated quantum frequency conversion module and the stability of the module, as shown in Figure 1 copper is selected as the material of the hollow packaging body in this preferred embodiment, i.e., the wavelength division multiplexer and the waveguide are fixed in a copper packaging structure.

[0042] In embodiment two, an up-conversion single photon detector is provided, which includes the all-fiber integrated quantum frequency conversion module in each of the above embodiments, and further includes a single photon counter.

[0043] In the upconversion single-photon detector, the signal-end optical fiber in the all-fiber integrated quantum frequency conversion module is used for accessing signal light, the pump-end optical fiber in the all-fiber integrated quantum frequency conversion module is used for accessing pump light, and the exit optical fiber in the all-fiber integrated quantum frequency conversion module is connected to the single-photon counter.

[0044] The beneficial effects brought by the special structure of the all-fiber integrated quantum frequency conversion module to the upconversion single-photon detector or the upconversion detection system have been described in the above embodiments, and the present embodiment will not be described again.

[0045] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. An all-fiber integrated quantum frequency conversion module, characterized in that, The application relates to a full-fiber integrated quantum frequency conversion module. The wavelength division multiplexer and the waveguide are in the same straight line, and the straight line distance between the common end of the wavelength division multiplexer and the incident end of the waveguide is equal to the length of the coupling optical fiber. The length of the coupling optical fiber is less than 5 cm.

2. The all-fiber integrated quantum frequency conversion module of claim 1, wherein, The waveguide is a ridge waveguide.

3. The all-fiber integrated quantum frequency conversion module of claim 2, wherein, The waveguide is an up-conversion periodically poled lithium niobate thin film.

4. The all-fiber integrated quantum frequency conversion module of claim 1, wherein, The coupling optical fiber is a PM1550 gyro optical fiber, the signal end optical fiber is a PM1550 optical fiber, the pump end optical fiber is a PM980 optical fiber, the signal end optical fiber is used for accessing 1550 nm signal light, and the pump end optical fiber is used for accessing 1064 nm pump light; or the signal end optical fiber is a PM980 optical fiber, the pump end optical fiber is a PM1550 optical fiber, the signal end optical fiber is used for accessing 1064 nm signal light, and the pump end optical fiber is used for accessing 1550 nm pump light.

5. The all-fiber integrated quantum frequency conversion module of claim 4, wherein, The hollow packaging body is made of copper.

6. The all-fiber integrated quantum frequency conversion module of any of claims 1-5, wherein, The application further relates to a single photon detector, which comprises the full-fiber integrated quantum frequency conversion module.

7. The all-fiber integrated quantum frequency conversion module of claim 1, wherein, The signal end optical fiber in the full-fiber integrated quantum frequency conversion module is used for accessing signal light, the pump end optical fiber in the full-fiber integrated quantum frequency conversion module is used for accessing pump light, and the exit optical fiber in the full-fiber integrated quantum frequency conversion module is connected to the single photon counter.

8. An upconversion single-photon detector, comprising: ​ ​

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