KR102363400B1 - Quantum light-microwave bidirectional conversion device - Google Patents

Abstract

The present invention provides a quantum light-microwave bidirectional conversion device, which includes: a first optical fiber which receives light from a light source; a ferromagnetic material and a cavity which are disposed in contact with an output end of the first optical fiber; a magnet for generating a magnetic field defined in one direction in the cavity; a resonator having a first opening and a second opening facing each other with the cavity therebetween; and an optical converter disposed on the second opening side and converting the light output from the resonator into parallel light, wherein the output end of the first optical fiber and the ferromagnetic material are disposed in the cavity through the first opening. Accordingly, it is possible to implement a miniaturized quantum light-microwave interconversion device by simplifying an optical system.

Description

Quantum light-microwave interconversion device {QUANTUM LIGHT-MICROWAVE BIDIRECTIONAL CONVERSION DEVICE}

The present invention relates to a quantum light-microwave interconversion apparatus, and more particularly, to a quantum light-microwave interconversion apparatus capable of being miniaturized by simplifying an optical system.

The optical-microwave interconversion technology using the coupling of the spin mode of the Yttrium Iron Garnet single crystal and the microwave mode of the resonator is a Hamiltonian coupling between spin ensembles by quantum electrodynamics effect. Hamiltonian), not only conversion between normal light and microwaves in the near-infrared region, but also between quantum light and microwaves is possible.

For the construction of the quantum light-microwave interconversion system, a spherical yttrium iron garnet single crystal is installed at the center of a corner of a microwave resonator where a magnetic field is generated the strongest, and the input laser light is disposed so that the yttrium iron garnet single crystal is transmitted. In this case, the diameter of a generally used single crystal is 1 mm or less, and when the yttrium iron garnet single crystal is transmitted, the laser light should be focused to a very small diameter in order to minimize the loss of laser light.

Therefore, in order to construct a quantum light-microwave interconversion system using yttrium iron garnet single crystal in free space, the light incident through the optical fiber is converted into parallel light using a collimator, and the diameter of the parallel light is enlarged through the beam expander. , again, through a condensing lens, should be focused on a single crystal of yttrium iron garnet which is placed inside the microwave resonator. The laser light interacting with the yttrium iron garnet and the microwave resonator again passes through the beam expander and the condensing lens, is focused so that the diameter becomes smaller, passes through the optical converter that converts the polarization change into the intensity of the light source, and then through the collimator for receiving the converted signal. It is transmitted through the optical fiber of the receiving side.

1, Yong Sup Ihn, Su-Yong Lee, Dongkyu Kim, Sin Hyuk Yim, and Zaeill Kim, Phys. Rev. B 102, 064418 (2020). 2. R. Hisatomi, A. Osada, Y. Tabuchi, T. Ishikawa, A. Noguchi, R. Yamazaki, K. Usami, and Y. Nakamura, Physical Review B 93, 174427 (2016).

However, such a conventional quantum light-microwave interconversion device has a problem in that an optical system such as a beam expander and a focusing lens is required to focus the spherical yttrium iron garnet single crystal.

The diameter of the beam during focusing may be expressed by Equation 1 below.

[Equation 1]

는 레이저의 파장이다.where W _f is the diameter of the beam upon focusing, W ₀ is the diameter of the beam before focusing, f is the f number of the lens,

is the wavelength of the laser.

Therefore, the larger the diameter ( W ₀ ) of the beam before focusing, the smaller the diameter ( W _f ) of the beam during focusing when the same lens is used. The diameter ( W ₀ ) is made large through the beam expander.

At this time, the beam expander should be installed so that the two lenses are separated by the sum of their respective f values. For example, when the f-value of one lens constituting the beam expander is 25 mm, the f-value of the other lens must be 50 mm in order to double the beam diameter. Thus, one beam expander requires a total length of 75 mm. The length required for the beam expander to quadruple the beam diameter reaches 125 mm, and has a diameter larger than the theoretical value due to the precision of the lens installation and the aberration of the lens itself.

Accordingly, the conventional quantum light-microwave interconversion device requires not only a long system, but also a mount for fixing each component. In addition, the laser light may be exposed to the free space and may be sensitive to changes according to the external environment.

An object of the present invention is to solve various problems including the above problems, and an object of the present invention is to provide a miniaturized quantum light-microwave interconversion device. However, these problems are exemplary, and the scope of the present invention is not limited thereto.

According to one aspect of the present invention, a quantum light-microwave interconversion device that can be miniaturized by simplifying an optical system is provided.

Quantum light-microwave interconversion device according to an embodiment of the present invention, a first optical fiber receiving light from a light source, disposed in contact with an output end of the first optical fiber, a ferromagnetic material, a cavity, the cavity in one direction A magnet for generating a defined magnetic field, a resonator having a first opening and a second opening facing each other with the cavity therebetween, disposed on the side of the resonator and the second opening, converting light output from the resonator into parallel light and an optical converter, wherein the output end of the first optical fiber and the ferromagnetic material are disposed in the cavity through the first opening.

In an embodiment, the ferromagnetic material may be directly bonded to the output terminal of the first optical fiber.

In an embodiment, the ferromagnetic material may be Yttrium iron garnet.

In one embodiment, a first optical connector coupled to the output end of the first optical fiber and having a ferrule aligned with an axis of the first optical fiber, the ferromagnetic material may be bonded to the ferrule.

In one embodiment, the optical converter may include a lens.

In one embodiment, the optical converter may further include a half-wave plate and a polarization beam splitter.

In an embodiment, the quantum light-microwave interconversion device may further include a collimator for condensing the input parallel light and a second optical fiber for receiving the light focused by the collimator.

In one embodiment, the collimator may include a condensing lens.

In one embodiment, the quantum light-microwave interconversion device is coupled to a position adjuster for converting a distance and an angle of the collimator, and an input end of the second optical fiber, connecting the collimator and the second optical fiber, a second light It may further include a connector.

In one embodiment, the quantum optical microwave interconversion device includes a condensing lens for condensing the light output from the optical converter, a second optical fiber receiving the light condensed by the condensing lens, and the first optical fiber, the resonator, It may include a housing for integrally fixing the optical converter, the condensing lens, and the second optical fiber.

Other aspects, features and advantages other than those described above will become apparent from the following drawings, claims, and detailed description of the invention.

According to an embodiment of the present invention made as described above, it is possible to implement a miniaturized quantum light-microwave interconversion device by simplifying the optical system. Of course, the scope of the present invention is not limited by these effects.

1 is a diagram schematically illustrating a quantum light-microwave interconversion apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram schematically illustrating a first optical fiber and a ferromagnetic body having the optical connector shown in FIG. 1 .
3 is a diagram schematically illustrating an apparatus for quantum optical-microwave interconversion without using a beam expander, according to an embodiment of the present invention.
4 is a diagram schematically illustrating a quantum optical-microwave interconversion device in which a resonator and an optical converter are integrally provided, according to an embodiment of the present invention.
5A is a diagram schematically showing a quantum light-microwave interconversion device including a collimator from the side according to an embodiment of the present invention, and FIG. 5B is a quantum light-microwave interconversion device including a collimator from the top view. It is a drawing schematically showing.
6 is a diagram schematically illustrating a quantum light-microwave interconversion device that can be used in a cryogenic environment, according to an embodiment of the present invention.

Since the present invention can apply various transformations and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail in the detailed description. Effects and features of the present invention, and a method for achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the drawings. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various forms.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, and when described with reference to the drawings, the same or corresponding components are given the same reference numerals, and the overlapping description thereof will be omitted. .

In the present specification, terms such as first, second, etc. are used for the purpose of distinguishing one component from other components without limiting meaning.

In this specification, the singular expression includes the plural expression unless the context clearly dictates otherwise.

In the present specification, the terms include or have means that the features or components described in the specification are present, and the possibility that one or more other features or components may be added is not excluded in advance.

In the present specification, when it is said that a part such as a film, region, or component is on or on another part, not only when it is directly on the other part, but also when another film, region, component, etc. is interposed therebetween. include

In this specification, when a membrane, a region, or a component is connected, when the membrane, a region, or the components are directly connected, or/and another membrane, a region, or a component is interposed between the membranes, the region, and the components. Indirect connection is also included. For example, in the present specification, when it is said that a film, region, component, etc. are electrically connected, when the film, region, component, etc. are directly electrically connected, and/or another film, region, component, etc. is interposed therebetween. This indicates an indirect electrical connection.

In the present specification, "A and/or B" refers to A, B, or A and B. And, "at least one of A and B" represents the case of A, B, or A and B.

In the present specification, the x-axis, y-axis, and z-axis are not limited to three axes on a Cartesian coordinate system, and may be interpreted in a broad sense including them. For example, the x-axis, y-axis, and z-axis may be orthogonal to each other, but may refer to different directions that are not orthogonal to each other.

In cases where certain embodiments are otherwise practicable in this specification, a specific process sequence may be performed differently from the described sequence. For example, two processes described in succession may be performed substantially simultaneously, or may be performed in an order opposite to the order described.

In the drawings, the size of the components may be exaggerated or reduced for convenience of description. For example, since the size and thickness of each component shown in the drawings are arbitrarily indicated for convenience of description, the present invention is not necessarily limited to the illustrated bar.

1 is a diagram schematically illustrating a quantum light-microwave interconversion apparatus according to an embodiment of the present invention.

Referring to FIG. 1 , a quantum light-microwave interconversion device 100 according to an embodiment of the present invention may include a first optical fiber 11 , a ferromagnetic material 15 , a resonator 20 , and an optical converter 30 . can

The first optical fiber 11 receives light from the laser light source and transmits it to the quantum light-microwave interconversion device 100 . That is, the input end of the first optical fiber 11 is connected to the laser light source, and the output end is connected to the quantum light-microwave interconversion device 100 .

In an embodiment, the output end of the first optical fiber 11 may be connected to the first optical connector 13 as shown in FIG. 1 . For example, the first optical connector 13 may be an FC/PC connector. The first optical connector 13 may have a ferrule 13f aligned with the axis of the first optical fiber 11 . The ferromagnetic material 15 may be attached to the ferrule 13f.

In another embodiment, the ferromagnetic material 15 may be directly bonded to the output terminal of the first optical fiber 11 . In this specification, the fact that the ferromagnetic material 15 is directly bonded to the output end of the first optical fiber 11 means that the ferromagnetic material 15 of the first optical fiber 11 is attached to one end of the first optical fiber 11 without a coupling member such as an optical connector. means to be fixed in contact. For example, the ferromagnetic material 15 may be directly bonded to the output terminal of the first optical fiber 11 using an optically transparent adhesive.

The ferromagnetic material 15 may be a Yttrium iron garnet (YIG) single crystal. In an embodiment, the ferromagnetic material 15 may be a spherical bead having a diameter sufficiently larger than the diameter of the core of the first optical fiber 11 . For example, when the diameter of the core of the first optical fiber 11 is 9 μm, the diameter of the ferromagnetic material 15 bead may be 1 mm.

The resonator 20 includes a cavity 20c and magnets 21a and 21b (see FIG. 5b ) for coupling the Kittel mode and the resonator mode of the ferromagnetic material 15 . Here, the magnets 21a and 21b generate a magnetic field defined in one direction in the cavity 20c to determine the Kittel mode frequency of the ferromagnetic material 15 by the magnitude of the magnetic field, and may be a permanent magnet or an electromagnet. . Although not shown in FIG. 1 , an SMA connector and a cable for generating and measuring microwaves may be further included.

A first opening 20a is disposed on one sidewall of the resonator 20, and a second opening 20b is disposed on the other sidewall to face the first opening 20a with the cavity 20c interposed therebetween. . The first opening 20a and the second opening 20b may be positioned on a straight line. The first optical fiber 11 and the ferromagnetic material 15 attached to the first optical fiber 11 may be introduced through the first opening 20a. As described above, when the first optical connector 13 is coupled to the output end of the first optical fiber 11, the first opening 20a has a shape corresponding to the first optical connector 13, and the ferromagnetic material 15 can be easily fixed to be placed in an appropriate position within the cavity 20c.

Light passing through the ferromagnetic material 15 is output from the output end of the first optical fiber 11 introduced into the cavity 20c through the first opening 20a, and the output light is in line with the first opening 20a It may proceed out of the cavity 20c through the second opening 20b disposed in the .

The optical converter 30 may be disposed on the side of the second opening 20b of the resonator 20 . In FIG. 1 , it is illustrated that the optical converter 30 is composed of one lens, but the optical converter 30 includes a plurality of lenses, a half-wave plate, a polarization beam splitter, a mirror, and the like. may include

FIG. 2 is a diagram schematically illustrating a first optical fiber and a ferromagnetic body having the optical connector shown in FIG. 1 .

Referring to FIG. 2 , the first optical connector 13 may be coupled to the output terminal of the first optical fiber 11 , and the ferromagnetic material 15 may be directly bonded to the ferrule 13f of the first optical connector 13 . By attaching the ferromagnetic material 15 to the output end of the first optical fiber 11 or the ferrule 13f of the first optical connector 13, an optical system for focusing light on the ferromagnetic material 15 such as a beam expander and a lens can be omitted. can Accordingly, the configuration of the quantum light-microwave interconversion apparatus 100 may be simplified.

For example, when the first optical fiber 11 is a single-mode optical fiber, the diameter of the core is about 9 μm, and the ferromagnetic material 15 having a diameter of about 1 mm is used at the output end of the first optical fiber 11 or the ferrule 13f. When attached to the ferromagnetic material 15, the diameter of the incident light may be sufficiently small. Accordingly, light can be focused on the ferromagnetic material 15 without a complex optical system such as a beam expander and a lens. The transmitted light B passing through the ferromagnetic material 15 is refracted in the direction in which the light sources are collected due to the refractive index of the ferromagnetic material 15, so the diffusion angle is lower than that of the light B' output without passing through the ferromagnetic material 15 greatly reduced Therefore, if an appropriate lens is installed in the path of the light passing through the ferromagnetic material 15, the transmitted light B can be made to have a diameter sufficiently small to be focused back into the optical fiber using the laser collimator.

3 is a diagram schematically illustrating an apparatus for quantum optical-microwave interconversion without using a beam expander, according to an embodiment of the present invention.

The quantum light-microwave interconversion device 100 shown in FIG. 3 is similar to the quantum light-microwave interconversion device 100 shown in FIG. 1 , but the configuration of the optical converter 30 and the collimator 40 and the second There is a difference in that it further includes two optical fibers (51). Hereinafter, overlapping content will be omitted, and differences will be mainly described.

As described above, the optical converter 30 may be disposed on the side of the second opening 20b of the resonator 20 . The optical converter 30 may include a lens 31 , mirrors 32a and 32b , a half-wave plate 33 , and a polarizing beam splitter 35 .

The lens 31 may convert the output light output through the second opening 20b of the resonator 20 into parallel light traveling with a constant diameter. Since the light output through the ferromagnetic material 15 inside the resonator 20 has a small diffusion angle, it can be easily converted into parallel light by using the single lens 31 .

The parallel light passing through the mirrors 32a and 32b is incident on the half-wave plate 33 and the polarization beam splitter 35 . The half-wave plate 33 may change the polarization state so that the light in the polarization direction of the slow axis with respect to the fast axis of the incident light differs by half a wavelength. By combining the half-wave plate 33 and the polarization beam splitter 35, a polarization/light source intensity converter that converts a signal converted into polarization information of microwave light into intensity information of light wave may be configured.

The collimator 40 may focus the light onto the second optical fiber 51 for analysis of the signal converted through the optical converter 30 . The second optical fiber 51 may transmit the converted light to the signal analysis device. A second optical connector 53 may be interposed between the collimator 40 and the second optical fiber 51 . In an embodiment, the second optical connector 53 may be fixed to the input end of the second optical fiber 51 , and the collimator 40 may include a coupling unit corresponding to the second optical connector 53 . Accordingly, the axes of the collimator 40 and the second optical fiber 51 can be easily aligned by using the second optical connector 53 .

4 is a diagram schematically illustrating a quantum optical-microwave interconversion device in which a resonator and an optical converter are integrally provided, according to an embodiment of the present invention.

FIG. 4 is similar to the quantum optical-microwave interconversion device 1 shown in FIG. 1 , but is different in that the optical converter 30 is integrally provided with the resonator 20 . Hereinafter, overlapping content will be omitted, and differences will be mainly described.

A space for inserting the optical transducer 30 may be provided behind the second opening 20b of the resonator 20 based on the light propagation path. For example, as shown in FIG. 4 , the outer wall of the resonator 20 on the side of the second opening 20b is thicker than the outer wall of the other side, and the second opening 20b extends in the propagation direction of light and extends along the wall. space can be provided. The light converter 30 may be inserted into the expanded space of the second opening 20b. In FIG. 4 , it is illustrated that the optical converter 30 is configured with only a single lens 31 for making light parallel, but the present invention is not limited thereto. In another embodiment, as shown in FIGS. 5A and 5B , the optical converter 30 may include a lens 31 , a half-wave plate 33 , and a polarization beam splitter 35 , and additionally as needed. It may further include optical elements.

As shown in FIG. 4 , the resonator 20 and the lens 31 are integrally provided to output laser light having a defined diameter parallel to the free space. Therefore, it can be easily applied to optical systems for performing various analyzes on laser light.

5A is a diagram schematically from a side view of a quantum light-microwave interconversion device including a collimator according to an embodiment of the present invention, and FIG. 5B is a quantum light-microwave interconversion device including a collimator from the top view. It is a drawing schematically showing.

5A and 5B , the optical converter 30 is fixed to the side of the second opening 20b of the resonator 20 , and the collimator 40 and the second optical fiber 51 to the other side of the optical converter 30 . ) can be fixed.

At the side of the first opening 20a of the resonator 20 , magnets 21a and 21b for applying a magnetic field defined in one direction to the ferromagnetic material 15 may be disposed to face the outside of the resonator 20 . The ferromagnetic material 15 may be fixed in the cavity 20c by being attached to the ferrule 13f of the first optical connector 13 and being drawn in. Meanwhile, the resonator 20 may further include an SMA connector and a cable for generating and measuring microwaves.

As described above, the optical converter 30 may include a lens 31 , a half-wave plate 33 , and a polarization beam splitter 35 , and may further include additional optical elements as necessary. The photoconverter 30 may align these optical elements on the same axis as the second opening 20b. That is, as the optical transducer 930 is fixed to the side of the second opening 20b of the resonator 20 or provided integrally, the optical elements can be easily aligned and fixed on the propagation path of light.

A collimator 40 and a second optical fiber 51 may be disposed on the light output side of the optical converter 30 . As described above, the input end of the second optical fiber 51 may be coupled to the second optical connector 53 , and the collimator 40 may have a coupling portion corresponding to the second optical connector 53 . The outer wall of the collimator 40 and the light converter 30 may be fixed using the position adjuster 60 . The position adjuster 60 may be a Tip&Tilt two-axis adjuster or a Tip&Tilt and X&Y four-axis adjuster, and may replace the mirrors 32a and 32b shown in FIG. 3 to convert the distance and angle of the collimator.

The quantum light-microwave interconversion apparatus 100 according to the present embodiment not only reduces the number of required optical components, but also does not require an optical table for fixing them. Accordingly, not only miniaturization is possible, but also the sensitivity to the external environment is reduced, so that a certain result can be obtained even in a change of the external environment.

6 is a diagram schematically illustrating a quantum light-microwave interconversion device that can be used in a cryogenic environment, according to an embodiment of the present invention.

Referring to FIG. 6 , the quantum optical-microwave interconversion apparatus 100 may omit the optical connector and use the first optical fiber 11 and the second optical fiber 51 .

In one embodiment, the first optical fiber 11 , the resonator 20 , the optical converter 30 , the collimator 40 , and the second optical fiber 51 may be integrally provided by a single housing. The first optical fiber 11 may be fixed to an opening in one wall of the housing, and the second optical fiber 51 may be fixed to an opening in the other wall of the housing. In the housing, the cavity 20c, the optical converter 30 and the collimator 40 may be arranged in alignment with the optical axes of the first optical fiber 11 and the second optical fiber 51 .

In this case, the collimator 40 may be replaced with one condensing lens 41 . That is, the parallel light converted through the optical converter 30 is incident on the condensing lens 41 , and the second optical fiber 51 fixed to the focus of the condensing lens 41 may receive the focused light.

As shown in FIG. 6 , by maximally omitting optical elements constituting the quantum light-micro interconversion device, the effect of temperature change can be minimized. Accordingly, the quantum photo-micro interconversion device according to the present embodiment can be utilized in a cryogenic cooling device.

Although the present invention has been described with reference to the embodiments shown in the drawings, which are merely exemplary, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

100: quantum light-microwave interconversion device
13f: Ferrule
15: ferromagnetic material
20: resonator
20a: first opening
20b: second opening
20c: Cavity
21a, 21b: magnet
31: lens
32a, 32b: mirror
33: half-wave plate
40: collimator
41: condensing lens
53: second optical connector
60: position adjuster

Claims (11)

a first optical fiber for receiving light from the light source;
a first optical connector coupled to an output end of the first optical fiber and having a ferrule aligned with an axis of the first optical fiber;
a ferromagnetic material bonded to the ferrule;
a resonator having a cavity, a magnet for generating a magnetic field defined in one direction in the cavity, and first and second openings facing each other with the cavity therebetween; and
and an optical converter disposed on the second opening side and converting the light output from the resonator into parallel light;
and the output end of the first optical fiber and the ferromagnetic material are disposed in the cavity through the first opening. delete According to claim 1,
The ferromagnetic material is Yttrium iron garnet (Yttrium iron garnet), quantum light-microwave interconversion device. delete The method of claim 1,
The photoconverter comprises a lens, quantum light-microwave interconversion device. 6. The method of claim 5,
The optical converter further comprises a half-wave plate (Half-Wave Plate) and a polarization beam splitter (Polarization Beam Splitter), quantum light-microwave interconversion device. The method of claim 1,
a collimator for condensing the input parallel light; and
The second optical fiber receiving the light focused by the collimator; further comprising, quantum light-microwave interconversion device. 8. The method of claim 7,
wherein the collimator comprises a condensing lens. 8. The method of claim 7,
a position adjuster for converting the distance and angle of the collimator; and
A second optical connector coupled to the input end of the second optical fiber to connect the collimator and the second optical fiber; According to claim 1,
a condensing lens for condensing the light output from the light converter;
a second optical fiber receiving the light focused by the condensing lens; and
and a housing for integrally fixing the first optical fiber, the resonator, the optical converter, the condensing lens, and the second optical fiber. a first optical fiber for receiving light from the light source;
a ferromagnetic material directly bonded to the output end of the first optical fiber;
a resonator having a cavity, a magnet for generating a magnetic field defined in one direction in the cavity, and first and second openings facing each other with the cavity therebetween; and
and an optical converter disposed on the second opening side and converting the light output from the resonator into parallel light;
and the output end of the first optical fiber and the ferromagnetic material are disposed in the cavity through the first opening.

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