Miniaturized polarization-independent spatial separation bi-pass acousto-optic frequency shift system and method

Abstract

The invention relates to a miniaturized polarization-independent spatial separation bi-pass acousto-optic frequency shift system, and the system comprises an acousto-optic modulator which is used for carrying out the frequency modulation of incident target laser, and obtaining first diffraction light which is transmitted along one side of a lens; modulating the first diffracted light returned by the lens to obtain second diffracted light; the lens is used for converging the first diffracted light into parallel light; the pyramid reflector is used for reflecting an incident light path of the parallel light; the reflecting mirror is used for receiving and outputting the second diffracted light; and the six-dimensional adjusting frame is used for adjusting the lens or the pyramid reflector, so that the diffraction efficiency of the target laser penetrating through the acousto-optic modulator is maximum. According to the invention, the emitted light is separated when encountering the emergent space through the reasonably designed light path, so that the optical power loss caused by the polarization state change is effectively avoided, the efficient acousto-optic modulation can be realized in different polarization states, and the stability and flexibility of the system are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of acousto-optic frequency shifting, and in particular to a miniaturized polarization-independent spatially separated dual-pass acousto-optic frequency shifting system and method. Background Art

[0002] When using the acousto-optic frequency shifting technology, since the frequency change of the acousto-optic modulator (AOM) will change the direction of the diffracted light, a double-pass acousto-optic frequency shifting (AOM double pass) technical structure is usually used in the integrated optical path to ensure that the direction of light remains unchanged when the AOM changes the frequency. The traditional method usually uses a quarter-wave plate and a polarization beam splitter (PBS) to achieve AOM double pass. However, this method has two disadvantages. The first is that the system is sensitive to the polarization state of light, and changes in the polarization state will directly affect the system performance. The second is that the reflected light and the outgoing light on the crystal surface of the AOM may cause signal attenuation and introduce phase noise when they co-path. Therefore, it is particularly important to develop a polarization-independent spatially separated AOM doublepass system. Summary of the invention

[0003] To solve the problems raised by the background technology, a first aspect of the present invention provides a miniaturized polarization-independent spatially separated dual-pass acousto-optic frequency shifting system, comprising: an acousto-optic modulator, used to frequency modulate an incident target laser to obtain a first diffracted light propagating along one side of a lens; and modulate the first diffracted light returned by the lens to obtain a second diffracted light; a lens, used to converge the first diffracted light into parallel light; a corner cube reflector, used to reflect the incident light path of the parallel light; a reflector, used to receive and output the second diffracted light; and a six-dimensional adjustment frame, used to adjust the lens or the corner cube reflector to maximize the diffraction efficiency of the target laser through the acousto-optic modulator.

[0004] In some embodiments of the present invention, the AOM and the retroreflector are located on both sides of the lens.

[0005] In some embodiments of the present invention, the present invention further includes: a first light blocking plate for blocking zero-order light of the incident target laser.

[0006] In some embodiments of the present invention, the device further comprises: a second light blocking plate for emitting zero-order light of the second diffracted light.

[0007] In some embodiments of the present invention, the focal length of the lens is 50MM.

[0008] In some embodiments of the present invention, the surface finish of the corner reflector is 40 / 20 to 60 / 40.

[0009] In some embodiments of the present invention, the corner reflector is fixed by a metal gasket and ultraviolet glue.

[0010] The second aspect of the present invention provides a layered glue coating method for an optical element, comprising: determining the optical path adjustment value of the optical element to maximize the diffraction efficiency; placing a metal gasket on a metal base; fixing the optical element to the metal gasket by ultraviolet glue; and curing the metal gasket and the metal base plate by AB glue.

[0011] The third aspect of the present invention provides a miniaturized polarization-independent spatially separated dual-pass acousto-optic frequency shifting system, comprising: an acousto-optic modulator, which performs frequency modulation on an incident target laser to obtain a first diffracted light propagating along one side of a lens; and modulates the first diffracted light returned by the lens to obtain a second diffracted light; a lens converges the first diffracted light into parallel light; a corner cube reflector reflects the incident light path of the parallel light; a reflector receives and outputs the second diffracted light; and a six-dimensional adjustment frame adjusts the lens or the corner cube reflector to maximize the diffraction efficiency of the target laser through the acousto-optic modulator.

[0012] The beneficial effects of the present invention are: (1) Polarization independence: By rationally designing the optical path, the optical power loss caused by the change of polarization state is effectively avoided, ensuring efficient acousto-optic modulation under different polarization states; (2) Spatial separation: The spatial separation of reflected light and emitted light improves the stability and flexibility of the system, avoiding the influence of the co-path of the reflected light and emitted light in the AOM; (3) System stability: The use of a corner cube reflector allows the optical path to return in complete parallelism, which is more stable than using two reflectors for adjustment. At the same time, the innovative layered glue coating method is designed to effectively avoid the influence of stress changes caused by glue curing when the optical element is fixed to the metal, which also improves the stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A schematic diagram of the basic structure of a miniaturized polarization-independent spatially separated dual-pass acousto-optic frequency shifting system in some embodiments of the present invention; Figure 2 A side view of a miniaturized polarization-independent spatially separated dual-pass acousto-optic frequency shifting system in some embodiments of the present invention; Figure 3 A top view of a miniaturized polarization-independent spatially separated dual-pass acousto-optic frequency shifting system in some embodiments of the present invention; Figure 4 Schematic diagram of the principle of the layered glue coating method of the optical element in some embodiments of the present invention; Figure 5 Schematic diagram of the process of layered gluing of optical elements in some embodiments of the present invention.

[0014] Reference numerals 10. acousto-optic modulator; 20. lens; 30. corner cube reflector; 40. reflector; 50. first light baffle; 60. Second light barrier; DETAILED DESCRIPTION The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0015] refer to Figures 1 to 3 In a first aspect of the present invention, a miniaturized polarization-independent spatially separated dual-pass acousto-optic frequency shifting system is provided, comprising: an acousto-optic modulator 10, used for frequency modulating an incident target laser to obtain a first diffracted light propagating along one side of a lens 20; and modulating the first diffracted light returned by the lens 20 to obtain a second diffracted light; the lens 20, used for converging the first diffracted light into parallel light; a corner reflector 40, used for reflecting the incident light path of the parallel light; a reflector 40, used for receiving and outputting the second diffracted light; and a six-dimensional adjustment frame, used for adjusting the lens 20 or the corner reflector 40 to maximize the diffraction efficiency of the target laser through the acousto-optic modulator 10.

[0016] It can be understood that the incident light takes the first-order diffraction light and passes through the center of the lens height, and then is reflected to the upper part of the lens by raising the light path through the corner reflector. Since the lens has the function of converging light, the position of the upper light at the lens focus AOM is the same as the light height of the incident light again. After the light passes through the AOM again, the light height will be lower than the light height of the incident light, and the outgoing light can be directly reflected by a reflector. An acousto-optic modulator is a device that uses the interaction between sound waves and light waves to modulate optical signals. This modulator modulates the light beam by generating sound waves in crystal or glass materials, thereby changing the refractive index of the material. Acousto-optic modulators can be used to control the intensity, frequency or direction of laser beams, and are widely used in optical communications, optical signal processing, laser technology and other fields.

[0017] refer to Figure 1 and Figure 2 In some embodiments of the present invention, the AOM 10 and the retroreflector 40 are located on both sides of the lens 20 .

[0018] Specifically, the light entering the AOM takes the first-order diffraction light and is incident on one side of the lens (not the center), is converged into parallel light by the lens, and after reflection by the corner reflector, the light returns to the AOM along the original path, and the light passing through the AOM again takes the first-order diffraction light, to ensure that the light passing through the AOM twice returns along the original path in the top view, and the zero-order light of the incident light and the zero-order light of the reflected light are respectively blocked by the first light baffle 50 (light baffle 1 shown in the figure) and the second light baffle 60 (light baffle 2 shown in the figure) to prevent them from affecting the light path outside the system.

[0019] In the figure, the distance between the AOM 10 and the lens 20 is f, and the distance between the corner reflector and the lens is f, that is, the AOM and the corner reflector are located on a focal plane that is 1 times the focal length of the lens.

[0020] In one embodiment of the present invention, a light source is a laser with a wavelength of 397nm, a maximum output power of 2W, and output through an optical fiber. The AOM is an AOM with a wavelength of 397nm, a frequency of 100Mhz, a maximum aperture of 1mm, and a maximum power of 2W. The lens is a plano-convex lens with a diameter of 10mm, a focal length of 50mm, and a wavelength range of 350-700nm. The corner reflector is a corner reflector made of optical glass, with a diameter of 10mm, a diameter tolerance of +0.0 / -0.1mm, a height of 9mm, a height tolerance of ±0.2mm, and a surface finish of 40 / 20-60 / 40. Insert the optical fiber into the adjustable focus collimator, and adjust the collimator to obtain a collimated parallel light with a spot diameter of ≤1mm, which is reflected by a right-angle prism reflector into the AOM. Connect the AOM to the RF source, and you can see the +1-order diffraction light. Use the precision six-dimensional adjustment frame to adjust the right-angle prism reflector to maximize the diffraction efficiency of the first pass. Use the light baffle 1 to block the zero-order light, and then use the layered glue coating method to fix the lens and the corner cube reflector to ensure that the diffraction efficiency of the +1-order diffraction light passing through the AOM for the second time is the maximum. Use the light baffle 2 to block the return zero-order light, and use the reflector to reverse the +1-order diffraction light that passes the second time. At this time, the 397nm light with a frequency shift of +200Mhz is obtained.

[0021] In actual operation, since this system has high requirements for the accuracy of the miniaturized optical path, we use a precision six-dimensional adjustment frame for adjustment, which can be adjusted in x, y, z, θ x ,θ y ,θ z The six directions are precisely adjusted to ensure that the diffraction efficiency of light passing through the AOM is maximized. The specific method is to first use a small amount of UV glue to stick the optical element to be installed on the tooling connected to the precision six-dimensional adjustment frame, and then use the adjustment frame to maximize the diffraction efficiency of light passing through the AOM, and then use an appropriate amount of glue to fix the optical element to the metal base plate. After that, the adjustment frame and the optical element are separated. Since the fixing method of the optical element and the base plate is more secure, the separation process will not affect the direction of the optical element.

[0022] It can be understood that the present invention provides a miniaturized polarization-independent spatially separated dual-pass acousto-optic frequency shifting system, which ensures efficient acousto-optic modulation under different polarization states; spatially separates the reflected light and the outgoing light on the crystal surface inside the AOM to avoid the negative impact of their common path; and improves the stability of the system through material selection and process.

[0023] Example 2 refer to Figure 4 and Figure 5 According to a second aspect of the present invention, a layered glue coating method for an optical element is provided, comprising: S100. determining the optical path adjustment value of the optical element to maximize the diffraction efficiency; S200. placing a metal gasket on a metal base; S300. fixing the optical element and the metal gasket by ultraviolet glue; S400. curing the metal gasket and the metal base plate by AB glue.

[0024] Specifically, when realizing the connection between the optical element and the metal base plate, UV glue is first applied between the optical element and the metal, and then cured with a UV lamp. However, when there is a certain angle between the optical element and the metal base plate, the stress change of the UV glue during the curing process will cause the optical element to move slightly, resulting in the deflection of the light direction, and then resulting in a decrease in diffraction efficiency, which is unacceptable in precision optical systems. Therefore, this system innovatively designed a new glue coating method - layered glue coating. In this system, the most important factor affecting accuracy is the corner conical reflector, so the corner conical reflector is used as an example. The schematic diagram of the layered glue coating process is shown below. Figure 4 As shown in the figure, when the optical path is adjusted to the point where the diffraction efficiency is maximum, the metal gasket is placed on the metal base, and the reflector and a thin metal gasket are fixed with UV glue. At this time, the reflector and the metal gasket can be regarded as a whole. Since there is no angle deviation between the metal gasket and the metal base, AB glue can be used for curing directly. During the curing process, the metal gasket and the metal base are completely fitted, so the angle and position of the reflector will not change, and the direction of the reflected light will not be affected. Experiments have shown that this layered glue coating method can greatly improve the stability of the miniaturized optical path.

[0025] In the third aspect of the present invention, a miniaturized polarization-independent spatially separated dual-pass acousto-optic frequency shifting method is provided, comprising: an acousto-optic modulator, which performs frequency modulation on an incident target laser to obtain a first diffracted light propagating along one side of a lens; and modulates the first diffracted light returned by the lens to obtain a second diffracted light; a lens converges the first diffracted light into parallel light; a corner-cone reflector reflects the incident light path of the parallel light; a reflector receives and outputs the second diffracted light; and a six-dimensional adjustment frame adjusts the lens or the corner-cone reflector to maximize the diffraction efficiency of the target laser through the acousto-optic modulator.

[0026] The flow chart and block diagram in the accompanying drawings illustrate the possible architecture, function and operation of the system, method and computer program product according to various embodiments of the present disclosure. In this regard, each box in the flow chart or block diagram can represent a module, a program segment or a part of a code, and the module, the program segment or a part of the code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should be noted that each box in the block diagram and / or flow chart, and the combination of the boxes in the block diagram and / or flow chart can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0027] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A miniaturized polarization-independent spatially separated dual-pass acousto-optic frequency shifting system, characterized in that: include: an acousto-optic modulator, used for frequency modulating the incident target laser to obtain a first diffracted light propagating along one side of the lens; and modulating the first diffracted light returned by the lens to obtain a second diffracted light; A lens, used for converging the first diffracted light into parallel light; A corner reflector is used to reflect the incident light path of parallel light; A reflector, used for receiving and outputting the second diffracted light; The six-dimensional adjustment frame is used to adjust the lens or the corner cone reflector so as to maximize the diffraction efficiency of the target laser through the acousto-optic modulator.

2. The miniaturized polarization-independent spatially separated dual-pass acousto-optic frequency shifting system according to claim 1, characterized in that: The acousto-optic modulator and the corner cube reflector are located on both sides of the lens.

3. The miniaturized polarization-independent spatially separated dual-pass acousto-optic frequency shifting system according to claim 1, characterized in that: The acousto-optic modulator and the corner cube reflector are respectively located at the focal length positions on both sides of the lens.

4. The miniaturized polarization-independent spatially separated dual-pass acousto-optic frequency shifting system according to claim 1, characterized in that: Also includes: The first light blocking plate is used to block the zero-order light of the incident target laser.

5. The miniaturized polarization-independent spatially separated dual-pass acousto-optic frequency shifting system according to claim 1, characterized in that: Also includes: The second light blocking plate is used for the zero-order light of the emitted second diffracted light.

6. The miniaturized polarization-independent spatially separated dual-pass acousto-optic frequency shifting system according to claim 1, characterized in that: The focal length of the lens is 50MM.

7. The miniaturized polarization-independent spatially separated dual-pass acousto-optic frequency shifting system according to claim 1, characterized in that: The surface finish of the corner reflector is 40 / 20 to 60 / 40.

8. The miniaturized polarization-independent spatially separated dual-pass acousto-optic frequency shifting system according to claim 1, characterized in that: The corner reflector is fixed by a metal gasket and ultraviolet glue.

9. A layered gluing method for optical elements, characterized in that: include: Determine the optical path adjustment value of the optical element to maximize the diffraction efficiency; Place the metal spacer on the metal base; Fixing the optical element to the metal gasket by ultraviolet glue; The metal gasket and the metal base plate are cured by AB glue.

10. A miniaturized polarization-independent spatially separated dual-pass acousto-optic frequency shifting method, characterized in that: include: an acousto-optic modulator, which performs frequency modulation on the incident target laser to obtain a first diffracted light propagating along one side of the lens; The first diffracted light returned by the lens is modulated to obtain the second diffracted light; the lens converges the first diffracted light into parallel light; the corner cube reflector reflects the incident light path of the parallel light; the reflector receives and outputs the second diffracted light; the six-dimensional adjustment frame adjusts the lens or the corner cube reflector to maximize the diffraction efficiency of the target laser through the acousto-optic modulator.

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