KR102299787B1 - Quantum light source - Google Patents

Abstract

The quantum light source according to the present embodiment includes a semiconductor base and one or more hole groups including a plurality of holes passing through the semiconductor base and spaced apart from the center, and a plurality of holes included in the same hole group. They are spaced the same distance from the center.

Description

Quantum Light Source {QUANTUM LIGHT SOURCE}

The present technology relates to quantum light sources.

Quantum information uses "quantum bits" that can express 1 and 0 simultaneously using the superposition principle instead of bits that are divided into 1 and 0. There are various approaches to quantum information processing, such as atoms, light, and super-conducting devices, and attention is focused on quantum information processing using light, that is, photons. This is because quantum bits can be implemented like the spin of electrons by using the polarization, time, and path information of light.

Recently, a quantum light source that exhibits superimposition, quantum entanglement, and non-radiability, which are characteristics of quantum physics, has been developed, and applied technologies such as quantum simulators, quantum transmission, and quantum cryptography are being actively studied. A quantum light source means a light source that generates single or entangled photons that are differentiated from a classical light source, and light is generated from a single quantum structure such as a single atom or a single quantum dot.

Among the existing solid-state quantum light sources, the Bull's eye structure is representative of a structure capable of vertically emitting quantum light at a narrow angle. The existing bull's eye structure has a multi-ring structure in the form of a circular grating. The light emitted from the existing bull's eye structure is not small enough to couple with the optical fiber having a small numerical aperture (NA), so an additional optical system is required for high-efficiency photon signal transmission. Therefore, in order to maintain high efficiency while being easy to combine with optical fibers, it is necessary to develop a quantum light source combined with an optical structure capable of vertical light emission at a narrow angle.

The problem to be solved by the present technology is to solve the problems of the quantum light source according to the prior art. That is, one of the problems to be solved by the present technology is to provide a quantum light source capable of obtaining high vertical light extraction efficiency.

The quantum light source according to the present embodiment includes a base including a semiconductor quantum structure, and one or more hole groups including a plurality of holes passing through the semiconductor base and spaced apart from the center, and in the same hole group. The included plurality of holes are spaced apart from the center by the same distance.

The quantum light source array according to this embodiment includes a semiconductor layer including a quantum structure, a semiconductor base for a high-efficiency unit quantum light source, and a plurality of holes passing through the semiconductor base and spaced apart from the center. One or more hole groups are included, and the plurality of holes included in the same hole group includes a unit quantum light source spaced apart from the center by the same distance and a bridge connecting the unit quantum light source and the semiconductor substrate, The light sources are arranged in an array.

The quantum light source according to the present embodiment has the advantages of being able to obtain high light coupling efficiency with respect to an optical fiber having a low aperture ratio, high light extraction efficiency, and light emission at a narrow angle.

1 is a plan view showing an outline of a quantum light source according to the present embodiment.
FIG. 2 is an enlarged view of an area indicated by a solid line circle in FIG. 1 .
FIG. 3(a) is a cross-sectional view taken along line A-A' in FIG. 1, and FIG. 3(b) is a cross-sectional view taken along line C-C' in FIG.
4 is a plan view of a base included in a quantum light source according to another embodiment.
5 is a microscope (SEM) photograph of a quantum light source array in which quantum light sources are arranged in an array form.
6 is a diagram for schematically explaining an embodiment of an operation of a quantum light source according to the present embodiment.
7 is a diagram for schematically explaining another embodiment of the operation of the quantum light source according to the present embodiment.
FIG. 8(a) is a microscope (SEM) photograph of a quantum light source, and FIG. 8(b) is a graph illustrating a spectrum of emitted light.
9(a) and 9(b) are diagrams illustrating optical modes of an electric field emitted by a quantum light source according to the present embodiment and a quantum light source according to the present embodiment.
10 is a graph comparing light collection efficiencies for each structure according to an aperture ratio of an optical system related to a collection angle for collecting light from a sample.

Since the description of the present invention is merely an embodiment for structural or functional description, the scope of the present invention should not be construed as being limited by the embodiment described in the text. That is, since the embodiment may have various changes and may have various forms, it should be understood that the scope of the present invention includes equivalents capable of realizing the technical idea.

On the other hand, the meaning of the terms described in the present application should be understood as follows.

The singular expression is to be understood as including the plural expression unless the context clearly dictates otherwise, and terms such as "comprises" or "have" refer to the described feature, number, step, action, component, part or these It is to be understood that this is intended to indicate that a combination exists, and does not preclude the possibility of addition or existence of one or more other features or numbers, steps, operations, components, parts, or combinations thereof.

Each step may occur in a different order than the stated order unless the context clearly dictates a specific order. That is, each step may occur in the same order as specified, may be performed substantially simultaneously, or may be performed in the reverse order.

All terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. Terms such as those defined in a commonly used dictionary should be interpreted as being consistent with the meaning in the context of the related art, and cannot be interpreted as having an ideal or excessively formal meaning unless explicitly defined in the present application. .

Hereinafter, a quantum light source according to the present embodiment will be described with reference to the accompanying drawings. 1 is a plan view illustrating an outline of a quantum light source 100 according to the present embodiment, and FIG. 2 is an enlarged view of an area indicated by a solid circle in FIG. 1 . 1 and 2 , a quantum light source 100 according to the present embodiment includes a semiconductor base and a plurality of holes passing through the semiconductor base and spaced apart from the center. The plurality of holes including the above hole groups HG1, HG2, ..., HGK, and included in the same hole group, are spaced apart from the center by the same distance.

The hole groups HG1, HG2, ..., HGK include a plurality of holes H. 1 and 2, the holes H included in the same hole group may have the same radius r and may be spaced apart from each other so that the spacing d between the centers of adjacent holes is the same. The adjacent hole group and the hole group may be spaced apart from each other so that the distance therebetween is the same. Each of the holes H is formed through a semiconductor base.

The wavelength of light provided by the quantum light source 100 is determined by the distance rc between the first hole group from the center, the radius r of the holes, the distance G between adjacent hole groups, and the distance d between the centers of adjacent holes.

The light wavelength λ is largely determined by the distance G between the hole groups and the effective refractive index ( n _eff ) of the material, and the main relationship is as follows. λ=G× n _{eff .} Variables such as rc, r, and d can be optimized through simulation. For example, the structure used in FIG. 8 is an example of an optical structure having an optical wavelength of 1300 nm in an InP material, and the parameters used are as follows. G = 485 nm, rc = 2.7 x G, r = 0.105 x G, d = 0.6 x G.

3(a) is a cross-sectional view taken along line A-A' of FIG. 1 , and FIG. 3(b) is a cross-sectional view taken along line C-C' of FIG. 1 . Referring to FIGS. 3A and 3B , the quantum light source 100 is formed from a substrate on which a semiconductor layer 130 , a sacrificial layer 120 , and a semiconductor layer 110 are stacked. The semiconductor layer 110 is patterned to form one or more hole groups HG1 , HG2 , ..., HGK penetrating the semiconductor layer 110 and including a plurality of holes spaced apart from the center to form a base. ) can be formed.

In the process of forming the quantum light source 100 , the sacrificial layer 120 under the base is etched and removed. The semiconductor base and the layer are connected by a bridge B, but portions in which the bridge B is not formed are spaced apart from each other. The layer may be a portion of the semiconductor layer 110 that is not patterned with the semiconductor base and/or the bridge B.

The semiconductor base may be formed of any one of a III-V semiconductor and a II-VI semiconductor. For example, the III-V semiconductor may be InP, GaAs, or GaN, and the II-VI semiconductor may be ZnO or CdSe. In addition, it may be a material such as diamond or SiC having a quantum structure. In an embodiment, the semiconductor membrane, the bridge B, and the semiconductor base may be formed by patterning the same semiconductor substrate.

3(a) and 3(b), the semiconductor base comprises a quantum structure (QS). For example, the quantum structure may be one of InAs, InGaAs, GaN, and InGaN quantum dots, and the quantum dots may be positioned between semiconductor layers. According to another embodiment not shown, the semiconductor base may include any one or more of a solid point defect, silver doping ions, and a two-dimensional material. The doping ion may be an erbium (Er) ion, and the two-dimensional material may be any one of tungsten diselenide (WSe2) and hexagonal boron nitride (hBN). Quantum dots, NV center structures (nitrogen-vacancy center structures), doping ions, and two-dimensional materials serve as light sources to generate quantum light sources. A base comprising a quantum structure increases the efficiency of vertically emitting the generated quantum light source.

4 is a plan view of a base included in a quantum light source according to another embodiment. For convenience of description, the bridge (B) and the layer (layer) are omitted from illustration. According to the embodiment illustrated in FIG. 4 , the radii of the plurality of holes included in the same hole group located at the same distance from the center are the same, and the radius of the plurality of holes included in the same hole group is the same as the distance from the center is increased. is decreased Also, the spacing between adjacent hole groups decreases as the distance between the hole groups increases from the center.

According to another embodiment (not shown), the radii of the plurality of holes included in the same hole group located at the same distance from the center may be the same, but as the distance from the center changes, the plurality of holes included in the same hole group may be the same. The radius of the holes in can be varied. Also, the spacing between adjacent hole groups may change as the distance from the center of the hole groups changes.

5 is a microscope (SEM) photograph of a quantum light source array in which quantum light sources are arranged in an array form. Referring to FIG. 5 , a plurality of unit quantum light source arrays may be disposed on a single semiconductor substrate to form a quantum light source array. One or more quantum light sources included in the quantum light source array are spaced apart from each other so that the holes (H) included in the same hole group have the same radius (r), and the spacing (d) between the centers of adjacent holes is the same as illustrated in FIG. 1 . The adjacent hole group and the hole group may be spaced apart from each other so that the distance therebetween is the same, and each hole H may have a structure formed through a semiconductor base.

One or more quantum light sources included in the quantum light source array are positioned at the same distance from the center as illustrated in FIG. 2 , so that the radius of a plurality of holes included in the same hole group is the same, and as the distance from the center increases, the same hole groups are formed. The radius of the plurality of holes included in the ? may decrease, and the spacing between adjacent hole groups may have a structure in which the distance between the adjacent hole groups decreases as the distance from the center of the hole groups increases.

In addition, one or more quantum light sources included in the quantum light source array are located at the same distance from the center, so that the radius of the plurality of holes included in the same hole group is the same, and the more spaced from the center, the more the plurality of holes included in the same hole group are located. The radius of the holes may increase, and the spacing between adjacent hole groups may have a structure that increases as the distance between the hole groups increases from the center.

Hereinafter, a quantum light source according to the present embodiment will be described with reference to FIGS. 6 to 7 . The quantum light source 100 is transferred to an adhesive transfer substrate (not shown, adhesive transfer substrate). In one embodiment, when the quantum light source 100 formed on the semiconductor substrate comes into contact with the adhesive transfer substrate, the bridge B connecting the base and the substrate 100 is destroyed, and the quantum light source 100 is the adhesive transfer substrate. is transcribed into In one embodiment, the adhesive transfer substrate may be a polymer substrate having an adhesive surface, for example, the adhesive transfer substrate may be a transparent PDMS substrate. The quantum light source 100 irradiated onto the adhesive transfer substrate is aligned with the core of the optical fiber 500 and attached thereto.

The transfer process can be performed through an optical microscope, and the position of the optical fiber core can be confirmed by irradiating a guide laser from the opposite side of the optical fiber. The high-magnification microscope and precise positioning stage enable precise alignment and coupling between the quantum light source and the optical fiber core.

6 is a diagram schematically illustrating an embodiment of the operation of the quantum light source 100 according to the present embodiment. Referring to FIG. 6 , the quantum light source 100 is located at the center of one end of the optical fiber. A first surface of the quantum light source 100 is electrically connected to the first electrode E1 , and a second surface thereof is connected to the second electrode E2 . A voltage source is connected to the first electrode E1 and the second electrode E2 to provide driving power to the quantum light source 100 . In the embodiment illustrated in FIG. 6 , the first electrode E1 and the second electrode E2 are connected to a voltage source, but in an embodiment not shown, the first electrode E1 and the second electrode E2 are a current source Connected. In one embodiment, the first electrode E1 formed on the first surface to prevent single or entangled photons from being emitted to the surface that is not coupled to the optical fiber has a high reflectance such as gold and silver. It may be formed of a material. The first electrode E1 may function as a mirror that reflects the quantum emitted by the quantum light source 100 in an undesired direction.

As energy is provided to the quantum light source 100 by power sources such as a voltage source and a current source, the quantum light source 100 provides single or entangled photons through an optical fiber, and efficient optical coupling is possible to an optical fiber having a low aperture ratio.

7 is a diagram schematically illustrating another embodiment of the operation of the quantum light source 100 according to the present embodiment. Referring to FIG. 7 , a laser source irradiates a laser to the quantum light source 100 through a coupler. The quantum light source 100 generates and outputs single or entangled photons by the energy of the laser irradiated to the quantum light source 100 . In an embodiment, a mirror M may be formed in the quantum light source 100 to prevent quantum emission in an undesirable direction.

A single or entangled photon emitted from the quantum light source 100 is provided to an optical fiber coupler via an optical fiber 500 . Quantum light passing through a fiber coupler is guided through an optical fiber. In an embodiment not shown, an optical fiber wavelength filter or a polarizing filter may be included to prevent a partial laser other than the quantum light source from being partially included in the optical fiber. The illustrated quantum light source 100 is provided with the advantage that efficient optical coupling with an optical fiber having a low aperture ratio is possible.

simulation example

Hereinafter, the experimental results of the quantum light source according to the present embodiment will be described with reference to FIGS. 8(a) and 8(b). FIG. 8(a) is a microscope (SEM) photograph of the quantum light source 100, and FIG. 8(b) is a graph illustrating a spectrum of emitted light. Referring to FIG. 8(a), in the quantum light source, the distance between the center and the adjacent hole group is 1000 nm, the radius of a plurality of holes included in the quantum light source is 52.5 nm, the spacing between the neighboring hole groups is 500 nm, the same The center-to-center distance between the holes belonging to the hole group is designed to be 300 nm, and the emission wavelength is designed to be 1300 nm. It can be seen from FIG. 8(b) that the quantum light source designed in this way has a wavelength of 1300 nm.

9(a) and 9(b) are diagrams illustrating an optical mode of an electric field emitted by a conventional quantum light source and a quantum light source according to the present embodiment. Referring to FIGS. 9( a ) and 9 ( b ), it can be confirmed from the optical mode confirmed above and the optical mode from the side that the conventional quantum light source widely radiates an electric field. However, it can be seen from FIG. 9(b) that the quantum light source according to the present embodiment radiates the electric field at a narrower angle.

10 is a graph comparing light collection efficiencies for each structure according to an aperture ratio of an optical system related to a collection angle for collecting light from a sample. Referring to FIG. 10 , it can be seen that when NA=0.1, which is a light collection angle corresponding to the optical fiber, the efficiency is more than twice that of the prior art. Furthermore, even when NA=0.35 and NA=0.7, it can be confirmed that the efficiency is higher than that of the prior art.

Although it has been described with reference to the embodiment shown in the drawings in order to help the understanding of the present invention, this is an embodiment for implementation, it is merely an example, and those of ordinary skill in the art have various modifications and equivalents therefrom. It will be appreciated that other embodiments are possible. Accordingly, the true technical protection scope of the present invention should be defined by the appended claims.

100: quantum light source
rc: the distance between the center and the first group of holes
B: Bridge H: Hall
r: radius of holes G: distance between adjacent groups of holes
d: spacing between centers of adjacent holes sub: semiconductor substrate
base: semiconductor base QD: quantum dots
cladding: cladding core: core
E1: first electrode E2: second electrode
Laser Source: laser source coupler: coupler
M:Mirror 500: Fiber Optic
QS: Quantum Structure
HG1, HG2, ...HGK: Hall group

Claims (23)

semiconductor base;
one or more hole groups penetrating the semiconductor base and including a plurality of holes spaced apart from the center;
The plurality of holes included in the same hole group are spaced apart from the center by the same distance, and the plurality of holes included in the same hole group are spaced apart from each other by the same distance. According to claim 1,
The semiconductor base (base) is a quantum light source comprising any one of III-V semiconductor, II-VI semiconductor, diamond, and SiC. 3. The method of claim 2,
The III-V semiconductor is any one of InP, GaAs, and GaN, and the II-VI semiconductor is A quantum light source of any one of ZnO and CdSe. According to claim 1,
The semiconductor base (base) is a quantum light source including any one of a quantum dot, a solid point defect (defect center structure), doping ions, and a two-dimensional material. 5. The method of claim 4,
The quantum dots are III-V semiconductor quantum dots,
The doping ion is an erbium (Er) ion,
The two-dimensional material is a quantum light source of any one of tungsten diselenide (WSe2) and hexagonal fluorine nitride (hBN, hexagonal boron nitride). According to claim 1,
A quantum light source having the same radius of the plurality of holes included in the same hole group. According to claim 1,
A quantum light source having different radii of a plurality of holes included in the different hole groups. According to claim 1,
The radius of the holes included in the plurality of hole groups decreases as the distance from the center increases. According to claim 1,
The quantum light source is
A quantum light source connected by one or more bridges to a layer. According to claim 1,
The quantum light source is
a first electrode connected to a first surface of the quantum light source;
and a second electrode connected to a second surface opposite to the direction of the first surface of the quantum light source,
A quantum light source providing single or entangled photons by energy provided to the first electrode and the second electrode. According to claim 1,
The quantum light source is
A quantum light source that provides single or entangled photons by the energy provided by irradiating a laser. According to claim 1,
The quantum light source is
A quantum light source whose wavelength is controlled according to at least one of a separation distance between the center and the hole group, a separation distance between the hole groups, and a radius of holes belonging to the hole group. semiconductor layer;
one or more hole groups including a semiconductor base and a plurality of holes passing through the semiconductor base and spaced apart from a center, wherein the plurality of holes included in the same hole group are identical from the center A unit quantum light source spaced apart by a distance, and the plurality of holes included in the same hole group are spaced apart by the same distance from each other;
a bridge connecting the unit quantum light source and the semiconductor layer;
A quantum light source array in which a plurality of the unit quantum light sources are arranged in an array. 14. The method of claim 13,
wherein the semiconductor base and the semiconductor layer include any one of a III-V semiconductor and a II-VI semiconductor. 15. The method of claim 14,
The III-V semiconductor is any one of InP, GaAs, and GaN and the II-VI semiconductor is Quantum light source array of any one of ZnO and CdSe. 14. The method of claim 13,
The semiconductor base is a quantum dot, a solid dot defect (defect center structure), a quantum light source array including any one of doping ions and a two-dimensional material. 17. The method of claim 16,
The quantum dots are III-V semiconductor quantum dots,
The doping ion is an erbium (Er) ion,
The two-dimensional material is a quantum light source array of any one of tungsten diselenide (WSe2) and hexagonal fluorine nitride (hBN, hexagonal boron nitride). 14. The method of claim 13,
A quantum light source array having the same radius of the plurality of holes included in the same hole group. 14. The method of claim 13,
A quantum light source array in which radii of a plurality of holes included in the different hole groups are different from each other. 14. The method of claim 13,
A quantum light source array in which a radius of the holes included in the plurality of hole groups decreases as a distance from the center increases. 14. The method of claim 13,
The unit quantum light source is
a first electrode connected to a first surface of the unit quantum light source;
a second electrode connected to a second surface in the direction of the first surface of the unit quantum light source;
A quantum light source array providing single or entangled photons by energy provided to the first electrode and the second electrode. 14. The method of claim 13,
The quantum light source array,
A quantum light source array that provides single or entangled photons by the energy provided by irradiating a laser. 14. The method of claim 13,
The unit quantum light source is
A quantum light source array in which a wavelength to provide is controlled according to at least one of a separation distance between the center and the hole group, a separation distance between the hole groups, and a radius of holes belonging to the hole group.

Images