Optical isolation device and method based on double-cavity optical power system

Abstract

The invention discloses an optical isolation device and method based on a double-cavity light power system, and belongs to the technical field of optical devices in modern information networks, and the optical isolation device comprises the double-cavity light power system, a driving light input unit and a detection light input unit. The double-cavity light power system comprises a left optical cavity, a right optical cavity and a mechanical oscillator, and the mechanical oscillator is located between the left optical cavity and the right optical cavity; the left optical cavity and the right optical cavity interact through linear coupling; the driving light input unit and the detection light input unit are both used for inputting light with preset amplitude and frequency into the left optical cavity and the right optical cavity respectively. According to the optical isolator based on the double-cavity optical power system, perfect optical isolation can be achieved, that is, light can be completely transmitted to the other side from one side of the system, energy loss is avoided, and when the light is transmitted in the opposite direction, output is completely forbidden by the system; meanwhile, the optical isolator based on the double-cavity optical power system is small in size and can be integrated on a chip with the existing superconducting technology.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical devices in modern information networks, and particularly relates to an optical isolation device and method based on a dual-cavity optomechanical system. Background Art

[0002] An optical isolator is a device that only allows unidirectional transmission of optical signals. Since it can effectively suppress incorrect or unwanted optical signals, it has become an indispensable quantum device in modern information processing. For example, they can protect devices from the noise emitted by electronic devices in quantum superconducting circuits. The unidirectional transmission of signals generally requires the system to have optical non-reciprocity, that is, to break optical reciprocity. In order to break reciprocity and obtain asymmetric transmission, any such device needs to break time-reversal symmetry. Traditionally, non-reciprocal transmission relies on an externally applied strong magnetic field to break the time-reversal symmetry of the system. The condition of a strong magnetic field makes these traditional devices usually bulky, resulting in incompatibility between these devices and ultra-low-loss superconducting circuits. Recently, a cavity optomechanics system alternative has been proposed to replace traditional non-reciprocal devices. This solution is particularly promising because they can be integrated with existing superconducting technologies on a chip. However, the problem of perfect optical isolation has not been solved among these cavity optomechanics solutions, that is, light can be completely transmitted from one side of the system to the other side without energy loss during transmission, while in the opposite direction of transmission, the output is completely prohibited by the system, that is, zero output. Summary of the Invention

[0003] To solve the above technical problems, the present invention proposes an optical isolation device and method based on a dual-cavity optomechanical system to solve the problems existing in the above prior art.

[0004] To achieve the above object, the present invention provides an optical isolation device based on a dual-cavity optomechanical system, including:

[0005] A dual-cavity optomechanical system, a driving light input unit, and a probe light input unit;

[0006] The dual-cavity optomechanical system includes a left optical cavity, a right optical cavity, and a mechanical oscillator, and the mechanical oscillator is located between the left optical cavity and the right optical cavity; the left optical cavity and the right optical cavity of the dual-cavity optomechanical system interact with each other through linear coupling;

[0007] Both the driving light input unit and the probe light input unit are used to input light with a preset amplitude and frequency into the left and right optical cavities respectively.

[0008] Optionally, the expression for the linear coupling strength between the left optical cavity and the right optical cavity is:

[0009] ;

[0010] In the formula, They are the dissipation rates of the left optical cavity and the right optical cavity respectively.

[0011] Optionally, the expression of the optomechanical coupling coefficient of the double-cavity optomechanical system is:

[0012] ;

[0013] In the formula, is the optomechanical coupling coefficient of the th optical cavity interacting with the mechanical oscillator optomechanically, is the dissipation rate of the th optical cavity, is the dissipation rate of the mechanical oscillator.

[0014] Optionally, the driving light input unit inputs light with a preset amplitude and frequency into the left and right optical cavities to form a driving field, and the frequency detuning of the driving field satisfies the mechanical red detuning condition.

[0015] Optionally, the phase difference of the driving field is .

[0016] The present invention also provides an optical isolation method based on a double-cavity optomechanical system, including the following steps:

[0017] Set the dissipation rates of the left optical cavity and the right optical cavity to be , respectively, the dissipation rate of the mechanical oscillator to be , and adjust the linear coupling strength between the left cavity and the right cavity to make it satisfy ;

[0018] Input driving light with a preset frequency into the left optical cavity and the right optical cavity, and adjust the phase difference of the driving field to be to make the optomechanical coupling coefficient satisfy ; where , are the optomechanical coupling constants of the left and right cavities with the mechanical oscillator respectively;

[0019] Select the left optical cavity or the right optical cavity to input the detection light with a preset frequency, detect the output field amplitude, and verify whether the forward transmission amplitude and the backward transmission amplitude meet the requirements;

[0020] Adapt to different frequency band requirements by adjusting the dissipation rate of the mechanical oscillator to be or the driving field strength.

[0021] Optionally, the dissipation rates of the left optical cavity and the right optical cavity are equal or in a proportional relationship.

[0022] The present invention also provides a computer device, including: a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the above method.

[0023] The present invention also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the above method are implemented.

[0024] The present invention also provides a computer program product, including a computer program, and when the computer program is executed by a processor, the steps of the above method are implemented.

[0025] Compared with the prior art, the present invention has the following advantages and technical effects:

[0026] The optical isolator based on the double-cavity optomechanical system of the present invention can achieve perfect optical isolation, that is, light can be completely transmitted from one side of the system to the other side without energy loss, while when light is transmitted in the opposite direction, the output is completely prohibited by the system, that is, perfect optical isolation is achieved. At the same time, the optical isolator based on the double-cavity optomechanical system is tiny in volume and can be integrated with existing superconducting technologies on a chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings constituting a part of this application are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation to this application. In the drawings:

[0028] Figure 1 is a schematic diagram of the optical isolator according to an embodiment of the present invention. (a) is a double-cavity optomechanical system, and (b) is a schematic diagram of the optomechanical interaction between the double-cavity optomechanical system and the intermediate mechanical oscillator;

[0029] Figure 2 is the non-reciprocal angle according to an embodiment of the present invention The curve of the transmission amplitude varying with the relative frequency detuning;

[0030] Figure 3 is the non-reciprocal angle according to an embodiment of the present invention The schematic diagram of the influence of the optical cavity dissipation on the transmission amplitude;

[0031] Figure 4 is the non-reciprocal angle according to an embodiment of the present invention The schematic diagram of the influence of the mechanical oscillator dissipation on the transmission amplitude. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The following will refer to the drawings and combine the embodiments to detail this application.

[0033] It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. And although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0034] Embodiment 1

[0035] As Figures 1-4 shown, in this embodiment, an optical isolation device based on a double-cavity optomechanical system is provided, including:

[0036] I. Structure of the double-cavity optomechanical system;

[0037] The double-cavity optomechanical system includes three parts: two optical cavities on the left and right and a middle mechanical oscillator, as Figure 1 (a) shown. The annihilation operator and creation operator of the mechanical oscillator (with an eigenfrequency of ) are represented by and respectively, and satisfy the commutation relation . Let the optical cavity frequencies on both the left and right sides be , and the annihilation (creation) operators be represented by and respectively. The operators satisfy the commutation relations and ( ). Among them, both optical cavities and have an optomechanical interaction with the mechanical oscillator . The interaction Hamiltonian is , where , are optomechanical coupling constants. Optical cavity interacts with cavity through linear coupling, and the interaction Hamiltonian is , where is the coupling strength. Two driving lights with frequencies of and amplitudes of and drive optical cavities and from the left and right sides respectively. At the same time, probe lights with frequencies of and amplitudes of and are input into optical cavities and from the left and right sides respectively. Then the Hamiltonian of the entire system is ( ).

[0038] (1)

[0039] The last four terms in the above formula are the interaction Hamiltonians between the left and right probe lights, the left and right driving fields, and the optical cavity and respectively. There are multiple time- dependent factors in the above formula. To simplify the above formula, the coordinate system is rotated along the driving field frequency . After rotation, the Hamiltonian is:

[0040] (2)

[0041] where is the frequency detuning between the optical cavity and the driving field, and is the frequency detuning between the probe field and the driving field.

[0042] II. Heisenberg-Langevin equation and its linearization;

[0043] From the Hamiltonian of the system, the Heisenberg-Langevin equation satisfied by the system operators can be obtained as:

[0044] (3)

[0045] 、 and are the dissipation rates of the left and right optical cavities and the mechanical oscillator respectively, and 、 and are the vacuum noise operators of the left and right optical cavities and the mechanical oscillator respectively. The average values of these noises are all zero, that is . Since the main research is on the average optical response of the double-cavity optomechanical system to the probe light, the influence of these noises can be ignored in this embodiment.

[0046] To obtain the average value equation of each operator in the system, when there is no probe field input ( ), the commonly used operator factorization hypothesis in cavity optomechanics can be adopted, that is . Then, from formula (3), the steady-state mean values of each operator can be obtained as:

[0047] (4)

[0048] where , and represent the effective detunings between the left and right optical cavities and the driving field respectively. When there is a probe field input, the system operator can be written in the form of the sum of the operator mean value and the fluctuation operator, that is:

[0049] , , (5)

[0050] The fluctuation operator is generally much smaller than the mean value of the operator. Therefore, when substituting Equation (5) into Equation (3), only the linear terms of the fluctuation operator need to be retained, and the substitution , , . Thus, the linearized Heisenberg-Langevin equation is obtained as:

[0051] (6)

[0052] where , . Without loss of generality, it can be assumed that , and are all positive real numbers. It can be seen from Equation (4) that by adjusting the driving field amplitudes and , the phase difference between the optomechanical coupling coefficients can be effectively adjusted. The phase difference is a key parameter for determining whether the system exhibits optical non-reciprocity. Additionally, for simplicity of description, the fluctuation operator is replaced by using ( ).

[0053] If the frequency of the driving field satisfies the mechanical red detuning, i.e., , and the frequency of the mechanical oscillator is much greater than and , then the rotating-wave approximation can be used to simplify Equation (6) to:

[0054] (7)

[0055] where .

[0056] Since Equation (7) is a linear equation and there is only one time exponential factor in it, its solution has the form of , . Substituting into Equation (7) and solving it gives:

[0057] (8)

[0058] and .

[0059] III. Output field of the optical cavity;

[0060] To study the optical non-reciprocity of the system, it is necessary to study the output fields and . The properties of the output field can be obtained from the input-output relationship of the optical cavity, i.e.:

[0061] (9)

[0062] where . Still adopting the assumptions mentioned above , the solution of the output field can be obtained as:

[0063] (10)

[0064] and .

[0065] IV. Optical isolator;

[0066] If the above-mentioned optomechanical system is to achieve the function of an optical isolator, light can only be transmitted unidirectionally, which means that the light input from one side cannot be output from the other side, i.e., the output must be zero. If it is further required that the intensity remains unchanged when the signal is transmitted unidirectionally, then the transmission amplitude of the probe field from to must satisfy the condition:

[0067] ,, (11)

[0068] Or,

[0069] , (12)

[0070] where the subscript ( ) indicates that there is no input signal of the probe field on the ( ) side. For the sake of convenience in description, these subscripts will be omitted in the following content , and the transmission amplitude will be abbreviated as .

[0071] From equations (8) and (10), it can be obtained that:

[0072] (13)

[0073] (14)

[0074] It can be seen from equation (13) that when ( ) or , the system will have no non-reciprocity, so the origin of the non-reciprocity of the system lies in the optomechanical interaction , Quantum interference effect with linear coupling interaction The following takes Equation (11) as an example to study the generation mechanism of the optical isolator. If Equation (11) holds, then Equation (14) must be equal to zero. From the condition that the numerator of Equation (14) is zero, we can obtain:

[0075] (15)

[0076] The left side of the above equation is a complex number. If the above equation holds, the real part and the imaginary part of the left side of the above equation must be zero at the same time. So the following equation holds:

[0077] (16)

[0078] (16) is the necessary condition for the system to generate the optical isolation effect. That is, when Equation (16) holds, from Equation (11), we know that , and is not zero, thus realizing unidirectional transmission.

[0079] Actually, it can be easily seen from Equation (13) and Equation (14) that when or is an integer multiple of, Equation (13) and Equation (14) are exactly equal, that is , and at this time the system has no non-reciprocity. Therefore, in order for the system to exhibit non-reciprocity, the value of this non-reciprocal angle must not be zero. For example, when and the dissipation rate , it can be found that when the system parameters satisfy Equations (17) and (18), the system can exhibit perfect non-reciprocity, as shown in Figure 2 .

[0080] (17)

[0081] (18)

[0082] When the non-reciprocal angle , from Equation (16), we know that , then Equation (13) and Equation (14) are simplified to:

[0083] (19)

[0084] (20)

[0085] When , from Equation (16), we know that , substituting it into Equations (19) and (20), we get:

[0086] (21)

[0087] (22)

[0088] If ideal optical isolation is to be achieved, the following equation holds, i.e.:

[0089] (23)

[0090] From equation (23), the unique solution can be obtained as:

[0091] (24)

[0092] As can be seen from equation (16), the magnitude of the linear coupling constant at this time is:

[0093] (25)

[0094] That is, when the parameters satisfy the conditions of (24) and (25), the system can exhibit a perfect optical isolation effect, as shown in Figure 3 and Figure 4 .

[0095] In this embodiment, an optical isolation method based on a double - cavity optomechanical system is also provided. Attached Figure 1 (b) is the structural diagram of this scheme, including:

[0096] Step 1: Adjust the intensities and phases of the two driving fields in the system to make the effective optomechanical coupling constants , satisfy ([[]] ) (see equation (24)), and the non - reciprocal angle . Adjust the linear coupling strength between the two double - cavities to make it satisfy with the magnitudes of the dissipation rates of the two cavities, as shown in equation (25).

[0097] Step 2: When the system parameters satisfy the conditions in Step 1, the influence of the magnitude of the dissipation rate of the mechanical oscillator on the unidirectional light - transmission characteristics is numerically simulated in this embodiment. In this embodiment, the dissipation rates of the mechanical oscillator are taken as , , , respectively. The curves of the transmission amplitudes (black dashed line) and (red solid line) versus the relative frequency detuning are shown, with other parameters , as shown in Attached Figure 4(a) - 4(d). It can be clearly seen from the figure that the magnitude of the dissipation rate of the mechanical oscillator has a significant impact on the width and magnitude of the transmission amplitude spectrum. However, regardless of the magnitude of the dissipation rate of the mechanical oscillator , as long as the coupling strength satisfies equations (24) and (25), a perfect optical isolation effect will be achieved at .

[0098] This embodiment also provides a computer device, including: a memory, a processor, and a computer program stored on the memory and executable on the processor, where the processor executes the computer program to implement the steps of the above method.

[0099] This embodiment also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the above method are implemented.

[0100] This embodiment also provides a computer program product, including a computer program, and when the computer program is executed by a processor, the steps of the above method are implemented.

[0101] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An optical isolation device based on a double - cavity optomechanical system, characterized in that, Comprising: A double - cavity optomechanical system, a driving light input unit, and a probe light input unit; The double - cavity optomechanical system includes a left optical cavity, a right optical cavity, and a mechanical oscillator, and the mechanical oscillator is located between the left optical cavity and the right optical cavity; there is an interaction between the left optical cavity and the right optical cavity of the double - cavity optomechanical system through linear coupling; Both the driving light input unit and the probe light input unit are used to input light with a preset amplitude and frequency into the left and right optical cavities respectively.

2. The optical isolation device based on a double - cavity optomechanical system according to claim 1, wherein The expression of the linear coupling strength between the left optical cavity and the right optical cavity is: ； wherein, are the dissipation rates of the left optical cavity and the right optical cavity, respectively.

3. The optical isolation device based on a double - cavity optomechanical system according to claim 1, wherein The expression of the optomechanical coupling coefficient of the double - cavity optomechanical system is: ； In the formula, is the optomechanical coupling coefficient of the th optical cavity interacting with the mechanical oscillator, is the dissipation rate of the th optical cavity, is the dissipation rate of the mechanical oscillator.

4. The optical isolation device based on a double - cavity optomechanical system according to claim 1, wherein The driving light input unit inputs light with a preset amplitude and frequency into the left and right optical cavities to form a driving field, and the frequency detuning of the driving field satisfies the mechanical red - detuning condition.

5. The optical isolation device based on a double - cavity optomechanical system according to claim 4, wherein The phase difference of the driving field is .

6. An optical isolation method based on a double - cavity optomechanical system, characterized in that, Comprising the following steps: Set the dissipation rates of the left optical cavity and the right optical cavity to be respectively , and the dissipation rate of the mechanical oscillator to be , and adjust the linear coupling strength between the left cavity and the right cavity to satisfy ; Input driving light with a preset frequency into the left optical cavity and the right optical cavity, and adjust the driving field phase difference to be , so that the optomechanical coupling coefficient satisfies ; where , are the optomechanical coupling constants of the left and right cavities with the mechanical oscillator respectively; Select the left optical cavity or the right optical cavity to input the probe light with a preset frequency, detect the output field amplitude, and verify whether the forward - transmission amplitude and the backward - transmission amplitude meet the requirements; By adjusting the dissipation rate of the mechanical oscillator to be or the driving field intensity, adapt to different frequency - band requirements.

7. The optical isolation method based on a double - cavity optomechanical system according to claim 6, wherein The dissipation rates of the left optical cavity and the right optical cavity are equal or in a proportional relationship.

8. A computer device, comprising: A memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method according to any one of claims 6 - 7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the method according to any one of claims 6 - 7.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the method according to any one of claims 6 - 7.

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