CN104184038A - Er-doped optical fiber source and near-Gaussian spectrum output generating method thereof - Google Patents

Abstract

The invention discloses an erbium-doped fiber light source and a method for producing near-Gaussian spectrum output. The method specifically comprises: dividing the erbium-doped fiber into multiple sections, and connecting filters between each section of the erbium-doped fiber; using a pump with a wavelength of 980nm The pump laser light source pumps all erbium-doped fibers, the filter filters out the 1530nm band seed light generated in each section of erbium-doped fiber, and restricts the 1530nm band seed light to enter the next section of erbium-doped fiber for stimulated radiation amplification, and the final output average wavelength is 1550nm The near-Gaussian spectrum of the band. The invention is based on the cascaded filtering gain modulation technology, which can have higher output power and larger spectral width while obtaining near-Gaussian spectrum output.

Description

Erbium-doped fiber optic light source and method for producing near-Gaussian spectral output

technical field

The invention belongs to the field of fiber optic gyroscope applications, in particular to an erbium-doped fiber optic light source and a method for generating near-Gaussian spectrum output.

Background technique

Currently, the optical fiber gyroscope light source used in low-to-medium precision is mainly SLD. The SLD light source has the advantages of small size, wide spectrum, and near-Gaussian spectral output. However, SLD also has obvious shortcomings such as limited output power and average wavelength sensitivity to temperature. place. The stability of the scale factor of the high-precision inertial navigation grade fiber optic gyroscope requires the average wavelength stability of the light source to be less than 1ppm. SLD is difficult to meet the requirements, and the erbium-doped fiber optic light source has high average wavelength stability, making it a high-precision fiber optic gyroscope application. preferred light source. Erbium-doped fiber light source is a kind of amplified spontaneous emission light source (ASE light source), which has the advantages of high output power, wide-spectrum output, good average wavelength stability and non-polarized radiation, but its output spectrum is generally located in the dual bands of 1530nm and 1560nm Peak spectrum type, while the fiber optic gyroscope uses the interference of broad-spectrum light to measure angular velocity. It requires the light source to have a Gaussian or near-Gaussian spectrum type so that the value of the spectral coherence function decreases rapidly to reduce the influence of parasitic interference. It can be seen that the double-peak spectrum type seriously affects The application of Erbium-doped fiber optic light source in fiber optic gyroscope. At present, the research on the spectral type of erbium-doped fiber light source mainly focuses on the rectangular spectrum, which is mainly obtained by filtering the original spectral type through a fiber grating filter or a dielectric thin film filter. However, such a rectangular spectrum needs to be used in a fiber optic gyro. Spectral shaping from rectangular spectrum to Gaussian spectrum. The spectral filtering and shaping from the original bimodal spectrum to the Gaussian spectrum is not only technically complicated, but also will inevitably affect the output stability of the erbium-doped fiber source, and the power loss will be very large, which makes the erbium-doped fiber source no longer used in the fiber optic gyroscope. There are advantages to speak of.

Contents of the invention

The purpose of the present invention is to address the problem of the spectral output of the existing erbium-doped fiber source for fiber optic gyroscopes, to propose a method for producing an erbium-doped fiber source and its near-Gaussian spectrum output, based on the gain modulation technology of cascade filtering, in obtaining The near-Gaussian spectrum output can have higher output power and larger spectral width at the same time.

The purpose of the present invention is achieved by the following technical solutions: a kind of erbium-doped fiber light source, including pumping laser light source, wavelength division multiplexer, n sections of erbium-doped fiber, n-1 filters; wherein, pumping laser The light source is connected with the wavelength division multiplexer, and the other end of the wavelength division multiplexer is connected with n sections of erbium-doped optical fiber in sequence, and a filter is connected between each section of erbium-doped optical fiber. the

Further, an optical isolator connected with the wavelength division multiplexer is also included, and the end of the last erbium-doped optical fiber is looped to form a loss end.

Further, an optical isolator connected with the wavelength division multiplexer is also included, and the end of the last erbium-doped optical fiber is connected with a reflector.

Further, the reflector is a fiber optic reflector or a Faraday rotating mirror.

Further, the pumping laser light source is a semiconductor laser with a laser wavelength of 980nm.

Further, the wavelength division multiplexer is a 980nm/1550nm wavelength division multiplexer.

Further, the length of each of the n sections of erbium-doped optical fibers is equal to 2-6m, and the number of cascades of erbium-doped optical fibers is 3-6.

Further, the filter is a long-period fiber grating band-stop filter or a dielectric film band-stop filter with a center wavelength of 1530 nm.

A method for producing near-Gaussian spectrum output by an erbium-doped fiber light source, specifically: dividing the erbium-doped fiber into multiple sections, and connecting filters between each section of the erbium-doped fiber; using a pumping laser light source with a wavelength of 980nm to pump all erbium-doped fibers Optical fiber, the filter filters out the 1530nm band seed light generated in each section of erbium-doped fiber, restricts the 1530nm band seed light to enter the next section of erbium-doped fiber for stimulated radiation amplification, and finally outputs a near-Gaussian spectrum with an average wavelength of 1550nm.

Beneficial effects of the present invention: the specific implementation scheme of the method of the present invention is simple and flexible, and is easy to optimize design; the average wavelength of the output near-Gaussian spectrum is in the 1550nm band; the erbium-doped fiber light source has higher output power and larger output spectral width.

Description of drawings

Fig. 1 is the structural representation of the specific technical realization scheme of the present invention;

Fig. 2 is the embodiment structure schematic diagram that the present invention is used for one-way backward four-stage cascade filtering structure erbium-doped fiber optic light source;

Fig. 3 is the structural representation of the embodiment of the erbium-doped optical fiber light source used for the dual-pass backward four-stage cascaded filtering structure of the present invention;

Fig. 4 is specific embodiment one, filter transmission spectrum in specific embodiment two;

Fig. 5 is the output spectrogram of erbium-doped fiber optic light source in the specific embodiment one;

Fig. 6 is the output spectrogram of erbium-doped fiber optic light source in the specific embodiment two;

In the figure, a pumping laser light source 1, a wavelength division multiplexer 2, an erbium-doped fiber 3, a filter 4, an optical isolator 5, and a mirror 6.

Detailed ways

The present invention will be described in further detail below with reference to the accompanying drawings and in conjunction with specific embodiments.

The output superfluorescence of the erbium-doped fiber source is the stimulated radiation amplification of the spontaneous emission seed light, and the double-peak spectral structure of the erbium-doped fiber source is caused by the higher gain of the erbium ion radiation characteristics in the 1530nm and 1560nm bands. In the erbium-doped fiber light source, the erbium-doped fiber is divided into multiple sections, and the length of each erbium-doped fiber is relatively short. A filter is connected between each section of erbium-doped fiber, and the pumping laser light source is used to pump all the erbium-doped fibers. The filter filters out the 1530nm-band seed light generated in each section of erbium-doped fiber, and restricts the 1530nm-band seed light to enter the next section of erbium-doped fiber for stimulated radiation amplification. The number of available inversion particles is greatly increased, and light in other wavebands can obtain more significant amplification of stimulated radiation than light in the 1530nm waveband. In this way, more inversion particle numbers are utilized by the seed light of other bands, and the light of other bands is stimulated to amplify the light of other bands. With this gain modulation technology, the double-peak spectral structure in the erbium-doped fiber light source is eliminated, and finally the average wavelength is 1550nm. Gaussian spectrum.

A kind of erbium-doped optical fiber light source of the present invention, as shown in Figure 1, comprises pumping laser light source 1, wavelength division multiplexer 2, n section erbium-doped optical fiber 3, n-1 filter 4; Wherein, pumping laser light source 1 is connected to the A terminal of the wavelength division multiplexer 2, and the B terminal of the wavelength division multiplexer 2 is connected to n sections of erbium-doped optical fibers 3 in sequence, and a filter 4 is connected between each section of erbium-doped optical fibers 3 .

N sections of erbium-doped optical fiber 3 can not be too long, in order to avoid the initial seed light in the 1530nm wave band being sufficiently stimulated and amplified in a section of erbium-doped optical fiber 3, the length of each section of erbium-doped optical fiber 3 is generally 2m-6m according to the optimization result, and the erbium-doped optical fiber 3 The cascading number of optical fibers is in the range of 3-6 according to the optimization results.

n-1 filters 4 are band-stop filters with a central wavelength of 1530nm, and the filters 4 are used to filter out the initial seed light of the 1530nm band in each section of erbium-doped optical fiber 3, so as to avoid the initial seed light of the 1530nm band from entering the next section Erbium-doped fiber 3 is stimulated to amplify. Preferably, the filter 4 may be a long period fiber grating filter or a dielectric thin film filter.

The pumping laser light source 1 is a semiconductor laser with a laser wavelength of 980nm. The pumping laser light source 1 is connected to the A-end of the wavelength division multiplexer 2 through a pigtail for pumping the n-section erbium-doped optical fiber 3 .

The wavelength division multiplexer 2 is a 980nm/1550nm wavelength division multiplexer, the 980nm port (A port) of the wavelength division multiplexer 2 is connected to the 980nm semiconductor laser pigtail, and the 1550nm port (B port) is connected to the first section of erbium-doped optical fiber 3 connected.

Embodiment one:

As shown in Figure 2, the present invention is used for a single-pass backward 4-stage cascaded filter structure erbium-doped fiber light source, including a pumping laser light source 1, a wavelength division multiplexer 2, four sections of erbium-doped fiber 3, and three filters 4 and the optical isolator 5; the pump laser light source 1 is connected to the A terminal of the wavelength division multiplexer 2, the optical isolator 5 is connected to the C terminal of the wavelength division multiplexer 2, and the B terminal of the wavelength division multiplexer 2 is connected to four Sections of erbium-doped optical fibers 3, and filters 4 are connected between each section of erbium-doped optical fibers 3.

The pumping laser light source 1 is a semiconductor laser (LD) with a wavelength of 980nm.

The core radius of the four sections of erbium-doped optical fiber 3 is 1.47 μm, the numerical aperture is 0.232, and the length is 5 m.

The end of the fourth erbium-doped optical fiber 3 is looped to form a loss end, which prevents the end face of the optical fiber from becoming a reflective surface to form resonant lasing inside the light source.

As shown in FIG. 4, the transmission spectrum of the filter used in this embodiment is the same. The parameters of the three filters 4 are the same, and the parameters of the filter 4 are as follows: the peak loss is 20 dB, the loss center wavelength is 1530 nm, and the 3 dB loss bandwidth is 16 nm.

When the pumping power of the pumping laser light source 1 was 80mW, a kind of output spectrum diagram of the erbium-doped fiber light source in the present embodiment was obtained, as shown in Figure 5, by comparing with the ideal Gaussian spectrum, it can be known that the gained output spectrum is nearly Gaussian spectrum. The output parameters of the light source are as follows: the output power is 26mW, the average wavelength is 1553.52nm, and the output spectral width is 20nm. Compared with the Gaussian spectrum output by traditional direct filtering, the light source of the invention has a larger spectral width and higher output power while outputting a near-Gaussian spectrum.

Embodiment two:

As shown in Fig. 3, the present invention is used for a two-way backward four-stage cascaded filter structure erbium-doped fiber light source, including a pumping laser light source 1, a wavelength division multiplexer 2, four sections of erbium-doped fiber 3, and three filters 4, optical isolator 5, reflector 6; Pu laser light source 1 is connected with A end of wavelength division multiplexer 2, optical isolator 5 is connected with C end of wavelength division multiplexer 2, and the end of wavelength division multiplexer 2 is connected with each other. The B end is connected with four sections of erbium-doped optical fibers 3 in turn, and a filter 4 is connected between each section of erbium-doped optical fibers 3, and the end of the fourth erbium-doped optical fiber 3 is connected with the reflector 6; the C end of the wavelength division multiplexer 2 is also placed There is an optical isolator 5 .

The pumping laser light source 1 is a semiconductor laser (LD) with a wavelength of 980nm.

Preferably, the reflection mirror 6 is a fiber optic reflection mirror or a Faraday rotation mirror.

The core radius of the four sections of erbium-doped optical fiber 3 is 1.47 μm, the numerical aperture is 0.232, and the length is 3 m.

As shown in FIG. 4 , the filter transmission spectrum used in this embodiment, the parameters of the three filters 4 are the same, and the filter parameters are as follows: peak loss 20dB, loss center wavelength 1530nm, 3dB loss bandwidth 16nm.

When the pumping power of the pumping laser light source 1 is 80mW and the reflectivity of the reflector is 80%, a kind of output spectrogram of the erbium-doped fiber light source in the present embodiment is obtained, as shown in Figure 6, by performing with the ideal Gaussian spectrum In comparison, it can be seen that the obtained output spectrum is a near-Gaussian spectrum. The output parameters of the light source are as follows: the output power is 39mW, the average wavelength is 1555.38nm, and the output spectral width is 18nm.

The erbium-doped fiber light source of the present invention and the method for producing near-Gaussian spectrum output are not limited to the above-mentioned embodiments. In the specific implementation, it is a single-pass structured light source when there is no reflector, and it is a double-pass structured light source when there is a reflector. Erbium-doped fiber light sources with different structures and near-Gaussian spectrum output can be obtained by optimizing the parameters of the number of erbium-doped fiber cascades, the length of the erbium-doped fiber, and the filter, and these should be within the scope of protection of the present invention.

Claims (9)

1. an Er-Doped superfluorescent fiber source, is characterized in that, comprises pumping laser light source, wavelength division multiplexer, n section Er-doped fiber, n-1 filter; Wherein, pumping laser light source is connected with wavelength division multiplexer, and the other end of wavelength division multiplexer connects n section Er-doped fiber successively, between every section of Er-doped fiber, is connected with filter.

2. a kind of Er-Doped superfluorescent fiber source according to claim 1, is characterized in that, also comprises an optical isolator being connected with wavelength division multiplexer, and final stage Er-doped fiber end breaks into loops to form loss end.

3. a kind of Er-Doped superfluorescent fiber source according to claim 1, is characterized in that, also comprises an optical isolator being connected with wavelength division multiplexer, and final stage Er-doped fiber end is connected with a speculum.

4. according to a kind of Er-Doped superfluorescent fiber source described in claims 3, it is characterized in that, described speculum is fiber reflector or faraday rotation mirror.

5. according to a kind of Er-Doped superfluorescent fiber source described in claims 1,2 or 3, it is characterized in that, described pumping laser light source is semiconductor laser, and optical maser wavelength is 980nm.

6. according to a kind of Er-Doped superfluorescent fiber source described in claims 1,2 or 3, it is characterized in that, described wavelength division multiplexer is 980nm/1550nm wavelength division multiplexer.

7. according to a kind of Er-Doped superfluorescent fiber source described in claims 1,2 or 3, it is characterized in that, in described n section Er-doped fiber, every section of Er-doped fiber is equal in length, and is 2-6m, and the cascade number of Er-doped fiber is 3-6 level.

8. according to a kind of Er-Doped superfluorescent fiber source described in claims 1,2 or 3, it is characterized in that, centered by described filter, wavelength is at long period fiber grating band stop filter or the thin dielectric film band stop filter band of 1530nm wave band.

9. according to the Er-Doped superfluorescent fiber source described in claims 1,2 or 3, produce the method for nearly Gaussian spectrum output, it is characterized in that: Er-doped fiber is divided into multistage, between each section of Er-doped fiber, connects filter; Use all Er-doped fibers of pumping laser light source pumping that wavelength is 980nm, the 1530nm wave band seed light producing in each section of Er-doped fiber of filter filtering, restriction 1530nm wave band seed light enters next section of Er-doped fiber and carries out stimulated radiation amplification, and finally exporting mean wavelength is the nearly Gaussian spectrum of 1550nm wave band.