CN102620808B - Local resonance type phononic crystal filtering optical fiber hydrophone - Google Patents

Abstract

The invention relates to the technical field of optical fiber sensing, in particular to a phonon crystal filter optical fiber hydrophone for filtering acoustic signals through a phonon crystal. The invention includes a fiber optic hydrophone measuring device and a local resonance phononic crystal. The local resonance phononic crystal is composed of periodically arranged elements, and the fiber optic hydrophone measuring device is placed on the local resonance phononic crystal. middle. The primitive includes a spherical core, a cladding layer and a cubic base, and the spherical core covered by the cladding is encapsulated at the center of the cubic base. The main body of the fiber optic hydrophone hydroacoustic measurement unit is a DFB fiber laser, and the cladding layer fixes the DFB fiber laser on the outer wall of the spherical core of the fiber optic hydrophone hydroacoustic measurement unit. The fiber laser and cladding are housed in the center of the cube. The invention has small size, powerful low frequency filtering effect and frequency division multiplexing function.

Description

A Local Resonance Phononic Crystal Filter Fiber Optic Hydrophone

technical field

The invention relates to the technical field of optical fiber sensing, in particular to a phonon crystal filter optical fiber hydrophone for filtering acoustic signals through a phonon crystal.

Background technique

Compared with the corresponding conventional sensors, fiber optic sensors have obvious advantages in terms of sensitivity, dynamic range, and reliability.

Optical fiber hydrophone is an instrument that detects signals such as pressure and sound in liquids by using the light transmission characteristics of optical fiber and various modulation responses generated by its interaction with the surrounding environment. Compared with traditional piezoelectric sensors, it has the following main advantages: wide frequency band, high sound pressure sensitivity, no electromagnetic interference, light weight, can be designed into any shape, and combines information sensing and optical information transmission Etc.

Local resonance phononic crystals were first proposed by Professor Liu Zhengyou et al. in 2000. They arranged lead balls coated with very soft silicone rubber materials in an epoxy resin matrix according to a simple cubic lattice structure, forming a three-dimensional three-component phononic crystal. Both theoretical and experimental results have found that the wavelength corresponding to the band gap of the phononic crystal is much larger than the lattice constant, which breaks through the limitation of the Bragg scattering mechanism. Moreover, when the scatterers are not strictly periodically distributed, the composite structure also has a band gap, thus a local resonance mechanism of the elastic wave band gap is proposed. The local resonance mechanism holds that under the excitation of an elastic wave of a specific frequency, each scatterer resonates and interacts with the traveling wave of the elastic wavelength, thereby inhibiting its propagation. Since the generation of the local resonance bandgap depends on the interaction between the self-resonant properties of the scatterer and the long-wave traveling wave in the matrix, its bandgap frequency is closely related to the inherent vibration properties of a single scatterer. This has created a new situation for the application of phononic crystals in low-frequency vibration and noise reduction.

Contents of the invention

The main purpose of the present invention is to provide a local resonance type phonon crystal filter fiber optic hydrophone which can improve the sensitivity of the fiber optic hydrophone and filter the acoustic signal through the phonon crystal.

The purpose of the present invention is achieved like this:

The local resonance type phononic crystal filter fiber optic hydrophone includes a fiber optic hydrophone measuring device and a local resonance type phononic crystal, and is characterized in that: the local resonance type phononic crystal is composed of periodically arranged elements, and the optical fiber The hydrophone measurement device is arranged in the local resonance type phononic crystal.

The primitive includes a spherical core, a cladding layer and a cubic base, and the spherical core covered by the cladding is encapsulated at the center of the cubic base.

The optical fiber hydrophone measurement device is a fiber optic hydrophone hydroacoustic measurement unit embedded in a local resonance phononic crystal. The main body of the fiber optic hydrophone hydroacoustic measurement unit is a DFB fiber laser, and the cladding layer is made of DFB optical fiber. The laser is fixed on the outer wall of the spherical core of the optical fiber hydrophone hydroacoustic measurement unit, and the cubic base encapsulates the spherical core, the DFB fiber laser and the cladding layer at the center of the cubic base.

The present invention has the following beneficial effects:

1. The present invention enables the optical fiber hydrophone to have the function of low-frequency filtering through the low-frequency vibration and noise reduction function of the phononic crystal.

2. The main part of the hydrophone in the present invention is a local resonance type phononic crystal, which greatly reduces the volume of the hydrophone.

3. By changing the structure or material of the local resonant phononic crystal, the present invention can change its filtering frequency, so that the optical fiber hydrophone provided by the present invention has a powerful function of frequency division and multiplexing.

Description of drawings

Figure 1 Schematic diagram of the internal structure of the optical fiber hydrophone underwater acoustic measurement unit;

Fig. 2 Schematic diagram of the structure of the underwater acoustic measurement unit of the fiber optic hydrophone;

Fig. 3 Schematic diagram of the internal structure of the local resonance type phononic crystal element;

Figure 4 Schematic diagram of the structure of the local resonance type phononic crystal unit;

Fig. 5 is a structural schematic diagram of a local resonance type phononic crystal filter fiber optic hydrophone.

Detailed ways

In order to make the purpose and technical solution of the present invention clearer, the present invention will be described in detail below in combination with specific conditions and with reference to the accompanying drawings.

The fiber optic hydrophone measurement part includes a DFB fiber laser; the local resonance phononic crystal part includes a plurality of primitives arranged in a simple cubic lattice structure; the primitive part includes a spherical core, a cladding layer, and a cubic matrix. The main body of the fiber optic hydrophone is a local resonance phononic crystal composed of multiple primitives arranged in a simple cubic lattice structure, which can filter the sound field; the DFB fiber laser is placed in one or several primitives, Used to measure underwater acoustic signals.

As shown in FIG. 1 , FIG. 1 is a schematic diagram of the internal structure of the underwater acoustic measurement unit of the optical fiber hydrophone of the present invention. The main body of the optical fiber hydrophone measuring element is a cubic matrix 3 with a centrally symmetrical structure, and includes a spherical core 1; a DFB fiber laser 4 installed on the outer wall of the spherical core 1; through a cladding layer 2 The DFB fiber laser is fixed on the outer wall of the spherical core 1; the cubic base 3 encapsulates the spherical core 1, the DFB fiber laser 4 and the cladding layer 2 at its center. The spherical core 1 is composed of shot balls with uniform mass, and its radius is 5mm. The DFB fiber laser is installed on the outer wall of the spherical core 1 and is in close contact with it. The covering layer 2 consists of a very soft silicone rubber material. The material of the cubic matrix 3 is generally composed of epoxy resin.

As shown in Fig. 2, Fig. 2 is a schematic structural diagram of the underwater acoustic measurement unit of the fiber optic hydrophone of the present invention. The cube primitive 6 in the figure is the above-mentioned fiber optic hydrophone underwater acoustic measurement primitive, which is used for underwater acoustic measurement. Pigtail 5 is used for signal transmission.

As shown in FIG. 3 , FIG. 3 is a schematic diagram of the internal structure of the local resonance type phononic crystal element of the present invention. The main body of the local resonance type phononic crystal is a cubic matrix 9 (same as the above-mentioned cubic matrix 3) made of epoxy resin, and this part also includes a lead ball with uniform quality as the spherical core 7 (same as the above-mentioned cubic matrix 3). The spherical core 1 is the same), and the outer wall of the spherical core 7 is covered with a coating layer 8 of silicon rubber material (same as the above coating layer 2).

As shown in FIG. 4 , FIG. 4 is a schematic diagram of the structure of the local resonance type phononic crystal unit of the present invention. The cubic unit 10 in the figure is a unit of the local resonance type phononic crystal.

As shown in Fig. 5, Fig. 5 is a structural schematic diagram of the local resonance type phononic crystal filter fiber optic hydrophone of the present invention. The pigtail 11 in the figure is used for signal transmission, and the cube 12 in the figure is a local resonant phononic crystal formed by arranging multiple primitives in a simple cubic lattice structure, which is used for filtering acoustic signals and low-frequency Noise reduction, the primitive 13 in the figure is a local resonance type phononic crystal primitive, the optical fiber hydrophone hydroacoustic measurement primitive used for underwater acoustic signal measurement is located in the center of the overall structure, and on this basis can also be arranged Multiple optical fiber hydrophone hydroacoustic measurement primitives are placed for array measurement.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be Included within the protection scope of the present invention.

Claims (1)

1. A local resonance type phononic crystal filter optical fiber hydrophone, comprising an optical fiber hydrophone measuring device, a local resonance type phononic crystal, is characterized in that: the local resonance type phononic crystal is composed of periodically arranged base The optical fiber hydrophone measurement device is arranged in the local resonance type phononic crystal. The basic element includes a spherical core, a cladding layer and a cubic matrix, and the spherical core covered by the cladding layer It is packaged at the center of the cube matrix; the optical fiber hydrophone measurement device is a fiber optic hydrophone hydroacoustic measurement unit embedded in a local resonance type phononic crystal, and the main body of the fiber optic hydrophone hydroacoustic measurement unit It is a DFB fiber laser, and the cladding layer fixes the DFB fiber laser on the outer wall of the spherical core of the fiber optic hydrophone hydroacoustic measurement unit, and the cubic matrix encapsulates the spherical core, DFB fiber laser and cladding in the cubic matrix at the center.

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