High-speed and multi-dimensional spatial light field regulation and control device

Abstract

The invention provides a high-speed and multi-dimensional spatial light field regulation and control device, which can realize high-speed regulation of multiple dimensions such as amplitude, phase, polarization and the like of a spatial light field. Comprising a pumping regulation and control system, a collimation focusing shaping system and a laser resonance system which are sequentially installed through a three-dimensional adjusting frame along a light path, and the three systems are located on the same horizontal optical axis and are vertically arranged. The pumping regulation and control system comprises a signal generator, a driving circuit and a pumping source; the collimating focusing shaping system comprises a collimating lens, a conical lens or a cylindrical lens and a focusing lens, the laser resonance system comprises a laser crystal and a laser resonant cavity, and the laser resonant cavity comprises a compact parallel plane cavity and an open type optical resonant cavity. Laser pulses with different amplitude characteristics can be output at different moments; laser pulses with different phase characteristics can be output at different moments; and laser pulses with different polarization characteristics can be output at different moments.

Description

Technical Field

[0001] This invention relates to the field of spatial light field manipulation, and more particularly to a high-speed, multi-dimensional spatial light field manipulation device. Background Technology

[0002] High-speed manipulation of spatial light fields has important applications in several cutting-edge fields. Its core lies in the rapid and precise control of the spatial distribution characteristics of light, such as amplitude, phase, and polarization, and it has wide applications across various sectors. In communications, spatial division multiplexing technology utilizes orbital angular momentum beams to overcome traditional channel capacity limitations; in spatial optical information transmission, rapidly switching beam direction or mode can significantly improve the anti-interference capability of information transmission. In laser processing and manufacturing, rapidly adjusting the beam shape to adapt to different materials improves processing accuracy and efficiency. In quantum technology, high-dimensional quantum state preparation is achieved through light field manipulation, increasing the encoding dimension of quantum key distribution. In laser ranging, dynamically controlling beam characteristics significantly improves ranging accuracy, speed, and adaptability. Currently, common high-speed modulated laser transverse mode devices include spatial light modulators, digital micromirrors, and deformable mirrors.

[0003] Spatial Light Modulator (SLM) is an optical device that achieves dynamic spatial modulation of the phase, amplitude, or polarization state of light waves through a pixelated array. SLMs mainly include liquid crystal type (LC-SLM) and ferroelectric liquid crystal type (FLC-SLM). LC-SLM is based on the electro-optic effect of liquid crystal molecules and supports continuous phase modulation from 0 to 2π[1]. However, due to the physical characteristics of liquid crystal molecule rearrangement, its response time is usually 5–30 milliseconds and the update rate is 30–240 Hz. FLC-SLM utilizes the bistable switching of ferroelectric liquid crystals to achieve fast binary phase modulation (0 or π)[2]. The response time is less than 100 microseconds and the update rate can reach 1–10 kHz. However, the millisecond-level response speed bottleneck of LC-SLM limits its performance in high-speed dynamic light field manipulation, while the binary modulation characteristics of FLC-SLM reduce the phase resolution and make it difficult to meet the requirements of high-order wavefront shaping. The phase modulation efficiency of LC-SLM is usually over 90%, but it is limited by the polarization dependence of liquid crystal materials and is only effective for specific polarization states [3]. The modulation efficiency of FLC-SLM is about 80–85%, and the lower modulation efficiency further affects its application performance.

[0004] Digital micromirror devices (DMDs) are spatial light modulators based on microelectromechanical systems (MEMS), consisting of millions of independently controllable micromirror units, and are mainly used to achieve high-precision amplitude modulation. Each micromirror typically has two stable tilt states (e.g., ±12°), and the propagation direction of reflected light is controlled by high-speed tilt switching, thereby realizing functions such as image projection, beam shaping, and light intensity distribution control [4]. DMDs have extremely fast response speeds, typically less than 10 microseconds, and update rates can reach thousands to tens of thousands of hertz. However, due to their binary amplitude modulation nature, DMDs cannot directly achieve continuous phase modulation. In applications requiring phase control, indirect methods such as spatial coding or time multiplexing are usually used to simulate phase modulation [5], which significantly increases the complexity of system design and reduces modulation efficiency. Therefore, in optical applications with high requirements such as high-precision wavefront shaping, phase control, and complex light field control, the inherent limitations of DMDs are more prominent.

[0005] A deformable mirror (DM) is a device that uses mechanical means to adjust the shape of a mirror to achieve phase modulation of the light wavefront [6]. A DM consists of multiple independently driven tiny actuators that can change the local morphology of the mirror in sub-millisecond response time to achieve high-precision, continuous phase modulation. Its phase modulation range can usually reach several micrometers, corresponding to optical path differences of multiple wavelengths, and can be used to compensate for large-amplitude wavefront distortion. The typical update rate of a DM is between several hundred hertz and several thousand hertz, depending on the type of drive and the mirror structure. The main disadvantage of a DM is that it can only control the phase of light and cannot directly modulate the amplitude. In addition, the spatial resolution of a DM is limited by the number of drivers and is relatively expensive [7]. The driver spacing is generally in the range of several hundred micrometers to millimeters, and the low pixel density limits its ability to control the details of high spatial frequency light fields. Therefore, a DM cannot achieve fine adjustment of light intensity distribution or amplitude modulation on its own and must be used in conjunction with other devices to complete more complex light field control tasks.

[0006] Given that the high-speed modulation of spatial light fields has important applications in many cutting-edge fields, and that current modulation technologies all have their own shortcomings, the purpose of this invention is to provide a high-speed multidimensional spatial light field modulation device that can quickly and accurately control the spatial distribution characteristics of light, such as amplitude, phase, and polarization. Summary of the Invention

[0007] The main technical problem to be solved by the present invention is to provide a high-speed, multi-dimensional spatial light field control device that can realize high-speed adjustment of the amplitude, phase and polarization characteristics of the spatial light field.

[0008] To address the aforementioned technical problems, this invention provides a high-speed, multi-dimensional spatial light field manipulation device. Using a solid-state laser as a carrier, and based on pump control technology, it enables high-speed adjustment of the amplitude, phase, and polarization characteristics of the spatial light field. The device includes a pump control system (1), a collimation and focusing system (2), and a laser resonance system (3) arranged sequentially along the optical path. The pump control system (1), the collimation and focusing system (2), and the laser resonance system (3) are all located on the same horizontal optical axis and are arranged vertically.

[0009] The pump control system (1) includes a signal generator (1-1), a drive circuit (1-2), and a pump source (1-3); the signal generator (1-1) provides the drive circuit (1-2) with electrical signals of different high and low levels and different periods, the electrical signals including analog signals and digital signals; the drive circuit (1-2) provides the pump source (1-3) with corresponding operating voltage and operating current according to the received electrical signals, so that the pump source (1-3) emits pump laser;

[0010] The collimation and focusing system (2) includes a collimating lens (2-1), a beam shaping mirror (2-2), and a focusing lens (2-3) arranged sequentially along the optical path. The beam shaping mirror (2-2) includes a conical lens or a cylindrical lens. The collimating lens (2-1), the conical lens or cylindrical lens, and the focusing lens (2-3) are placed perpendicular to the same horizontal optical axis.

[0011] The laser resonant system (3) includes a laser crystal (3-1) and a laser resonant cavity including an input mirror (3-2) and an output mirror (3-3); the laser resonant cavity includes a plano-plano cavity formed by coating the surfaces at both ends of the laser crystal (3-1), and an open optical resonant cavity composed of the input mirror (3-2) and the output mirror (3-3); the open optical resonant cavity includes one of the following cavity structures: plano-plano cavity, plano-concave cavity, "V"-shaped cavity, "Z"-shaped cavity, folded cavity, and composite cavity;

[0012] The pump control technology involves adjusting the period and power of the pump laser output by the pump control system (1) by changing the signal characteristics of the signal generator (1-1); the output pump laser passes through the collimation and focusing shaping system (2) to adjust the intensity distribution of the pump laser.

[0013] After being adjusted by pump control technology, the pump laser is incident into the laser resonant system (3), forming a corresponding gain distribution in the laser crystal (3-1), and stimulated emission occurs to generate laser. The generated laser oscillates back and forth in the open optical resonant cavity composed of the input mirror (3-2) and the output mirror (3-3) and forms a stable spatial light field output (4).

[0014] The spatial light field output (4) can realize laser pulses with different amplitude characteristics at different times; can realize laser pulses with different phase characteristics at different times; and can realize laser pulses with different polarization characteristics at different times.

[0015] In a preferred embodiment, the drive circuit (1-2) allows external input electrical signals to control and enable it; the voltage of the drive circuit (1-2) is adjustable from 0 to 10V, the current is adjustable from 0 to 30A, and the frequency is adjustable from 0 kHz to 5 MHz.

[0016] In a preferred embodiment, the pump source (1-3) is a semiconductor laser with output via fiber coupling, having a wavelength range of 300-1100nm selectable; a power range of 0-30W adjustable; a fiber core diameter of 100-400μm selectable; and a numerical aperture of 0.1-0.6 selectable.

[0017] In a preferred embodiment, the collimating lens (2-1) and the focusing lens (2-3) are two molded aspherical lenses, with a focal length selectable from 1.5 to 18.4 mm and a numerical aperture selectable from 0.15 to 0.7 mm.

[0018] In a preferred embodiment, the cone angle of the cone lens is selectable from 0-40°, the deflection angle is selectable from 0-30°, and the axial thickness is selectable from 0-16mm;

[0019] Alternatively, the cylindrical lens may include a plano-convex lens or a plano-concave lens. The focal length of the cylindrical lens may be selected from 3 to 1000 mm, the length from 6 to 140 mm, the height from 10 to 100 mm, the radius of curvature from 6.6 to 516.8 mm, the center thickness from 2.3 to 21.6 mm, and the edge thickness from 2 to 3 mm.

[0020] In a preferred embodiment, the laser crystal (3-1) includes a gain crystal, a Raman crystal, and a nonlinear crystal; the gain crystal is selected from one of Nd:YAG, Nd:GdVO4, Nd:YVO4, Nd:YLF, Yb:YAG, Yb:KGW, Yb:CaF2, Er:YAG, and Tm:YAG; the Raman crystal is selected from one of YVO4, diamond, Ba(NO3)2, and KGW; and the nonlinear crystal is selected from one of KTP, KDP, KTA, LiNbO3, LBO, and BBO. In a preferred embodiment, the flat cavity formed by coating the surfaces at both ends of the laser crystal (3-1) includes a high-reflectivity film of 99.99% coated on the incident surface of the laser crystal (3-1) for laser wavelengths of 300-2000nm, and a partially transmissive film of 1%-60% coated on the exit surface of the laser crystal (3-1) for laser wavelengths of 300-2000nm.

[0021] In a preferred embodiment, the input mirror (3-2) includes a planar input mirror and a curved input mirror, and the surface of the input mirror (3-2) is coated with a high-reflectivity film selectable for laser wavelengths of 300-2000nm, with a reflectivity of 99.99% and a radius of curvature selectable for 20-200mm; the output mirror (3-3) includes a planar output mirror and a curved output mirror, and the surface of the output mirror (3-3) is coated with a partially transmissive film selectable for laser wavelengths of 300-2000nm, with a transmittance selectable for 1%-60% and a radius of curvature selectable for 20-200mm.

[0022] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0023] 1. The present invention can adjust the digital signal input to the driving pump source module to generate different high and low levels, thereby controlling the amplitude, phase and polarization of the spatial light field respectively. It has multiple adjustment dimensions, high degree of freedom, and is simple and flexible to operate.

[0024] 2. The present invention achieves gain control by adjusting the driving signal of the pump source, and directly generates spatial light fields with different amplitudes, phases and polarizations in the laser resonant cavity. It does not require the insertion of additional components in the resonant cavity, which is conducive to the miniaturization and micro-chipping of lasers, and improves the purity of the generated vortex mode spatial light mode and the optical conversion efficiency.

[0025] 3. The present invention can adjust the period of the driving digital signal to achieve high-speed modulation of the amplitude, phase and polarization of the spatial light field, with a modulation speed of up to MHz;

[0026] 4. The present invention can use different crystal materials and different cavity structures to modulate the amplitude, phase and polarization of the spatial light field, and has high compatibility and high system flexibility. Attached Figure Description

[0027] Figure 1 A simplified structural diagram and a schematic diagram illustrating the principle of the high-speed, multi-dimensional spatial light field manipulation device of this invention;

[0028] Figure 2 This is a simplified structural diagram of the LG mode spatial characteristic control system in the first embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the digital signal set by the signal generator in the first embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of the time series of the output laser with input signal one in the first embodiment of the present invention;

[0031] Figure 5 yes Figure 3 Experimental diagram of the light intensity distribution of the LG mode output corresponding to each pulse;

[0032] Figure 6 This is a striped light intensity distribution diagram generated by the interference of vortex laser and plane wave in the output LG mode in the first embodiment of the present invention.

[0033] Figure 7 This is a schematic diagram of the digital signal two set by the signal generator in the first embodiment of the present invention;

[0034] Figure 8 This is a schematic diagram of the output laser time sequence with input signal two in the first embodiment of the present invention;

[0035] Figure 9 This is a schematic diagram of the digital signal set in the signal generator in the first embodiment of the present invention;

[0036] Figure 10 This is a schematic diagram of the output laser time sequence with input signal three in the first embodiment of the present invention;

[0037] Figure 11 This is a simplified structural diagram of the HG mode spatial characteristic control system in the second embodiment of the present invention. Detailed Implementation

[0038] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0039] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "top / bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0040] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed", "equipped", "sleeved / connected", "connected", etc., should be interpreted broadly. For example, "connection" can be a wall-mounted connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0041] refer to Figure 1 This invention provides a high-speed, multi-dimensional spatial optical field manipulation device and a manipulation technique capable of rapidly adjusting the amplitude, phase, and polarization characteristics of a spatial optical field. This technique can be implemented using solid-state lasers with different crystal materials, cavity structures, and pump light distributions as carriers, combined with mode matching and cavity mode matching. It can controllably adjust different spatial characteristics of the spatial optical field, such as amplitude, phase, and polarization, at high speed. Amplitude adjustment includes adjustable amplitudes for petal-like Laguerre-Gaussian (PLG) modes and Hermite-Gaussian (HG) modes. Phase modulation enables high-order tunability of the circumferential Laguerre-Gaussian (LG) mode, i.e., adjustable number of phase singularities. Polarization characteristics allow for adjustable radial polarization, angular polarization, and mixed polarization.

[0042] Combination Figure 1 As shown, the technical solution adopted in this invention is to use a solid-state laser as a carrier and, based on pump control technology, to achieve high-speed adjustment of the amplitude, phase, and polarization characteristics of the spatial light field. By selecting different laser crystals and different laser cavity structures to construct a high-speed, multi-dimensional spatial light control system, it is possible to control the spatial distribution characteristics of the spatial light field, such as amplitude, phase, and polarization. The spatial light field control device consists of a pump control system (1), a collimation and focusing shaping system (2), and a laser resonator system (3) arranged sequentially along the optical path. All three systems are installed using a three-dimensional adjustment frame, which facilitates the adjustment of the position of each system along the optical axis and the spacing between adjacent systems.

[0043] The pump control system (1) includes a signal generator (1-1), a drive circuit (1-2), and a pump source (1-3). The drive circuit (1-2) allows external input electrical signals for control and enable. Based on the received electrical signals, the drive circuit (1-2) provides the pump source (1-3) with corresponding operating voltage and current, causing the pump source (1-3) to emit pump laser light. By changing the magnitude of the drive voltage, the magnitude of the constant current supplied to the pump source (1-3) is changed. The signal generator (1-1) provides the drive circuit (1-2) with digital signals of different high and low levels and different periods, thereby realizing the control of the pump light of the pump source (1-3).

[0044] The input voltage of the driving circuit (1-2) is adjustable from 0 to 10V, and the output current is adjustable from 0 to 30A. It allows external input electrical signals for control and enable, and the pump light modulation frequency is adjustable from 0 to 5kHz. The pump source (1-3) is a semiconductor laser with fiber-coupled output, with a wavelength range of 300-1100nm selectable; the power range is adjustable from 0 to 30W; the fiber core diameter is selectable from 100-400μm; and the numerical aperture is selectable from 0.1-0.6.

[0045] The collimation and focusing system (2) includes a collimating lens (2-1), a beam shaping mirror (2-2), and a focusing lens (2-3) arranged sequentially along the optical path. The beam shaping mirror (2-2) includes a conical lens or a cylindrical lens. The collimating lens (2-1), the conical lens or cylindrical lens, and the focusing lens (2-3) are placed perpendicular to the same horizontal optical axis. The collimating lens (2-1) and the focusing lens (2-3) are two molded aspherical lenses with a focal length selectable from 1.5 to 18.4 mm and a numerical aperture selectable from 0.15 to 0.7.

[0046] The laser resonant system (3) includes a laser crystal (3-1) and a laser resonant cavity including an input mirror (3-2) and an output mirror (3-3). The laser resonant cavity includes a compact parallel planar cavity formed by coating the surfaces at both ends of the laser crystal (3-1) and an open optical resonant cavity composed of the input mirror (3-2) and the output mirror (3-3). The open optical resonant cavity includes one of the following cavity structures: plano-concave cavity, "V"-shaped cavity, "Z"-shaped cavity, folded cavity, and composite cavity.

[0047] The pump control technology involves adjusting the period and power of the pump laser output by the pump control system (1) by changing the signal characteristics of the signal generator (1-1). The output pump laser passes through the collimation and focusing shaping system (2) to adjust the intensity distribution of the pump laser. The pump laser, after being adjusted by the pump control technology, is incident on the laser resonant system (3), forming a corresponding gain distribution in the laser crystal (3-1) and generating laser through stimulated emission. The generated laser oscillates back and forth in the open optical resonant cavity composed of the input mirror (3-2) and the output mirror (3-3) to form a stable spatial light field output (4). The spatial light field output (4) can realize laser pulses with different amplitude characteristics at different times; can realize laser pulses with different phase characteristics at different times; and can realize laser pulses with different polarization characteristics at different times.

[0048] The laser crystal (3-1) includes a gain crystal, a Raman crystal, and a nonlinear crystal; the gain crystal can be selected from one of Nd:YAG, Nd:GdVO4, Nd:YVO4, Nd:YLF, Yb:YAG, Yb:KGW, Yb:CaF2, Er:YAG, and Tm:YAG; the Raman crystal can be selected from one of YVO4, diamond, Ba(NO3)2, and KGW; and the nonlinear crystal can be selected from one of KTP, KDP, KTA, LiNbO3, LBO, and BBO.

[0049] The flat cavity formed by coating the surfaces at both ends of the laser crystal (3-1) includes a high-reflectivity film of 99.99% coated on the incident surface of the laser crystal (3-1) for laser wavelengths of 300-2000nm, and a partially transmissive film of 1%-60% coated on the exit surface of the laser crystal (3-1) for laser wavelengths of 300-2000nm.

[0050] The input mirror (3-2) includes a planar input mirror and a curved input mirror, and the surface of the input mirror (3-2) is coated with a high-reflectivity film selectable for laser wavelengths of 300-2000nm, with a reflectivity of 99.99% and a curvature radius selectable for 20-200mm; the output mirror (3-3) includes a planar output mirror and a curved output mirror, and the surface of the output mirror (3-3) is coated with a partially transmissive film selectable for laser wavelengths of 300-2000nm, with a transmittance selectable for 1%-60% and a curvature radius selectable for 20-200mm.

[0051] LG 0,lThe experimental setup for the vortex beam includes a pump source (1-3), a collimating lens (2-1), a conical lens, a focusing lens (2-3), and a laser resonator arranged sequentially. The pump source (1-3), collimating lens (2-1), conical lens, focusing lens (2-3), and laser resonator are all located on the same horizontal optical axis and are vertically aligned. The laser crystal (3-1) is a gain crystal. The optical path and positions of this setup are as follows:

[0052] The pump light emitted from the pump source (1-3) (semiconductor laser) is collimated by the collimating lens (2-1), and then generates ring light through a conical lens. The focusing lens (2-3) directs the generated ring pump light into the laser resonant cavity. The laser resonant cavity adopts a planar cavity structure, consisting of a laser gain crystal (using a Yb:YAG crystal) and a planar output coupling mirror coated with a partial reflective film (wavelength 1000-1100nm). The laser gain crystal and the planar output coupling mirror are connected and fixed together by a clamp, forming a "sandwich" structure, and fixed on a three-dimensional adjustment frame. The pump light focus is adjusted to be outside the crystal, directly generating LG light within the cavity. 0,l Vortex laser output.

[0053] The experimental setup for generating an HG beam includes a pump source (1-3), a collimating lens (2-1), a cylindrical lens, a focusing lens (2-1), and a laser resonator arranged sequentially along the optical path. The pump source (1-3), collimating lens (2-1), focusing lens (2-1), and laser resonator are all located on the same horizontal optical axis and are vertically aligned. The laser crystal (3-1) is a gain crystal. The HG beam is generated by controlling the asymmetry of the resonator and disrupting its vertical symmetry. 0,n The beam disrupts the horizontal symmetry of the resonant cavity to generate HG. m,0 The light beam. The optical path and position that generate the HG light beam are as follows:

[0054] The pump light emitted from the pump source (1-3) (semiconductor laser) passes through a collimating and focusing lens group (composed of a collimating lens (2-1), a cylindrical lens, and a focusing lens (2-1)) and then enters the laser resonant cavity. The laser resonant cavity adopts a plano-concave cavity structure, consisting of a laser gain crystal (a Yb:YAG crystal with a high-reflectivity coating for 1000-1100nm on its end face) and a concave output coupling mirror with a partially reflective coating (wavelength 1000-1100nm) on one side. The radius of curvature of the concave output coupling mirror is 70mm. The laser crystal and the output coupling mirror are discrete structures, fixed separately by a three-dimensional adjustment frame, located on the same horizontal optical axis and vertically positioned. The appropriate laser cavity length is adjusted to meet the stable cavity conditions for laser resonance. The relative position of the concave output coupling mirror in the x-direction perpendicular to the optical axis plane is adjusted to break the symmetrical structure of the resonant cavity in the horizontal direction, constructing an asymmetric cavity structure to achieve HG.0,n Mode output. Adjust the relative position of the concave output coupling mirror in the y-direction perpendicular to the optical axis plane to break the symmetrical structure of the resonant cavity in the vertical direction, construct an asymmetric cavity structure, and realize HG. m,0 Mode output.

[0055] This invention provides two embodiments: the first embodiment is for generating an LG beam, and the second embodiment is for generating an HG beam. The pump control system is the same in these two embodiments, but the collimation, focusing and shaping system and the laser resonance system are different, which will be described in detail below.

[0056] The collimation and focusing shaping system (2) has different components in the two embodiments: in the embodiment for generating LG beams, the system consists of a collimating lens (2-1), a focusing lens (2-3), and a conical lens; in the embodiment for generating HG beams, the system consists of a collimating lens (2-1), a focusing lens (2-3), and a cylindrical lens.

[0057] The laser resonant system has different component compositions in the two embodiments: in the embodiment for generating an LG beam, the laser resonant cavity consists of a laser gain medium (laser crystal Yb:YAG) and a planar output coupling mirror, which are fixed to the same fixture by a "sandwich" structure to form a compact planar resonant cavity; in the embodiment for generating an HG beam, the laser resonant cavity consists of a laser gain medium (laser crystal Yb:YAG) and a concave output coupling mirror, which are fixed independently to form a plano-concave long resonant cavity.

[0058] The following examples illustrate how the laser of this invention, through gain control, maps different spatial characteristics of the beam, such as amplitude, phase, and polarization, onto different spatiotemporal planes:

[0059] First embodiment (Generating LG beam embodiment), see reference Figures 2-10 .

[0060] This embodiment is for generating LG. 0,l The light beam and its path are as follows: (Combined) Figure 2 As shown, from Figure 2 The leftmost signal generator receives an electrical signal input to the drive circuit, thereby driving the 940nm fiber-coupled semiconductor laser. The pump light emitted from the fiber-coupled semiconductor laser first passes through a collimating, focusing, and shaping lens (composed of a collimating lens, a conical lens, and a focusing lens) to generate a ring pump light, and finally passes through a compact laser resonator to generate LG. 0,l beam.

[0061] Combination Figure 2As shown, the pump control system consists of a signal generator, a drive circuit, and a pump source. The drive circuit provides a constant current input to the pump source, which can be changed according to the input control voltage. The input voltage range of the drive circuit is 0-5V, and the output current range is 0-12.5A. The drive circuit allows external input electrical signals for control and enable. The signal generator (RIGOLDS2302A) provides digital signals of different high and low levels and different periods to achieve pump control. The pump source is a fiber-coupled semiconductor laser with a center wavelength of 940nm, a maximum output power of 10W, a fiber core diameter of 200μm, and a numerical aperture of 0.22.

[0062] The collimation and focusing shaping system described above is as follows: Figure 2 As shown, the system consists of a collimating lens, a focusing lens, and a conical lens. The collimating and focusing lens group comprises two molded aspherical lenses (Thorlabs, A240TM-B) with a focal length of 8mm. The conical lens has a cone angle of 5°, a deflection angle of 2.2°, an axial thickness of 6.1mm, and is coated with an anti-reflection coating with a wavelength of 1050-1700nm (Thorlabs, AX255-C). The conical lens is inserted between the collimating and focusing lenses, and all three are placed perpendicular to the optical axis plane. The 940nm pump light output from the fiber coupling is collimated by the collimating lens, then converted into a ring-shaped light distribution by the conical lens, and finally incident into the laser crystal as a ring-shaped pump light after passing through the focusing lens. By adjusting the position of the laser resonator along the optical axis, the focal point of the ring-shaped pump light is located outside the laser crystal. At this time, the gain distribution in the laser crystal also exhibits a ring-shaped distribution. Utilizing the mode-matching principle, LG is directly generated within the resonator. 0,l Laser. The intensity distribution and collimation / focusing effect of the ring pump light can be altered by changing the distance between the collimating lens, conical lens, and focusing lens.

[0063] The laser resonant system consists of a laser gain medium (a Yb:YAG laser crystal) and a planar output coupling mirror. The Yb:YAG crystal (ytterbium-doped yttrium aluminum garnet crystal) has a diameter of 10 mm and a thickness of 1 mm. 3+ The Yb:YAG crystal, with a doping concentration of 10 at.%, is coated with an antireflection film with a wavelength of 940 nm and a high-reflectivity film with a wavelength of 1000-1100 nm facing the focusing lens, serving as the incident cavity mirror of the laser resonator. The planar output coupling mirror has a diameter of 15 mm and a thickness of 3 mm, and the side facing the Yb:YAG laser crystal is coated with a partial reflective film with a wavelength of 1000-1100 nm and a reflectivity of 95%, serving as the output cavity mirror of the laser resonator. The Yb:YAG crystal and the planar output coupling mirror are fixed together by a copper clamp as described above.

[0064] The aforementioned pump source, collimating lens, conical lens, focusing lens, and laser resonator are all fixed on a three-dimensional adjustment frame, facilitating movement along the optical axis and in planes perpendicular to the optical axis. The relative positions of the pump control system, collimating and focusing system, and laser resonator system are optimized to fix the pump light distribution and determine the size and relative position of the pump light focal point.

[0065] Under the same pump light distribution, different pump light powers incident on the laser crystal result in different gains within the laser resonant cavity, meaning different inversion particle number distributions exist within the laser crystal. Different inversion particle number distributions can be well matched with LG modes of different orders (l), with the LG mode exhibiting the highest matching degree with the pump light distribution. 0,l The mode will preferentially oscillate within the laser resonator, suppressing the generation of other modes. Higher incident pump power results in higher gain at the edge of the ring pump light, making it easier to generate higher-order LG modes. Therefore, different orders of LG modes can be generated by precisely controlling the incident pump light power. 0,l Vortex light, and corresponding to different threshold powers P th-l .

[0066] The experimental method in this embodiment is as follows:

[0067] In continuous optical pump mode, a signal generator is used to set DC signals of different voltage levels and input them to the drive circuit to change the incident pump light power. Recording different LG... 0,l The corresponding driving voltage value U of the mode vortex beam I and pump power value P I With input drive voltage U1 and pump power P1, the output vortex beam mode is LG. 0,1 When the input drive voltage U2 and the pump power P2 are both equal, the output vortex beam mode is LG. 0,2 When the input drive voltage U3 and the pump power P3 are both set, the output vortex beam mode is LG. 0,3 When the input drive voltage U4 and the pump power P4 are both at the specified values, the output vortex beam mode is LG. 0,4 When the input drive voltage U5 and the pump power P5 are both set, the output vortex beam mode is LG. 0,5 .

[0068] Determine different LGs 0,l The corresponding driving voltage value U of the mode vortex beam l and pump power value P l Next, in the signal generator, the high and low levels and period of the electrical signal are set according to specific requirements and transmission conditions to drive the pump source. The following is a detailed explanation using a set of data:

[0069] Figure 3To set the first type of electrical signal: an electrical signal whose voltage increases in a stepwise manner over time is input to the drive circuit, with a signal period of 1.5Hz, and the high-level state and the low-level state last for the same duration. Different voltages U... l (l = 1, 2, ..., 5) correspond to different pump light input powers P l (l=1,2,…,5) also corresponds to the generation of LGs of orders 1 to 5. 0,l (l=1,2,…,5) Vortex beam. U1=2.6V, P1=2.98W, output LG 0,1 Vortex laser; U2 = 2.9V, P2 = 3.42W, output LG 0,2 Vortex laser; U3 = 3.2V, P3 = 3.90W, output LG 0,3 Vortex laser; U4 = 3.8V, P4 = 4.72W, output LG 0,4 Vortex laser; U5 = 5.0V, P5 = 6.59W, output LG 0,5 Vortex laser. The generated output laser light is incident on a photomultiplier tube (Thorlabs, DET10C / M) and connected to an oscilloscope (Tektronix, MDO3104) to observe the timing characteristics of the laser, such as... Figure 4 As shown, five optical pulses were generated at times t1, t2, t3, t4, and t5, corresponding to five different LG modes. 0,l (l=1,2,…,5) Vortex laser, with pulse intensity gradually increasing.

[0070] Figure 5 To observe the transverse intensity distribution of the aforementioned laser using a CCD (Spiricon, SPU620), the LG values ​​generated at times t1, t2, t3, t4, and t5 are shown. 0,1 LG 0,2 LG 0,3 LG 0,4 LG 0,5 Lateral intensity distribution of the vortex beam (spot diagram) Figure 4 From left to right, LG 0,1 LG 0,2 LG 0,3 LG 0,4 LG 0,5 (The image shows the spot pattern of the vortex beam). Furthermore, the vortex characteristics of the generated laser were further verified using a Mach-Zehnder interferometer. The generated laser was coherently superimposed with a plane wave, and the results were observed using a CCD. Figure 5 The interference fringe pattern shown is a diagram of light spots. Figure 6 (a) The number of stripes on the left and right sides differs by 1, which means there is one phase singularity; Figure 6 (b) The difference in the number of fringes between the left and right sides is 2, which means there are 2 phase singularities; Figure 6 (c) The number of stripes on the left and right sides differs by 3, meaning there are 3 phase singularities; Figure 6 (d) The difference in the number of stripes on the left and right sides is 4, which means there are 4 phase singularities; Figure 6 In (e), the difference in the number of fringes between the left and right sides is 5, meaning there are 5 phase singularities. Therefore, it is possible to realize different orders LG at different times. 0,l The output of the laser pulse sequence in the mode realizes the mapping of the spatial characteristics (amplitude characteristics, phase characteristics) of light to the spatiotemporal characteristics.

[0071] Figure 7 For the second type of signal set: in Figure 3 Based on this, by lengthening the low-level duration at the end of the signal, it is possible to separate each group of signals in time, such as... Figure 7 The diagram shows a schematic of the drive signal sequence measured with an oscilloscope. Figure 8 The diagram shows the laser pulse sequence generated under the driving signal, measured using a photomultiplier tube, and the corresponding transverse mode intensity distribution of the laser, measured using a CCD.

[0072] Figure 9 The third signal is set as follows: the first driving voltage is U2, corresponding to the output LG. 0,2 Vortex light; the second driving voltage is U5, corresponding to the output LG. 0,5 Vortex light; the high-level state and the low-level state last for the same duration, such as... Figure 9 The diagram shows a schematic of the drive signal sequence measured with an oscilloscope. Figure 10 This diagram shows the laser pulse sequence generated under this driving signal, measured using a photomultiplier tube, and the corresponding transverse mode intensity distribution of the laser, measured using a CCD. Under this signal control, LG... 0,2 Model and LG 0,5 The output is a sequence of laser pulses that switches back and forth between two modes.

[0073] This embodiment enables control via a signal generator to achieve LG 0,l The output of the laser pulse sequence, which varies with time in the vortex beam mode, can be actively controlled and the amplitude and phase spatial characteristics of the vortex beam can be rapidly adjusted.

[0074] Second embodiment (HG beam generation embodiment), see reference Figure 11 .

[0075] This embodiment is for generating HG. n,0 HG 0,m The light beam and its path are as follows: (Combined) Figure 11 As shown, from Figure 11The leftmost signal generator sets the electrical signal input to the drive circuit, thereby driving the 940nm fiber-coupled semiconductor laser. The pump light emitted from the fiber-coupled semiconductor laser passes through a collimating and focusing system, and finally passes through a plano-concave laser resonator to generate HG. n,0 HG 0,m beam.

[0076] Combination Figure 11 As shown, the pump control system is the same as that in the first embodiment.

[0077] Combination Figure 11 As shown, the collimation and focusing system consists of two molded aspherical lenses with a focal length of 8mm, which are divided into a collimating lens and a focusing lens.

[0078] Combination Figure 11 As shown, the laser resonant system consists of a laser gain medium (laser crystal Yb:YAG) and a concave output coupling mirror. The laser crystal is a Yb:YAG crystal (ytterbium-doped aluminum garnet crystal) with the same parameters as in the first embodiment. The concave output coupling mirror is a curved output coupling mirror with a diameter of 15 mm, a radius of curvature of 70 mm, and a thickness of 5 mm. The side facing the Yb:YAG laser crystal is coated with a partially reflective film with a wavelength of 1000-1100 nm and a reflectivity of 95%, serving as the output cavity mirror of the laser resonant cavity. The laser crystal and the concave output coupling mirror are fixed independently, and the Yb:YAG crystal is held in place with a copper clamp for heat dissipation. The reflective films coated on the Yb:YAG crystal and the concave output coupling mirror respectively constitute a plano-concave resonant cavity.

[0079] The pump source, collimating lens, cylindrical lens, focusing lens, and laser resonator system are all fixed on a three-dimensional adjustment frame, facilitating movement along the optical axis and in planes perpendicular to the optical axis. Adjusting the relative position of the concave output coupling mirror in the x-direction perpendicular to the optical axis breaks the symmetrical structure of the resonator in the horizontal direction, constructing an asymmetric cavity structure to achieve HG. 0,n Mode output. Adjust the relative position of the concave output coupling mirror in the y-direction perpendicular to the optical axis plane to break the symmetrical structure of the resonant cavity in the vertical direction, construct an asymmetric cavity structure, and realize HG. m,0 Mode output.

[0080] The experimental method for this example is as follows:

[0081] First, the adjustment method is similar to that of the first embodiment, optimizing collimation and focusing, and determining the position of the concave output coupling mirror to meet the stability conditions of the resonant cavity.

[0082] The position of the movable concave output coupling mirror perpendicular to the horizontal direction in the optical axis plane will generate HG. m,0Mode laser output. Based on the first embodiment, an electrical signal is input to the drive circuit via a signal generator; similarly, three electrical signals as in Example 1 can be set. By repeating the experimental steps in the first embodiment, HG with different amplitudes corresponding to different times can be obtained. m,0 The laser pulse sequence is output in the mode.

[0083] The position of the movable concave output coupling mirror is perpendicular to the plane perpendicular to the optical axis, at which point HG will be generated. n,0 Mode laser output. Based on the first embodiment, an electrical signal is input to the drive circuit via a signal generator. The three electrical signals described in the first embodiment can also be set. By repeating the experimental steps in the first embodiment, HG with different amplitudes corresponding to different times can be obtained. 0,n The laser pulse sequence is output in the mode.

[0084] This embodiment enables HG to be controlled via a signal generator. n,0 HG 0,m The output of laser pulse sequences with vortex beam amplitude varying over time can be controlled at high speed and the amplitude characteristics of the vortex beam can be mapped to spatiotemporal characteristics.

[0085] The above description is merely a preferred embodiment of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention by those skilled in the art within the scope of the technology disclosed in the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A high-speed, multi-dimensional spatial light field manipulation device, characterized in that: Using solid-state lasers as a carrier and based on pump control technology, high-speed adjustment of the amplitude, phase, and polarization characteristics of spatial optical fields can be achieved. It includes a pump control system (1), a collimation and focusing shaping system (2), and a laser resonant system (3) arranged sequentially along the optical path; the pump control system (1), the collimation and focusing shaping system (2), and the laser resonant system (3) are all located on the same horizontal optical axis and are arranged vertically; The pump control system (1) includes a signal generator (1-1), a drive circuit (1-2), and a pump source (1-3); the signal generator (1-1) provides the drive circuit (1-2) with electrical signals of different high and low levels and different periods, the electrical signals including analog signals and digital signals; the drive circuit (1-2) provides the pump source (1-3) with corresponding operating voltage and operating current according to the received electrical signals, so that the pump source (1-3) emits pump laser; The collimation and focusing system (2) includes a collimating lens (2-1), a beam shaping mirror (2-2), and a focusing lens (2-3) arranged sequentially along the optical path. The beam shaping mirror (2-2) includes a conical lens or a cylindrical lens. The collimating lens (2-1), the conical lens or cylindrical lens, and the focusing lens (2-3) are placed perpendicular to the same horizontal optical axis. The laser resonant system (3) includes a laser crystal (3-1) and a laser resonant cavity including an input mirror (3-2) and an output mirror (3-3); the laser resonant cavity includes a plano-plano cavity formed by coating the surfaces at both ends of the laser crystal (3-1), and an open optical resonant cavity composed of the input mirror (3-2) and the output mirror (3-3); the open optical resonant cavity includes one of the following cavity structures: plano-plano cavity, plano-concave cavity, "V"-shaped cavity, "Z"-shaped cavity, folded cavity, and composite cavity; The pump control technology involves adjusting the period and power of the pump laser output by the pump control system (1) by changing the signal characteristics of the signal generator (1-1); the output pump laser passes through the collimation and focusing shaping system (2) to adjust the intensity distribution of the pump laser. After being adjusted by pump control technology, the pump laser is incident into the laser resonant system (3), forming a corresponding gain distribution in the laser crystal (3-1), and stimulated emission occurs to generate laser. The generated laser oscillates back and forth in the open optical resonant cavity composed of the input mirror (3-2) and the output mirror (3-3) and forms a stable spatial light field output (4). The spatial light field output (4) can realize laser pulses with different amplitude characteristics at different times; can realize laser pulses with different phase characteristics at different times; and can realize laser pulses with different polarization characteristics at different times.

2. The high-speed, multi-dimensional spatial light field manipulation device according to claim 1, characterized in that: The drive circuit (1-2) allows external input electrical signals to control and enable it; the voltage of the drive circuit (1-2) is adjustable from 0 to 10V, the current is adjustable from 0 to 30A, and the frequency is adjustable from 0kHz to 5MHz.

3. The high-speed, multi-dimensional spatial light field manipulation device according to claim 1, characterized in that: The pump source (1-3) is a semiconductor laser with output via fiber coupling, with a wavelength range of 300-1100nm selectable; a power range of 0-30W adjustable; a fiber core diameter of 100-400μm selectable; and a numerical aperture of 0.1-0.6 selectable.

4. The high-speed, multi-dimensional spatial light field manipulation device according to claim 1, characterized in that: The collimating lens (2-1) and focusing lens (2-3) are two molded aspherical lenses with a focal length selectable from 1.5 to 18.4 mm and a numerical aperture selectable from 0.15 to 0.7 mm.

5. The high-speed, multi-dimensional spatial light field manipulation device according to claim 1, characterized in that: The cone angle of the cone lens is selectable from 0-40°, the deflection angle is selectable from 0-30°, and the axial thickness is selectable from 0-16mm; Alternatively, the cylindrical lens may include a plano-convex lens or a plano-concave lens. The focal length of the cylindrical lens may be selected from 3 to 1000 mm, the length from 6 to 140 mm, the height from 10 to 100 mm, the radius of curvature from 6.6 to 516.8 mm, the center thickness from 2.3 to 21.6 mm, and the edge thickness from 2 to 3 mm.

6. The high-speed, multi-dimensional spatial light field manipulation device according to claim 1, characterized in that: The laser crystal (3-1) includes a gain crystal, a Raman crystal, and a nonlinear crystal; the gain crystal can be selected from one of Nd:YAG, Nd:GdVO4, Nd:YVO4, Nd:YLF, Yb:YAG, Yb:KGW, Yb:CaF2, Er:YAG, and Tm:YAG; the Raman crystal can be selected from one of YVO4, diamond, Ba(NO3)2, and KGW; and the nonlinear crystal can be selected from one of KTP, KDP, KTA, LiNbO3, LBO, and BBO.

7. The high-speed, multi-dimensional spatial light field manipulation device according to claim 1, characterized in that: The flat cavity formed by coating the surfaces at both ends of the laser crystal (3-1) includes a high-reflectivity film of 99.99% coated on the incident surface of the laser crystal (3-1) for laser wavelengths of 300-2000nm, and a partially transmissive film of 1%-60% coated on the exit surface of the laser crystal (3-1) for laser wavelengths of 300-2000nm.

8. The high-speed, multi-dimensional spatial light field manipulation device according to claim 1, characterized in that: The input mirror (3-2) includes a planar input mirror and a curved input mirror, and the surface of the input mirror (3-2) is coated with a high-reflectivity film selectable for laser wavelengths of 300-2000nm, with a reflectivity of 99.99% and a curvature radius selectable for 20-200mm; the output mirror (3-3) includes a planar output mirror and a curved output mirror, and the surface of the output mirror (3-3) is coated with a partially transmissive film selectable for laser wavelengths of 300-2000nm, with a transmittance selectable for 1%-60% and a curvature radius selectable for 20-200mm.

Images