Filtering-adjustable ultra-narrow bandwidth fiber grating filtering device

Abstract

The utility model relates to an ultra-narrow bandwidth fiber grating filtering device with adjustable filtering, comprising an optical input end used for receiving an optical signal to be filtered; the optical output end is used for outputting the filtered optical signal; the adjustable screw is used for adjusting the filtering wavelength range; the circulator is used for realizing one-way transmission of optical signals; the grating is used for reflecting a specific required light wavelength; and the adjustable base is used for installing the grating. The ultra-narrow bandwidth fiber grating filtering device with adjustable filtering has the characteristics of simple operation, stable structure, high filtering precision, external factor interference resistance and the like.

Description

Technical field:

[0001] The utility model relates to the technical field of optics, in particular to an ultra-narrow bandwidth optical fiber grating filter device with adjustable filtering. Background technology:

[0002] Commonly used fiber filters include fiber grating filters, Fabry-Perot filters, WDM wavelength division multiplexers, etc. These different types of filters have different structures and principles, but their core functions are to select and filter specific wavelengths. Fabry-Perot filter is an optical filter made based on the Fabry-Perot interference principle. Its basic structure is a resonant cavity formed between two parallel reflection surfaces, which uses the interference effect of light reflecting back and forth between the reflection surfaces to achieve the filtering function. The advantages of FP filters are narrowband, high performance and tunable wavelength, so they are widely used in laser spectroscopy, optical communication, spectral instruments and other fields. However, the performance indicators of FP filters such as tuning range and bandwidth are limited by the resonant cavity, and its manufacturing process is relatively complicated. FBG filter is a filter based on fiber grating, and its core component is fiber grating. Fiber grating is a function of reflecting and filtering specific wavelengths by writing grating structures on optical fibers. The advantage of FBG filter is that its wavelength response is highly flexible, and different central wavelengths, bandwidths and shapes can be customized. In addition, FBG filters also have the advantages of anti-electromagnetic interference and high stability, so they are also widely used in optical fiber sensing, lidar and other fields.

[0003] At present, the domestic fiber Bragg grating filter technology is relatively mature, but there is no relevant technology disclosed in China for high-precision ultra-narrow bandwidth adjustable fiber Bragg grating filter devices. Utility model content:

[0004] The technical problem to be solved by the utility model is to provide a simple, convenient and reliable ultra-narrow bandwidth fiber Bragg grating filtering device with adjustable filtering, in view of the fact that the fiber Bragg grating is easily affected by external factors such as temperature and vibration. The device has the characteristics of simple structure, simple operation, stable structure, high filtering accuracy, and resistance to interference from external factors.

[0005] The technical solution of the utility model is to provide an ultra-narrow bandwidth fiber grating filter device with adjustable filtering, including

[0006] An optical input end, receiving an optical signal to be filtered;

[0007] An optical output terminal outputs a filtered optical signal;

[0008] Adjustable screw to adjust the filtering wavelength range;

[0009] Circulator, which realizes unidirectional transmission of optical signals;

[0010] Gratings, which reflect specific desired wavelengths of light;

[0011] Adjustable base for mounting the grating;

[0012] and a packaging shell.

[0013] The optical signal to be filtered enters the first port of the circulator of the filtering device through the optical input end, is output from the second port of the circulator, enters the grating, and then the grating reflects the filtered optical signal and outputs it from the third port of the circulator to the optical output end.

[0014] Preferably, the adjustable base is arranged horizontally, one end of the adjustable base is fixed on the package shell, and the other end cooperates with the adjustable screw, the adjustable screw is screwed into the package shell from the outside and is threadedly connected with the adjustable base, the grating is fixed on the adjustable base by spot welding or gluing, and the grating is arranged along the axial direction of the adjustable base. By rotating the pitch of the thread of the adjustable screw, the reflection wavelength of the grating can be adjusted, thereby realizing the precise adjustment of the filtering wavelength. There are four fixing holes on the package shell to facilitate the installation and fixation of the device.

[0015] Preferably, both the filter grating and the circulator are made of anti-microbend optical fiber, which has the characteristics of low bending sensitivity, strong mechanical strength, high reliability, etc., which can make the size of the entire device smaller and easier to use.

[0016] Preferably, the grating center wavelength is 1550 nm and the bandwidth is 10 GHz.

[0017] Preferably, the adjustable base is packaged with a negative temperature coefficient material, such as nickel, chromium, etc. When the external temperature changes, the negative temperature coefficient material can offset the impact of the change in the positive temperature coefficient of the grating, thereby ensuring the stability of the filtering wavelength.

[0018] Preferably, the packaging shell can be made of metal material or engineering plastic to ensure the stability of the structure.

[0019] Preferably, the interior of the packaging shell is filled with heat insulating material, and the heat insulating material can be heat insulating glue.

[0020] The filter device of the utility model belongs to the FBG filter. The grating is an optical device with wavelength selection characteristics. It can be regarded as a narrow-band optical filter or reflector formed in the fiber core. When broadband light is injected into the grating, a very narrow part of the light that meets the grating selection conditions is reflected so that it cannot pass through the grating. That is, the grating can change the propagation properties of light in the optical fiber, prevent the propagation of light of a specific wavelength, and reflect it back.

[0021] Grating wavelength selection condition: FBG wavelength λ B , which depends on the effective refractive index n of the grating eff and period Λ, as described by the following equation:

[0022] λ B =2n eff Λ

[0023] Therefore, when the effective refractive index and period of the fiber FBG grating change, the central wavelength of the reflected light wave will also change. At this time, there is a difference Δλ between the central wavelength of the reflected light wave and the initial central wavelength of the grating. B When external stress or strain is applied to the fiber grating, or the surrounding temperature or pressure changes, the effective refractive index neff and grating period Λ of the FBG grating will change, and its reflection wavelength will drift accordingly, thus realizing the filtering and adjustment function of the fiber FBG for a specific wavelength.

[0024] ΔλB=2neffΔΛ+2Δneff

[0025] Compared with the prior art, the beneficial effects of the utility model are:

[0026] The utility model has a narrow filtering bandwidth, the narrowest of which can reach 1GHz, and has a wavelength adjustable function with high adjustment accuracy. It can accurately locate the required wavelength range, filter out unnecessary optical signals, and effectively filter out stray noise signals. It can also offset and isolate the influence of external factors such as temperature and vibration, and has the characteristics of strong resistance to external interference. At the same time, the filtering device has a simple structure, light weight, and small size, and is suitable for integrated use. Description of the drawings:

[0027] Figure 1 It is a structural schematic diagram of the utility model.

[0028] In the figure: 1, light input end; 2, light output end; 3, adjustable screw; 4, fixing hole; 5, circulator; 6, grating; 7, adjustable base; 8, packaging shell; 51, first port; 52, second port; 53, third port. Specific implementation method:

[0029] The present invention will be further described below with reference to the accompanying drawings:

[0030] Reference Figure 1 The utility model discloses an ultra-narrow bandwidth fiber grating filter device with adjustable filtering, comprising

[0031] An optical input terminal 1 receives an optical signal to be filtered;

[0032] Optical output terminal 2, outputting filtered optical signals;

[0033] Adjustable screw 3, adjusts the filtering wavelength range;

[0034] Circulator 5, realizing unidirectional transmission of optical signals;

[0035] Grating 6, reflecting a specific desired wavelength of light;

[0036] An adjustable base 7 for mounting the grating 6;

[0037] and a packaging housing 8.

[0038] The optical signal to be filtered enters the first port 51 of the circulator 5 of the filtering device through the optical input end 1, is output from the second port 52 of the circulator 5, enters the grating 6, and then the grating 6 reflects the filtered optical signal and outputs it from the third port 53 of the circulator 5 to the optical output end 2.

[0039] In this embodiment, the adjustable base 7 is in the shape of a long strip and is arranged horizontally. The rear end of the adjustable base 7 is fixed on the inner wall of the package shell 8. The front end of the adjustable base 7 is connected and matched with the adjustable screw 3. The adjustable screw 3 is screwed in from the outside of the package shell 8 and is threadedly connected to the adjustable base 7. The adjustable base 7 is deformed by changing the pitch of the adjustable screw 3, thereby adjusting the size of the grating area of ​​the grating 6, and then selecting a specific filtering wavelength. Correspondingly, the grating 6 is fixed on the adjustable base 7 along the axial direction of the adjustable base 7 by spot welding. By rotating the pitch of the thread of the adjustable screw 3, the reflection wavelength of the grating 6 can be adjusted, thereby realizing the precise adjustment of the filtering wavelength. There are four fixing holes 4 on the package shell 8 to facilitate the installation and fixation of the device.

[0040] As an implementation mode, the adjustable base 7 is packaged with a negative temperature coefficient material. Nickel is selected in this embodiment. Thus, when the external temperature changes, the negative temperature coefficient material can offset the impact of the change in the positive temperature coefficient of the grating, thereby ensuring the stability of the filtering wavelength.

[0041] As an implementation mode, both the grating 6 and the circulator 5 use anti-microbend optical fiber, which has the characteristics of low bending sensitivity, strong mechanical strength, high reliability, etc., which can make the size of the entire device smaller and easier to use.

[0042] As an implementation mode, the packaging shell 8 is made of stainless steel material that is not easily deformed to ensure the stability of the structure.

[0043] As an implementation mode, the interior of the packaging shell 8 is filled with a heat insulating material, and in this embodiment, the heat insulating material is heat insulating glue.

[0044] The FBG filter based on the utility model has the following usage process:

[0045] 1. The optical signal to be filtered is input into the optical input port 1, enters the filtering optical path from the first port 51 of the circulator 5, and then outputs from the second port 52 of the circulator 5 and enters the grating 6;

[0046] 2. After the optical signal to be filtered enters the grating 6, due to the wavelength selectivity of the grating, the optical signal of a specific wavelength is reflected, and other useless optical signals are passed through, and the optical signal of the specific wavelength is reflected to enter the second port 52 of the circulator 5, and is output from the third port 53, and then enters the optical output end 2 of the filtering device;

[0047] 3. The grating 6 is fixed on the adjustable base 7 by gluing. The adjustable base 7 is made of a negative temperature coefficient material to offset the positive wavelength drift of the grating 6 caused by temperature changes.

[0048] 4. The size of the grating area of ​​the grating 6 is adjusted by changing the pitch of the adjustable screw 3, so as to select a specific filtering wavelength;

[0049] 5. The heat insulating glue filled inside the packaging shell 8 is used for heat insulation, and the fixing holes 4 on the packaging shell 8 can be easily installed and used.

[0050] The optical fiber filter device has a narrow filtering bandwidth and has a wavelength adjustable function with high adjustment accuracy. It can accurately locate the required wavelength range, filter out unnecessary optical signals, effectively filter out stray noise signals, and has strong anti-interference ability, simple structure, light weight, small size, and is suitable for integrated use. As a high-performance and high-stability optical device, it can be used to realize the filtering, multiplexing, demultiplexing, and beam splitting of optical signals, thereby realizing the processing and manipulation of optical signals, and has broad application prospects in the fields of optical fiber communications, lasers, sensors, and optical signal processing.

[0051] The above is only an explanation of the preferred embodiments of the utility model, which cannot be understood as a limitation of the claims. Any equivalent structure or equivalent process changes made using the utility model specification are included in the patent protection scope of the utility model.

Claims

1. A filter-adjustable ultra-narrow bandwidth fiber Bragg grating filter device, characterized in that: include An optical input end, receiving an optical signal to be filtered; An optical output terminal outputs a filtered optical signal; Adjustable screw to adjust the filtering wavelength range; Circulator, which realizes unidirectional transmission of optical signals; Gratings, which reflect specific desired wavelengths of light; Adjustable base for mounting the grating; and a packaging shell; The optical path of the filtering device is as follows: the optical signal to be filtered enters the first port of the circulator through the optical input end, is output from the second port of the circulator, enters the grating, and then the grating reflects the filtered optical signal and outputs it from the third port of the circulator to the optical output end.

2. The ultra-narrow bandwidth fiber Bragg grating filter device with adjustable filtering according to claim 1, characterized in that: The grating is fixed on the adjustable base by spot welding or gluing, and the grating is parallel to the axial direction of the adjustable base.

3. The ultra-narrow bandwidth fiber Bragg grating filter device with adjustable filtering according to claim 2, characterized in that: The adjustable base is set horizontally, one end of the adjustable base is fixed on the packaging shell, and the other end cooperates with the adjustable screw. The adjustable screw is screwed in from the outside of the packaging shell and is threadedly connected to the adjustable base. The size of the grating area is adjusted by changing the pitch of the adjustable screw, thereby selecting a specific filtering wavelength.

4. The ultra-narrow bandwidth fiber Bragg grating filter device with adjustable filtering according to claim 1, characterized in that: The interior of the packaging shell is filled with heat insulation material.

5. The ultra-narrow bandwidth fiber Bragg grating filter device with adjustable filtering according to claim 1, characterized in that: The packaging shell is provided with fixing holes.

6. The ultra-narrow bandwidth fiber Bragg grating filter device with adjustable filtering according to claim 1, characterized in that: Both the grating and the circulator are made of microbend-resistant optical fiber.

7. The ultra-narrow bandwidth fiber Bragg grating filter device with adjustable filtering according to claim 1, characterized in that: The adjustable base is packaged with negative temperature coefficient material.

8. The ultra-narrow bandwidth fiber Bragg grating filter device with adjustable filtering according to claim 7, characterized in that: Negative temperature coefficient materials are nickel or chromium.

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