Method and system for realizing continuous and controllable excitation of spin wave phase based on circularly polarized light pulses

Abstract

The present invention relates to a method and system for achieving continuous and controllable excitation of spin wave phases based on circularly polarized light pulses, wherein the system includes a light source, a spectroscopic unit, and a conversion unit; the spectroscopic unit is arranged in the direction of an initial light beam emitted by the light source, and the spectroscopic unit splits the initial light beam in a linear polarization state into a first spectroscopic beam and a second spectroscopic beam according to the polarization state; the conversion unit is arranged between the spectroscopic unit and a magnetic material, converting the first spectroscopic beam in a linear polarization state into a first excitation beam in a circular polarization state, and converting the second spectroscopic beam in a linear polarization state into a second excitation beam in a circular polarization state; the first excitation beam and the second excitation beam are simultaneously irradiated on the surface of the magnetic material, exciting the magnetic material to generate spin waves; and the settings of the spectroscopic unit and the conversion unit are changed to achieve spin wave phase control. The present invention can achieve continuous and controllable excitation of spin waves with a phase of 0-2π.

Description

Technical Field

[0001] The present invention relates to the field of magnon spin electronics, and in particular to a method and system for realizing continuous and controllable excitation of spin wave phase based on circularly polarized light pulses. Background Art

[0002] In today's era of rapidly growing information, with the continuous improvement of current semiconductor device technology and integration, the energy consumption and heat dissipation problems of devices are becoming increasingly prominent. Quantum effects are directly limiting the further development of traditional semiconductor electronic technology. To address these problems, people have proposed the development of spin electronics technology that utilizes the spin properties of electrons. Magnon spin electronics technology is an important branch of this technology, aiming to achieve information transmission and processing through spin waves rather than traditional charge transport. Spin waves are the collective motion of spins in a specific form in magnetic materials. Using spin waves as information carriers can not only break through quantum barriers in terms of size, but also avoid the generation of Joule heating in terms of heat dissipation. Information can be carried through the frequency, amplitude, phase and other properties of spin waves. Therefore, it is of great significance to develop coherent excitation and control methods for spin waves. Summary of the Invention

[0003] Based on this, the purpose of the present invention is to provide a system for realizing continuous and controllable excitation of the spin wave phase based on circularly polarized light pulses. By changing the circular polarization state and energy density ratio of the first excitation light beam and the second excitation light beam to control the spin precession phase, the spin waves excited by the magnetic material can be continuously controlled in the full phase range of 0-2π, thereby realizing flexible control of the spin wave phase.

[0004] A system for achieving continuous and controllable excitation of spin wave phases based on circularly polarized light pulses comprises a light source, a spectroscopic unit and a conversion unit. The spectroscopic unit is arranged in the direction of an initial light beam emitted by the light source, and splits the initial light beam in a linearly polarized state into a first spectroscopic beam and a second spectroscopic beam according to the polarization state. The conversion unit is arranged between the spectroscopic unit and a magnetic material, and converts the first spectroscopic beam in a linearly polarized state into a first excitation beam in a circularly polarized state, and converts the second spectroscopic beam in a linearly polarized state into a second excitation beam in a circularly polarized state. The first excitation beam and the second excitation beam are simultaneously irradiated on the surface of the magnetic material, exciting the magnetic material to generate spin waves. Spin wave phase control is achieved by changing the settings of the spectroscopic unit and the conversion unit.

[0005] Furthermore, the spectroscopic unit includes an excitation control wave plate and an excitation spectroscopic structure. The excitation control wave plate is a half-wave plate, which is arranged between the light source and the excitation spectroscopic structure. The angle between its optical axis and the polarization direction of the light beam is variable. The angle is changed to change the polarization direction of the initial light beam, thereby changing the energy density ratio of the first spectroscopic light beam and the second spectroscopic light beam after passing through the excitation spectroscopic structure.

[0006] Furthermore, the conversion unit includes a first conversion wave plate and a second conversion wave plate; the first conversion wave plate converts the first split light beam in a linear polarization state into a first excitation light beam in a circular polarization state; the second conversion wave plate converts the second split light beam in a linear polarization state into a second excitation light beam in a circular polarization state; the first conversion wave plate and the second conversion wave plate are both quarter wave plates, and the circular polarization state of the first excitation light beam is adjusted to a left-handed circular polarization state or a right-handed circular polarization state by changing the angle between the optical axis of the first conversion wave plate and the polarization direction of the first split light beam; the circular polarization state of the second excitation light beam is adjusted to a left-handed circular polarization state or a right-handed circular polarization state by changing the angle between the optical axis of the second conversion wave plate and the polarization direction of the second split light beam.

[0007] Furthermore, the spectroscopic unit also includes a detection spectroscopic structure, which is arranged between the light source and the excitation control wave plate, and the detection spectroscopic structure and the excitation spectroscopic structure are both polarization spectroscopes; the initial light beam in the linear polarization state is orthogonally decomposed by the detection spectroscopic structure according to polarization to form a pre-detection beam and a pre-split beam, the pre-detection beam is emitted from the spectroscopic unit and irradiated on the magnetic material to form a magneto-optical effect beam, and the pre-split beam is orthogonally decomposed by the excitation spectroscopic structure according to polarization to form a first split beam and a second split beam.

[0008] Furthermore, the spectroscopic unit also includes a detection spectroscopic structure, which is arranged between the light source and the excitation control wave plate, the detection spectroscopic structure is a polarization spectroscope, and the excitation spectroscopic structure includes a first double prism and a second double prism; the initial light beam in the linear polarization state is decomposed by the detection spectroscopic structure according to polarization orthogonality to form a pre-detection beam and a pre-split beam, the pre-detection beam is emitted from the spectroscopic unit and irradiated on the magnetic material to form a magneto-optical effect beam, the pre-split beam is irradiated on the first double prism, and is transmitted and separated to form a first prism split beam and a second prism split beam with different directions, the first prism split beam is transmitted through the second double prism and collimated to form a first split beam, and the second prism split beam is transmitted through the second double prism and collimated to form a second split beam.

[0009] Furthermore, it also includes a detection unit, which includes a detection and control wave plate, a polarization prism and a differential photodetector. The detection and control wave plate is a half-wave plate, and the angle between its optical axis and the polarization direction of the magneto-optical effect light beam is variable. The angle is changed so that the polarization direction of the magneto-optical effect light beam changes after passing through the detection and control wave plate; the polarization prism polarizes the magneto-optical effect light beam and splits it into two detection light beams; the differential photodetector is provided with two photoelectric probes, which receive the differential output of the two detection light beams and analyze the polarization changes therein.

[0010] Furthermore, it also includes a delay device, which is arranged between the detection spectroscopic structure and the magnetic material. After the pre-detection light beam enters the delay device, it forms a detection light beam with controllable optical path, thereby realizing time-resolved spin wave detection.

[0011] Furthermore, it also includes an adjustable attenuation plate, which is arranged between the first conversion wave plate and the magnetic material.

[0012] The present invention also provides a method for achieving continuous and controllable excitation of spin wave phase based on circularly polarized light pulses, comprising: dividing an initial light beam in a linearly polarized state emitted by a light source into a first split light beam and a second split light beam according to the polarization state, converting the first split light beam in the linearly polarized state into a first excitation light beam in a circularly polarized state, converting the second split light beam in the linearly polarized state into a second excitation light beam in a circularly polarized state, irradiating the first excitation light beam and the second excitation light beam simultaneously onto the surface of a magnetic material to excite the magnetic material to generate spin waves; and changing the circular polarization state and energy density ratio between the second excitation light beam and the first excitation light beam to achieve spin wave phase control.

[0013] Furthermore, the pre-detection beam is delayed to form a detection beam, thereby realizing time-resolved detection; the detection beam is irradiated on the surface of the magnetic material after the controllable delay to form a magneto-optical effect beam, the magneto-optical effect beam is received to detect and analyze the spin wave signal, and the excited spin wave phase is obtained in combination with the time-resolved analysis, and the circular polarization state and energy density ratio between the second excitation beam and the first excitation beam can be changed according to the detection results to realize controllable excitation of the spin wave phase.

[0014] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the relative delay of light pulses in the method for realizing continuous controllable excitation of spin waves based on circularly polarized light pulses of the present invention.

[0016] Figure 2 Schematic diagram of the spin wave control principle in the method for realizing continuous and controllable excitation of spin waves phase based on circularly polarized light pulses of the present invention.

[0017] Figure 3 This is a system structure diagram of the first embodiment of the present invention's system for realizing continuous and controllable spin wave phase excitation based on circularly polarized light pulses.

[0018] Figure 4 This is a system structure diagram of the second embodiment of the present invention's system for realizing continuous and controllable spin wave phase excitation based on circularly polarized light pulses. DETAILED DESCRIPTION

[0019] In the past, optical methods could also be used to control the phase change of spin waves (or magnetization precession), but the actual effect was not good and the control range was small. This is because in previous studies on optically excited spin waves in ordinary ferromagnetic films, although the previous technology could control the phase of the spin wave by changing the circular polarization state of a single excitation light pulse, the circularly polarized light pulse was either left-handed or right-handed circularly polarized. Therefore, the phase of the spin wave was only of two types, 0 or π, which depended on the circular polarization state type of the only excitation light pulse, and it was impossible to continuously control the phase of the spin wave. To this end, a method for continuously controlling the spin wave phase using two circularly polarized light pulses is proposed. Please refer to Figure 1 Specifically, a linearly polarized initial light pulse emitted by a light source is split into a first excitation light pulse and a second excitation light pulse with an adjustable energy density ratio, as well as a detection light pulse, wherein t is the time delay between the first excitation light pulse and the detection light pulse, there is no time delay between the first excitation light pulse and the second excitation light pulse, and the first excitation light pulse, the second excitation light pulse and the detection light pulse are all ultrashort laser pulses. The first excitation light pulse and the second excitation light pulse simultaneously arrive at the surface of the magnetic material to induce an inverse Faraday giant magnetic pulse to generate spin waves. The detection light pulse arrives at the surface of the magnetic material after a controllable delay and extracts information containing the spin wave phase. The detection light pulse is received by a detection unit to clearly obtain the spin wave information; by changing the circular polarization state and energy density ratio between the second excitation light pulse and the first excitation light pulse, continuous controllable excitation of the phase from 0 to 2π is achieved.

[0020] Specifically, see Figure 2 , Figure 2 The change of magnetization vector M under transient excitation is shown in detail. In the static state, the magnetization vector M in the magnetic material always moves in one direction, which is the initial effective magnetic field H composed of the vector superposition of the anisotropic field inside the material, the demagnetization field and the external applied magnetic field. ekff Determine the direction of the magnetization vector M inside the material and the initial effective magnetic field H eff Stay consistent in direction.

[0021] Taking the case of in-plane magnetization as an example, the direction of the equilibrium magnetization M falls in the xz plane, while the first excitation light pulse and the second excitation light pulse are in the yz plane. Preferably, the incident plane of the first excitation light pulse and the second excitation light pulse is perpendicular to the plane of the effective field.

[0022] The first excitation light pulse and the second excitation light pulse are incident on the magnetic material at the same time, but with different fixed incident angles, for example, the first excitation light pulse is incident from the left, and the second excitation light pulse is incident from the right. They each induce an inverse Faraday giant magnetic pulse H IFE1 and H IFE2 , H IFE1and H IFE2 The direction of the light pulse is determined by the incident angle θ H1 and θ H2 Determine. Then the inverse Faraday giant magnetic pulse H synthesized by the two IFE The angle with the normal is:

[0023] θ H =arctan[H IEF2 sinθ H2 / (H IEF2 cosθ H2 +H IEF1 )]

[0024] Among them H IEF1 and H IEF2 can be positive or negative, depending on the direction of circular polarization, so θ H The value range is 0-360°.

[0025] In the present invention, the inverse Faraday giant magnetic pulse H is generated by the first excitation light pulse and the second excitation light pulse. IFE The magnetization of the magnetic material will be locally disturbed, resulting in the initial effective magnetic field H eff The direction deviates to the new effective magnetic field H ′ eff The magnetization vector M of the magnetic material will be affected by the new effective magnetic field H ′ eff The torque deviates from the original direction. The initial effective magnetic field H eff Deviated direction H ′ eff The direction of the inverse Faraday giant magnetic pulse H IFE direction, subjected to the inverse Faraday giant magnetic pulse H IFE After the influence of the system is in a non-equilibrium state, the magnetization vector M will revolve around the new effective magnetic field H ′ eff Continue to precess until M and H eff Parallel, during which the magnetization (spin) precession will exist and propagate in the form of spin waves. Therefore, the new effective magnetic field H in different directions ′ eff The torque on the magnetization in different directions will determine the initial phase of the spin wave, so the inverse Faraday giant magnetic pulse H induced by the first excitation light pulse and the second excitation light pulse IFE Angle θ H It can determine the phase of the excited spin wave.

[0026] It can be seen that by changing H IEF1 and H IEf2 The intensity ratio and direction between them can continuously control θ H , and then control H′ eff The angle of θ generates torques in different directions on M, thereby controlling the phase of the spin wave, that is, the phase of the excited spin wave is related to θ H When θ H The initial phase of the spin wave varies in the range of 0-360°, and is controllable in the range of 0-2π. This indicates that the spin wave phase can be continuously controlled by adjusting the different circular polarization states and energy density ratios of the first excitation light pulse and the second excitation light pulse.

[0027] Based on the above-mentioned inventive concept, the present invention provides a system for achieving continuous and controllable excitation of spin wave phases based on circularly polarized light pulses, comprising a light source, a spectrometer, a delay device, a conversion unit, and a detection unit. The spectrometer is arranged in the direction of the initial light beam emitted by the light source and divides the initial light beam into a pre-detection beam, a first spectrometer beam, and a second spectrometer beam. The delay device converts the pre-detection beam into a detection beam. The conversion unit converts the first spectrometer beam into a first excitation beam and the second spectrometer beam into a second excitation beam. The first excitation beam and the second excitation beam are irradiated on the surface of a magnetic material to excite the magnetic material to generate spin waves. The circular polarization state and energy density ratio between the first excitation beam and the second excitation beam are changed to achieve spin wave phase control. The pre-detection beam is delayed by the delay device to form a detection beam, thereby achieving time-resolved detection. After passing through a delay device, the probe beam is controllably delayed and illuminated on the surface of the magnetic material, where it is reflected to form a magneto-optical effect beam. The detection unit receives the magneto-optical effect beam, detects and analyzes the spin wave signal, and combines this with the time-resolved analysis of the delay device to determine the excited spin wave phase. The configurations of the spectrometer and conversion unit can be modified based on the detection results to achieve spin wave phase control. Because the present invention's system for achieving continuous and controllable spin wave phase excitation using circularly polarized light pulses is subject to significant structural deformation, the specific structure and implementation principles of the present invention are described below through two exemplary embodiments.

[0028] Example 1

[0029] See also Figure 3 , this embodiment 1 provides a system for realizing continuous and controllable excitation of spin wave phase based on circularly polarized light pulses, including a light source 10, a detection control wave plate 21, an excitation control wave plate 22, a detection control wave plate 23, a detection spectrometer structure 31, an excitation spectrometer structure 32, a first reflector 41, a second reflector 42, a third reflector 43, a fourth reflector 44, a fifth reflector 45, a sixth reflector 46, a seventh reflector 47, a delay device 50, a spectrometer 60, a first conversion wave plate 71, a second conversion wave plate 72, a detection focusing lens 83, a first focusing lens 81, a second focusing lens 82, a polarization prism 100 and a differential photodetector 110.

[0030] The light source 10 is a laser light source, and the initial light beam emitted by it is an ultrashort pulse laser sequence of linearly polarized light. In particular, in the present application, each light beam is a laser beam composed of an ultrashort pulse sequence. It will be understood by those skilled in the art that the light beam described in the present application refers only to the laser beam composed of an ultrashort pulse sequence that acts in the system of the present application for realizing continuous and controllable excitation of spin wave phase based on circularly polarized light pulses; the present application adopts a pulse sequence laser in order to simultaneously realize ultrafast time-resolved detection, and pulse lasers that exist in a non-sequential manner can also be applied to the system of the present application.

[0031] The detection spectrometer structure 31, the excitation spectrometer structure 32, the detection control wave plate 21, and the excitation control wave plate 22 constitute a spectrometer unit of a system for realizing continuous controllable excitation of a spin wave phase based on a circularly polarized light pulse according to the present invention. The detection spectrometer structure 31 is arranged in the direction of the initial light beam emitted by the light source 10, the detection control wave plate 21 is arranged between the detection spectrometer structure 31 and the light source 10, and the excitation control wave plate 22 is arranged between the detection spectrometer structure 31 and the excitation spectrometer structure 32, wherein the detection control wave plate 21 and the excitation control wave plate 22 are both half-wave plates, and the detection spectrometer structure 31 and the excitation spectrometer structure 32 are both polarization spectroscopes. The linearly polarized initial light beam from the light source 10 passes through the detection control wave plate 21 and enters the detection spectrometer structure 31. The detection spectrometer structure 31 decomposes the initial light beam orthogonally according to polarization. A portion of the linearly polarized light beam is reflected to form a pre-detection light beam, while another portion of the linearly polarized light beam is transmitted to form a pre-split light beam. The pre-detection light beam exits the spectrometer unit. The pre-split light beam passes through the excitation control wave plate 22 and enters the excitation spectrometer structure 32. The pre-split light beam decomposes the initial light beam orthogonally according to polarization after passing through the excitation spectrometer structure 32. A portion of the linearly polarized light beam is reflected to form a first split light beam, while another portion of the linearly polarized light beam is transmitted to form a second split light beam. The detection control wave plate 21 can be rotated to change the angle between its optical axis and the polarization direction of the initial light beam. The polarization direction of the initial light beam can be set by rotating the detection control wave plate so that it changes the energy density ratio of the pre-detection light beam and the pre-split light beam after passing through the detection spectrometer structure 31. The excitation control wave plate 22 can be rotated to change the angle between its optical axis and the polarization direction of the light beam. The polarization direction of the pre-split light beam can be set by rotating the excitation control wave plate 22, so that the energy density ratio of the first split light beam and the second split light beam is changed after the pre-split light beam passes through the excitation light-splitting structure 32. It will be understood that by changing the angle of the excitation control wave plate 22, the polarization direction of the pre-split light beam after passing through the excitation control wave plate 22 can be changed, and thus the energy density of the two separated light beams when passing through the excitation light-splitting structure 32 will also change.

[0032] The first reflector 41 is positioned in the direction of the pre-probe beam and reflects the pre-probe beam into the delay device 50. The delay device 50 includes a moving mechanism and a reflecting mechanism. The reflecting mechanism is mounted on the moving mechanism and can be moved by the moving mechanism. The pre-probe beam is incident on the reflecting mechanism in the delay device 50 and reflected to form a probe beam. The moving mechanism can be used to change the optical path of the pre-probe beam, thereby controlling the time it takes for it to reach the magnetic material.

[0033] In particular, the reflective mechanism in the delay device 50 can use two 90° tilted reflectors or corner reflectors to reflect the delayed light beam parallel to the direction opposite to the original light path. Alternatively, it can be directly implemented using a reflector and a beam splitter perpendicular to the original light path. The specific configuration can be adjusted according to actual needs, as long as it can reflect the delayed light beam in the direction opposite to the original light path. It will be understood by those skilled in the art that the purpose of the delay device 50 is to make the arrival time of the detection light beam controllable, and it is not limited to extending the arrival time of the detection light beam.

[0034] The beam splitter 60 is disposed between the magnetic material 90 and the delay device 50 and has the structure of an ordinary beam splitter, configured to transmit the probe beam entering from the back and reflect the magneto-optical effect beam entering from the front. Those skilled in the art will appreciate that the core function of the beam splitter 60 is to change the propagation direction of the magneto-optical effect beam, and that the use of the beam splitter 60 is not limited to the use of the beam splitter 60. Its core function can actually be replaced by an ordinary reflector. However, compared to an ordinary reflector, the beam splitter 60 can be disposed in the optical path of the mixed beam without worrying about obstruction, thereby saving some space.

[0035] The first conversion wave plate 71 and the second conversion wave plate 72 constitute a conversion unit of the present invention for realizing a spin wave phase continuous controllable excitation system based on circularly polarized light pulses. The first conversion wave plate 71 is arranged in the emission direction of the first split light beam and converts the linearly polarized first split light beam into a circularly polarized first excitation light beam. The first excitation light beam is reflected by the third reflector 43 and the fourth reflector 44 and then irradiates the magnetic material. The second conversion wave plate 72 is arranged in the emission direction of the second split light beam and converts the linearly polarized second split light beam into a circularly polarized second excitation light beam. The second excitation light beam is reflected by the sixth reflector 46 and the seventh reflector 47 and then irradiates the magnetic material. The first conversion wave plate 71 and the second conversion wave plate 72 are quarter-wave plates, which can convert linearly polarized light into circularly polarized light. By changing the angle between the optical axis of the first conversion wave plate 71 and the polarization direction of the first split light beam, the circular polarization state of the first excitation light beam can be adjusted to a left-handed circular polarization state or a right-handed circular polarization state; by changing the angle between the optical axis of the second conversion wave plate 72 and the polarization direction of the second split light beam, the circular polarization state of the second excitation light beam can be adjusted to a left-handed circular polarization state or a right-handed circular polarization state; by adjusting the different polarization states of the first excitation light beam and the second excitation light beam, the phase of the generated spin wave can be changed.

[0036] The first focusing lens 81 is disposed between the first conversion wave plate 71 and the magnetic material 90 to focus the first excitation beam; the second focusing lens 82 is disposed between the second conversion wave plate 72 and the magnetic material 90 to focus the second excitation beam; the detection focusing lens 83 is disposed between the delay device 50 and the magnetic material 90 to focus the detection beam and the magneto-optical effect beam reflected from the surface of the magnetic material 90, thereby reducing energy loss caused by light escaping and improving the energy utilization of the system. The incident angles of the first and second excitation beams relative to the surface of the magnetic material are not limited.

[0037] The magnetic material 90 is an ordered magnetic material. The inverse Faraday effect generated by the circularly polarized laser pulse can change not only the magnitude of the magnetization but also its direction. This is primarily because the circularly polarized light pulse incident on the magnetic material induces an inverse Faraday giant magnetic pulse. The laser pulse irradiating the surface of the magnetic material 90 induces the inverse Faraday giant magnetic pulse to excite and generate spin waves. After the probe beam is irradiated on the surface of the magnetic material 90, the magneto-optical effect beam formed by the magneto-optical effect contains spin wave information. The time-resolved spin wave information in the magneto-optical effect beam can be detected by combining a delay device detection unit.

[0038] The detection and control wave plate 23, the polarization prism 100 and the differential photodetector 110 constitute the detection unit of the present invention's method for realizing a spin wave phase continuous controllable excitation system based on circularly polarized light pulses, which is used to detect the polarization state change of the magneto-optical effect light beam. The detection and control wave plate 23 is a half-wave plate that can be rotated to change the angle between its polarization direction and the optical axis. Changing the angle of the detection and control wave plate 23 can change the polarization state of the magneto-optical effect light beam; the polarization prism 100 is used to separate the magneto-optical effect light beam and decompose it into two detection beams of orthogonal polarization components; the detection beam is received by the differential photodetector 110, thereby realizing accurate detection of extremely small polarization state changes of the detection beam. Preferably, the detection and control wave plate 23 is adjusted in the initial state without an excitation beam so that the detection beam passes through the polarization prism 100 and is decomposed into two detection beams of equal light intensity. In the subsequent process, the light intensity of the two detection beams changes with the change of the spin wave.

[0039] In one embodiment, the detection beam is not reflected after being irradiated on the magnetic material 90, but is transmitted through the magnetic material 90 to form a magneto-optical effect beam. At this time, there is no need to add a reflection device to change the direction of the magneto-optical effect beam so that the detection unit can receive it. The detection unit can be directly set behind the magnetic material 90 in the direction of the detection beam to receive the magneto-optical effect beam.

[0040] The operating principle of a system for realizing continuous controllable excitation of spin wave phase based on circularly polarized light pulses in this embodiment 1 will be described below from the perspective of a complete light beam change path.

[0041] The light source 10 starts working and emits an initial light beam outward; the initial light beam is irradiated on the detection control wave plate 21, and after being transmitted, it is irradiated on the detection spectroscopic structure 31, and is reflected to form a pre-detection light beam. The pre-detection light beam is reflected by the first reflector 41 and enters the delay device 50 to form a detection light beam; the initial light beam is irradiated on the detection spectroscopic structure 31, and is transmitted to form a pre-split light beam; the pre-split light beam passes through the excitation control wave plate 22 and irradiates the excitation spectroscopic structure 32, and is reflected to form a first split light beam. The first split light beam passes through the first reflector 41 and enters the delay device 50 to form a detection light beam. A first excitation beam is formed after a conversion wave plate 71. The first excitation beam is reflected by the third reflector 43 and the fourth reflector 44, and is focused by the first focusing lens 81 to the surface of the magnetic material 90; the pre-split beam passes through the excitation control wave plate 22 and transmits the excitation splitting structure 32 to form a second split beam, which is reflected by the fifth reflector 45 and converted by the second conversion wave plate 72 to form a second excitation beam. The second excitation beam is reflected by the sixth reflector 46 and the seventh reflector 47, and is focused by the second focusing lens 82 to the surface of the magnetic material 90.

[0042] After being reflected back along the same direction of the pre-detection beam by the second reflector 42, the detection beam is irradiated on the back of the spectrometer 60 and transmitted through the spectrometer 60, and then focuses on the surface of the magnetic material 90 after passing through the detection focusing lens 83, and is emitted on the surface of the magnetic material 90 to form a magneto-optical effect beam; the magneto-optical effect beam propagates in the opposite direction of the detection beam, irradiates the front of the spectrometer 60 and is reflected, and after transmitting the detection control wave plate 23, it is divided into two light detection beams by the polarizing prism 100, and the two detection beams respectively enter the two probes of the differential photodetector 110.

[0043] In particular, those skilled in the art should understand that the “first” and “second” mentioned in this application are intended to distinguish between two components with similar structures and functions, rather than to specifically limit them to “first” or “second”. There is no distinction in time or order under this statement, and “first” and “second” are completely interchangeable, as long as the names of the other corresponding components are distinguished and correctly interchanged. Similarly, the “front” and “back” mentioned in this application are intended to distinguish between two sides of a component with the same structure, rather than to specifically limit them to “front” or “back”. There is no distinction in features under this statement, and “front” and “back” are completely interchangeable, as long as the names of the other corresponding surfaces are distinguished and correctly interchanged.

[0044] Example 2

[0045] See also Figure 4 , this embodiment 2 provides a system for realizing continuous and controllable excitation of the spin wave phase based on circularly polarized light pulses, including a light source 10, a detection control wave plate 21, an excitation control wave plate 22, a detection spectrometer structure 31, an excitation spectrometer structure 32, a second reflector 42, an eighth reflector 48, a ninth reflector 49, a delay device 50, an adjustable attenuation plate A, a spectrometer 60, a first conversion wave plate 71, a second conversion wave plate 72, a focusing lens 80, a polarization prism 100 and a differential photodetector 110.

[0046] The structure differs from that in Example 1 in that the excitation spectrometer structure 32 in Example 2 is not composed of a single spectroscope, but rather a first double prism 321 and a second double prism 322. The detection beam, the first excitation beam, and the second excitation beam are collectively focused on the surface of the magnetic material 90 via a large focusing lens 80. An adjustable attenuation plate A is also provided between the second conversion wave plate 72 and the focusing lens 80. The adjustable attenuation plate A can be rotated to change the energy density of the second excitation beam after it passes through, thereby achieving an adjustable energy density ratio between the first and second excitation beams. The number and position of the reflectors can be adaptively adjusted. The remaining component structures are the same as those in Example 2 and will not be repeated here.

[0047] The operating principle of a system for realizing continuous controllable excitation of spin wave phase based on circularly polarized light pulses in this embodiment 2 will be described below from the perspective of a complete light beam change path.

[0048] The light source 10 starts working and emits an initial light beam outward; the initial light beam is irradiated on the detection and control wave plate 21, and after being transmitted, it is irradiated on the detection spectroscopic structure 31. After being transmitted, it forms a pre-detection light beam and then enters the delay device 50 to form a detection light beam; the initial light beam is irradiated on the detection spectroscopic structure 31, and is reflected to form a pre-split light beam; the pre-split light beam passes through the excitation and control wave plate 22 and is irradiated on the first double prism 321, and is transmitted and separated to form a first prism split light beam and a second prism split light beam with different directions. The first prism split light beam and the second prism split light beam are transmitted through the second double prism 322 and collimated into a first split light beam and a second split light beam with parallel directions; the first split light beam passes through the first conversion wave plate 71 to form a first excitation light beam, and the first excitation light beam is focused by the focusing lens 80 to the surface of the magnetic material 90; the second split light beam is converted by the second conversion wave plate 72 to form a second excitation light beam, and the second excitation light beam is focused by the focusing lens 80 to the surface of the magnetic material 90 after passing through the adjustable attenuation plate A.

[0049] The detection light beam is reflected back along the vertical direction of the pre-detection light beam by the second reflector 42, the eighth reflector 48 and the ninth reflector 49, and then irradiates the back of the spectrometer 60 and transmits the spectrometer 60, and then passes through the focusing lens 80 and focuses on the surface of the magnetic material 90, and is emitted on the surface of the magnetic material 90 to form a magneto-optical effect light beam; the magneto-optical effect light beam propagates in the opposite direction of the detection light beam, irradiates the front of the spectrometer 60 and is reflected, and after passing through the detection control wave plate 23, it is divided into two detection light beams with equal light intensity through the polarizing prism 100 in the initial state without an excitation light beam, and the two detection light beams respectively enter the two probes of the differential photodetector 110.

[0050] It is foreseeable that the present invention's method for achieving continuous, controllable excitation of spin wave phases based on circularly polarized light pulses can achieve functions similar to those of a phase shifter and can be combined with time-resolved detection of spin waves. Furthermore, the circular polarization state and energy density ratio between the second excitation beam and the first excitation beam can be changed based on the detection results and actual needs to achieve spin wave phase control, achieving precise and continuous control of the spin wave phase and fixing it at the desired state. For situations where continuous spin wave phase control is not required but a fixed spin wave phase is required, selective presetting of the spin wave phase can be achieved under a fixed circular polarization state and energy density ratio. This method of fixing the circular polarization state and energy density ratio can simplify system design and operation, providing stable and reliable phase control in applications. Specifically, the circular polarization state of the first excitation beam and the second excitation beam can be preset through a conversion unit; the energy density ratio of the first excitation beam and the second excitation beam can be preset by changing the spectrometer unit, thereby controlling the phase of the excited spin wave and achieving the function of spin wave phase setting, thereby meeting the needs of various specific applications.

[0051] The above-described embodiments merely represent several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous modifications and improvements without departing from the spirit of the present invention, and the present invention is intended to encompass such modifications and variations.

Claims

1. A system for achieving continuous and controllable phase excitation of spin waves based on circularly polarized light pulses, characterized by: The invention comprises a light source, a spectroscopic unit and a conversion unit; the spectroscopic unit is arranged in the direction of the initial light beam emitted by the light source, and the spectroscopic unit splits the initial light beam in a linear polarization state into a first spectroscopic beam and a second spectroscopic beam according to the polarization state; the conversion unit is arranged between the spectroscopic unit and the magnetic material, and converts the first spectroscopic beam in a linear polarization state into a first excitation beam in a circular polarization state, and converts the second spectroscopic beam in a linear polarization state into a second excitation beam in a circular polarization state; the first excitation beam and the second excitation beam are simultaneously irradiated on the surface of the magnetic material, exciting the magnetic material to generate spin waves; and the settings of the spectroscopic unit and the conversion unit are changed to realize spin wave phase control.

2. The system for realizing continuous and controllable phase excitation of spin waves based on circularly polarized light pulses according to claim 1, characterized in that: The spectroscopic unit includes an excitation control wave plate and an excitation spectroscopic structure. The excitation control wave plate is a half-wave plate, which is arranged between the light source and the excitation spectroscopic structure. The angle between its optical axis and the polarization direction of the light beam is variable. The angle is changed to change the polarization direction of the initial light beam, thereby changing the energy density ratio of the first spectroscopic light beam and the second spectroscopic light beam after passing through the excitation spectroscopic structure.

3. The system for realizing continuous and controllable phase excitation of spin waves based on circularly polarized light pulses according to claim 2, characterized in that: The conversion unit includes a first conversion wave plate and a second conversion wave plate; the first conversion wave plate converts the first split light beam in a linear polarization state into a first excitation light beam in a circular polarization state; the second conversion wave plate converts the second split light beam in a linear polarization state into a second excitation light beam in a circular polarization state; the first conversion wave plate and the second conversion wave plate are both quarter wave plates, and the circular polarization state of the first excitation light beam is adjusted to a left-handed circular polarization state or a right-handed circular polarization state by changing the angle between the optical axis of the first conversion wave plate and the polarization direction of the first split light beam; the circular polarization state of the second excitation light beam is adjusted to a left-handed circular polarization state or a right-handed circular polarization state by changing the angle between the optical axis of the second conversion wave plate and the polarization direction of the second split light beam.

4. The system for realizing continuous and controllable phase excitation of spin waves based on circularly polarized light pulses according to claim 3, characterized in that: The spectroscopic unit also includes a detection spectroscopic structure, which is arranged between the light source and the excitation control wave plate. The detection spectroscopic structure and the excitation spectroscopic structure are both polarization spectroscopes; the initial light beam in the linear polarization state is orthogonally decomposed by the detection spectroscopic structure according to polarization to form a pre-detection beam and a pre-split beam. The pre-detection beam is emitted from the spectroscopic unit and irradiated on the magnetic material to form a magneto-optical effect beam. The pre-split beam is orthogonally decomposed by the excitation spectroscopic structure according to polarization to form a first split beam and a second split beam.

5. The system for realizing continuous and controllable phase excitation of spin waves based on circularly polarized light pulses according to claim 3, characterized in that: The spectroscopic unit also includes a detection spectroscopic structure, which is arranged between the light source and the excitation control wave plate. The detection spectroscopic structure is a polarization spectroscope, and the excitation spectroscopic structure includes a first double prism and a second double prism. The initial light beam in the linear polarization state is decomposed by the detection spectroscopic structure according to polarization orthogonality to form a pre-detection beam and a pre-split beam. The pre-detection beam is emitted from the spectroscopic unit and irradiated on the magnetic material to form a magneto-optical effect beam. The pre-split beam is irradiated on the first double prism and is transmitted and separated to form a first prism split beam and a second prism split beam with different directions. The first prism split beam is transmitted through the second double prism and collimated to form a first split beam. The second prism split beam is transmitted through the second double prism and collimated to form a second split beam.

6. The system for realizing continuous and controllable phase excitation of spin waves based on circularly polarized light pulses according to claim 4 or 5, characterized in that: It also includes a detection unit, which includes a detection and control wave plate, a polarization prism and a differential photodetector. The detection and control wave plate is a half-wave plate, and the angle between its optical axis and the polarization direction of the magneto-optical effect light beam is variable. The angle is changed so that the polarization direction of the magneto-optical effect light beam changes after passing through the detection and control wave plate; the polarization prism polarizes the magneto-optical effect light beam to form two detection light beams; the differential photodetector is provided with two photoelectric probes, which receive the differential output of the two detection light beams and analyze the polarization changes therein.

7. The system for realizing continuous and controllable phase excitation of spin waves based on circularly polarized light pulses according to claim 6, characterized in that: It also includes a delay device, which is arranged between the detection spectroscopic structure and the magnetic material. After the pre-detection light beam enters the delay device, it forms a detection light beam with controllable optical path, realizing time-resolved spin wave detection.

8. The system for realizing continuous and controllable phase excitation of spin waves based on circularly polarized light pulses according to claim 6, characterized in that: The invention also includes an adjustable attenuation plate, which is arranged between the first conversion wave plate and the magnetic material.

9. A method for realizing continuous and controllable excitation of spin wave phase based on circularly polarized light pulses, characterized in that: include: An initial light beam in a linear polarization state emitted by a light source is split into a first split light beam and a second split light beam according to the polarization state, the first split light beam in the linear polarization state is converted into a first excitation light beam in a circular polarization state, and the second split light beam in the linear polarization state is converted into a second excitation light beam in a circular polarization state. The first excitation light beam and the second excitation light beam are simultaneously irradiated on the surface of a magnetic material to excite the magnetic material to generate spin waves; and the circular polarization state and energy density ratio between the second excitation light beam and the first excitation light beam are changed to achieve spin wave phase control.

10. The method for realizing continuous phase controllable excitation of spin waves based on circularly polarized light pulses according to claim 9, characterized in that: The pre-detection beam is delayed to form a detection beam, thereby realizing time-resolved detection. The detection beam is irradiated on the surface of a magnetic material after the controllable delay to form a magneto-optical effect beam. The magneto-optical effect beam is received to detect and analyze the spin wave signal, and the excited spin wave phase is obtained in combination with the time-resolved analysis. The circular polarization state and energy density ratio between the second excitation beam and the first excitation beam are further changed according to the detection results to realize controllable excitation of the spin wave phase.

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