Tunable optical filter

Abstract

The application provides a tunable optical filter. The tunable optical filter comprises a double-core fiber collimator, a first prism, a transmission grating, a second prism and a tunable mirror arranged in sequence. The double-core fiber collimator and the tunable mirror are arranged along an axis of the tunable optical filter. The tunable mirror is used for reflecting a light beam output forward by the second prism, so that the light beam returns to the double-core fiber collimator and is output outward through an output pigtail of the double-core fiber collimator. In operation, different wavelengths of light beams can be output by adjusting a reflection angle of the tunable mirror, so that a tunable filtering function is realized. The tunable optical filter has a small number of components, and each device is arranged along the axis, so that the tunable optical filter has a small volume and is convenient to debug.

Description

Technical Field

[0001] This application relates to the field of optical filtering technology, and in particular to an adjustable optical filter. Background Technology

[0002] A traditional tunable filter, as shown in CN202182973U, includes a signal input terminal, a signal output terminal, a focusing element, and a grating. Along the optical path are input and output collimators, a first grating, a first reflector, a beam expander, a second grating, and a second reflector. The first reflector is rotatable; wavelength selection is achieved by changing the incident angle between the first and second gratings using this rotatable mirror. This type of tunable filter has complex components and a convoluted optical path, causing numerous inconveniences in manufacturing and assembly. Summary of the Invention

[0003] To address the aforementioned technical problems, this application provides an adjustable optical filter with a simple structure that is easy to adjust and assemble.

[0004] An adjustable optical filter includes a dual-core fiber collimator, a first prism, a transmission grating, a second prism, and an adjustable mirror arranged sequentially from front to back; the dual-core fiber collimator and the adjustable mirror are both arranged along the axis of the adjustable optical filter. The dual-core fiber collimator is used to collimate the optical signal input from an input pigtail and output a collimated beam that propagates along the axis. The first prism is used to deflect the collimated beam into a beam that forms a first angle with the axis; The transmissive grating is used to split the beam output from the first prism; The second prism is used to deflect the light beam output by the transmissive grating so that it continues to travel along the axis; The adjustable reflector is used to reflect the light beam output forward by the second prism, so that the light beam returns backward to the dual-core fiber collimator and is output outward through an output pigtail of the dual-core fiber collimator; during operation, the reflection angle of the adjustable reflector can be adjusted to output light beams of different wavelengths, thereby realizing the adjustable filtering function.

[0005] In one embodiment, the dual-core fiber collimator, the first prism, the transmission grating, the second prism, and the adjustable mirror are all arranged on the axis.

[0006] In one embodiment, the surface of the first prism facing the transmissive grating and the surface of the second prism facing the transmissive grating are both perpendicular to the axis.

[0007] In one embodiment, the cross-sections of the first prism and the second prism are both isosceles triangles.

[0008] In one embodiment, the apex angle of the first prism and the apex angle of the second prism are located on the same side of the axis.

[0009] In one embodiment, the adjustable optical filter is linear, the axis is a straight line extending in a straight line, and the first included angle is between 43 degrees and 51 degrees.

[0010] In one embodiment, the dual-core fiber collimator is installed in a first encapsulation tube, the first prism, the transmissive grating, and the second prism are housed in a second encapsulation tube, and one end of the second encapsulation tube is attached to the first encapsulation tube, and the adjustable reflector is attached to the other end of the second encapsulation tube.

[0011] In one embodiment, the second encapsulation tube is an eccentric glass tube.

[0012] In one embodiment, a carrier plate is further included, one side of which is fixed to the second encapsulation tube, and the first prism, the transmissive grating, and the second prism are fixed to the other side of the carrier plate.

[0013] In one embodiment, the adjustable reflector is mounted on a base, and the adjustable reflector is a microelectromechanical reflector.

[0014] As can be seen from the above technical solution, this application has at least the following advantages and positive effects: This application provides an adjustable optical filter with relatively simple components. The dual-core fiber collimator and the adjustable mirror are both arranged along the axis of the adjustable optical filter in a linear design, which has the advantages of small size and easy manufacturing and adjustment. Attached Figure Description

[0015] Figure 1 A perspective view of an adjustable optical filter according to a preferred embodiment of this application; Figure 2 According to Figure 1 A cross-sectional view of the adjustable optical filter shown; Figure 3 According to Figure 1 The optical path diagram of the adjustable optical filter is shown below; Figure 4 According to Figure 1 A cross-sectional view of the adjustable optical filter from another angle; Figure 5 for Figure 1The diagram shows the optical path of the adjustable optical filter from another angle.

[0016] The reference numerals in the attached figures are explained as follows: 10, Adjustable optical filter; 11, Dual-core fiber collimator; 111, Input pigtail; 112, Output pigtail; 113, Two-hole tube; 114, Collimating lens; 12, First prism; 121, Incident surface; 122, First surface; 13, Transmission grating; 14, Second prism; 141, Second surface; 15, Adjustable mirror assembly; 151, Adjustable mirror; 152, Base; 153, Third encapsulation tube; 16, First encapsulation tube; 17, Second encapsulation tube; 18, Carrier plate; 21, 22, 23, 24, Beam. Detailed Implementation

[0017] Typical embodiments embodying the features and advantages of this application will be described in detail in the following description. It should be understood that this application can have various variations in different embodiments, all of which do not depart from the scope of this application, and the descriptions and illustrations therein are for illustrative purposes only and not intended to limit this application.

[0018] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and 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, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0019] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection. They can refer to a mechanical connection or an electrical connection. They can refer to a direct connection or an indirect connection through an intermediate medium, and they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0020] Reference Figure 1and Figure 2 A preferred embodiment of this application provides an adjustable optical filter. The adjustable optical filter 10 includes a dual-core fiber collimator 11, a first prism 12, a transmission grating 13, a second prism 14, and an adjustable reflector 151 arranged sequentially. The input optical signal enters the dual-core fiber collimator 11, becomes a collimated beam, is deflected by the first prism 12, dispersed by the transmission grating 13, and then deflected by the second prism 14 before incident on the adjustable reflector 151. Only optical signals that meet the reflection angle condition of the adjustable reflector 151 can return to the dual-core fiber collimator 11 along the original path.

[0021] Within the aforementioned adjustable optical filter 10, the dual-core fiber collimator 11 and the adjustable mirror are both arranged along the axis L of the adjustable optical filter 10. The optical axes of the dual-core fiber collimator 11, the transmission grating 13, and the adjustable mirror 151 coincide or are parallel to each other, and the external shape of the adjustable optical filter 10 is linear. Compared to conventional adjustable optical filters, the adjustable optical filter 10 of this embodiment has each optical element arranged along the axis L of the adjustable optical filter in a linear distribution, resulting in a smaller volume and easier assembly and debugging. It is worth mentioning that the arrangement of optical elements along the axis L in this application does not mean that the optical elements are symmetrically distributed vertically along the axis L, but rather that the optical elements are generally arranged on the axis L, but each optical element can be offset vertically upwards or downwards by a small distance according to actual needs.

[0022] Specifically, in this embodiment, the dual-core fiber collimator 11 includes an input pigtail 111, an output pigtail 112, a dual-aperture tube 113, and a collimating lens 114. The input pigtail 111 is used to input optical signals with multiple different wavelengths. The output pigtail 112 is used to output optical signals with the desired wavelength. The dual-aperture tube 113 is used to fix the input pigtail 111 and the output pigtail 112. Preferably, the end faces of the input pigtail 111 and the output pigtail 112 are located at the front focal plane of the collimating lens 114, thus minimizing the overall optical system loss.

[0023] The dual-core fiber collimator 11 is used to collimate the optical signal input from the input pigtail 111 and output a collimated beam 21 that propagates along the axis L. It is worth mentioning that in this preferred embodiment, the collimated beam 21 is described as propagating parallel to the axis L, while in other possible embodiments, the collimated beam 21 may have a very small angle with the axis L, for example, within 3 degrees.

[0024] The dual-core fiber optic collimator 11 is preferably installed within a first encapsulation tube 16. Specifically, the collimating lens 114 is housed within the first encapsulation tube 16. The front end of the dual-hole tube 113 is sealed to the first encapsulation tube 16. The first encapsulation tube 16 can be a glass tube or a plastic tube. Preferably, the axis of the dual-core fiber optic collimator 11 and the axis of the first encapsulation tube 16 are collinear.

[0025] like Figure 3 As shown, the first prism 12 is used to deflect the forward path of the collimated beam 21. The collimated beam 21 enters from the rear side of the first prism 12 and exits from the front side, deflecting the collimated beam 21 advancing along the axis into a beam 22 forming a first angle b with the axis L, wherein the first angle b is preferably between 43 degrees and 51 degrees. The cross-sectional shape of the first prism 12 is preferably an isosceles triangle. One side of the isosceles triangle is close to the dual-core fiber collimator 11, and the other side is close to the transmissive grating 13. The side side close to the dual-core fiber collimator 11 is the incident surface 121 of the first prism 12, and the other side side close to the transmissive grating 13 is the exit surface (first surface 122) of the first prism 12. The collimated beam 21 enters from the incident surface 121 and exits from the first surface 122, wherein the first surface 122 is preferably perpendicular to the axis L.

[0026] Please also refer to Figure 3 Specifically, in this embodiment, the collimated beam 21 is parallel to the axis L of the adjustable optical filter 10. Therefore, the incident angle α of the collimated beam 21 on the incident surface 121 is equal to the apex angle of the first prism 12. The incident angle α of the collimated beam 21 is preferably between 45 degrees and 55 degrees. Therefore, the apex angle of the first prism 12 is also preferably set to between 45 degrees and 55 degrees.

[0027] The first prism 12 is preferably coated with an anti-reflection film (not shown) to reduce light energy loss. The anti-reflection film can enhance the transmittance of light.

[0028] The transmissive grating 13 is used to split the beam 22 output from the first prism 12. The beam 22 is incident on the transmissive grating 13 and is transmitted through the transmissive grating 13 to produce a beam 23. The beam 23 has been split into multiple beams of different wavelengths.

[0029] The cross-sectional shape of the second prism 14 is preferably an isosceles triangle. The apex angle of the second prism 14 and the apex angle of the first prism 12 are preferably located on the same side of the axis L (from...). Figure 3 (Look at the upper side of axis L). The second prism 14 can also reduce light energy loss by coating with an anti-reflective coating.

[0030] The side of the second prism 14 closest to the transmission grating 13 is a second surface 141, which is perpendicular to the axis L. A beam 23 passing through the transmission grating 13 is incident on the second prism 14, preferably at an angle of incidence between 43 and 51 degrees. The second prism 14 deflects the beam 23 output from the transmission grating 13 into a beam 24 that continues to propagate forward along the axis L.

[0031] Since the second surface 141 is perpendicular to the axis L, the beam 24 propagates parallel to the axis L. Therefore, the exit angle d of the beam 24 is equal to the apex angle of the second prism 14. Specifically, in this embodiment, the exit angle d of the beam 24 is preferably between 61 degrees and 73 degrees, and the apex angle of the second prism 14 is also preferably between 61 degrees and 73 degrees.

[0032] Therefore, as the beam 21 passes through the first prism 12, the transmission grating 13, and the second prism 14 in sequence, the propagation direction of the beam 21 remains essentially unchanged; only the exit position of the beam 24 changes, causing dispersion of the beam 24. Thus, the first prism 12, the transmission grating 13, and the second prism 14 constitute a dispersive assembly.

[0033] The first prism 12, the transmission grating 13, and the second prism 14 are preferably housed in a second encapsulation tube 17, thereby fixing the relative positions of their dispersive components.

[0034] Please see Figure 4 The aforementioned adjustable optical filter preferably also includes a carrier plate 18. The first prism 12, the transmissive grating 13, and the second prism 14 are fixed to the upper side of the carrier plate 18. The lower side of the carrier plate 18 is fixed to the second encapsulation tube 17, providing a stable mounting surface for the first prism 12, the transmissive grating 13, and the second prism 14. This allows for easy assembly by first fixing the first prism 12, the transmissive grating 13, and the second prism 14 integrally onto the carrier plate 18, and then positioning and fixing the carrier plate 18 to the second encapsulation tube 17, facilitating assembly and accurate alignment.

[0035] Both the first encapsulation tube 16 and the second encapsulation tube 17 extend along the axial direction L. Specifically, the second encapsulation tube 17 is preferably an eccentric glass tube. If it is found that the optical axis position of the dispersive component needs to be adjusted during assembly, the relative position between the dispersive component and the collimating lens 114 can be easily adjusted by rotating the second encapsulation tube 17, thereby achieving the purpose of adjusting the optical axis position of the dispersive component.

[0036] The rear end of the first encapsulation tube 16 is sealed together with the front end of the second encapsulation tube 17. The diameter of the second encapsulation tube 17 is preferably larger than the diameter of the first encapsulation tube 16, and the thickness of the second encapsulation tube 17 is also preferably larger than the thickness of the first encapsulation tube 16, so as to ensure that the rear end of the first encapsulation tube 16 can be sealed together with the front end of the second encapsulation tube 17 to prevent external dust from entering.

[0037] The adjustable reflector assembly 15 is preferably a microelectromechanical system (MEMS), which includes an adjustable reflector 151, a base 152, and a third encapsulation tube 153. The adjustable reflector 151 and the base 152 are hermetically mounted within the third encapsulation tube 153.

[0038] The adjustable reflector 151 is mounted on the base 152. By adjusting the angle of the adjustable reflector 151, the propagation direction of the reflected light can be changed. Please refer to [link / reference]. Figure 5 The adjustable reflector 151 can be pressed... Figure 5 The rotation of the indicator changes the reflection angle of the incident light, allowing light of a specific wavelength to be reflected and reflected back through the second prism 14, the transmission grating 13, the first prism 12, and the collimating lens 114 before entering the output fiber 112. The light is then output outward through the output fiber 112, thus achieving the filtering function.

[0039] The base 152 of the adjustable reflector assembly 15 is horizontally aligned with the dispersive component, and the third encapsulation tube 153 is horizontally attached to the other end (i.e., the front end) of the second encapsulation tube 17 away from the first encapsulation tube 16. The first encapsulation tube 16, the second encapsulation tube 17, and the third encapsulation tube 153 are arranged coaxially and in a stepped manner.

[0040] like Figure 2-4 As shown, the dual-core fiber collimator 114, the first prism 12, the transmission grating 13, the second prism 14, and the adjustable mirror 151 are arranged approximately in a straight line on the axis L of the adjustable optical filter 10. This allows the adjustable optical filter 10 to have a linear structure, resulting in simpler components and a simpler manufacturing process. Furthermore, since the axes of the dual-core fiber collimator 114 and the adjustable mirror 151 are largely aligned, the adjustment dimension is smaller and easier to adjust during angle adjustment.

[0041] Furthermore, the dual-core fiber collimator 11 can be encapsulated within the first encapsulation tube 16. The dispersion component can also be encapsulated within the second encapsulation tube 17. Therefore, the dual-core fiber collimator 11 and the dispersion component can be fabricated separately first, and then the first encapsulation tube 16 and the second encapsulation tube 17 can be fixed together after simple adjustments. The entire encapsulation process is simple and easy to operate.

[0042] Although this application has been described with reference to preferred embodiments, it should be understood that the terminology used is descriptive and exemplary, and not restrictive. Since this application can be embodied in many forms without departing from its spirit or substance, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims. Therefore, all variations and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. An adjustable optical filter, comprising a first packaged tube, a second packaged tube, a third packaged tube, a dual-core fiber collimator, a dispersive component, and an adjustable reflector, characterized in that: The dispersive component includes a first prism, a transmission grating, and a second prism; The dual-core fiber collimator, the first prism, the transmission grating, the second prism, and the adjustable mirror are arranged sequentially along one axis of the adjustable optical filter; The dual-core fiber collimator includes a collimating lens, and the dual-core fiber collimator is installed inside the first encapsulation tube; The first prism, the transmissive grating, and the second prism are housed within the second encapsulation tube; The adjustable reflector is installed inside the third encapsulation tube; The second encapsulation tube is an eccentric glass tube and is attached between the first encapsulation tube and the third encapsulation tube. The second encapsulation tube is configured to adjust the relative position between the dispersive component and the collimating lens by rotation.

2. The tunable optical filter according to claim 1, characterized in that, The surface of the first prism facing the transmissive grating and the surface of the second prism facing the transmissive grating are both perpendicular to the axis.

3. The tunable optical filter according to claim 1, characterized in that, The cross-sections of the first prism and the second prism are both isosceles triangles.

4. The tunable optical filter according to claim 3, characterized in that, One apex of the first prism and one apex of the second prism are located on the same side of the axis.

5. The tunable optical filter according to claim 1, characterized in that: The dual-core fiber collimator also includes an input pigtail, an output pigtail, and a dual-hole tube; The double-hole tube is used to fix the input pigtail and the output pigtail; One end face of the input fiber and one end face of the output fiber are located at a front focal plane of the collimating lens.

6. The tunable optical filter according to claim 5, characterized in that, The collimating lens is used to collimate an optical signal input from the input pigtail and output a collimated beam that travels along the axis.

7. The tunable optical filter according to claim 6, characterized in that, The first prism is used to deflect the collimated beam into a beam that forms a first angle with the axis, the first angle being between 43 degrees and 51 degrees.

8. The tunable optical filter according to claim 1, characterized in that, The first prism has a vertex angle between 45 and 55 degrees, and the second prism has a vertex angle between 61 and 73 degrees.

9. The tunable optical filter according to claim 1, characterized in that, The transmissive grating is used to split the beam output from the first prism; The second prism is used to deflect the beam output by the transmissive grating so that it continues to travel along the axis.

10. The tunable optical filter according to claim 5, characterized in that, The adjustable reflector is used to reflect the light beam output forward by the second prism, so that the light beam returns backward to the dual-core fiber collimator and is output outward via the output pigtail of the dual-core fiber collimator.

11. The tunable optical filter according to claim 1, characterized in that, The adjustable optical filter further includes a carrier plate, one side of which is fixed to the second encapsulation tube, and the first prism, the transmissive grating, and the second prism are fixed to the other side of the carrier plate.

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