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

Abstract

The invention relates to a method and a system for realizing spin wave phase continuous controllable excitation based on circularly polarized light pulses. The system comprises a light source, a light splitting unit and a conversion unit, the light splitting unit is arranged in the direction of an initial light beam emitted by the light source and divides the initial light beam in the linear polarization state into a first light splitting light beam and a second light splitting light beam according to the polarization state; the conversion unit is arranged between the light splitting unit and the magnetic material and is used for converting the first light splitting light beam in the linear polarization state into a first excitation light beam in the circular polarization state and converting the second light splitting light beam in the linear polarization state into a second excitation light beam in the circular polarization state; the first excitation light beam and the second excitation light beam simultaneously irradiate the surface of the magnetic material to excite the magnetic material to generate spin waves; spinning wave phase control is realized by changing the arrangement of the light splitting unit and the conversion unit. By adopting the device and the method, continuous controllable excitation of the phase 0-2pi of the spin wave can be realized.

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 new era of rapid development of information, with the continuous improvement of current semiconductor device technology and integration, the energy consumption and heat dissipation problems of devices have become increasingly prominent, and quantum effects have directly restricted the further development of traditional semiconductor electronic technology. In order to solve these problems, people have proposed to develop spin electronics technology that utilizes the spin properties of electrons. Magnon spin electronics technology is one of the important branches, which aims to realize the transmission and processing of information by spin waves rather than traditional charge transport. Spin waves are the collective motion of spins in a certain 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 heat in terms of heat dissipation. Information can be carried through the frequency, amplitude, phase and other properties of spin waves, so it is of great significance to develop coherent excitation and control methods of 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 spin wave phase based on circularly polarized light pulses. By changing the circular polarization state of the first excitation light beam and the second excitation light beam and the energy density ratio 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 realizing continuous and controllable excitation of spin wave phase 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 the spectroscopic unit divides the initial light beam in a linear polarization state into a first spectroscopic light beam and a second spectroscopic light beam according to the polarization state; the conversion unit is arranged between the spectroscopic unit and a magnetic material, and converts the first spectroscopic light beam in a linear polarization state into a first excitation light beam in a circular polarization state, and converts the second spectroscopic light beam in a linear polarization state into a second excitation light beam in a circular polarization state; the first excitation light beam and the second excitation light beam are irradiated on the surface of the magnetic material at the same time, and the magnetic material is excited to generate spin waves; the spin wave phase is controlled 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 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 irradiated on the first double prism, 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 control wave plate, a polarization prism and a differential photodetector. The detection 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 control wave plate; the polarization prism forms two detection light beams after polarization splitting of the magneto-optical effect light beam; 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 realizing continuous and controllable excitation of spin wave phase based on circularly polarized light pulses, comprising: dividing an initial light beam in a linear polarization 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 a linear polarization state into a first excitation light beam in a circular polarization state, converting the second split light beam in a linear polarization state into a second excitation light beam in a circular polarization state, irradiating the first excitation light beam and the second excitation light beam on the surface of a magnetic material at the same time to excite the magnetic material to generate spin waves; changing the circular polarization state and energy density ratio between the second excitation light beam and the first excitation light beam to realize spin wave phase control.

[0013] Furthermore, the pre-detection beam is delayed to form a detection beam to achieve time-resolved detection; the detection beam is irradiated on the surface of the magnetic material after 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 result to achieve 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 It is a schematic diagram of the relative delay of light pulses in the method for realizing continuous controllable excitation of spin wave phase based on circularly polarized light pulses of the present invention.

[0016] Figure 2 It is a 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 system for realizing continuous and controllable excitation of spin wave phase based on circularly polarized light pulses of the present invention.

[0018] Figure 4 This is a system structure diagram of a second embodiment of the system for realizing continuous and controllable excitation of spin wave phase based on circularly polarized light pulses of the present invention. 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 the past research 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 type of circular polarization state of the only excitation light pulse, and the phase of the spin wave could not be continuously controlled and excited. To this end, a method for continuously controlling the phase of the spin wave 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, and 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 the inverse Faraday giant magnetic pulse to generate spin waves, and the detection light pulse arrives at the surface of the magnetic material after a controllable delay to extract the information containing the spin wave phase, and the detection unit receives the detection light pulse 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, the phase continuous controllable excitation 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 anisotropic field inside the material, the demagnetization field and the externally applied magnetic field through vector superposition. ekff Determines 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 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 obliquely 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 respective circular polarization handedness, so θ H The value range is 0-360°.

[0025] In the present invention, the inverse Faraday giant magnetic pulse H induced 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 direction, 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, the system is in a non-equilibrium state, and 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 The 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 produces 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 inventive concept, the present invention provides a system for realizing continuous and controllable excitation of spin wave phase based on circularly polarized light pulses, including a light source, a spectroscopic unit, a delay device, a conversion unit and a detection unit, wherein the spectroscopic unit is arranged in the direction of the initial light beam emitted by the light source, and the initial light beam is divided into a pre-detection light beam, a first spectroscopic light beam and a second spectroscopic light beam, the delay device converts the pre-detection light beam into a detection light beam, the conversion unit converts the first spectroscopic light beam into a first excitation light beam, and converts the second spectroscopic light beam into a second excitation light beam, the first excitation light beam and the second excitation light 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 light beam and the second excitation light beam are changed to realize spin wave phase control. The pre-detection light beam is delayed by the delay device to form a detection light beam, so as to realize time-resolved detection. After the detection beam passes through the delay device, it is controlled to irradiate the surface of the magnetic material with a time delay, and is reflected to form a magneto-optical effect beam. The detection unit receives the magneto-optical effect beam to detect and analyze the spin wave signal, and combines the time resolution analysis of the delay device to obtain the excited spin wave phase. Further, the settings of the spectroscopic unit and the conversion unit can be changed according to the detection result to realize spin wave phase control. Since there are many possibilities of structural deformation in the system of the present invention that realizes continuous and controllable excitation of spin wave phase based on circularly polarized light pulses, the specific structure and implementation principle of the present invention are described below through two embodiments.

[0028] Example 1

[0029] See also Figure 3 , a system for realizing continuous and controllable excitation of spin wave phase based on circularly polarized light pulses provided in this embodiment 1 includes a light source 10, a detection control wave plate 21, an excitation control wave plate 22, a detection control wave plate 23, a detection spectroscopic structure 31, an excitation spectroscopic 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 spectroscope 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 light beam composed of an ultrashort pulse sequence. It can be understood by those skilled in the art that the light beam described in the present application only refers to the laser light beam composed of an ultrashort pulse sequence that acts in the system of the present application for realizing continuous and controllable excitation of the 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 spectroscopic structure 31, the excitation spectroscopic structure 32, the detection control wave plate 21 and the excitation control wave plate 22 constitute a spectroscopic unit of a spin wave phase continuous controllable excitation system based on circularly polarized light pulses of the present invention. The detection spectroscopic 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 spectroscopic structure 31 and the light source 10, and the excitation control wave plate 22 is arranged between the detection spectroscopic structure 31 and the excitation spectroscopic structure 32, wherein the detection control wave plate 21 and the excitation control wave plate 22 are both half wave plates, and the detection spectroscopic structure 31 and the excitation spectroscopic structure 32 are both polarization spectroscopes. The initial light beam of linear polarization state from the light source 10 enters the detection spectroscopic structure 31 after passing through the detection control wave plate 21. The initial light beam is orthogonally decomposed according to polarization through the detection spectroscopic structure 31. A part of the light beam of linear polarization state will be reflected to form a pre-detection light beam, while another part of the light beam of linear polarization state will be transmitted to form a pre-split light beam. The pre-detection light beam exits the spectroscopic unit; the pre-split light beam enters the excitation spectroscopic structure 32 after passing through the excitation control wave plate 22. The pre-split light beam passes through the excitation spectroscopic structure 32 to decompose the initial light beam orthogonally according to polarization. A part of the light beam of linear polarization state will be reflected to form a first split light beam, while another part of the light beam of linear polarization state will be transmitted to form a second split light beam. Among them, 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 spectroscopic 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 can be changed after passing through the excitation light splitting structure 32. It can 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, so that 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 arranged in the direction of the pre-detection beam, and reflects the pre-detection beam to the delay device 50. The delay device 50 includes a moving mechanism and a reflecting mechanism. The reflecting mechanism is arranged on the moving mechanism and can be driven to move by the moving mechanism. The pre-detection beam is incident on the reflecting mechanism in the delay device 50, and forms a detection beam after reflection. The optical path of the pre-detection beam can be changed by the moving mechanism, so as to control the time when it reaches the magnetic material.

[0033] In particular, the reflection mechanism in the delay device 50 can use two 90° inclined reflectors or corner reflectors to reflect the delayed light beam parallel to the direction opposite to the original light path, or directly use a reflector and a beam splitter prism perpendicular to the original light path. The specific setting can be adjusted according to actual needs, and it only needs to satisfy the requirement that the delayed light beam can be reflected back in the direction opposite to the original light path. It can 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 prolonging 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, and is used to allow the detection light beam entering from the back to pass through, and to reflect the magneto-optical effect light beam entering from the front. It can be understood by those skilled in the art that the core function of the beam splitter 60 is to change the propagation direction of the magneto-optical effect light beam, and it is not limited to the use of the beam splitter 60. Its core function can actually be replaced by an ordinary reflector, but compared with an ordinary reflector, the beam splitter 60 can be disposed on the optical path of the mixed light beam without worrying about blocking, thereby saving a part of the space.

[0035] The first conversion wave plate 71 and the second conversion wave plate 72 constitute a conversion unit of a spin wave phase continuous controllable excitation system based on circularly polarized light pulses of the present invention. The first conversion wave plate 71 is arranged in the emission direction of the first split light beam, converts the first split light beam in a linear polarization state into a first excitation light beam in a circular polarization state, and the first excitation light beam is irradiated on the magnetic material after being reflected by the third reflector 43 and the fourth reflector 44; the second conversion wave plate 72 is arranged in the emission direction of the second split light beam, converts the second split light beam in a linear polarization state into a second excitation light beam in a circular polarization state, and the second excitation light beam is irradiated on the magnetic material after being reflected by the sixth reflector 46 and the seventh reflector 47. The first conversion wave plate 71 and the second conversion wave plate 72 are quarter wave plates, which can convert linear polarized light into circular 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 generated spin wave phase can be changed.

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

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

[0038] The detection and control wave plate 23, polarization prism 100 and differential photodetector 110 constitute the detection unit of the present invention for realizing the 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, which 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 light beams of orthogonal polarization components; the detection light beam is received by the differential photodetector 110, so as to realize accurate detection of extremely small polarization state changes of the detection light beam. Preferably, the detection and control wave plate 23 is adjusted in the initial state without the excitation light beam so that the detection light beam is decomposed into two detection light beams with equal light intensity through the polarization prism 100, and the light intensity of the two detection light beams changes with the change of the spin wave in the subsequent process.

[0039] In one embodiment, after the detection light beam is irradiated on the magnetic material 90, it is not reflected, but is transmitted through the magnetic material 90 to form a magneto-optical effect light beam. At this time, there is no need to add a reflection device to change the direction of the magneto-optical effect light 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 light beam to receive the magneto-optical effect light 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 and regulation 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 regulation 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, and the first excitation beam is reflected by the third reflector 43 and the fourth reflector 44, and then 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 then converted by the second conversion wave plate 72 to form a second excitation beam, and the second excitation beam is reflected by the sixth reflector 46 and the seventh reflector 47, and then 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 side of the spectrometer 60 and transmitted through the spectrometer 60, and then is focused 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, is irradiated on the front side of the spectrometer 60 and is reflected, and after transmitting through the detection control wave plate 23, it is divided into two light detection beams through the polarization 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 the present application are 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 and sequence under this statement, and "first" and "second" are completely interchangeable, and it is only necessary to distinguish the names of other corresponding components and correctly interchange them. Similarly, the "front" and "back" mentioned in the present application are 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 characteristic distinction under this statement, and "front" and "back" are completely interchangeable, and it is only necessary to distinguish the names of other corresponding surfaces and correctly interchange them.

[0044] Example 2

[0045] See also Figure 4 , a system for realizing continuous and controllable excitation of spin wave phase based on circularly polarized light pulses provided in this embodiment 2 includes a light source 10, a detection control wave plate 21, an excitation control wave plate 22, a detection spectroscopic structure 31, an excitation spectroscopic structure 32, a second reflector 42, an eighth reflector 48, a ninth reflector 49, a delay device 50, an adjustable attenuation plate A, a spectroscope 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 difference between the structure in the embodiment 1 is that the excitation spectroscopic structure 32 in the embodiment 2 is not composed of a spectroscope, but is composed of a first double prism 321 and a second double prism 322; the detection beam and the first excitation beam and the second excitation beam are focused on the surface of the magnetic material 90 through 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 after the second excitation beam passes through, so as to achieve an adjustable energy density ratio between the first excitation beam and the second excitation beam. The number and position of the reflectors are adaptively adjusted. The remaining component structures are the same as those in the embodiment 2 and will not be described 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 to work and emits an initial light beam outward; the initial light beam is irradiated on the detection and regulation wave plate 21, and after being transmitted, it is irradiated on the detection spectroscopic structure 31, and after being transmitted to form a pre-detection light beam, it 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 regulation 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, and 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 and the second prism split light beam are 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 transmitting the adjustable attenuation plate A.

[0049] After being reflected back along the vertical direction of the pre-detection beam by the second reflector 42, the eighth reflector 48 and the ninth reflector 49, the detection beam is irradiated on the back side of the spectrometer 60 and transmitted through the spectrometer 60, and then is focused on the surface of the magnetic material 90 after passing through the focusing lens 80, 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, is irradiated on the front side of the spectrometer 60 and is reflected, and after transmitting through the detection control wave plate 23, it is divided into two detection beams with equal light intensities by the polarization prism 100 in the initial state without an excitation beam, and the two detection beams respectively enter the two probes of the differential photodetector 110.

[0050] It is foreseeable that the method of the present invention for realizing continuous and controllable excitation of the spin wave phase based on circularly polarized light pulses can realize a function similar to that of a phase shifter, and can be combined with time-resolved detection of spin waves. Further, the circular polarization state and energy density ratio between the second excitation light beam and the first excitation light beam can be changed according to the detection results and actual needs to realize spin wave phase control, realize precise and continuous control of the spin wave phase, and fix it in the desired state. For situations where continuous control of the spin wave phase is not required, but a fixed selection of the spin wave phase is required, the selective preset of the spin wave phase can be realized 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, and provide stable and reliable phase control in applications. Specifically, the circular polarization state of the first excitation light beam and the second excitation light beam can be preset by the conversion unit; the energy density ratio of the first excitation light beam and the second excitation light beam can be preset by changing the light splitting unit, and then the phase of the excited spin wave can be controlled to achieve the function of setting the spin wave phase, thereby meeting the needs of various specific applications.

[0051] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, and the present invention is also intended to include these modifications and modifications.

Claims

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

2. The system for realizing continuous and controllable excitation of spin wave phase 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 excitation of spin wave phase 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 a 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 a 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 excitation of spin wave phase 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, 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 light beam and a pre-split light beam, the pre-detection light beam is emitted from the spectroscopic unit and irradiated on the magnetic material to form a magneto-optical effect light beam, and the pre-split light beam is orthogonally decomposed by the excitation spectroscopic structure according to polarization to form a first split light beam and a second split light beam.

5. The system for realizing continuous and controllable excitation of spin wave phase 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 orthogonally decomposed by the detection spectroscopic structure according to polarization to form a pre-detection light beam and a pre-split light beam, the pre-detection light beam is emitted from the spectroscopic unit and irradiated on the magnetic material to form a magneto-optical effect light beam, the pre-split light beam is irradiated on the first double prism, 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 is transmitted through the second double prism and collimated to form a first split light beam, and the second prism split light beam is transmitted through the second double prism and collimated to form a second split light beam.

6. The system for realizing continuous and controllable excitation of spin wave phase 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 the magneto-optical effect light beam passes 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.

7. The system for realizing continuous and controllable excitation of spin wave phase 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, thereby realizing time-resolved spin wave detection.

8. The system for realizing continuous and controllable excitation of spin wave phase based on circularly polarized light pulses according to claim 6, characterized in that: The invention also comprises an adjustable attenuation plate, wherein the adjustable attenuation plate 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 divided into a first split light beam and a second split light beam according to the polarization state, the first split light beam in a linear polarization state is converted into a first excitation light beam in a circular polarization state, and the second split light beam in a 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 a spin wave; 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 and controllable phase 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 to achieve time-resolved detection; the detection beam is irradiated on the surface of the magnetic material after 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 result to achieve controllable excitation of the spin wave phase.

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