CN214041803U - Optical element for polarization quantum state preparation and polarization modulation device - Google Patents
Optical element for polarization quantum state preparation and polarization modulation device Download PDFInfo
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- CN214041803U CN214041803U CN202023102355.1U CN202023102355U CN214041803U CN 214041803 U CN214041803 U CN 214041803U CN 202023102355 U CN202023102355 U CN 202023102355U CN 214041803 U CN214041803 U CN 214041803U
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Abstract
The application provides an optical element and a polarization modulation device for polarization quantum state preparation, wherein the optical element comprises a self-focusing collimating lens, a self-focusing coupling lens and a polarization beam splitter; the self-focusing collimating lens and the self-focusing coupling lens are both positioned on the same side of the polarizing beam splitter, and the horizontal direction of the self-focusing collimating lens and the horizontal direction of the self-focusing coupling lens are both aligned in parallel with the horizontal direction of the polarizing beam splitter. Therefore, the function of the circulator can be realized through the two groups of lenses of the self-focusing collimating lens and the self-focusing coupling lens, and the self-focusing collimating lens and the self-focusing coupling lens are one of the collimating lenses, so that the ports of the polarization beam splitter, the self-focusing collimating lens and the self-focusing coupling lens, which are connected, do not need to be additionally provided with collimators, at least two groups of collimators are saved by the optical element, the structure is simple and compact, and the manufacturing and assembling are easy.
Description
Technical Field
The application relates to the technical field of quantum communication equipment, in particular to an optical element and a polarization modulation device for polarization quantum state preparation.
Background
Quantum key distribution is one of core research contents in the field of quantum communication, and quantum key distribution equipment mainly comprises a transmitter and a receiver and respectively corresponds to a quantum coding device and a decoding device. At present, the mainstream coding scheme of the transmitter comprises polarization coding, phase coding and time-phase coding, wherein the polarization coding has the advantages of low insertion loss of a receiving end, low cost and simple structure, and is a great hotspot for the research of a quantum communication coding mode.
The existing polarization encoding device is generally mainly formed by connecting a circulator and a polarization beam splitter through an optical fiber, wherein the circulator is generally formed by 3 double reflectors and 2 Faraday rotators, so that the polarization encoding device in the prior art is large in size, high in cost and low in integration degree.
Disclosure of Invention
The application provides an optical element and polarization modulation device for polarization quantum state preparation, optical element wherein small, the degree of integration is higher, can reduce polarization modulation device cost to solve the optical element among the polarization coding device in the current scheme and integrate low, bulky problem.
The application provides an optical element for polarization quantum state preparation, which comprises a self-focusing collimating lens, a self-focusing coupling lens and a polarization beam splitter;
the self-focusing collimating lens and the self-focusing coupling lens are both positioned on the same side of the polarization beam splitter, and the horizontal direction of the self-focusing collimating lens and the horizontal direction of the self-focusing coupling lens are both aligned in parallel with the horizontal direction of the polarization beam splitter.
Preferably, the self-focusing collimating lens and the self-focusing coupling lens are arranged up and down, and the self-focusing collimating lens and the self-focusing coupling lens are attached.
Preferably, the self-focusing collimating lens and the self-focusing coupling lens are both attached to the polarization beam splitter.
Preferably, the height of the self-focusing collimating lens and the height of the self-focusing coupling lens are equal, and the sum of the height of the self-focusing collimating lens and the height of the self-focusing coupling lens is equal to the height of the polarization beam splitter.
Preferably, the self-focusing collimating lens, the self-focusing coupling lens and the polarization beam splitter are connected by gluing.
A polarization modulation device comprising any one of the above optical element for polarization quantum state fabrication, a first polarization maintaining fiber, a single mode fiber, a sagnac loop optical path, and a phase modulator;
one end of the first polarization maintaining fiber is used as an input port, the other end of the first polarization maintaining fiber is connected with a self-focusing collimating lens, and the slow axis direction of the first polarization maintaining fiber is aligned by rotating 45 degrees relative to the horizontal direction of the self-focusing collimating lens;
one end of the single-mode optical fiber is used as an output port, and the other end of the single-mode optical fiber is connected with the self-focusing coupling lens;
the Sagnac annular light path is an annular light path formed by a second polarization maintaining optical fiber and a third polarization maintaining optical fiber, the slow axis direction of the second polarization maintaining optical fiber is aligned with the vertical direction of the polarization beam splitter, the slow axis direction of the third polarization maintaining optical fiber is aligned with the horizontal direction of the polarization beam splitter, and the phase modulator is arranged in the annular light path of the Sagnac annular light path.
Preferably, the polarization modulation device further comprises a first fiber collimator and a second fiber collimator;
the first optical fiber collimator is used as a first output port of the polarization beam splitter, and the second polarization-maintaining optical fiber is connected with the first optical fiber collimator;
the second optical fiber collimator is used as a second output port of the polarization beam splitter, and the third polarization-maintaining optical fiber is connected with the second optical fiber collimator.
Preferably, the first optical fiber collimator and the second optical fiber collimator are both attached to the polarization beam splitter.
Preferably, the first fiber collimator and the second fiber collimator are both glued to the polarization beam splitter.
Preferably, the optical fibers in the first polarization maintaining optical fiber, the second polarization maintaining optical fiber and the third polarization maintaining optical fiber are panda polarization maintaining optical fibers.
Compared with the prior art, the scheme has the following advantages that:
1. the optical element for polarization quantum state preparation comprises a self-focusing collimating lens, a self-focusing coupling lens and a polarization beam splitter; the self-focusing collimating lens and the self-focusing coupling lens are both positioned on the same side of the polarization beam splitter, and the horizontal direction of the self-focusing collimating lens and the horizontal direction of the self-focusing coupling lens are both aligned in parallel with the horizontal direction of the polarization beam splitter. Therefore, the function of the circulator can be realized through the two groups of lenses of the self-focusing collimating lens and the self-focusing coupling lens, so that the volume of the optical element is greatly reduced, and the circulator has the characteristic of high integration.
2. The self-focusing collimating lens and the self-focusing coupling lens not only realize the function of a circulator, but also are one of collimating lenses, so that the ports of the polarization beam splitter, the self-focusing collimating lens and the self-focusing coupling lens are connected without additionally arranging collimators, and at least two groups of collimators are saved by the optical element, so that the structure is simple and compact, and the manufacturing and the assembly are easy.
Drawings
In order to more clearly explain the technical solution of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious to those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic diagram of an optical element for polarized quantum state fabrication according to the present application;
fig. 2 is a schematic structural diagram of a polarization modulation device according to the present application.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present application more comprehensible, the present application is described in further detail with reference to the drawings and the detailed description shown in fig. 1 and 2.
The application provides an optical element for polarization quantum state preparation, and a structural schematic diagram of the optical element can refer to the schematic diagram shown in fig. 1, and the specific structure of the optical element comprises a self-focusing collimating lens 1, a self-focusing coupling lens 2 and a polarization beam splitter 3; the self-focusing collimating lens 1 and the self-focusing coupling lens 2 are both located on the same side of the polarization beam splitter 3, and the horizontal direction of the self-focusing collimating lens 1 and the horizontal direction of the self-focusing coupling lens 2 are both aligned in parallel with the horizontal direction of the polarization beam splitter 3. When the self-focusing collimating lens 1 works, light enters from the focus end of the self-focusing collimating lens 1 and exits from the divergence end of the self-focusing collimating lens 1, and due to the characteristics of the self-focusing collimating lens 1, the light is a plurality of parallel light beams when exiting from the divergence end of the self-focusing collimating lens 1 and enters the polarization beam splitter 3 in parallel, and similarly, the parallel light emitted from the polarization beam splitter 3 is coupled into an optical fiber through the self-focusing coupling lens 2, so that the self-focusing collimating lens 1 and the self-focusing coupling lens 2 not only realize the function of a circulator, but also the self-focusing collimating lens 1 and the self-focusing coupling lens 2 are one of the collimating lenses, so that the ports of the polarization beam splitter 3, the self-focusing collimating lens 1 and the self-focusing coupling lens 2, which are connected, do not need to be additionally provided with collimators, therefore, the optical element of the self-focusing collimating lens saves at least two groups of collimators, and has a simple and compact structure, and easy to manufacture and assemble. In addition, the function of the circulator in the prior art can be realized through the two groups of lenses of the self-focusing collimating lens 1 and the self-focusing coupling lens 2, so that the volume of the optical element is greatly reduced, and the high-integration characteristic is realized.
The self-focusing collimating lens 1 and the self-focusing coupling lens 2 are arranged up and down, and the self-focusing collimating lens 1 and the self-focusing coupling lens 2 are attached. The self-focusing collimating lens 1 and the self-focusing coupling lens 2 are both attached to the polarization beam splitter 3. The optical element of the present application is composed of three optical devices, one structure is shown in fig. 1, the self-focusing collimating lens 1 and the self-focusing coupling lens 2 are located on the left side of the polarization beam splitter 3, and the self-focusing collimating lens 1 is located above the self-focusing coupling lens 2. The fitting of the self-focusing collimating lens 1 and the self-focusing coupling lens 2 means that the lower surface of the self-focusing collimating lens 1 is fitted with the upper surface of the self-focusing coupling lens 2. The self-focusing collimating lens 1 and the self-focusing coupling lens 2 are both attached to the polarization beam splitter 3, which means that the parallel light end surface of the self-focusing collimating lens 1 and the parallel light end surface of the self-focusing coupling lens 2 are attached to the left end surface of the polarization beam splitter 3. In addition, the attaching mode of the present application includes, but is not limited to, process means such as vacuum attaching, air gap attaching, gluing, coating, etc. performed between two devices, wherein preferably one of the self-focusing collimating lens 1, the self-focusing coupling lens 2, and the polarization beam splitter 3 is connected by gluing, and the gluing devices are firmly combined without arranging other fixing accessories or performing packaging, so that the volume of the optical element can be reduced to the maximum extent, and the integration level of the optical element can be improved to the maximum extent.
The height of the self-focusing collimating lens 1 is equal to the height of the self-focusing coupling lens 2, and the sum of the height of the self-focusing collimating lens 1 and the height of the self-focusing coupling lens 2 is equal to the height of the polarization beam splitter 3. That is, the upper surface of the self-focusing collimating lens 1 is flush with the upper surface of the polarizing beam splitter 3, the lower surface of the self-focusing coupling lens 2 is flush with the lower surface of the polarizing beam splitter 3, and the lower surface of the self-focusing collimating lens 1 and the upper surface of the self-focusing coupling lens 2 are located in the middle of the polarizing beam splitter 3. Since the height of the self-focusing collimating lens 1 and the self-focusing coupling lens 2 are the collimating lenses, the self-focusing collimating lens 1 is jointed with the parallel light output by one side of the polarization beam splitter 3, and the light of the polarization beam splitter 3 enters the self-focusing coupling lens 2 and then is converged, so that the self-focusing collimating lens 1 and the self-focusing coupling lens 2 are arranged according to the above conditions, the light loss can be reduced, and the jointing and the assembling are convenient.
Another aspect of the present application provides a polarization modulation device, the structural schematic diagram of which can refer to the schematic diagram shown in fig. 2, and the specific structure of which includes any one of the optical elements for polarization quantum state preparation described above, a first polarization maintaining fiber 4, a single mode fiber 5, a sagnac loop optical path 6, and a phase modulator 7; one end of the first polarization-maintaining fiber 4 (i.e. port1 in fig. 2) is used as an input port, the other end of the first polarization-maintaining fiber 4 is connected with the self-focusing collimating lens 1, and the slow axis direction of the first polarization-maintaining fiber 4 is aligned by rotating 45 degrees relative to the horizontal direction of the self-focusing collimating lens 1; one end of the single-mode fiber 5 (i.e., port2 in fig. 2) serves as an output port, and the other end of the single-mode fiber 5 is connected to the self-focusing coupling lens 2; the sagnac loop optical path 6 is a loop optical path composed of a second polarization maintaining fiber 61 (i.e. port3 in fig. 2) and a third polarization maintaining fiber 62 (i.e. port4 in fig. 2), the slow axis direction of the second polarization maintaining fiber 61 is aligned with the vertical direction of the polarization beam splitter 3, the slow axis direction of the third polarization maintaining fiber 62 is aligned with the horizontal direction of the polarization beam splitter 3, the phase modulator 7 is arranged in the loop optical path of the sagnac loop optical path 6
In operation, after being input from the first polarization maintaining fiber 4, the pulsed light is output as parallel light by the self-focusing collimating lens 1 to the polarization beam splitter 3, the polarization beam splitter 3 outputs light pulse components with mutually perpendicular polarization directions, the perpendicular light pulse components are incident on the second polarization maintaining fiber 61, and the horizontal light pulse components are incident on the third polarization maintaining fiber 62. That is, the two optical pulse components respectively pass through the phase modulator 7 on the sagnac loop optical path 6 in the counterclockwise direction and the clockwise direction, then the phase modulator 7 performs phase modulation on one or both of the two optical pulses, the phase-modulated optical pulse components return to the polarization beam splitter 3, and superposition occurs in the polarization beam splitter 3, because the total paths of the two optical pulse components in the interferometer are consistent, the attenuation is consistent, and the polarization changes caused by environmental noise can be mutually compensated, the polarization state of the superposed output only depends on the phase difference loaded between the two optical pulse components by the phase modulator 7, for example, when the phase difference loaded between the two optical pulse components by the phase modulator 7 is 0, pi/2 or 3 pi/2, the +45 degree polarized light P and the-45 degree polarized light N can be respectively prepared, right-hand polarized light R or left-hand polarized light L. Meanwhile, due to the divergence of the light in the polarization beam splitter 3, the light incident on the polarization beam splitter 3 can fill the polarization beam splitter 3, and thus can enter the sagnac loop-shaped light path 6 or the self-focusing coupling lens 2, and the polarized light modulated in the same way can fill the polarization beam splitter 3, and thus can be incident on the single-mode fiber 5 for output.
The polarization modulation device also comprises a first optical fiber collimator 8 and a second optical fiber collimator 9; the first optical collimator 8 is configured to serve as a first output port of the polarization beam splitter 3, and the second optical collimator 9 is configured to serve as a second output port of the polarization beam splitter 3. Generally, both ends of the sagnac loop-shaped optical path 6 are respectively connected with the first fiber collimator 8 and the second fiber collimator 9, that is, the second polarization-maintaining fiber 61 is connected with the first fiber collimator 8, and the third polarization-maintaining fiber 62 is connected with the second fiber collimator 9. In addition, the first optical fiber collimator 8 and the second optical fiber collimator 9 are respectively connected with the polarization beam splitter 3 by adopting the above attaching mode or gluing mode of the present application, and serve as a first output port and a second output port of the polarization beam splitter 3.
In addition, the optical fibers of the first polarization maintaining fiber 4, the second polarization maintaining fiber 61, and the third polarization maintaining fiber 62 are all panda polarization maintaining fibers. The panda type polarization maintaining optical fiber can be widely applied to the technical field of optical fiber communication and optical fiber sensing, and has the characteristics of accurate refractive index distribution, good geometric symmetry of the cross section, good longitudinal uniformity and excellent optical performance.
The present application has been described in detail with reference to specific embodiments and illustrative examples, but the description is not intended to limit the application. Those skilled in the art will appreciate that various equivalent substitutions, modifications or improvements may be made to the presently disclosed embodiments and implementations thereof without departing from the spirit and scope of the present disclosure, and these fall within the scope of the present disclosure. The protection scope of this application is subject to the appended claims.
Claims (10)
1. An optical element for polarized quantum state fabrication, characterized in that it comprises a self-focusing collimating lens (1), a self-focusing coupling lens (2) and a polarizing beam splitter (3);
the self-focusing collimating lens (1) and the self-focusing coupling lens (2) are both located on the same side of the polarizing beam splitter (3), and the horizontal direction of the self-focusing collimating lens (1) and the horizontal direction of the self-focusing coupling lens (2) are both aligned in parallel with the horizontal direction of the polarizing beam splitter (3).
2. The optical element for polarized quantum state fabrication according to claim 1, wherein the self-focusing collimating lens (1) and the self-focusing coupling lens (2) are arranged above each other, and the self-focusing collimating lens (1) and the self-focusing coupling lens (2) are attached.
3. Optical element for polarized quantum state fabrication according to claim 2, characterized in that the self-focusing collimating lens (1) and the self-focusing coupling lens (2) are both attached to the polarizing beam splitter (3).
4. Optical element for polarized quantum state fabrication according to claim 3, characterized in that the height of the self-focusing collimating lens (1) and the height of the self-focusing coupling lens (2) are equal and the sum of the height of the self-focusing collimating lens (1) and the height of the self-focusing coupling lens (2) is equal to the height of the polarizing beam splitter (3).
5. Optical element for polarized quantum state fabrication according to any of claims 1-4, characterized in that the auto-focusing collimating lens (1), the auto-focusing coupling lens (2) and the polarizing beam splitter (3) are glued together.
6. A polarization modulation device comprising the optical element for polarization quantum state fabrication according to any one of claims 1 to 5, a first polarization maintaining fiber (4), a single mode fiber (5), a sagnac loop optical path (6), and a phase modulator (7);
one end of the first polarization maintaining fiber (4) is used as an input port, the other end of the first polarization maintaining fiber (4) is connected with the self-focusing collimating lens (1), and the slow axis direction of the first polarization maintaining fiber (4) is aligned in a way of rotating 45 degrees relative to the horizontal direction of the self-focusing collimating lens (1);
one end of the single-mode optical fiber (5) is used as an output port, and the other end of the single-mode optical fiber (5) is connected with the self-focusing coupling lens (2);
the Sagnac annular optical path (6) is an annular optical path composed of a second polarization maintaining optical fiber (61) and a third polarization maintaining optical fiber (62), the slow axis direction of the second polarization maintaining optical fiber (61) is aligned with the vertical direction of the polarization beam splitter (3), the slow axis direction of the third polarization maintaining optical fiber (62) is aligned with the horizontal direction of the polarization beam splitter (3), and the phase modulator (7) is arranged in the annular optical path of the Sagnac annular optical path (6).
7. The polarization modulation device according to claim 6, further comprising a first fiber collimator (8) and a second fiber collimator (9);
the first optical fiber collimator (8) is used as a first output port of the polarization beam splitter (3), and the second polarization-maintaining optical fiber (61) is connected with the first optical fiber collimator (8);
the second optical fiber collimator (9) is used as a second output port of the polarization beam splitter (3), and the third polarization-maintaining optical fiber (62) is connected with the second optical fiber collimator (9).
8. The polarization modulation device according to claim 7, wherein the first fiber collimator (8) and the second fiber collimator (9) are both attached to the polarization beam splitter (3).
9. The polarization modulation device according to claim 7, wherein the first fiber collimator (8) and the second fiber collimator (9) are both glued to the polarization beam splitter (3).
10. A polarization modulation device according to any one of claims 6 to 9, wherein the optical fibers of the first polarization maintaining fiber (4), the second polarization maintaining fiber (61) and the third polarization maintaining fiber (62) are panda polarization maintaining fibers.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202023102355.1U CN214041803U (en) | 2020-12-22 | 2020-12-22 | Optical element for polarization quantum state preparation and polarization modulation device |
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| CN202023102355.1U CN214041803U (en) | 2020-12-22 | 2020-12-22 | Optical element for polarization quantum state preparation and polarization modulation device |
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| CN214041803U true CN214041803U (en) | 2021-08-24 |
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