CN115001593A - Hybrid integrated receiving chip for quantum key distribution - Google Patents
Hybrid integrated receiving chip for quantum key distribution Download PDFInfo
- Publication number
- CN115001593A CN115001593A CN202210929215.6A CN202210929215A CN115001593A CN 115001593 A CN115001593 A CN 115001593A CN 202210929215 A CN202210929215 A CN 202210929215A CN 115001593 A CN115001593 A CN 115001593A
- Authority
- CN
- China
- Prior art keywords
- port
- optical waveguide
- polarization
- beam splitting
- polarization beam
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000010287 polarization Effects 0.000 claims abstract description 425
- 230000003287 optical effect Effects 0.000 claims abstract description 256
- 239000000758 substrate Substances 0.000 claims abstract description 4
- 230000002457 bidirectional effect Effects 0.000 claims description 28
- 230000010354 integration Effects 0.000 abstract description 6
- 238000004891 communication Methods 0.000 abstract description 3
- 239000013307 optical fiber Substances 0.000 description 11
- 230000000694 effects Effects 0.000 description 8
- 238000000034 method Methods 0.000 description 6
- 230000001419 dependent effect Effects 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000000644 propagated effect Effects 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 230000002123 temporal effect Effects 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/60—Receivers
- H04B10/66—Non-coherent receivers, e.g. using direct detection
- H04B10/67—Optical arrangements in the receiver
- H04B10/671—Optical arrangements in the receiver for controlling the input optical signal
-
- 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
-
- 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
- G02B6/2773—Polarisation splitting or combining
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/70—Photonic quantum communication
-
- 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
- H04L9/0855—Quantum cryptography involving additional nodes, e.g. quantum relays, repeaters, intermediate nodes or remote nodes
Landscapes
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Optical Integrated Circuits (AREA)
Abstract
The utility model provides a mix integrated chip that receives for quantum key distribution, belongs to quantum security communication technical field, includes optical waveguide chip, half wave plate and Faraday optical rotation piece, optical waveguide chip is including integrated first polarization beam splitting circulator, second polarization beam splitting circulator, third polarization beam splitting circulator, two-way unequal arm interferometer and the grooving on same substrate. Compared with the prior art, the invention realizes the receiving and decoding which are irrelevant to the polarization, and improves the stability of the system; and the two polarization component pulses respectively pass through the primary interferometer, so that the loss of a receiving end cannot be additionally increased. In addition, the Faraday optical rotation sheet is used for carrying out 45-degree polarization rotation on the optical signal through hybrid integration, so that the problem that the 45-degree polarization rotation of the optical waveguide is difficult to realize can be solved, the output port and the input port can be separated, and the use of a circulator is avoided. The size of an optical system at a receiving end is greatly reduced, the miniaturization of equipment can be realized, and the device has the characteristic of immune channel polarization disturbance.
Description
Technical Field
The invention relates to the technical field of quantum secure communication, in particular to a hybrid integrated receiving chip for quantum key distribution.
Background
Quantum key distribution can provide unconditionally secure key distribution for both communication parties at a long distance, and the most mature protocol at present is the BB84 quantum key distribution protocol. On one hand, the optical fiber quantum key distribution system generally adopts a single mode optical fiber as a transmission channel, but because the optical fiber channel has an intrinsic birefringence effect, the polarization state of photons can change in the transmission process, and can change along with the change of the external environment. However, when decoding interference is performed at a receiving end in a conventional scheme based on a double unequal arm mach-zehnder interference ring, the polarization state changes randomly due to disturbance of an optical fiber channel, and the long arm and the short arm of the interferometer change differently in polarization, so that the stability of interference is affected, and thus the system has poor stability and is easily subjected to environmental interference. On the other hand, in the prior art, a quantum key distribution system is usually constructed by discrete optical elements, and has the disadvantages of large volume, complex structure, poor stability, high cost and difficulty in mass production, and the manufacturing precision of the interferometer with poor arm length is low, which may result in poor system stability and also fail to meet the requirements of integration and miniaturization of the system requirements.
Because the polarization state of the optical signal at the transmitting end is generally stable, special processing is not needed, and the encoding device is easy to integrate. However, the receiving end needs to receive the optical signal with randomly changed polarization, and needs a special receiving structure to realize polarization-independent decoding, so as to ensure the stable operation of the system. In the prior art, one solution to the polarization disturbance is to use an optical fiber faraday-michelson interferometer, so that the influence of the birefringence effect of the optical fiber and the environmental disturbance on the polarization state can be eliminated, the polarization change of the long and short arms can be automatically compensated, and the system is very stable. Still another solution is a fiber optic interferometer as disclosed in patent CN210041849U, which uses a faraday rotator to automatically compensate for channel polarization perturbations and different polarization changes in the long and short arms, also based on the faraday effect. Patent CN109391471B and document Zhang G W, et al, Polarization-induced interference based on a hybrid integrated planar light-wave circuit [ J ]. Photonics Research, 2021, 9(11): 2176-2171, mix and integrate faraday-michelson interferometer, because this scheme uses a reflective structure, one path of signal will be output from the input port, thus inevitably needing to use a circulator, making it difficult to further miniaturize the receiving end. CN1106020662A and Xu H, et al, Photonic Integrated Phase Decoder Scheme for High-Speed, Efficient and Stable Quantum Key Distribution System [ J ]. arXiv prepropressin: 1910.08327, 2019. However, this solution needs to use 2 integrated waveguide sagnac loop structures, which reduces the loss uniformity of the long and short arms, thereby affecting the interference visibility, and this solution is a round-trip structure, which also needs to use a circulator, and cannot further reduce the size of the receiving end.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a hybrid integrated receiving chip for quantum key distribution.
The technical scheme of the invention is realized as follows:
a hybrid integrated receiving chip for quantum key distribution comprises an optical waveguide chip, a half-wave plate and a Faraday optical rotation plate, wherein the optical waveguide chip comprises a first polarization beam splitting rotator, a second polarization beam splitting rotator, a third polarization beam splitting rotator, a two-way unequal arm interferometer and a notch which are integrated on the same substrate,
a first port and a fourth port of the first polarization beam splitting rotator are respectively used as an input port In and a first output port Out1 of the receiving chip, and a fourth port of the third polarization beam splitting rotator is used as a second output port Out2 of the receiving chip;
the second port of the first polarization beam splitting rotator is connected with the second port of the second polarization beam splitting rotator through an optical waveguide L1, and the third port of the first polarization beam splitting rotator is connected with the third port of the second polarization beam splitting rotator through an optical waveguide L2;
the first port of the second polarization beam splitting rotator is connected with the first port of the third polarization beam splitting rotator through an optical waveguide L3;
the second port and the third port of the third polarization beam splitting rotator are correspondingly connected with the two ports of the two-way unequal arm interferometer through an optical waveguide L4 and an optical waveguide L5 respectively;
the optical waveguide L1, the optical waveguide L2, the optical waveguide L4 and the optical waveguide L5 are mutually parallel, the notch is arranged in the vertical direction of the optical waveguide L1, the partial width of the notch in the area where the optical waveguide L1 and the optical waveguide L2 are located is the sum of the widths of a half wave plate and a Faraday rotation plate, and the partial width of the notch in the area where the optical waveguide L4 and the optical waveguide L5 are located is the same as the width of the Faraday rotation plate;
the length of the half-wave plate is different from that of the Faraday optical rotation plate, one end of the half-wave plate is aligned with that of the Faraday optical rotation plate, one end of the Faraday optical rotation plate is tightly attached to the other end of the optical rotation plate, and the half-wave plate and the Faraday optical rotation plate are inserted into the notch groove, so that optical signals transmitted in the optical waveguide L1 and the optical waveguide L2 can pass through the half-wave plate and the Faraday optical rotation plate, and optical signals transmitted in the optical waveguide L4 and the optical waveguide L5 can pass through the Faraday optical rotation plate;
the bidirectional unequal-arm interferometer is provided with a long arm and a short arm and is used for splitting two orthogonal polarization components of an optical signal to the long arm and the short arm respectively and carrying out polarization beam combination after adjusting the phase difference between the polarization components transmitted by the long arm and the short arm.
Preferably, both ports of the double unequal arm interferometer can input optical signals or output optical signals, and when one port is used as an input port, the other port is used as an output port.
Preferably, the bi-directional unequal arm interferometer comprises a fourth polarization beam splitting rotator, an optical waveguide delay line and a first phase modulator,
the first port and the fourth port of the fourth polarization beam splitting rotator are correspondingly connected with the optical waveguide L4 and the optical waveguide L5 respectively;
the second port of the fourth polarization beam splitting rotator is connected with a Faraday rotation sheet through an optical waveguide delay line to form a long arm of the bidirectional unequal arm interferometer; a third port of the fourth polarization beam splitting rotator is connected with a Faraday optical rotation sheet through a first phase modulator to form a short arm of the bidirectional unequal arm interferometer;
and a reflecting film is plated at the corresponding position of the other side of the optical waveguide delay line and the first phase modulator, which are connected with the Faraday optical rotation sheet.
Preferably, the bi-unequal arm interferometer comprises a fifth polarization beam splitting rotator, a sixth polarization beam splitting rotator and a second phase modulator,
the first port of the fifth polarization beam splitting rotator is connected with an optical waveguide L4, and the first port of the sixth polarization beam splitting rotator is connected with an optical waveguide L5;
the second port of the fifth polarization beam splitting rotator is connected with the second port of the sixth polarization beam splitting rotator to form a short arm of the bidirectional unequal arm interferometer; and the third port of the fifth polarization beam splitting rotator is connected with the third port of the sixth polarization beam splitting rotator through a second phase modulator to form a long arm of the two-way unequal arm interferometer.
Preferably, the bi-directional anisometric interferometer includes a seventh polarization beam splitting rotator and a third phase modulator,
the first port and the second port of the seventh polarization beam splitting rotator are correspondingly connected with the optical waveguide L4 and the optical waveguide L5 respectively; and a third port and a fourth port of the seventh polarization beam splitting rotator are connected through a third phase modulator to form a long arm of the bidirectional unequal-arm interferometer.
Preferably, the included angle between the fast axis direction of the half-wave plate and the TE polarization direction in the optical waveguide is 22.5 °, and the polarization rotation angle of the faraday optical rotation plate is 45 °.
Preferably, the optical waveguide L1 and the optical waveguide L2 have the same length, and the optical waveguide L4 and the optical waveguide L5 have the same length.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides a hybrid integrated receiving chip for quantum key distribution, which can realize receiving and decoding irrelevant to polarization and improve the stability of a system by respectively carrying out polarization synthesis and polarization beam splitting on received optical signals and then carrying out merging and output after polarization beam splitting. And two polarization component pulses respectively pass through the primary interferometer, which is equivalent to the fact that the whole pulse passes through the primary interferometer, and the loss of a receiving end cannot be additionally increased. In addition, the Faraday optical rotation sheet is used for carrying out 45-degree polarization rotation on the optical signal through hybrid integration, the problem that the 45-degree polarization rotation of the optical waveguide is difficult to realize can be solved, the output port and the input port can be separated, and the use of a circulator is avoided. Therefore, the invention greatly reduces the volume of the receiving end optical system through hybrid integration, can realize the miniaturization of equipment, has the characteristic of polarization disturbance of an immune channel and realizes the long-term working stability of the system.
Drawings
FIG. 1 is a schematic diagram of a hybrid integrated receiving chip for quantum key distribution according to the present invention;
FIG. 2 is a top view of a hybrid integrated receiving chip structure for quantum key distribution according to the present invention;
FIG. 3 is a top view of an embodiment of a hybrid integrated receiving chip for quantum key distribution according to the present invention;
FIG. 4 is a top view of a hybrid integrated receiving chip for quantum key distribution according to a second embodiment of the present invention;
fig. 5 is a top view of three structures of an embodiment of a hybrid integrated receiving chip for quantum key distribution according to the present invention.
In the figure: the polarization beam splitting device comprises an optical waveguide chip 1, a first polarization beam splitting rotator 1-1, a second polarization beam splitting rotator 1-2, a third polarization beam splitting rotator 1-3, a bidirectional unequal arm interferometer 1-4, a fourth polarization beam splitting rotator 1-4-1, an optical waveguide delay line 1-4-2, a first phase modulator 1-4-3, a fifth polarization beam splitting rotator 1-4-5, a reflecting film 1-4-4, a sixth polarization beam splitting rotator 1-4-6, a second phase modulator 1-4-7, a seventh polarization beam splitting rotator 1-4-8, a third phase modulator 1-4-9, a notch 1-5, a half-wave plate 2 and a Faraday rotation plate 3.
Detailed Description
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown.
As shown in fig. 1 and fig. 2, the hybrid integrated receiving chip for quantum key distribution comprises an optical waveguide chip 1, a half-wave plate 2 and a faraday rotation plate 3, wherein the optical waveguide chip 1 comprises a first polarization beam splitting rotator 1-1, a second polarization beam splitting rotator 1-2, a third polarization beam splitting rotator 1-3, a bidirectional unequal arm interferometer 1-4 and a notch 1-5 which are integrated on the same substrate,
a first port and a fourth port of the first polarization beam splitting rotator 1-1 are respectively used as an input port In and a first output port Out1 of the receiving chip, and a fourth port of the third polarization beam splitting rotator 1-3 is used as a second output port Out2 of the receiving chip;
the second port of the first polarization beam splitting rotator 1-1 is connected with the second port of the second polarization beam splitting rotator 1-2 through an optical waveguide L1, and the third port of the first polarization beam splitting rotator 1-1 is connected with the third port of the second polarization beam splitting rotator 1-2 through an optical waveguide L2;
the first port of the second polarization beam splitting rotator 1-2 is connected with the first port of the third polarization beam splitting rotator 1-3 through an optical waveguide L3;
the second port and the third port of the third polarization beam splitting rotator 1-3 are correspondingly connected with the two ports of the two-way unequal arm interferometer 1-4 through an optical waveguide L4 and an optical waveguide L5 respectively;
the optical waveguide L1, the optical waveguide L2, the optical waveguide L4 and the optical waveguide L5 are mutually parallel, the notch 1-5 is arranged in the vertical direction of the optical waveguide L1, the partial width of the notch 1-5 in the area where the optical waveguide L1 and the optical waveguide L2 are located is the sum of the widths of the half-wave plate 2 and the Faraday rotation plate 3, and the partial width of the notch 1-5 in the area where the optical waveguide L4 and the optical waveguide L5 are located is the same as the width of the Faraday rotation plate 3;
the lengths of the half-wave plate 2 and the Faraday optical rotation plate 3 are different, and one ends of the half-wave plate 2 and the Faraday optical rotation plate 3 are aligned and tightly attached and then inserted into the notches 1-5, so that optical signals transmitted in the optical waveguide L1 and the optical waveguide L2 can pass through the half-wave plate 2 and the Faraday optical rotation plate 3, and optical signals transmitted in the optical waveguide L4 and the optical waveguide L5 can pass through the Faraday optical rotation plate 3;
the bidirectional unequal-arm interferometer 1-4 is provided with a long arm and a short arm and is used for splitting two orthogonal polarization components of an optical signal to the long arm and the short arm respectively, and carrying out polarization beam combination after adjusting the phase difference between the polarization components transmitted by the long arm and the short arm; two ports of the bidirectional unequal arm interferometer 1-4 can input and output optical signals, wherein when one port serves as an input port, the other port serves as an output port;
the included angle between the fast axis direction of the half-wave plate 2 and the TE polarization direction in the optical waveguide is 22.5 degrees, and the polarization rotation angle of the Faraday optical rotation plate 3 is 45 degrees.
The lengths of the optical waveguide L1 and the optical waveguide L2 are equal, and the lengths of the optical waveguide L4 and the optical waveguide L5 are equal.
The specific receiving and decoding process is as follows:
the phase difference between the front time mode and the rear time mode of the phase coding state sent by the sending end is
And the same polarization can be written as
The polarization states of temporal modes |0> and |1> are assumed to be both horizontally polarized. After passing through a single-mode optical fiber channel, due to the existence of birefringence effect and the disturbance of the environment where the channel is located, the phase encoding state changes into a random polarization state when reaching a receiving end, and therefore the polarization state of the phase encoding pulse entering the decoding device can be written as
Wherein,
。
as shown In fig. 2, an optical pulse of an arbitrary polarization enters an input port In of the hybrid integrated receiving chip, first enters a first port of the first polarization beam splitter rotator 1, and is split into a first signal light component and a second signal light component having the same polarization. The two beams respectively exit from the second port and the third port of the first polarization beam splitting rotator 1, and respectively propagate along the optical waveguide L1 and the optical waveguide L2 in a TE polarization mode, and simultaneously reach the half-wave plate 2, and because the included angle between the fast axis of the half-wave plate 2 and the TE polarization direction is 22.5 degrees, the polarization state of the horizontal polarized light after passing through the half-wave plate is changed into a polarization state
The effect is to rotate the polarization of the light by 45 °, and then the first signal light component and the second signal light component are changed into 45 ° polarization state after passing through the half-wave plate 2.
Since the polarization rotation angle of the faraday rotation plate 3 is 45 °, the polarization state of the 45 ° linearly polarized light is changed after passing through the faraday rotation plate 3
Therefore, the first signal light component and the second signal light component are rotated by 90 ° with respect to the polarization before entering the half-wave plate 2, both of which become TM polarization, are transmitted to the second port and the third port of the second polarization beam splitter rotator 1-2, respectively, are combined into the third signal light by them, and the polarization state becomes
Wherein,
the phase difference introduced by the optical waveguides L1 and L2 is included.
The third signal light reaches the first port of the third polarization beam splitting rotator 1-3 through the optical waveguide L3, is split into a fourth signal light component and a fifth signal light component with the same polarization, and exits from the second port and the third port thereof, respectively, and propagates along the optical waveguide L4 and the optical waveguide L5 in the TE polarization mode, respectively, where both are changed to 45 ° polarization after passing through the faraday rotator 3, and both respectively include the TE polarization component and the TM polarization component with the same amplitude.
Wherein the fourth signal light component enters one port of the bidirectional unequal-arm interferometer 1-4 through the optical waveguide L4, the TE polarization component and the TM polarization component of the fourth signal light component respectively travel the short arm and the long arm of the bidirectional unequal-arm interferometer 1-4, and the component traveling the long arm modulates the phase
Before polarization beam combination in the bi-directional unequal arm interferometers 1-4, the quantum states propagated in the long and short arms can be written as
Wherein, due to
Time pattern of
And component
Time pattern of
The optical paths are equal, the two are overlapped in time, and the signals are polarized and synthesized into sixth signal light in the bidirectional unequal-arm interferometer 1-4, wherein the polarization state is
Wherein the phase difference
. While
Time pattern of
And
time pattern of
The signal light and the sixth signal light are not overlapped in time, and the signal light and the sixth signal light can be filtered by setting the door opening time position of the single photon detector, so that the subsequent propagation process is not required to be considered.
The sixth signal light propagates along the optical waveguide L5, and after being subjected to 45 ° polarization rotation by the faraday rotation plate 3, the polarization state changes to
The sixth signal light then enters the third port of the third polarization beam splitting rotator 1-3 for polarization beam splitting, the TM polarization component of the sixth signal light directly exits from the fourth port of the third polarization beam splitting rotator 1-3 and is output from the second output port Out2 of the receiving chip, and the light intensity is
. The TE polarization component of the sixth signal light exits from the first port of the third polarization beam splitting rotator 1-3 to become TM polarization, and reaches the first port of the second polarization beam splitting rotator 1-2 through the optical waveguide L3, exits from the third port thereof, and propagates in the TM mode along the optical waveguide L2. Then the polarization passes through a Faraday rotation plate 3 and a half-wave plate 2 in sequence, the polarization is firstly rotated by 45 degrees and then is selected by 45 degrees, namely the polarization is not rotated and still is TM polarization, finally the polarization reaches a third port of a first polarization beam splitting rotator 1-1, is emitted from a fourth port of the first polarization beam splitting rotator and is output from a first output port Out1 of a receiving chip, and the light intensity is
。
Similarly, the fifth signal light component enters the other port of the bi-directional unequal arm interferometer 1-4 via the optical waveguide L5, the TE polarization component and the TM polarization component of the fifth signal light component respectively travel along the short arm and the long arm of the bi-directional unequal arm interferometer 1-4, and the component traveling along the long arm modulates the phase
Before polarization beam combination in the bi-directional unequal arm interferometers 1-4, the quantum states propagated in the long and short arms can be written as
Wherein, due to
Time pattern of
And component
Time pattern of
The optical paths are equal, the two are overlapped in time, and the two are polarized and synthesized into seventh signal light in the bidirectional unequal-arm interferometer 1-4, wherein the polarization state is
Wherein the phase difference
。
The seventh signal light propagates along the optical waveguide L4, and after being subjected to 45 ° polarization rotation by the faraday rotation plate 3, the polarization state changes to
The seventh signal light then enters the second port of the third polarization beam splitting rotator 1-3 for polarization beam splitting, the TM polarization component of the seventh signal light exits directly from the fourth port of the third polarization beam splitting rotator 1-3 and is output from the second output port Out2 of the receiving chip, and the light intensity is
. The TE polarization component of the seventh signal light is converted from the secondThe first port of the three polarization beam splitting rotator 1-3, which is still TE polarized, exits through the optical waveguide L3 to the first port of the second polarization beam splitting rotator 1-2, exits from the second port thereof, and propagates along the optical waveguide L1 in TM mode. Then the polarization is still TM polarization after passing through Faraday rotation plate 3 and half-wave plate 2 in turn, finally reaches the second port of the first polarization beam splitter rotator 1-1, exits from the fourth port thereof, and is output from the first output port Out1 of the receiving chip, and the light intensity is
。
Therefore, the light intensity from the first output port Out1 of the receiving chip is
The light intensity output from the second output port Out2 of the receiving chip is
It follows that the results output from the two output ports of the receive chip are only dependent on the modulated phase difference and not on the incident polarisation state, so that polarisation independent receive decoding can be achieved. In addition, the maximum value of the interference light intensity is 1/2, because only half of the pulses participate in the interference, and the energy utilization rate of the photons is 1/2.
As shown in fig. 3, a first embodiment of the hybrid integrated receiving chip for quantum key distribution according to the present invention:
the structure of the hybrid integrated receiving chip is as follows: the bidirectional unequal-arm interferometer 1-4 comprises a fourth polarization beam splitting rotator 1-4-1, an optical waveguide delay line 1-4-2 and a first phase modulator 1-4-3, wherein a first port and a fourth port of the fourth polarization beam splitting rotator 1-4-1 are correspondingly connected with an optical waveguide L4 and an optical waveguide L5 respectively; the second port of the fourth polarization beam splitting rotator 1-4-1 is connected with a Faraday optical rotation sheet 3 through an optical waveguide delay line 1-4-2 to form a long arm of a bidirectional unequal arm interferometer 1-4; the third port of the fourth polarization beam splitting rotator 1-4-1 is connected with a Faraday polariscope 3 through a first phase modulator 1-4-3 to form a short arm of the bidirectional unequal arm interferometer 1-4; and the optical waveguide delay line 1-4-2 and the first phase modulator 1-4-3 are connected with a reflecting film 1-4-4 at the corresponding position of the other side of the Faraday optical rotation sheet 3.
A specific receiving and decoding process of the embodiment is as follows:
an optical pulse with arbitrary polarization enters an input port In of the hybrid integrated receiver chip, first enters a first port of the first polarization beam splitter and rotator 1, and is split into a first signal light component and a second signal light component with the same polarization. The two beams respectively exit from the second port and the third port of the first polarization beam splitting rotator 1, and respectively propagate along the optical waveguide L1 and the optical waveguide L2 in a TE polarization mode, and simultaneously reach the half-wave plate 2, and because the included angle between the fast axis of the half-wave plate 2 and the TE polarization direction is 22.5 degrees, the polarization state of the horizontal polarized light after passing through the half-wave plate is changed into a polarization state
The effect is to rotate the polarization of light by 45 °, and then the first signal light component and the second signal light component are changed to the 45 ° polarization state after passing through the half-wave plate 2.
Since the polarization rotation angle of the faraday rotator 3 is 45 °, the polarization state of 45 ° linearly polarized light is changed after passing through the faraday rotator 3
Therefore, the first signal light component and the second signal light component are rotated by 90 ° with respect to the polarization before entering the half-wave plate 2, both of which become TM polarization, are transmitted to the second port and the third port of the second polarization beam splitter rotator 1-2, respectively, are combined into the third signal light by them, and the polarization state becomes
Wherein,
the phase difference introduced by the optical waveguide L1 and the optical waveguide L2 is included.
The third signal light reaches the first port of the third polarization beam splitting rotator 1-3 through the optical waveguide L3, is split into a fourth signal light component and a fifth signal light component having the same polarization, and exits from the second port and the third port thereof, respectively, and propagates along the optical waveguide L4 and the optical waveguide L5 in the TE polarization mode, respectively, and both become 45 ° polarized after passing through the faraday rotator 3, and each contain the TE polarization component and the TM polarization component having the same amplitude.
The fourth signal light component enters the first port of the fourth polarization beam splitting rotator 1-4-1 through the optical waveguide L4, the TE polarization component of the fourth signal light component is emitted from the second port and reaches the Faraday optical rotation sheet 3 through the optical waveguide delay line 1-4-2, the other side of the Faraday optical rotation sheet 3 is plated with a reflection film, the action of the reflection film is opposite to that of the Faraday reflection mirror, so that the TE polarization component is converted into TM polarization after being reflected, and is transmitted to the fourth port from the second port of the fourth polarization beam splitting rotator 1-4-1 after passing through the optical waveguide delay line 1-4-2 again to be converted into TE polarization; the TM polarization component of the fourth signal light component is emitted from the third end port of the fourth polarization beam splitting rotator 1-4-1 to be changed into TE polarization, reaches the Faraday polarization plate 3 after passing through the first phase modulator 1-4-3 and is reflected by a reflecting film to be changed into TM polarization, is transmitted to the fourth end port from the third end port of the fourth polarization beam splitting rotator 1-4-1 after passing through the first phase modulator 1-4-3 to be still TM polarization after passing through the phase modulation of the first phase modulator 1-4-3, and is subjected to two times of co-modulation phase
. The quantum states at the fourth port of the fourth polarization beam splitter rotator 1-4-1 can be written as
Wherein, due to
Time pattern of
And component
Time pattern of
The optical paths are equal, the optical paths are overlapped in time, and the optical paths are polarized and synthesized into sixth signal light by the fourth polarization beam splitting rotator 1-4-1, wherein the polarization state is
Wherein the phase difference
. While
Time pattern of
And
time pattern of
The signal light and the sixth signal light are not overlapped in time, and can be filtered by setting the door opening time position of the single photon detector, so that the subsequent propagation process does not need to be considered.
The sixth signal light propagates along the optical waveguide L5, and after being subjected to 45 ° polarization rotation by the faraday rotation plate 3, the polarization state changes to
Sixth signalThe light then enters a third port of the third polarization beam splitting rotator 1-3 for polarization beam splitting, the TM polarization component of the light directly exits from a fourth port of the third polarization beam splitting rotator 1-3 and is output from a second output port Out2 of the receiving chip, and the light intensity is
. The TE polarization component of the sixth signal light exits from the first port of the third polarization beam splitting rotator 1-3 to become TM polarization, and reaches the first port of the second polarization beam splitting rotator 1-2 through the optical waveguide L3, exits from the third port thereof, and propagates in the TM mode along the optical waveguide L2. Then the polarization passes through a Faraday rotation plate 3 and a half-wave plate 2 in sequence, the polarization is firstly rotated by 45 degrees and then is selected by 45 degrees, namely the polarization is not rotated and still is TM polarization, finally the polarization reaches a third port of a first polarization beam splitting rotator 1-1, is emitted from a fourth port of the first polarization beam splitting rotator and is output from a first output port Out1 of a receiving chip, and the light intensity is
。
Similarly, the fifth signal light component enters the fourth port of the fourth polarization beam splitting rotator 1-4-1 through the optical waveguide L5, and the TE polarization component thereof exits from the second port to become TM polarization, reaches the faraday rotation plate 3 through the optical waveguide delay line 1-4-2, is then reflected to become TE polarization, passes through the optical waveguide delay line 1-4-2 again, and is transmitted from the second port of the fourth polarization beam splitting rotator 1-4-1 to the first port, still being TE polarization; the TM polarization component of the fourth signal light component is emitted from the third end port of the fourth polarization beam splitting rotator 1-4-1, still is TM polarization, reaches a Faraday optical rotation sheet 3 after passing through the first phase modulator 1-4-3 and is reflected by a reflection film to become TE polarization, is transmitted to the first port from the third end port of the fourth polarization beam splitting rotator 1-4-1 after passing through the first phase modulator 1-4-3 again to become TM polarization after being phase modulated by the first phase modulator 1-4-3, and is phase-modulated twice
. The quantum states at the first port of the fourth polarization beam splitter rotator 1-4-1 can be written as
Wherein, due to
Time pattern of
And component
Time pattern of
The optical paths are equal, the optical paths are overlapped in time, and the optical paths are polarized and synthesized into seventh signal light by the fourth polarization beam splitting rotator 1-4-1, wherein the polarization state is
Wherein the phase difference
。
The seventh signal light propagates along the optical waveguide L4, and after being subjected to 45 ° polarization rotation by the faraday rotation plate 3, the polarization state changes to
The seventh signal light then enters the second port of the third polarization beam splitting rotator 1-3 for polarization beam splitting, the TM polarization component of the seventh signal light exits directly from the fourth port of the third polarization beam splitting rotator 1-3 and is output from the second output port Out2 of the receiving chip, and the light intensity is
. TE polarization component of seventh signal light from third polarization beam splitting rotator 1-3The first port exits, still TE polarized, and passes through optical waveguide L3 to the first port of the second polarization beam splitting rotator 1-2, exits from its second port, and propagates along optical waveguide L1 in TM mode. Then the optical fiber passes through a Faraday polarization plate 3 and a half-wave plate 2 in sequence, the polarization is still TM polarization, finally the optical fiber reaches a second port of the first polarization beam splitting rotator 1-1, is emitted from a fourth port of the first polarization beam splitting rotator, and is output from a first output port Out1 of a receiving chip, and the optical intensity is
。
Therefore, the light intensity from the first output port Out1 of the receiving chip is
The light intensity output from the second output port Out2 of the receiving chip is
It follows that the results output from the two output ports of the receive chip are only dependent on the modulated phase difference and not on the incident polarisation state, so that polarisation independent receive decoding can be achieved.
As shown in fig. 4, a second embodiment of the hybrid integrated receiving chip for quantum key distribution according to the present invention:
the structure of the hybrid integrated receiving chip is as follows: the bidirectional unequal-arm interferometer 1-4 comprises a fifth polarization beam splitting rotator 1-4-5, a sixth polarization beam splitting rotator 1-4-6 and a second phase modulator 1-4-7, wherein a first port of the fifth polarization beam splitting rotator 1-4-5 is connected with an optical waveguide L4, and a first port of the sixth polarization beam splitting rotator 1-4-6 is connected with an optical waveguide L5; the second port of the fifth polarization beam splitting rotator 1-4-5 is connected with the second port of the sixth polarization beam splitting rotator 1-4-6 to form a short arm of the bidirectional unequal arm interferometer 1-4; and the third port of the fifth polarization beam splitting rotator 1-4-5 is connected with the third port of the sixth polarization beam splitting rotator 1-4-6 through a second phase modulator 1-4-7 to form a long arm of the bidirectional unequal arm interferometer 1-4.
The second embodiment specifically receives the decoding process as follows:
an optical pulse with arbitrary polarization enters an input port In of the hybrid integrated receiver chip, first enters a first port of the first polarization beam splitter and rotator 1, and is split into a first signal light component and a second signal light component with the same polarization. The two beams respectively exit from the second port and the third port of the first polarization beam splitting rotator 1, and respectively propagate along the optical waveguide L1 and the optical waveguide L2 in a TE polarization mode, and simultaneously reach the half-wave plate 2, and because the included angle between the fast axis of the half-wave plate 2 and the TE polarization direction is 22.5 degrees, the polarization state of the horizontal polarized light after passing through the half-wave plate is changed into a polarization state
The effect is to rotate the polarization of light by 45 °, and then the first signal light component and the second signal light component are changed to the 45 ° polarization state after passing through the half-wave plate 2.
Since the polarization rotation angle of the faraday rotation plate 3 is 45 °, the polarization state of the 45 ° linearly polarized light is changed after passing through the faraday rotation plate 3
Therefore, the first signal light component and the second signal light component are rotated by 90 ° with respect to the polarization before entering the half-wave plate 2, both of which become TM polarization, are transmitted to the second port and the third port of the second polarization beam splitter rotator 1-2, respectively, are combined into the third signal light by them, and the polarization state becomes
Wherein,
the phase difference introduced by the optical waveguides L1 and L2 is included.
The third signal light reaches the first port of the third polarization beam splitting rotator 1-3 through the optical waveguide L3, is split into a fourth signal light component and a fifth signal light component having the same polarization, and exits from the second port and the third port thereof, respectively, and propagates along the optical waveguide L4 and the optical waveguide L5 in the TE polarization mode, respectively, and both become 45 ° polarized after passing through the faraday rotator 3, and each contain the TE polarization component and the TM polarization component having the same amplitude.
The fourth signal light component enters the first port of the fifth polarization beam splitting rotator 1-4-5 through the optical waveguide L4, and the TE polarization component exits from the second port, is transmitted to the second port of the sixth polarization beam splitting rotator 1-4-6, exits from the first port, and is still TE polarized; the TM polarized light component of the fourth signal light component is emitted from the third port of the fifth polarization beam splitting rotator 1-4-5 to become TE polarized light, and is modulated in phase by the second phase modulator 1-4-7
Then reaches the third port of the sixth polarization beam splitting rotator 1-4-6 and exits from the first port thereof, still with TM polarization. The quantum states at the first ports of the sixth polarization beam splitter rotators 1-4-6 may be written as
Wherein, due to
Time pattern of
And component
Time pattern of
The optical paths are equal, overlapped in time, and polarized by the sixth polarization beam splitter rotator 1-4-6Oscillating into sixth signal light with polarization state of
Wherein the phase difference
。
The sixth signal light propagates along the optical waveguide L5, and after being subjected to 45 ° polarization rotation by the faraday rotation plate 3, the polarization state changes to
The sixth signal light then enters the third port of the third polarization beam splitting rotator 1-3 for polarization beam splitting, the TM polarization component of the sixth signal light directly exits from the fourth port of the third polarization beam splitting rotator 1-3 and is output from the second output port Out2 of the receiving chip, and the light intensity is
. The TE polarization component of the sixth signal light exits from the first port of the third polarization beam splitting rotator 1-3 to become TM polarization, and reaches the first port of the second polarization beam splitting rotator 1-2 through the optical waveguide L3, exits from the third port thereof, and propagates in the TM mode along the optical waveguide L2. Then the polarization passes through a Faraday rotation plate 3 and a half-wave plate 2 in sequence, the polarization is firstly rotated by 45 degrees and then is selected by 45 degrees, namely the polarization is not rotated and still is TM polarization, finally the polarization reaches a third port of a first polarization beam splitting rotator 1-1, is emitted from a fourth port of the first polarization beam splitting rotator and is output from a first output port Out1 of a receiving chip, and the light intensity is
。
Similarly, the fifth signal light component enters the first port of the sixth polarization beam splitting rotator 1-4-6 through the optical waveguide L5, and the TE polarization component exits the second port, is transmitted to the second port of the fifth polarization beam splitting rotator 1-4-5, and exits therefromThe first port is emergent and still has TE polarization; the TM polarized light component of the fifth signal light component is emitted from the third port of the sixth polarization beam splitter/rotator 1-4-6 to become TE polarized light, and is phase-modulated by the second phase modulator 1-4-7
Then reaches the third port of the fifth polarization beam splitting rotator 1-4-5 and exits from the first port thereof, still with TM polarization. The quantum states at the first ports of the fifth polarization beam splitter rotators 1-4-5 can be written as
Wherein, due to
Time pattern of
And component
Time pattern of
The optical paths are equal, the optical paths are overlapped in time, and the optical paths are polarized and synthesized into seventh signal light by a fifth polarization beam splitter rotator 1-4-5, wherein the polarization state is
Wherein the phase difference
。
The seventh signal light propagates along the optical waveguide L4, and after being subjected to 45 ° polarization rotation by the faraday rotation plate 3, the polarization state changes to
The seventh signal light then enters the second port of the third polarization beam splitting rotator 1-3 for polarization beam splitting, the TM polarization component of the seventh signal light exits directly from the fourth port of the third polarization beam splitting rotator 1-3 and is output from the second output port Out2 of the receiving chip, and the light intensity is
. The TE polarization component of the seventh signal light exits from the first port of the third polarization splitting rotator 1-3, is still TE polarized, and passes through the optical waveguide L3 to reach the first port of the second polarization splitting rotator 1-2, exits from the second port thereof, and propagates along the optical waveguide L1 in the TM mode. Then the polarization is still TM polarization after passing through Faraday rotation plate 3 and half-wave plate 2 in turn, finally reaches the second port of the first polarization beam splitter rotator 1-1, exits from the fourth port thereof, and is output from the first output port Out1 of the receiving chip, and the light intensity is
。
Therefore, the light intensity from the first output port Out1 of the receiving chip is
The light intensity output from the second output port Out2 of the receiving chip is
It follows that the results output from the two output ports of the receive chip are only dependent on the modulated phase difference and not on the incident polarisation state, so that polarisation independent receive decoding can be achieved.
As shown in fig. 5, a third embodiment of the hybrid integrated receiving chip for quantum key distribution according to the present invention:
the structure of the hybrid integrated receiving chip is as follows: the bidirectional unequal arm interferometer 1-4 comprises a seventh polarization beam splitting rotator 1-4-8 and a third phase modulator 1-4-9, wherein a first port and a second port of the seventh polarization beam splitting rotator 1-4-8 are correspondingly connected with an optical waveguide L4 and an optical waveguide L5 respectively; and the third port and the fourth port of the seventh polarization beam splitting rotator 1-4-8 are connected through a third phase modulator 1-4-9 to form a long arm of the bidirectional unequal-arm interferometer 1-4.
The third embodiment specifically receives the decoding process as follows:
an optical pulse with any polarization enters an input port In of the hybrid integrated receiving chip, first enters a first port of the first polarization beam splitting rotator 1, and is split into a first signal light component and a second signal light component with the same polarization. The two beams respectively exit from the second port and the third port of the first polarization beam splitting rotator 1, and respectively propagate along the optical waveguide L1 and the optical waveguide L2 in a TE polarization mode, and simultaneously reach the half-wave plate 2, and because the included angle between the fast axis of the half-wave plate 2 and the TE polarization direction is 22.5 degrees, the polarization state of the horizontal polarized light after passing through the half-wave plate is changed into a polarization state
The effect is to rotate the polarization of light by 45 °, and then the first signal light component and the second signal light component are changed to the 45 ° polarization state after passing through the half-wave plate 2.
Since the polarization rotation angle of the faraday rotation plate 3 is 45 °, the polarization state of the 45 ° linearly polarized light is changed after passing through the faraday rotation plate 3
Therefore, the first signal light component and the second signal light component are rotated by 90 ° with respect to the polarization before entering the half-wave plate 2, both of which become TM polarization, are transmitted to the second port and the third port of the second polarization beam splitter rotator 1-2, respectively, are combined into the third signal light by them, and the polarization state becomes
Wherein,
the phase difference introduced by the optical waveguides L1 and L2 is included.
The third signal light reaches the first port of the third polarization beam splitting rotator 1-3 through the optical waveguide L3, is split into a fourth signal light component and a fifth signal light component having the same polarization, and exits from the second port and the third port thereof, respectively, and propagates along the optical waveguide L4 and the optical waveguide L5 in the TE polarization mode, respectively, and both become 45 ° polarized after passing through the faraday rotator 3, and each contain the TE polarization component and the TM polarization component having the same amplitude.
The fourth signal light component enters the first port of the seventh polarization beam splitting rotator 1-4-8 through the optical waveguide L4, and the TE polarization component of the fourth signal light component is directly emitted from the second port and is still TE polarization; the TM polarized light component of the fourth signal light component is emitted from the third port of the seventh polarization beam splitting rotator 1-4-8 to become TE polarized light, and is modulated in phase by the third phase modulator 1-4-9
Then reaches the fourth port of the seventh polarization beam splitting rotator 1-4-8 and exits from the second port thereof, still with TM polarization. The quantum states at the second ports of the seventh polarization beam splitting rotator 1-4-8 can be written as
Wherein, due to
Time pattern of
And component
Time pattern of
The optical paths are equal, the optical paths are overlapped in time, and the optical paths are polarized and synthesized into sixth signal light by a seventh polarization beam splitting rotator 1-4-8, wherein the polarization state is
Wherein the phase difference
。
The sixth signal light propagates along the optical waveguide L5, and after being subjected to 45 ° polarization rotation by the faraday rotation plate 3, the polarization state changes to
The sixth signal light then enters the third port of the third polarization beam splitting rotator 1-3 for polarization beam splitting, the TM polarization component of the sixth signal light directly exits from the fourth port of the third polarization beam splitting rotator 1-3 and is output from the second output port Out2 of the receiving chip, and the light intensity is
. The TE polarization component of the sixth signal light exits from the first port of the third polarization beam splitting rotator 1-3 to become TM polarization, and reaches the first port of the second polarization beam splitting rotator 1-2 through the optical waveguide L3, exits from the third port thereof, and propagates in the TM mode along the optical waveguide L2. Then the polarization passes through a Faraday rotation plate 3 and a half-wave plate 2 in sequence, the polarization is firstly rotated by 45 degrees and then is selected by 45 degrees, namely the polarization is not rotated and still is TM polarization, finally the polarization reaches a third port of a first polarization beam splitting rotator 1-1, is emitted from a fourth port of the first polarization beam splitting rotator and is output from a first output port Out1 of a receiving chip, and the light intensity is
。
Similarly, itThe middle fifth signal light component enters the second port of the seventh polarization beam splitting rotator 1-4-8 through the optical waveguide L5, and the TE polarization component of the middle fifth signal light component is directly emitted from the first port and still is TE polarization; the TM polarized light component of the fifth signal light component is emitted from the fourth port of the seventh polarization beam splitting rotator 1-4-8 to become TE polarized light, and is phase-modulated by the third phase modulator 1-4-9
Then reaches the third port of the seventh polarization beam splitting rotator 1-4-8 and exits from the first port thereof, still with TM polarization. The quantum states at the first ports of the seventh polarization beam splitting rotator 1-4-8 can be written as
Wherein, due to
Time pattern of
And component
Time pattern of
The optical paths are equal, the optical paths are overlapped in time, and the optical paths are polarized and synthesized into seventh signal light by a seventh polarization beam splitter rotator 1-4-8, wherein the polarization state is
Wherein the phase difference
。
The seventh signal light propagates along the optical waveguide L4, and after being subjected to 45 ° polarization rotation by the faraday rotation plate 3, the polarization state changes to
The seventh signal light then enters the second port of the third polarization beam splitting rotator 1-3 for polarization beam splitting, the TM polarization component of the seventh signal light exits directly from the fourth port of the third polarization beam splitting rotator 1-3 and is output from the second output port Out2 of the receiving chip, and the light intensity is
. The TE polarization component of the seventh signal light exits from the first port of the third polarization splitting rotator 1-3, is still TE polarized, and passes through the optical waveguide L3 to reach the first port of the second polarization splitting rotator 1-2, exits from the second port thereof, and propagates along the optical waveguide L1 in the TM mode. Then the optical fiber passes through a Faraday polarization plate 3 and a half-wave plate 2 in sequence, the polarization is still TM polarization, finally the optical fiber reaches a second port of the first polarization beam splitting rotator 1-1, is emitted from a fourth port of the first polarization beam splitting rotator, and is output from a first output port Out1 of a receiving chip, and the optical intensity is
。
Therefore, the light intensity from the first output port Out1 of the receiving chip is
The light intensity output from the second output port Out2 of the receiving chip is
It follows that the results output from the two output ports of the receive chip are only dependent on the modulated phase difference and not on the incident polarisation state, so that polarisation independent receive decoding can be achieved.
It can be known from the embodiments of the present invention that the present invention provides a hybrid integrated receiving chip for quantum key distribution, which performs polarization beam splitting on received optical signals to perform polarization synthesis, and performs combining output after polarization beam splitting, so as to implement polarization-independent receiving and decoding, and improve the stability of the system. And two polarization component pulses respectively pass through the primary interferometer, which is equivalent to the fact that the whole pulse passes through the primary interferometer, and the loss of a receiving end cannot be additionally increased. In addition, the Faraday optical rotation sheet is used for carrying out 45-degree polarization rotation on the optical signal through hybrid integration, the problem that the 45-degree polarization rotation of the optical waveguide is difficult to realize can be solved, the output port and the input port can be separated, and the use of a circulator is avoided. Therefore, the invention greatly reduces the volume of the receiving end optical system through hybrid integration, can realize the miniaturization of equipment, has the characteristic of polarization disturbance of an immune channel and realizes the long-term working stability of the system.
Claims (7)
1. A hybrid integrated receiving chip for quantum key distribution is characterized by comprising an optical waveguide chip (1), a half-wave plate (2) and a Faraday optical rotation plate (3), wherein the optical waveguide chip (1) comprises a first polarization beam splitting rotator (1-1), a second polarization beam splitting rotator (1-2), a third polarization beam splitting rotator (1-3), a two-way unequal arm interferometer (1-4) and a notch (1-5) which are integrated on the same substrate,
the first port and the fourth port of the first polarization beam splitting rotator (1-1) are respectively used as an input port In and a first output port Out1 of the receiving chip, and the fourth port of the third polarization beam splitting rotator (1-3) is used as a second output port Out2 of the receiving chip;
the second port of the first polarization beam splitting rotator (1-1) is connected with the second port of the second polarization beam splitting rotator (1-2) through an optical waveguide L1, and the third port of the first polarization beam splitting rotator (1-1) is connected with the third port of the second polarization beam splitting rotator (1-2) through an optical waveguide L2;
the first port of the second polarization beam splitting rotator (1-2) is connected with the first port of the third polarization beam splitting rotator (1-3) through an optical waveguide L3;
the second port and the third port of the third polarization beam splitting rotator (1-3) are correspondingly connected with the two ports of the two-way unequal arm interferometer (1-4) through an optical waveguide L4 and an optical waveguide L5 respectively;
the optical waveguide L1, the optical waveguide L2, the optical waveguide L4 and the optical waveguide L5 are mutually parallel, the notch (1-5) is arranged in the vertical direction of the optical waveguide L1, the partial width of the notch (1-5) in the area where the optical waveguide L1 and the optical waveguide L2 are located is the sum of the widths of the half-wave plate (2) and the Faraday optical rotation plate (3), and the partial width of the notch (1-5) in the area where the optical waveguide L4 and the optical waveguide L5 are located is the same as the width of the Faraday optical rotation plate (3);
the lengths of the half-wave plate (2) and the Faraday optical rotation plate (3) are different, one ends of the half-wave plate and the Faraday optical rotation plate are aligned and tightly attached, and then the two ends of the half-wave plate and the Faraday optical rotation plate are inserted into the notches (1-5), so that optical signals transmitted in the optical waveguide L1 and the optical waveguide L2 can pass through the half-wave plate (2) and the Faraday optical rotation plate (3), and optical signals transmitted in the optical waveguide L4 and the optical waveguide L5 can pass through the Faraday optical rotation plate (3);
the bidirectional unequal-arm interferometer (1-4) is provided with a long arm and a short arm and is used for splitting two orthogonal polarization components of an optical signal into the long arm and the short arm respectively and carrying out polarization beam combination after adjusting the phase difference between the polarization components transmitted by the long arm and the short arm.
2. The hybrid integrated receiver chip for quantum key distribution according to claim 1, wherein the bidirectional unequal arm interferometers (1-4) have both ports capable of inputting optical signals or outputting optical signals, and one port is an input port while the other port is an output port.
3. Hybrid integrated receiving chip for quantum key distribution according to claim 1, characterized in that the two-way unequal arm interferometer (1-4) comprises a fourth polarization beam splitting rotator (1-4-1), an optical waveguide delay line (1-4-2) and a first phase modulator (1-4-3),
the first port and the fourth port of the fourth polarization beam splitting rotator (1-4-1) are respectively and correspondingly connected with the optical waveguide L4 and the optical waveguide L5;
the second port of the fourth polarization beam splitting rotator (1-4-1) is connected with a Faraday optical rotation sheet (3) through an optical waveguide delay line (1-4-2) to form a long arm of the bidirectional unequal arm interferometer (1-4); a third port of the fourth polarization beam splitting rotator (1-4-1) is connected with a Faraday optical rotation sheet (3) through a first phase modulator (1-4-3) to form a short arm of the bidirectional unequal arm interferometer 1-4;
and the other side of the optical waveguide delay line (1-4-2) and the other side of the first phase modulator (1-4-3) which are connected with the Faraday optical rotation sheet (3) are plated with reflecting films (1-4-4).
4. Hybrid integrated receiving chip for quantum key distribution according to claim 1, characterized in that the two-way unequal arm interferometer (1-4) comprises a fifth polarization beam splitting rotator (1-4-5), a sixth polarization beam splitting rotator (1-4-6) and a second phase modulator (1-4-7),
the first port of the fifth polarization beam splitting rotator (1-4-5) is connected with an optical waveguide L4, and the first port of the sixth polarization beam splitting rotator (1-4-6) is connected with an optical waveguide L5;
the second port of the fifth polarization beam splitting rotator (1-4-5) is connected with the second port of the sixth polarization beam splitting rotator (1-4-6) to form a short arm of the bidirectional unequal arm interferometer (1-4); and a third port of the fifth polarization beam splitting rotator (1-4-5) is connected with a third port of the sixth polarization beam splitting rotator (1-4-6) through a second phase modulator (1-4-7) to form a long arm of the bidirectional unequal-arm interferometer (1-4).
5. Hybrid integrated receiving chip for quantum key distribution according to claim 1, characterized in that the two-way unequal arm interferometer (1-4) comprises a seventh polarization beam splitting rotator (1-4-8) and a third phase modulator (1-4-9),
the first port and the second port of the seventh polarization beam splitting rotator (1-4-8) are respectively and correspondingly connected with the optical waveguide L4 and the optical waveguide L5; and a third port and a fourth port of the seventh polarization beam splitting rotator (1-4-8) are connected through a third phase modulator (1-4-9) to form a long arm of the bidirectional unequal-arm interferometer (1-4).
6. The hybrid integrated receiver chip for quantum key distribution according to claim 1 or 2 or 3 or 4 or 5, wherein the fast axis direction of the half-wave plate (2) is at an angle of 22.5 ° to the TE polarization direction in the optical waveguide, and the polarization rotation angle of the faraday optical rotation plate (3) is 45 °.
7. The hybrid integrated receiving chip for quantum key distribution according to claim 1 or 2 or 3 or 4 or 5, wherein the lengths of the optical waveguide L1 and the optical waveguide L2 are equal, and the lengths of the optical waveguide L4 and the optical waveguide L5 are equal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210929215.6A CN115001593B (en) | 2022-08-03 | 2022-08-03 | Hybrid integrated receiving chip for quantum key distribution |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210929215.6A CN115001593B (en) | 2022-08-03 | 2022-08-03 | Hybrid integrated receiving chip for quantum key distribution |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN115001593A true CN115001593A (en) | 2022-09-02 |
| CN115001593B CN115001593B (en) | 2022-09-30 |
Family
ID=83022618
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210929215.6A Active CN115001593B (en) | 2022-08-03 | 2022-08-03 | Hybrid integrated receiving chip for quantum key distribution |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115001593B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115208478A (en) * | 2022-09-14 | 2022-10-18 | 北京中科国光量子科技有限公司 | Self-coherent receiving device based on single delay interferometer |
| CN115242315A (en) * | 2022-09-23 | 2022-10-25 | 北京中科国光量子科技有限公司 | Polarization-independent DQPSK demodulation integrated optical chip |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106161011A (en) * | 2016-08-19 | 2016-11-23 | 浙江神州量子网络科技有限公司 | A kind of plug and play quantum key dissemination system based on coding time phase and method and transmitting terminal and receiving terminal |
| CN109039625A (en) * | 2018-10-29 | 2018-12-18 | 中国电子科技集团公司电子科学研究院 | Quantum key distribution time bit-phase decoding method, apparatus and system based on polarized orthogonal rotation |
| CN110460384A (en) * | 2019-03-08 | 2019-11-15 | 中国电子科技集团公司电子科学研究院 | Quantum key distribution phase codec, corresponding coding and decoding device and system |
| WO2022123594A1 (en) * | 2020-12-07 | 2022-06-16 | INDIAN INSTITUTE OF TECHNOLOGY MADRAS (IIT Madras) | System and method for plug-and-play differential phase encoded measurement-device-independent quantum key distribution |
-
2022
- 2022-08-03 CN CN202210929215.6A patent/CN115001593B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106161011A (en) * | 2016-08-19 | 2016-11-23 | 浙江神州量子网络科技有限公司 | A kind of plug and play quantum key dissemination system based on coding time phase and method and transmitting terminal and receiving terminal |
| CN109039625A (en) * | 2018-10-29 | 2018-12-18 | 中国电子科技集团公司电子科学研究院 | Quantum key distribution time bit-phase decoding method, apparatus and system based on polarized orthogonal rotation |
| CN110460384A (en) * | 2019-03-08 | 2019-11-15 | 中国电子科技集团公司电子科学研究院 | Quantum key distribution phase codec, corresponding coding and decoding device and system |
| WO2022123594A1 (en) * | 2020-12-07 | 2022-06-16 | INDIAN INSTITUTE OF TECHNOLOGY MADRAS (IIT Madras) | System and method for plug-and-play differential phase encoded measurement-device-independent quantum key distribution |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115208478A (en) * | 2022-09-14 | 2022-10-18 | 北京中科国光量子科技有限公司 | Self-coherent receiving device based on single delay interferometer |
| CN115242315A (en) * | 2022-09-23 | 2022-10-25 | 北京中科国光量子科技有限公司 | Polarization-independent DQPSK demodulation integrated optical chip |
| CN115242315B (en) * | 2022-09-23 | 2022-12-20 | 北京中科国光量子科技有限公司 | Polarization-independent DQPSK demodulation integrated optical chip |
Also Published As
| Publication number | Publication date |
|---|---|
| CN115001593B (en) | 2022-09-30 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN115001593B (en) | Hybrid integrated receiving chip for quantum key distribution | |
| CN114900245B (en) | Polarization-independent phase decoding integrated chip and quantum key distribution system | |
| US7457548B2 (en) | Quantum optical transmission device and quantum optical generator device therefor | |
| JP6729852B2 (en) | Encoding device, and quantum key distribution device and system based on the same | |
| CN113676323B (en) | Irrelevant quantum key distribution system of polarization encoding measuring equipment | |
| US8242435B2 (en) | Quantum entangled photon pair generating device | |
| CN113708932B (en) | Phase encoding device for quantum key distribution and quantum key distribution system | |
| CN113708931B (en) | Polarization encoding device for quantum key distribution and quantum key distribution system | |
| CN114726451B (en) | Polarization insensitive efficient quantum key distribution decoding device | |
| CN105353520B (en) | 90 ° of frequency mixers of spatial light of high mixing efficiency | |
| CN113872701B (en) | Time phase coding device and quantum key distribution system | |
| CN114374441B (en) | Quantum key distribution phase decoding device for immune channel disturbance | |
| CN114553421B (en) | Quantum key distribution decoding device for immune channel disturbance | |
| CN115102630B (en) | Self-coherent receiving device based on polarization-independent delay interferometer | |
| CN109981182A (en) | A kind of four phase reflection formula coherent optical communication systems | |
| CN114629563B (en) | Polarization multiplexing quantum key distribution device and full-time full-pass quantum key distribution network | |
| WO2020151546A1 (en) | Sending end for decoy state encoding and polarization encoding, encoding method and quantum key distribution system | |
| CN109343173B (en) | Hybrid waveguide integrated interferometer | |
| US7221812B2 (en) | Compact optics assembly for a QKD station | |
| US11888531B1 (en) | Polarization independent DQPSK demodulation integrated optical chip | |
| CN114650133B (en) | Polarization encoding device for quantum key distribution and quantum key distribution system | |
| CN114465725B (en) | Quantum key distribution coding device | |
| US7224860B2 (en) | Multi-port optical switches | |
| CN213957807U (en) | Double-entanglement photon pair generation device based on collinear BBO crystal | |
| CN115225162A (en) | Integrated self-coherent receiving optical chip based on round-trip delay interferometer |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| TR01 | Transfer of patent right | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20240423 Address after: Room 016, 1st Floor, Building 15, Yongtai Village North, Qinghe, Haidian District, Beijing, 100080 Patentee after: Beijing Guoguang Xindun Technology Co.,Ltd. Country or region after: China Address before: Room 903, 9th Floor, Building 11, Yard 10, Kegu 1st Street, Beijing Economic and Technological Development Zone, Daxing District, Beijing 102600 (Beijing Pilot Free Trade Zone High-end Industry Zone Yizhuang Group) Patentee before: Beijing zhongkeguoguang Quantum Technology Co.,Ltd. Country or region before: China |