CN112104452B - Light splitting assembly, polarization decoding device for quantum key distribution and receiving end - Google Patents
Light splitting assembly, polarization decoding device for quantum key distribution and receiving end Download PDFInfo
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- CN112104452B CN112104452B CN201910831596.2A CN201910831596A CN112104452B CN 112104452 B CN112104452 B CN 112104452B CN 201910831596 A CN201910831596 A CN 201910831596A CN 112104452 B CN112104452 B CN 112104452B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
- H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
- H04L9/0819—Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s)
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/27—Optical coupling means with polarisation selective and adjusting means
- G02B6/2753—Optical coupling means with polarisation selective and adjusting means characterised by their function or use, i.e. of the complete device
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
- H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
- H04L9/0852—Quantum cryptography
Abstract
The invention relates to a light splitting component, integration thereof, a polarization decoding device and a receiving end based on the light splitting component and used for quantum key distribution without polarization mode dispersion. The optical splitting assembly achieves polarization results without polarization mode dispersion by splitting the optical pulse to be decoded into first and second components and subjecting them to phase modulation in a sagnac loop along the same optical axis of the polarization maintaining fiber, and coupling the phase modulated first and second components. In addition, the components of the light splitting assembly are directly connected by gluing, so that unnecessary polarization feedback can be avoided.
Description
Technical Field
The invention relates to the field of quantum secret communication, in particular to a light splitting component and integration thereof, and a polarization decoding device and a receiving end which are based on the light splitting component and have no polarization mode dispersion and are used for quantum key distribution.
Background
Since the 21 st century, optical communication has become a mainstream communication method. With the development of quantum mechanics, new communication methods for transmitting information using light quantum have been proposed. Among them, the quantum communication protocol most fully validated is the BB84 protocol proposed in 1984. The method has enough safety in theory, so that the BB84 protocol becomes a great hotspot and is widely concerned. In recent years, quantum communication has been developed more vigorously, and encoding methods are also diversified, and can be generally divided into a polarization encoding and decoding scheme, a phase encoding and decoding scheme, and a time phase encoding and decoding scheme.
The polarization encoding and decoding scheme commonly used in the BB84 protocol uses typical polarization states of H \ V \ + \ -four. A typical decoding scheme used by the receiving end is a passive decoding scheme, which is widely used due to its advantages of low insertion loss and high coding rate. However, the passive decoding scheme is constructed by traditional discrete optical components, and the receiving end Bob needs 4 single-photon detectors, so that the scheme has the defects of large volume, high cost and the like.
Compared with a passive decoding scheme, the active decoding scheme can reduce the use number of detectors, so that the cost is reduced. Fig. 1 shows a typical optical path for an active decoding scheme of the prior art. As shown in fig. 1, at the receiving end Bob, the polarization controller PC2 calibrates the polarization state perturbed by the optical fiber to align with the direction of the phase modulator PM 2. The polarization state is subjected to phase modulation by a phase modulator PM2, then orthogonal division is carried out on the demodulated polarization state by a polarization controller PC3 and a polarization beam splitter PBS, and the orthogonal division is output to 2 detector channels.
In the scheme shown in fig. 1, due to the problem of polarization mode dispersion of the polarization controller PC2, a phase modulator PM1 matched with Bob needs to be arranged at Alice end for polarization mode dispersion compensation, which puts requirements on Alice's devices, and from Alice's encoding angle analysis, polarization mode dispersion existing in the phase modulator PM1 in Alice may cause the polarization state to deviate from an ideal state and not meet encoding safety requirements. In addition, the optical fiber between the phase modulator PM2 and the polarization beam splitter PBS has disturbance, which needs to be feedback compensated by setting the polarization controller PC3, which adds corresponding optical devices such as a polarization controller, and in an automatic feedback system, the polarization controller PC3 is required to have a corresponding electronic driving signal for adjustment, further increasing the complexity of the system.
Fig. 2 shows another typical optical path for an active decoding scheme of the prior art, which is optimized for the optical path of fig. 1, wherein the setup of the polarization controller PC3 is omitted by performing a fusion process on the phase modulator PM2 and the polarization beam splitter PBS. However, the solution of fig. 2 still suffers from polarization mode dispersion introduced by the phase modulator.
Disclosure of Invention
In view of the above problems in the prior art, the present invention provides a splitter module, and a polarization decoding apparatus and a receiving end for quantum key distribution based on the splitter module, which can realize a polarization decoding function without polarization mode dispersion, and can realize a stable and disturbance-free polarization state orthogonal division function by performing a special integration process on the splitter module, for example, without providing a polarization controller PC3 as shown in fig. 1 to provide polarization feedback.
A first aspect of the present invention relates to a light splitting assembly comprising a first polarizing beam splitting element, a first unidirectional 90-degree rotator, a second unidirectional 90-degree rotator, and a second polarizing beam splitting element;
the first polarization beam splitting element is provided with a first port, a second port, a third port and a fourth port, wherein the second port and the third port are respectively a transmission end and a reflection end relative to the first port, and are respectively a reflection end and a transmission end relative to the fourth port;
the first and second unidirectional 90 degree rotators have a first port and a second port and are configured to: the polarization direction of the optical pulse input through the first port is not rotated when the optical pulse is output through the second port, and the polarization direction of the optical pulse input through the second port is rotated by 90 degrees when the optical pulse is output through the first port; wherein the second port of the first polarization beam splitting element is connected to the first port of the first unidirectional 90-degree rotator, and the third port of the first polarization beam splitting element is connected to the second port of the second unidirectional 90-degree rotator, or the second port of the first polarization beam splitting element is connected to the second port of the first unidirectional 90-degree rotator, and the third port of the first polarization beam splitting element is connected to the first port of the second unidirectional 90-degree rotator;
the second polarization beam splitting element has a first port, a second port and a third port, wherein the second port and the third port are a transmission end and a reflection end respectively relative to the first port; and the first port of the second polarization beam splitting element is connected with the fourth port of the first polarization beam splitting element, and the optical axis direction of the second polarization beam splitting element is aligned by rotating an angle of 45 degrees or-45 degrees relative to the optical axis direction of the first polarization beam splitting element.
Preferably, the first polarizing beam splitting element is a polarizing beam splitting cube or a polarizing beam splitter.
Preferably, the second polarizing beam splitting element is a polarizing beam splitter or a polarizing beam splitting cube.
Optionally, the unidirectional 90 degree rotator comprises a 45 degree faraday rotator plate and a half-wave plate with the fast axis at 67.5 degrees or 22.5 degrees.
Further, the optical splitting assembly further comprises a partial beam splitter disposed at least one of the second and third ports of the first polarizing beam splitting element.
Preferably, the first polarization beam splitting element directly connects the first unidirectional 90-degree rotator, the second unidirectional 90-degree rotator and the second polarization beam splitting element in a glued manner.
A second aspect of the present invention relates to a beam splitting assembly comprising a third polarizing beam splitting element, a circulator and a fourth polarizing beam splitting element;
the circulator is provided with a first port, a second port and a third port, wherein the optical pulse input by the first port is output through the second port, and the optical pulse input by the second port is output through the third port;
the third polarization beam splitting element has a first port, a second port and a third port, wherein the second port and the third port are a transmission end and a reflection end respectively relative to the first port;
the fourth polarization beam splitting element has a first port, a second port and a third port, wherein the second port and the third port are a transmission end and a reflection end respectively relative to the first port;
the second port of the circulator is connected to the first port of the third polarization beam splitting element, and the third port of the circulator is connected to the first port of the fourth polarization beam splitting element, wherein:
the circulator is aligned horizontally at the second port in parallel with the horizontal direction of the first port of the third polarizing beam splitting element, while the circulator is aligned horizontally at the third port rotated 45 or-45 degrees with respect to the fourth polarizing beam splitting element about the horizontal direction of the first port; alternatively, the first and second electrodes may be,
the circulator is aligned with a 45 or-45 degree rotation of the horizontal direction at the second port with respect to the horizontal direction of the first port of the third polarizing beam splitting element, while the circulator is aligned parallel at the third port with respect to the horizontal direction of the fourth polarizing beam splitting element with respect to the first port.
Preferably, the third port of the circulator and the first port of the fourth polarization beam splitting element are connected by a polarization maintaining fiber. Wherein the polarization maintaining fiber has one of its fast and slow axes coupled at one end rotated 45 or-45 degrees with respect to the horizontal of the third port of the circulator and at the other end aligned with the horizontal coupling of the fourth polarization beam splitting element with respect to the first port; alternatively, the polarization maintaining fiber has one of its fast and slow axes coupled to the horizontal direction of the third port of the circulator at one end and the one of the fast and slow axes coupled to the horizontal direction of the fourth polarization splitting element with respect to the first port at the other end.
Preferably, the third polarizing beam splitting element is a polarizing beam splitting cube or a polarizing beam splitter.
Preferably, the fourth polarizing beam splitting element is a polarizing beam splitter or a polarizing beam splitting cube.
Preferably, the circulator is directly connected to the third polarization beam splitting element in a glued manner.
A third aspect of the present invention relates to a polarization decoding apparatus for quantum key distribution, comprising:
a splitting assembly having a first port a, a second port B, a third port C, a fourth port D and a fifth port E and being arranged to split an optical pulse received via the first port a into a first component and a second component and to output the first component and the second component via the second port B and the third port C, respectively;
a sagnac loop formed by connecting the second port B and the third port C of the optical splitting assembly with a polarization maintaining fiber, one of a fast axis and a slow axis of the polarization maintaining fiber of which is aligned with the optical splitting assembly at the second port B and the third port C, such that the first and second components both propagate along the slow axis of the polarization maintaining fiber of the sagnac loop or both propagate along the fast axis of the polarization maintaining fiber of the sagnac loop;
a phase modulation unit arranged in the Sagnac loop for phase modulating at least one of the first component and the second component to form a phase difference phi therebetweende(ii) a And the number of the first and second electrodes,
the light splitting assembly is further configured to receive a beam having the phase difference phideAnd coupling the first and second components, and providing an output in at least one of the fourth port D and the fifth port E based on the coupling.
Preferably, the polarization maintaining fiber is a panda polarization maintaining fiber.
Preferably, the optical splitting assembly is any one of the optical splitting assemblies according to the first and second aspects of the present invention.
A fourth aspect of the present invention relates to a receiving end for quantum key distribution, which includes a wavelength division multiplexing unit, a synchronous optical detection unit, a polarization control unit, an optical detection unit, and the polarization decoding apparatus according to the third aspect of the present invention, wherein,
the wavelength division multiplexing unit is used for separating the synchronous light and the signal light pulse;
the synchronous light detection unit is used for receiving the synchronous light to perform synchronous light detection;
the polarization control unit is used for carrying out polarization control on the signal light pulse before the signal light pulse enters the polarization decoding device;
the polarization decoding device is used for carrying out polarization decoding on the signal light pulse; and
the optical detection unit is used for detecting the polarization decoding result output by the polarization decoding device.
As a specific example, the light detection unit includes two single photon detectors respectively connected to the fourth port D and the fifth port E of the polarization decoding device.
Preferably, the polarization control unit is an electric polarization controller.
Drawings
FIG. 1 illustrates a typical optical path for an active decoding scheme of the prior art;
FIG. 2 illustrates another typical optical path for an active decoding scheme of the prior art;
FIG. 3 illustrates an exemplary embodiment of a polarization decoding apparatus for quantum key distribution of the present invention;
FIG. 4 illustrates a first exemplary embodiment of a light splitting assembly of the present invention;
FIG. 5 illustrates an exemplary configuration of a unidirectional 90 degree rotator of the present invention;
FIG. 6 illustrates a second exemplary embodiment of a light splitting assembly of the present invention;
FIG. 7 illustrates a third exemplary embodiment of a light splitting assembly of the present invention;
fig. 8 shows an exemplary embodiment of the receiving end for quantum key distribution of the present invention.
Detailed Description
Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following examples are provided by way of illustration in order to fully convey the spirit of the invention to those skilled in the art to which the invention pertains. Accordingly, the present invention is not limited to the embodiments disclosed herein.
Fig. 3 shows an exemplary embodiment of a polarization decoding apparatus for quantum key distribution according to the present invention.
As shown, the polarization decoding apparatus may include an optical splitting assembly having a first port a, a second port B, a third port C, a fourth port D, and a fifth port E.
The light splitting assembly may be arranged to receive the light pulses via the first port a. For example, the optical pulse may be a polarization encoded signal optical pulse transmitted by the transmitting end Alice, which may be transmitted to the first port a via a single mode optical fiber.
The optical splitting component may split the received optical pulse into a first component and a second component and cause the two components to be output via a second port B and a third port C, respectively. As a preferred example, the first component and the second component may have the same strength.
The optical splitting assembly may also couple optical pulses input by the second port B and the third port C, respectively (which may be achieved, for example, by the first component and the second component being folded back into the optical splitting assembly at the same time), and provide an output from at least one of the fourth port D and the fifth port E of the optical splitting assembly.
The polarization decoding apparatus may further include a sagnac loop implemented by connecting the second port B and the third port C of the optical splitting assembly with a polarization maintaining fiber, and a phase modulation unit disposed in the sagnac loop. And the optical axes of the polarization-maintaining optical fibers of the Sagnac loop are aligned and coupled with the optical splitting assembly at the second port B and the third port C of the optical splitting assembly, so that the optical pulses output through the second port B and the third port C of the optical splitting assembly enter and propagate along the same optical axis of the polarization-maintaining optical fibers of the Sagnac loop. For example, one of the slow and fast axes of the polarization maintaining fiber is aligned with the horizontal direction (or vertical direction) of the optical splitting assembly at ports B and C at the same time.
As an example, the polarization maintaining fiber may be a panda polarization maintaining fiber.
As an example, the phase modulation unit may be a phase modulator PM.
The working principle of the polarization decoding apparatus of the present invention will be explained below by way of example.
In a preferred example, when a polarization encoded signal light pulse enters the optical splitting assembly via the first port a, the optical splitting assembly splits the signal light pulse into a first component and a second component having the same intensity and outputs them via the second port B and the third port C, respectively.
Since the second port B and the third port C of the optical splitting assembly are aligned with the same optical axis (e.g., slow axis) of the polarization maintaining fiber in the sagnac loop so that the optical pulses output by the optical splitting assembly enter the polarization maintaining fiber and propagate along the same optical axis, the first and second components output by the optical splitting assembly will enter the sagnac loop at the same time and will be transmitted along the loop in opposite directions on the same optical axis of the polarization maintaining fiber.
Controlling a first pair of phase modulating units (e.g., PM) in a Sagnac loopAnd at least one of the second components is phase modulated to load a phase difference phi between the twode。
With a phase difference phideWill return to the splitting assembly simultaneously for coupling and will depend on the phase difference phideThe coupling result is output at least one of the fourth port D and the fifth port E of the optical splitting assembly.
The coupling result output by the light splitting component is then transmitted to an optical detection unit such as a single-photon detector for detection, so as to realize polarization decoding of the signal light pulse from the transmitting end.
In the polarization decoding process implemented by the present invention, since the first and second components are transmitted in the sagnac loop along the same optical axis (e.g. slow axis) and are phase-modulated, the two optical components will experience the same total path (same attenuation), and such coaxial transmission (e.g. transmission along the slow axis of the loop of the polarization-maintaining sagnac interferometer) can completely avoid the problem of polarization mode dispersion existing in the phase modulator in the prior art, and avoid the phase difference between the fast axis and the slow axis, so that the polarization state of the finally superimposed output in the optical splitting component depends only on the phase difference loaded by the phase modulatorde。
Fig. 4 shows a first exemplary embodiment of a light splitting assembly of the present invention, which includes a first polarizing beam splitting element, first and second unidirectional 90-degree rotators (rotators), and a second polarizing beam splitting element.
The first polarization beam splitting element is for splitting an input optical pulse into first and second components having polarization directions perpendicular to each other, and may have first, second, third, and fourth ports, wherein for an optical pulse input via any one of the first, second, third, and fourth ports, a horizontal polarization component thereof will be output in transmission from the first polarization beam splitting element, and a vertical polarization component thereof will be output in reflection from the first polarization beam splitting element.
As non-limiting examples, the first polarizing beam splitting element may be a polarizing beam splitting cube (PBC) (as shown in fig. 4) or a polarizing beam splitter (not shown).
In the example of fig. 4, a first port of a first polarization beam splitting element (here, a polarization beam splitting cube) serves as an input port, which corresponds to a first port a of the polarization decoding apparatus; accordingly, the second port and the third port act as a transmissive and a reflective output port, respectively, with respect to the first port. Thus, when an optical pulse is input from the first port of the polarization beam splitting cube, the first component output from the second port will be its horizontal component (H light) and the second component output from the third port will be its vertical component (V light).
The unidirectional 90-degree rotator is provided to rotate the polarization direction of the light pulse passing in the forward direction by 90 degrees without rotating the polarization direction of the light pulse passing in the reverse direction. Figure 5 shows an exemplary configuration of a unidirectional 90 degree rotator that may include a 45 degree faraday rotator plate and a half-wave plate with the fast axis at 67.5 degrees. In another exemplary configuration, the unidirectional 90 degree rotator may include a 45 degree faraday rotator plate and a half-wave plate with the fast axis at 22.5 degrees.
In the present invention, first and second unidirectional 90-degree rotators are connected to second and third ports, respectively, of a first polarizing beam splitting element (in fig. 4, a polarizing beam splitting cube), wherein: the first unidirectional 90-degree rotator is arranged in a forward direction with respect to the output direction of the second port, and the second unidirectional 90-degree rotator is arranged in a reverse direction with respect to the output direction of the third port; or the first unidirectional 90-degree rotator is arranged in a reverse direction with respect to the output direction of the second port while the second unidirectional 90-degree rotator is arranged in a forward direction with respect to the output direction of the third port.
In the example of fig. 4, the first unidirectional 90-degree rotator is disposed in a forward direction with respect to the output direction of the second port of the polarization splitting cube, and the second unidirectional 90-degree rotator is disposed in a reverse direction with respect to the output direction of the third port. At this time, the first component (H light) output by the second port of the polarization beam splitting cube still remains as H light after passing through the first unidirectional 90-degree rotator in the forward direction, and the second component (V light) output by the third port of the polarization beam splitting cube rotates by 90 degrees after passing through the second unidirectional 90-degree rotator in the reverse direction, that is, the V light is changed into H light.
Subsequently, the first and second components, both H light, are input into the sagnac loop via the output of the first unidirectional 90-degree rotator (which corresponds to the second port B of the light splitting component) and the output of the second unidirectional 90-degree rotator (which corresponds to the third port C of the light splitting component), respectively. Since the same optical axis (e.g. slow axis) of the polarization maintaining fiber of the sagnac loop is arranged aligned with the horizontal direction of the polarization splitting cube at both the second port B and the third port C, the first and second components will propagate in the polarization maintaining fiber in opposite directions in the loop along the same optical axis (e.g. slow axis).
In a Sagnac loop, a phase difference phi is formed between the first and second components by means of a phase modulator PMde. The phase modulated first and second components are returned to the third port C and the second port B of the optical splitting component simultaneously along the same optical axis (e.g., slow axis) of the polarization maintaining fiber, where the first and second components are H light.
Then, the first component of the H light is directed through the second unidirectional 90 degree rotator to the third port of the polarization beam splitting cube, which is still H light; the second component of the H light will pass back through the first unidirectional 90 degree rotator to the second port of the polarization splitting cube where a 90 degree polarization direction rotation into V light occurs.
After passing through the unidirectional 90-degree rotator, the first component of the H light is input through the third port of the polarization beam splitting cube and reaches the fourth port of the polarization beam splitting cube through the transmission effect, the second component of the V light is input through the second port of the polarization beam splitting cube and reaches the fourth port of the polarization beam splitting cube through the reflection effect, and the first component and the second component are coupled at the fourth port of the polarization beam splitting cube.
If the phase difference between the first and second components is phide0, they will couple at the fourth port of the polarizing beam splitting cube to form
I.e. 45 degree polarized light.
If the phase difference between the first and second components is phideIs pi, they will couple at the fourth port of the polarizing beam splitting cube to form
I.e., -45 degree polarized light.
The second polarization beam splitting element is for splitting an input optical pulse into first and second components having polarization directions perpendicular to each other, and may have first, second, and third ports. By way of example, the second polarizing beam splitting element may be a polarizing beam splitter (as shown in FIG. 4), or a polarizing beam splitting cube (not shown).
As shown in fig. 4, the first port of the second polarization beam splitting element is optically connected to the fourth port of the first polarization beam splitting element as an input end, and is arranged such that the optical axis direction of the second polarization beam splitting element is aligned with a 45 (or-45) degree rotation with respect to the optical axis direction of the first polarization beam splitting element, for example, the H light direction output by the first polarization beam splitting element at the fourth port forms a 45 (or-45) degree angle with respect to the transmission direction (H light direction) of the second polarization beam splitting element with respect to the first port thereof. Thus, when the two optical axes are aligned at 45 degrees, the polarization state output by the first polarization beam splitting element at the fourth port is
Will be directed towards the transmission direction (H light direction) of the second polarization beam splitting element with respect to the first port, i.e. out of the transmission port of the second polarization beam splitting element, which corresponds to the fourth port D of the light splitting assembly; the polarization state output by the first polarization beam splitting element at the fourth port is
Will be directed towards the reflected direction (V light direction) of the second polarizing beam splitting element with respect to the first port, i.e. out of the reflected port of the second polarizing beam splitting element, which corresponds to the fifth port E of the light splitting assembly. As will be readily understood by those skilled in the art, when the two optical axes are rotated to-45 degrees of alignment, the polarization state is
From a second polarization beam splitting elementThe output of the reflecting port (i.e. the fifth port E of the light splitting component) has the polarization state
Will be output from the transmission port of the second polarization beam splitting element (i.e. the fourth port D of the light splitting assembly).
The light pulses output from the fourth port D and/or the fifth port E can be detected by a single photon detector to complete the polarization decoding process. For example, when phideWhen the number is 0 or pi, correspondingly, an optical pulse output can be generated from the fourth port D or the fifth port E of the light splitting component, so that a determined polarization state distinguishing result is obtained, and the result is a basis vector comparison consistent result at the moment; when phi isdeAt pi/2 or 3 pi/2, there will be optical signals (which usually have the same intensity) output at both the fourth port D and the fifth port E of the optical splitting component, so as to obtain the uncertain polarization state distinguishing result, which is the inconsistent result of the basis vector alignment. Furthermore, it will be readily understood by those skilled in the art that the decoding apparatus of the present invention can also be used for polarization states
And (4) decoding.
Further, the optical splitting assembly of the present invention may further include a partial beam splitter (NBS) provided at least one of the second port and the third port of the first polarization beam splitting element to adjust attenuation of the first component and the second component in the polarization decoding process. Preferably, the partial beam splitter may be arranged to have an adjustable splitting ratio to balance the attenuation of the first and second components. Alternatively, the partial beam splitter may have a fixed splitting ratio, e.g. it has a horizontal polarization transmittance Tp, and a vertical polarization transmittance TNBSTp.delta.where delta satisfies TAB*TP＝TAC*TPDelta, i.e. delta-TAB/TACWherein, TABFor the efficiency of the horizontal polarization component through the splitting assembly without partial beam splitters, TAcIs the efficiency with which the vertically polarized component passes through the splitting assembly without a partial beam splitter.
Further, an integrated light splitting assembly is formed by directly connecting the first polarization beam splitting element, the first unidirectional 90-degree rotator, the second unidirectional 90-degree rotator and the second polarization beam splitting element or the first polarization beam splitting element, the first unidirectional 90-degree rotator, the second polarization beam splitting element and a part of beam splitters through gluing, so that a stable and disturbance-free polarization state orthogonality distinguishing function can be provided without introducing a polarization controller to provide polarization feedback as in the prior art.
FIG. 6 illustrates a second exemplary embodiment of a light splitting assembly of the present invention, which includes a third polarizing beam splitting element, a circulator, and a fourth polarizing beam splitting element.
The third and fourth polarization beam splitting elements are for splitting an input optical pulse into first and second components having polarization directions perpendicular to each other, and may have first, second, and third ports. By way of example, the third and fourth polarizing beam splitting elements may be polarizing beam splitters (as shown in FIG. 6), or polarizing beam splitting cubes (not shown).
The circulator may have first, second and third ports, wherein the optical pulse input by the first port is output by the second port and the optical pulse input by the second port is output by the third port.
As shown in fig. 6, the first port of the circulator corresponds to the first port a of the light splitting assembly.
The circulator is optically connected to the third polarizing beam splitting element, and the horizontal direction of the second port of the circulator is aligned in parallel with the horizontal direction of the first port of the third polarizing beam splitting element, i.e., the horizontal direction of the second port of the circulator is aligned in parallel with the transmission direction of the third polarizing beam splitting element with respect to the first port. In the third polarization beam splitting element, the second port and the third port serve as a transmission output port (which corresponds to the second port B of the optical splitting component) and a reflection output port (which corresponds to the third port C of the optical splitting component) with respect to the first port, respectively.
When an optical pulse with a polarization state of 45 degrees enters the optical splitting assembly through the first port a, since the second port of the circulator is aligned with the horizontal direction of the first port of the third polarization beam splitting element, the optical pulse with the polarization state of 45 degrees is still 45 degrees polarized light when entering the first port of the third polarization beam splitting element through the second port of the circulator, and therefore, the optical pulse is split into a first component (H light) and a second component (V light) which have the same intensity and are vertical to each other in polarization directions in the third polarization beam splitting element, and the first component and the second component are respectively output from the second port and the third port of the third polarization beam splitting element.
The second port and the third port of the third polarization splitting element are connected to a polarization maintaining fiber to form a sagnac loop, wherein the second port and the third port are both in direct coupling alignment with the same optical axis (e.g., slow axis) of the polarization maintaining fiber, such that the first and second components will be input into the sagnac loop in the form of H light and V light, respectively, through the second port B and the third port C of the optical splitting assembly, propagating in the loop along the same optical axis (e.g., slow axis) of the polarization maintaining fiber.
In a Sagnac loop, a phase difference phi is formed between the first and second components by means of a phase modulator PMde. The phase modulated first and second components are returned to the third port C and the second port B of the optical splitting assembly simultaneously along the slow axis of the polarization maintaining fiber. At this time, due to the above-mentioned optical axis alignment relationship, for example, the slow axis of the polarization maintaining fiber is directly aligned and coupled with the third port C in the V light direction and directly aligned and coupled with the second port B in the H light direction, the first component in the polarization maintaining fiber (e.g., propagating along the slow axis) will return to the third polarization beam splitting element via the third port C in the form of V light, and the second component in the polarization maintaining fiber (e.g., propagating along the slow axis) will return to the third polarization beam splitting element via the second port B in the form of H light. At this point, the first and second components are coupled within the third polarizing beam splitting element and output an optical pulse through its first port towards the second port of the circulator, which is then transmitted to the third port of the circulator.
If the phase difference is phide0, then the light pulse output by the third polarization beam splitting element to the second port of the circulator has a polarization state of 45 degrees; if the phase difference is phideIs pi, then the light output by the third polarization beam splitting element to the second port of the circulatorThe pulse has a polarization state of-45 degrees.
The third port of the circulator is optically connected to the first port of the fourth polarizing beam splitting element and is positioned such that the horizontal direction of the circulator is rotated by 45 (or-45) degrees relative to the transmission or reflection direction of the fourth polarizing beam splitting element with respect to the first port.
As a preferred example, the third port of the circulator and the first port of the fourth polarization beam splitting element are connected by a polarization maintaining fiber, wherein the polarization maintaining fiber has one of its optical axes (fast or slow axis) coupled with a rotation of 45 (or-45) degrees to the horizontal direction of the circulator at one end, while having its optical axis (preferably the same optical axis) aligned with the fourth polarization beam splitting element coupled with respect to the transmission or reflection direction of the first port at the other end. Preferably, the polarization maintaining optical fiber can be connected by polarization maintaining fusion.
The working principle of this embodiment of the beam splitting assembly is further explained below by taking as an example that the horizontal direction of the circulator is aligned with respect to the fourth polarizing beam splitting element rotated by 45 degrees with respect to the transmission direction of the first port.
If the phase difference is phideAnd 0, the optical pulse coupled out by the third polarization beam splitting element to the circulator has a polarization state of 45 degrees, and since the horizontal direction of the circulator is aligned by rotating 45 degrees with respect to the transmission direction of the fourth polarization beam splitting element about the first port, the optical pulse reaches the first port of the fourth polarization beam splitting element through the circulator and the polarization maintaining fiber, and then the optical pulse is output outwards through the second port (corresponding to the fourth port D of the optical splitting component) of the fourth polarization beam splitting element through the transmission effect.
If the phase difference is phideAnd pi, the optical pulse coupled out by the third polarization beam splitting element to the circulator has a polarization state of-45 degrees, and since the horizontal direction of the circulator is aligned with a rotation of 45 degrees relative to the transmission direction of the fourth polarization beam splitting element about the first port, the optical pulse reaches the first port of the fourth polarization beam splitting element from the circulator and is then output outwards through the third port (corresponding to the fifth port E of the light splitting assembly) of the fourth polarization beam splitting element by reflection.
Further, the circulator and the third polarization beam splitting element are directly connected through gluing to form an integrated beam splitting assembly, so that a stable and undisturbed polarization state orthogonal distinguishing function can be provided, and a polarization controller is not required to be introduced to provide polarization feedback as in the prior art.
Fig. 7 shows a third exemplary embodiment of a light splitting assembly of the present invention, which again comprises a third polarizing beam splitting element, a circulator and a fourth polarizing beam splitting element. For the sake of brevity, only the differences between the third embodiment and the second embodiment will be described below, and the same parts will not be described again.
As shown in fig. 7, the circulator is connected to the third polarization beam splitting element, and the horizontal direction of the second port of the circulator is aligned with a 45-degree rotation of the horizontal direction of the first port of the third polarization beam splitting element, that is, the horizontal direction of the second port of the circulator is aligned with a 45-degree rotation of the third polarization beam splitting element with respect to the transmission direction of the first port.
When an optical pulse of H light enters the optical splitting assembly through the first port a, since the second port of the circulator is aligned with the first port of the third polarization beam splitting element with a 45-degree rotation in the horizontal direction, and the optical pulse of H light becomes 45-degree polarized light when entering the first port of the third polarization beam splitting element through the second port of the circulator, the optical pulse is split into a first component (H light) and a second component (V light) having the same intensity and having polarization directions perpendicular to each other in the third polarization beam splitting element, and the first and second components are output from the second and third ports of the third polarization beam splitting element, respectively.
Similarly, the first and second components are phase modulated in the Sagnac loop by phideThen, the light is returned to the third polarization beam splitter element in the form of V light through the third port C and in the form of H light through the second port B. At this point, the first and second components are coupled within the third polarizing beam splitting element and output an optical pulse through its first port towards the second port of the circulator.
If the phase difference is phide0, then the light pulse output by the third polarization beam splitting element to the second port of the circulator has a polarization state of 45 degrees; if the phase difference is phideIs pi, then the third polarization beam splitting element is directed to the circulatorThe light pulse output by the second port of (a) has a polarization state of-45 degrees. Since the second port of the circulator is aligned with the first port of the third polarization beam splitting element by rotating 45 degrees in the horizontal direction, the 45-degree polarized light output by the first port of the third polarization beam splitting element will become horizontal polarized light (H light) when entering the circulator through the second port of the circulator, and the-45-degree polarized light output by the first port of the third polarization beam splitting element will become vertical polarized light (V light) when entering the circulator through the second port of the circulator.
The third port of the circulator is connected to the first port of the fourth polarizing beam splitting element and is arranged such that the horizontal direction of the circulator is aligned with respect to the transmission or reflection direction of the fourth polarizing beam splitting element with respect to the first port. As a preferred example, the third port of the circulator and the first port of the fourth polarization beam splitting element are connected by a polarization maintaining fiber, wherein the polarization maintaining fiber has at one end its optical axis (e.g. slow axis) coupled with the horizontal direction of the circulator, while at the other end its optical axis (preferably the same optical axis) is aligned with the transmission or reflection direction coupling of the fourth polarization beam splitting element with respect to the first port. Preferably, the polarization maintaining optical fiber can be connected by polarization maintaining fusion.
The operation of this embodiment of the beam splitting assembly is further explained below by taking as an example the horizontal orientation of the circulator relative to the fourth polarizing beam splitting element with respect to the transmission direction of the first port.
As described above, at the phase difference phideAt 0, the optical pulse coupled out to the circulator by the third polarization beam splitting element will be horizontally polarized light, and since the horizontal direction of the circulator is aligned with respect to the transmission direction of the fourth polarization beam splitting element with respect to the first port, the optical pulse will reach the first port of the fourth polarization beam splitting element by the circulator and then be output outwards through the second port (corresponding to the fourth port D of the optical splitting component) thereof by transmission in the fourth polarization beam splitting element.
At a phase difference phideAt pi, the light pulse coupled out to the circulator via the third polarization beam splitting element will be vertically polarized light due to the horizontal orientation of the circulator with respect to the first port relative to the fourth polarization beam splitting elementThe transmission directions are aligned, and then the light pulse reaches the first port of the fourth polarization beam splitting element from the circulator, and is output outwards through the third port (corresponding to the fifth port E of the light splitting assembly) of the fourth polarization beam splitting element by reflection.
Further, the circulator and the third polarization beam splitting element can also be directly connected by gluing to form an integrated beam splitting assembly, so that a stable and undisturbed polarization state orthogonal distinguishing function can be provided without introducing a polarization controller to provide polarization feedback as in the prior art.
Fig. 8 shows an exemplary embodiment of a receiving end for quantum key distribution according to the present invention. As shown in the figure, the receiving end may include a wavelength division multiplexing unit, a synchronous optical detection unit, a polarization control unit, the above-mentioned polarization decoding device, and an optical detection unit.
The wavelength division multiplexing unit is used for separating the synchronous light from the signal light pulse from the transmitting end. As an example, the wavelength division multiplexing unit may be a Wavelength Division Multiplexer (WDM).
The synchronous light detection unit is used for receiving synchronous light to perform synchronous light detection. As an example, the synchronization light detection unit may be a PIN photodetector.
The polarization control unit is arranged in front of the polarization decoding device and used for carrying out polarization control on the signal light pulse. As an example, the polarization control unit may be an Electric Polarization Controller (EPC).
The polarization decoding apparatus of the present invention is for receiving signal light pulses and outputting the light pulses via at least one of the fourth port D and the fifth port E thereof based on a measured basis vector.
The fourth port D and the fifth port E of the polarization decoding device are respectively connected with optical detection units (Det0 and Det1) to detect the output optical pulses. As a preferred example, the light detection unit may comprise a single photon detector.
Although the present invention has been described in connection with the embodiments illustrated in the accompanying drawings, it will be understood by those skilled in the art that the embodiments described above are merely exemplary for illustrating the principles of the present invention and are not intended to limit the scope of the present invention, and that various combinations, modifications and equivalents of the above-described embodiments may be made by those skilled in the art without departing from the spirit and scope of the present invention.
Claims (12)
1. A light splitting assembly comprising a first polarizing beam splitting element, a first unidirectional 90 degree rotator, a second unidirectional 90 degree rotator, and a second polarizing beam splitting element;
the first polarization beam splitting element is provided with a first port, a second port, a third port and a fourth port, wherein the second port and the third port of the first polarization beam splitting element are respectively a transmission end and a reflection end relative to the first port of the first polarization beam splitting element, and are respectively a reflection end and a transmission end relative to the fourth port of the first polarization beam splitting element;
the first and second unidirectional 90 degree rotators have a first port and a second port and are configured to: the polarization direction of the optical pulse input through the first port of the unidirectional 90-degree rotator is not rotated when the optical pulse is output through the second port of the unidirectional 90-degree rotator, and the polarization direction of the optical pulse input through the second port of the unidirectional 90-degree rotator is rotated by 90 degrees when the optical pulse is output through the first port of the unidirectional 90-degree rotator;
the second port of the first polarization beam splitting element is connected with the first port of the first unidirectional 90-degree rotator, and the third port of the first polarization beam splitting element is connected with the second port of the second unidirectional 90-degree rotator; or the second port of the first polarization beam splitting element is connected with the second port of the first unidirectional 90-degree rotator, and the third port of the first polarization beam splitting element is connected with the first port of the second unidirectional 90-degree rotator;
the second polarization beam splitting element is provided with a first port, a second port and a third port, wherein the second port and the third port of the second polarization beam splitting element are a transmission end and a reflection end relative to the first port of the second polarization beam splitting element respectively; and the first port of the second polarization beam splitting element is connected with the fourth port of the first polarization beam splitting element, and the optical axis direction of the second polarization beam splitting element is aligned by rotating an angle of 45 degrees or-45 degrees relative to the optical axis direction of the first polarization beam splitting element.
2. The optical splitting assembly of claim 1, wherein the first polarizing beam splitting element is a polarizing beam splitting cube or a polarizing beam splitter; and/or the second polarization beam splitting element is a polarization beam splitter or a polarization beam splitting cube; and/or the unidirectional 90-degree rotator comprises a 45-degree Faraday rotator plate and a half-wave plate with the fast axis at 67.5 degrees or 22.5 degrees.
3. The optical splitting assembly of claim 1, further comprising a partial beam splitter disposed at least one of the second and third ports of the first polarizing beam splitting element.
4. The optical splitting assembly of claim 1, wherein the first polarizing beam splitting element directly connects the first unidirectional 90-degree rotator, the second unidirectional 90-degree rotator, and the second polarizing beam splitting element in a glued manner.
5. A beam splitting assembly comprising a third polarizing beam splitting element, a circulator and a fourth polarizing beam splitting element;
the circulator is provided with a first port, a second port and a third port, wherein the optical pulse input by the first port of the circulator is output through the second port of the circulator, and the optical pulse input by the second port of the circulator is output through the third port of the circulator;
the third polarization beam splitting element has a first port, a second port and a third port, wherein the second port and the third port of the third polarization beam splitting element are a transmission end and a reflection end respectively relative to the first port of the third polarization beam splitting element;
the fourth polarization beam splitting element has a first port, a second port and a third port, wherein the second port and the third port of the fourth polarization beam splitting element are a transmission end and a reflection end respectively relative to the first port of the fourth polarization beam splitting element;
the second port of the circulator is connected with the first port of the third polarization beam splitting element, and the third port of the circulator is connected with the first port of the fourth polarization beam splitting element;
the circulator is aligned at its second port with a horizontal direction parallel to the horizontal direction of the first port of the third polarizing beam splitting element, while the circulator is aligned at its third port with a horizontal direction rotated 45 or-45 degrees relative to the horizontal direction of the first port of the fourth polarizing beam splitting element; alternatively, the first and second electrodes may be,
the circulator is aligned at its second port with a 45 or-45 degree rotation of the horizontal direction from the first port of the third polarizing beam splitting element, while the circulator is aligned at its third port with a horizontal direction parallel to the horizontal direction of the first port of the fourth polarizing beam splitting element.
6. The optical splitting assembly of claim 5, wherein the third port of the circulator and the first port of the fourth polarizing beam splitting element are connected by a polarization maintaining fiber;
said polarization maintaining fiber having one of its fast and slow axes coupled at one end rotated 45 or-45 degrees with respect to the horizontal of the third port of said circulator and having said one of said fast and slow axes aligned at the other end with the horizontal coupling of the first port of said fourth polarization splitting element; or
The polarization maintaining fiber has one of its fast and slow axes coupled to the horizontal direction of the third port of the circulator at one end and aligned with the horizontal direction of the first port of the fourth polarization beam splitting element at the other end.
7. The optical splitting assembly of claim 5, wherein the third polarizing beam splitting element is a polarizing beam splitting cube or a polarizing beam splitter; and/or the fourth polarization beam splitting element is a polarization beam splitter or a polarization beam splitting cube; and/or the circulator is directly connected with the third polarization beam splitting element in a gluing mode.
8. A polarization decoding apparatus for quantum key distribution, comprising:
a splitting assembly having a first port a, a second port B, a third port C, a fourth port D and a fifth port E and being arranged to split an optical pulse received via the first port a into a first component and a second component and to output the first component and the second component via the second port B and the third port C, respectively;
a sagnac loop formed by connecting the second port B and the third port C of the optical splitting assembly with a polarization maintaining fiber, one of a fast axis and a slow axis of the polarization maintaining fiber of which is aligned with the optical splitting assembly at the second port B and the third port C, such that the first and second components both propagate along the slow axis of the polarization maintaining fiber of the sagnac loop or both propagate along the fast axis of the polarization maintaining fiber of the sagnac loop;
a phase modulation unit arranged in the Sagnac loop for phase modulating at least one of the first and second components to form a phase difference Φ therebetweende(ii) a And the number of the first and second electrodes,
the light splitting assembly is further arranged to receive the light having the phase difference phideAnd coupling the first and second components, and providing an output in at least one of the fourth port D and the fifth port E based on the coupling.
9. The polarization decoding apparatus of claim 8, wherein the polarization maintaining fiber is a panda polarization maintaining fiber.
10. The polarization decoding apparatus of claim 8, wherein the optical splitting assembly is the optical splitting assembly of any one of claims 1 to 7.
11. Receiving end for quantum key distribution comprising a wavelength division multiplexing unit, a synchronous light detection unit, a polarization control unit, a light detection unit, and a polarization decoding apparatus according to any one of claims 8 to 10,
the wavelength division multiplexing unit is used for separating the synchronous light and the signal light pulse;
the synchronous light detection unit is used for receiving the synchronous light to perform synchronous light detection;
the polarization control unit is used for carrying out polarization control on the signal light pulse before the signal light pulse enters the polarization decoding device;
the polarization decoding device is used for carrying out polarization decoding on the signal light pulse; and
the optical detection unit is used for detecting the polarization decoding result output by the polarization decoding device.
12. The receiving end according to claim 11, wherein the polarization control unit is an electric polarization controller; and/or the optical detection unit comprises two single photon detectors which are respectively connected with the fourth port D and the fifth port E of the polarization decoding device.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103475425A (en) * | 2013-07-26 | 2013-12-25 | 华东师范大学 | Single photon source based on Faraday-Sagnac loop and realization method thereof |
| CN105897413A (en) * | 2016-05-26 | 2016-08-24 | 安徽问天量子科技股份有限公司 | Phase modulation polarization coded QKD system based on sagnac ring |
| CN106130722A (en) * | 2016-06-13 | 2016-11-16 | 上海理工大学 | A kind of avalanche photoelectric diode detection array being applicable to ultrahigh speed quantum secret communication system |
| CN208797952U (en) * | 2018-07-24 | 2019-04-26 | 中国科学技术大学 | Polarization encoder device for optic communication |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105897413A (en) * | 2016-05-26 | 2016-08-24 | 安徽问天量子科技股份有限公司 | Phase modulation polarization coded QKD system based on sagnac ring |
| CN106130722A (en) * | 2016-06-13 | 2016-11-16 | 上海理工大学 | A kind of avalanche photoelectric diode detection array being applicable to ultrahigh speed quantum secret communication system |
| CN208797952U (en) * | 2018-07-24 | 2019-04-26 | 中国科学技术大学 | Polarization encoder device for optic communication |
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