Integrated high-sensitivity fiber phase modulation device

Abstract

The application provides an integrated high-sensitivity optical fiber phase modulation device, which comprises a device main body, a shell, an optical fiber coupler and a piezoelectric ceramic; the piezoelectric ceramic is fixedly installed on the middle part of the device main body through a piezoelectric ceramic fixing part; an optical fiber groove for disc optical fiber is formed on the upper surface of the device main body and located at the periphery of the piezoelectric ceramic; the optical fiber coupler is fixedly installed on the upper surface of the device main body and located at one side of the piezoelectric ceramic through an optical fiber interface fixing part; the shell is detachably installed on the upper part of the device main body and covers the upper surface of the device main body, the optical fiber interface fixing part, the optical fiber coupler, the piezoelectric ceramic, the optical fiber groove and the piezoelectric ceramic fixing part. The piezoelectric ceramic and the sensitive optical fiber are both encapsulated in the device, so that the length of the optical fiber can be modulated, the high-sensitivity phase modulation is realized, the layout is compact, the integration degree is high, the performance is stable, the portability and the installability are increased.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high-precision weak displacement measurement in space gravitational wave detection, and particularly relates to an integrated high-sensitivity optical fiber phase modulation device. BACKGROUND

[0002] A space gravitational wave detection project inverts a gravitational wave signal through the distance between two freely suspended test masses. In order to achieve the ranging requirement, the laser interferometric measurement system is required to have a displacement measurement precision of the order of picometer in the mHz frequency band. Therefore, the output precision realization of the laser interferometric measurement system is a key link of the entire gravitational wave detection project. At present, the method of laser heterodyne interferometric measurement is generally adopted. After a laser beam is emitted from a laser, it enters an optical platform with better optical performance through a modulation platform. The laser beam passes through a test mass during transmission in the optical platform and forms an interference signal. The interference signal is converted into an electronic signal by a detector and is extracted and analyzed by a phase meter. When the acquisition of the difference frequency signal is realized by connecting an acousto-optic modulator, an additional optical path noise is introduced due to the electronic coupling effect between the acousto-optic modulators. Considering that this part of the optical path is located before the optical platform, it is also referred to as front-end optical path noise. When the measurement precision requirement is better than the nm level in the mHz frequency band, the influence of the front-end optical path noise cannot be ignored.

[0003] In order to compensate for the influence of the front-end optical path noise, a mirror or an optical fiber can be arranged in the optical path. By adjusting the position of the mirror or the length of the optical fiber, phase modulation is realized to compensate for the optical path noise. Compared with introducing a mirror in the optical path, the optical fiber is more flexible in form. It not only can avoid the adjustment error, but also can be directly connected to the optical fiber interface of the rear-end optical platform. Considering that the piezoelectric ceramic has the characteristics of electrical signal and mechanical signal conversion, it is often used for optical fiber phase modulation. That is, the length of the optical fiber is related to the deformation of the piezoelectric ceramic. By changing the voltage of the piezoelectric ceramic, the length of the optical fiber is adjusted to realize the phase modulation of the interference signal. At present, the optical fiber phase modulation device used in the field of front-end optical path noise elimination directly winds and pastes the optical fiber on the circumferential surface of the piezoelectric ceramic in a cylindrical shape. This way, the optical fiber is greatly affected by the external environment. Uneven pasting can cause uneven deformation of the optical fiber, which affects the response accuracy of the device. Therefore, a new piezoelectric ceramic-based optical fiber phase modulation device needs to be developed for the suppression of the front-end optical path noise. SUMMARY

[0004] In view of the technical problems in the prior art, the present application provides an integrated high-sensitivity optical fiber phase modulation device, which connects part of an optical fiber with a piezoelectric ceramic, encapsulates the whole optical fiber, and then connects the whole device into an optical path, so that the actual demand for compensating front-end optical path noise can be met by feeding back the supply voltage of the piezoelectric ceramic through an interference signal, and the measurement accuracy can be effectively ensured, and the device can be widely applied to the fields of optical fiber sensing and front-end optical path noise elimination.

[0005] To solve the above technical problems, the present application provides an integrated high-sensitivity optical fiber phase modulation device, which comprises a device main body, an outer shell, an optical fiber coupler and a piezoelectric ceramic.

[0006] The integrated high-sensitivity optical fiber phase modulation device, wherein: a through hole is vertically and throughly formed in the middle of the device main body; a pair of T-shaped tables are symmetrically arranged in the through hole; the horizontal part of each T-shaped table is connected with the inner wall of the through hole as a whole, and the head of the vertical part is not in contact with the inner wall of the through hole and has a gap; and a semicircular groove for sticking and fixing an optical fiber is formed on the upper surface of the T-shaped table along the optical fiber wiring direction.

[0007] The integrated high-sensitivity optical fiber phase modulation device, wherein: one end of the piezoelectric ceramic fixing part is detachably assembled and fixed with the lower surface of the T-shaped table, and the other end of the piezoelectric ceramic fixing part is a "concave" shaped clamping groove.

[0008] The integrated high-sensitivity optical fiber phase modulation device, wherein: the piezoelectric ceramic is located between the horizontal parts of a pair of T-shaped tables, and the left and right end faces of the piezoelectric ceramic are pasted to the horizontal parts of a pair of T-shaped tables, and the lower part is placed in the clamping groove; electrodes are pasted on the front and back surfaces of the piezoelectric ceramic, and the electrodes are led out to the outside of the optical fiber phase modulation device through wires.

[0009] The integrated high-sensitivity fiber phase modulation device, wherein: the transverse part of the T-shaped table forms a flexible hinge structure, when the electric wire voltage of the front and back surfaces of the piezoelectric ceramic changes, the piezoelectric ceramic is mechanically deformed, the distance between the pair of T-shaped tables changes, and two sections of optical fibers are pasted in the semicircular grooves on the upper surfaces of the pair of T-shaped tables, the length of the suspended section of the optical fibers between the pair of T-shaped tables changes with the position fluctuation of the T-shaped tables.

[0010] The integrated high-sensitivity fiber phase modulation device, wherein: the device main body is also provided with a wire clamping groove on the upper surface between the pair of T-shaped tables.

[0011] The integrated high-sensitivity fiber phase modulation device, wherein: the fiber coupler has a pair, and the optical fiber is wound through the circular fiber groove and then connected to the internal interfaces of the pair of fiber couplers; and the external interfaces of the fiber couplers are used to access any optical path to introduce a section of optical fiber with adjustable length.

[0012] The integrated high-sensitivity fiber phase modulation device, wherein: the bottom of the device main body is also provided with a bottom plate; and the bottom plate is used to support the entire fiber phase modulation device, and the upper surface of the bottom plate is also provided with an avoiding groove for avoiding the motion of the T-shaped table from being disturbed.

[0013] The integrated high-sensitivity fiber phase modulation device, wherein: one side wall of the device main body is also provided with a mounting groove for mounting the fiber interface fixing member; and the fiber interface fixing member is L-shaped, the transverse part of the fiber interface fixing member is arranged in the mounting groove and fixed by bolts, and the longitudinal part of the fiber interface fixing member is also provided with a mounting hole for fixing the fiber coupler.

[0014] The integrated high-sensitivity fiber phase modulation device, wherein: the middle of the fiber groove is provided with a threaded positioning hole, and a circular cover plate is mounted by matching the threaded positioning hole with a fastener; and the circular cover plate is used to cover the fiber groove after the optical fiber is wound, so as to avoid pollution.

[0015] By adopting the above technical scheme, the present application has the following beneficial effects:

[0016] The integrated high-sensitivity fiber phase modulation device has a reasonable structure, is based on a piezoelectric ceramic, constructs a fiber phase modulation device based on the piezoelectric ceramic, and avoids the problem of low adjustment accuracy of a spatial reflecting mirror; the integrated design increases portability, can flexibly connect the fiber phase modulation device into an optical fiber optical path, and reduces the requirement for adjustment accuracy; considering that the fiber deforms with the piezoelectric ceramic, the voltage control sensitivity of the piezoelectric ceramic can affect the sensitivity of the fiber deformation, and the sensitivity of phase modulation can be further improved; the whole device has a compact layout, is flat, has a stable structure, and the height of the fiber coupler is low, so that the fiber can be effectively prevented from being affected by external vibration; compared with pasting a long fiber on the surface of the piezoelectric ceramic, the present application adopts a small section of fiber as a sensitive fiber, can reduce the problem of uneven fiber deformation caused by the pasting process and external disturbance, and improves the accuracy of the device.

[0017] The present application encapsulates the piezoelectric ceramic and the sensitive fiber in one device, can not only realize fiber length modulation and high-sensitivity phase modulation, but also has a compact layout, high integration, stable performance, increased portability and installability.

[0018] The present application takes the spatial gravitational wave detection high-precision weak displacement measurement technology as the background, takes eliminating the front optical path noise of a laser interference measurement system as the purpose, realizes real-time fiber length modulation through the characteristic that the fiber length changes with the external voltage fluctuation of the piezoelectric ceramic, reflects real-time phase modulation in the optical path, and reduces the influence of the optical path noise. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the following specific embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] Figure 1 The present application provides an integrated high-sensitivity fiber phase modulation device.

[0021] Figure 2 The present application provides an integrated high-sensitivity fiber phase modulation device.

[0022] Figure 3 The present application provides an integrated high-sensitivity fiber phase modulation device.

[0023] Figure 4A bottom view of an integrated high-sensitivity fiber optic phase modulation device provided in an embodiment of the present invention;

[0024] Figure 5 A bottom view of an integrated high-sensitivity fiber optic phase modulation device after removing the base plate, provided in an embodiment of the present invention;

[0025] Figure 6 This is a partial structural schematic diagram of an integrated high-sensitivity fiber optic phase modulation device provided in an embodiment of the present invention;

[0026] Figure 7 This is a schematic diagram of the structure of a piezoelectric ceramic fixture for an integrated high-sensitivity fiber optic phase modulation device provided in an embodiment of the present invention;

[0027] Figure 8 This is a schematic diagram of the installation of a piezoelectric ceramic fixture and a piezoelectric ceramic in an integrated high-sensitivity fiber optic phase modulation device provided in an embodiment of the present invention.

[0028] Note:

[0029] 1-Main body of the device; 2-Outer shell; 3-Base plate; 4-Fiber optic interface fastener; 5-Fiber optic coupler; 6-Piezoelectric ceramic; 7-Circular fiber optic groove; 8-T-shaped platform; 81-Semi-circular groove; 82-Fixing groove; 821-Assembly hole; 9-Wire clamping groove; 10-Piezoelectric ceramic fastener; 101-Fixing hole; 102-Card slot; 11-Through hole; 12-Stepped hole bolt. Detailed Implementation

[0030] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] The present invention will be further explained below with reference to specific embodiments.

[0032] like Figures 1-4 As shown in the figure, this embodiment provides an integrated high-sensitivity fiber optic phase modulation device, which includes a device body 1, a shell 2, a base plate 3, a fiber optic interface fixing component 4, a fiber optic coupler 5, a piezoelectric ceramic 6, a T-shaped platform 8, and a piezoelectric ceramic fixing component 10.

[0033] The device body 1 is integrally formed of aluminum material, symmetrical left and right, the upper surface is mainly responsible for optical fiber arrangement, the lower surface is used as support. Among them, the upper surface of the device body 1 is excavated with a circular optical fiber groove 7 for disc optical fiber left and right; the middle of the optical fiber groove 7 is provided with a threaded positioning hole and a circular cover plate is installed through the threaded positioning hole, the circular cover plate can cover the optical fiber groove 7 to avoid the pollution of the optical fiber. The length modulation of the optical fiber is realized by the horizontally placed optical fiber between the two optical fiber grooves 7, for this, the device body 1 is provided with a through hole 11 in the center part; the through hole 11 penetrates the upper and lower end surfaces of the device body 1 along the vertical direction and is internally and symmetrically provided with a pair of T-shaped tables 8; the transverse part of each T-shaped table 8 is integrally connected with the inner wall of the through hole 11 and has a smaller width, the head of the longitudinal part of each T-shaped table 8 is not in contact with the inner wall of the through hole 11 and has a gap, and has a wider width. In order to better fix the position of the optical fiber, a semicircular groove 81 is opened on the upper surface of the T-shaped table 8 along the optical fiber wiring direction, which is used for pasting and fixing the optical fiber, so as to ensure that the final horizontal optical fiber and the bottom surface of the optical fiber groove 7 are located in the same plane. As shown in Figure 6 the lower surface of the T-shaped table 8 is provided with a fixing groove 82 for installing a piezoelectric ceramic fixing part 10, and the groove bottom is matched with a mounting hole 821. The device body 1 is also matched with a wire clamping groove 9 for placing the wire on the upper surface between the pair of T-shaped tables 8.

[0034] As Figures 5-8 , the fixed end of the piezoelectric ceramic fixing part 10 is provided with a fixed hole 101, and the free end is a "concave" shaped clamping groove 102; wherein, the fixed end of the piezoelectric ceramic fixing part 10 is matched with the mounting hole 821 of the fixing groove 82 of the lower surface of the T-shaped table 8 through the fixed hole 101 and a fastener to realize the assembly and fixation of the fixed end of the piezoelectric ceramic fixing part 10 and the lower surface of the T-shaped table 8; the free end of the piezoelectric ceramic fixing part 10 is matched with the piezoelectric ceramic 6 through the clamping groove 102, finally making the piezoelectric ceramic 6 assembled and fixed with the T-shaped table 8 through the piezoelectric ceramic fixing part 10.

[0035] The piezoelectric ceramic 6 is a cuboid, the left and right end surfaces are pasted to the horizontal line part of the pair of T-shaped tables 8, forming left and right direction constraint, the lower part is placed in the "concave" shaped clamping groove 102 of the ceramic fixing part 10, forming vertical direction constraint. The front and rear surfaces of the piezoelectric ceramic 6 are pasted with electrodes, which are connected to the outside of the device through the wire clamping groove 9, realizing real-time voltage control. The transverse part of the T-shaped table 8 is thin, forming a flexible hinge structure; when the voltage of the wire on the surface of the piezoelectric ceramic 6 changes, the piezoelectric ceramic 6 deforms mechanically, causing the distance between the T-shaped tables 8 to change; because the two optical fibers are tightly pasted in the semicircular groove 81 on the surface of the T-shaped table 8, the length of the suspended optical fiber will change with the position fluctuation of the T-shaped table 8.

[0036] To encapsulate the entire optical fiber within the device and facilitate direct connection to the optical fiber phase modulation device in the optical path, two rectangular mounting slots are provided at one end of the main body 1 for mounting the optical fiber interface fixing piece 4. The optical fiber interface fixing piece 4 is L-shaped; its horizontal portion is placed within the mounting slot and secured with bolts, while its vertical portion has a circular mounting hole for mounting the optical fiber coupler 5, which is also secured with bolts. The internal optical fiber is wound through the optical fiber slot 7 and its two ends are connected to the internal interfaces of the two optical fiber couplers 5 respectively. The external interfaces of the optical fiber couplers 5 can be used to connect to any optical path, thus achieving the purpose of introducing an adjustable-length optical fiber into any optical path.

[0037] The outer casing 2 covers the upper part of the main body 1 of the device and is fixed by three stepped hole bolts 12. It can both protect the internal optical fiber from interference from the external environment and improve the portability of the device.

[0038] The bottom of the main body 1 of the device is provided with four threaded holes for fixing the base plate 3; the base plate 3 supports the entire device, and in order to avoid interference with the movement of the T-shaped platform 8, a square clearance groove is specially opened on the upper surface of the base plate 3.

[0039] To test the performance of the invented fiber optic phase modulation device, an external piezoelectric controller is needed to modulate the parameters of the piezoelectric ceramic 6. For example, in this invention, the power supply interface is designed as a Lemo to BNC interface, and the Lemo interface is connected to the digital piezoelectric controller operating module. According to the principle of laser differential interferometry, the phase of the interference signal... The relationship with the optical path s is as follows:

[0040]

[0041] Here, λ is the wavelength of light. To calibrate the performance of the fiber optic phase modulation device, i.e., to calibrate the relationship between the phase and the piezoelectric controller voltage, the voltage can be adjusted in real time, and the corresponding phase changes of the interference signal can be recorded. For example, when the voltage increases, the piezoelectric ceramic elongates, and the optical fiber elongates. Since the optical path length s is proportional to the optical fiber length, this leads to an increase in the optical path and the phase. Considering that the phase changes with a period of 2π, recording the voltage value corresponding to one phase period allows us to calibrate the coupling coefficient between the two. The specific coupling coefficient is related to the structural parameters of the device, and will not be discussed in detail here.

[0042] The present invention has a reasonable and compact structure. It establishes a connection between part of the optical fiber and the piezoelectric ceramic, encapsulates the entire optical fiber, and then connects the entire device into the optical path. By feeding back the power supply voltage of the piezoelectric ceramic through the interference signal, the actual need for compensating the front-end optical path noise can be solved, and the measurement accuracy can be effectively guaranteed. It can be widely used in the fields of optical fiber sensing and front-end optical path noise elimination.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An integrated high-sensitivity fiber optic phase modulation device, characterized in that... The fiber phase modulation device includes a main body (1), a shell (2), a fiber coupler (5), and a piezoelectric ceramic (6). The piezoelectric ceramic (6) is fixedly installed in the middle of the main body (1) of the device by a piezoelectric ceramic fastener (10). The upper surface of the main body (1) of the device has fiber grooves (7) for coiling optical fibers that are matched around the piezoelectric ceramic (6). On the upper surface of the main body (1) of the device, a fiber optic coupler (5) is fixedly installed on one side of the piezoelectric ceramic (6) via a fiber optic interface fixing piece (4). The main body (1) of the device has a through hole (11) extending vertically through the middle; a pair of T-shaped platforms (8) are symmetrically arranged inside the through hole (11). The transverse portion of each T-shaped platform (8) is integrally connected to the inner wall of the through hole (11), and the head of the longitudinal portion does not contact the inner wall of the through hole (11) and leaves a gap. The upper surface of the T-shaped platform (8) is provided with a semi-circular groove (81) for pasting and fixing optical fibers along the direction of optical fiber cabling. The outer shell (2) is detachably installed on the upper part of the device body (1) and covers the upper surface of the device body (1), the fiber optic interface fixing component (4), the fiber optic coupler (5), the piezoelectric ceramic (6), the fiber optic groove (7) and the piezoelectric ceramic fixing component (10).

2. The integrated high-sensitivity fiber phase modulation device as described in claim 1, characterized in that: One end of the piezoelectric ceramic fastener (10) is detachably assembled and fixed to the lower surface of the T-shaped platform (8), and the other end of the piezoelectric ceramic fastener (10) is a "U"-shaped slot (102).

3. The integrated high-sensitivity fiber phase modulation device as described in claim 2, characterized in that: The piezoelectric ceramic (6) is located between the transverse portions of the pair of T-shaped platforms (8), with its left and right end faces attached to the transverse portions of the pair of T-shaped platforms (8), and its lower part placed in the slot (102); the front and rear surfaces of the piezoelectric ceramic (6) are covered with electrodes, and the electrodes are led out to the outside of the optical fiber phase modulation device via wires.

4. The integrated high-sensitivity fiber phase modulation device as described in claim 3, characterized in that: The transverse portion of the T-shaped platform (8) forms a flexible hinge structure. When the voltage of the wires on the front and rear surfaces of the piezoelectric ceramic (6) changes, the piezoelectric ceramic (6) undergoes mechanical deformation, causing the spacing between the pair of T-shaped platforms (8) to change. Two optical fibers are pasted in the semi-circular groove (81) on the upper surface of the pair of T-shaped platforms (8). The length of the suspended optical fiber between the pair of T-shaped platforms (8) will change with the position fluctuation of the T-shaped platform (8).

5. The integrated high-sensitivity fiber phase modulation device as described in claim 3, characterized in that: The main body (1) of the device is also provided with a wire slot (9) for placing wires on its upper surface located between the pair of T-shaped platforms (8).

6. The integrated high-sensitivity fiber phase modulation device as described in claim 1, characterized in that: The fiber coupler (5) has a pair. After the fiber is wound through the fiber groove (7), the two ports are respectively connected to the internal interfaces of the pair of fiber couplers (5). The external interface of the fiber coupler (5) is used to access any optical path so as to introduce a section of fiber with adjustable length into any optical path.

7. The integrated high-sensitivity fiber phase modulation device as described in claim 1, characterized in that: The bottom of the main body (1) of the device is also fitted with a base plate (3); the base plate (3) is used to support the entire fiber phase modulation device, and its upper surface is fitted with a relief groove to avoid interference with the movement of the T-shaped stage (8).

8. The integrated high-sensitivity fiber phase modulation device as described in claim 1, characterized in that: The main body (1) of the device has a mounting groove on one side wall for installing the fiber optic interface fixing component (4); the fiber optic interface fixing component (4) is L-shaped, with its horizontal part placed in the mounting groove and fixed by bolts, and its vertical part having a mounting hole for fixing the fiber optic coupler (5).

9. The integrated high-sensitivity fiber phase modulation device as described in claim 1, characterized in that: The optical fiber slot (7) has a threaded positioning hole in the middle, and a circular cover plate is installed through the threaded positioning hole and fasteners; the circular cover plate is used to cover the optical fiber slot (7) after the optical fiber is coiled to avoid contamination.

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