Optical fiber type spectrum compressor

Abstract

The utility model discloses an optical fiber type spectrum compressor. Comprising a first optical fiber circulator, an optical fiber Bragg grating, a second optical fiber circulator, a first optical fiber collimator, a first half-wave plate, a polarization splitting prism, a first grating, a second grating, a Faraday rotator, a dielectric film reflector, a second half-wave plate, a second optical fiber collimator, an ytterbium-doped optical fiber amplifier and an optical fiber reflector. According to the utility model, the distance between the grating pairs can be flexibly adjusted to control the negative chirp amount introduced by the pulse, so that the spectrum compression effect is optimized; due to the arrangement of the ytterbium-doped optical fiber amplifier, the signal light power is improved while spectrum width compression is completed, and the problem of signal light transmission loss in the spectrum compression process is effectively solved; the signal light output power and the stability of spectrum compression are improved through the design of bi-pass amplification, a higher spectrum compression ratio can be achieved by simply cascading the multi-stage spectrum compression module, and the device flexibility is high.

Description

Technical Field

[0001] The utility model relates to the technical field of spectral compression, in particular to an optical fiber type spectral compressor. Background Technique

[0002] Ultrafast lasers have been widely used in the fields of biomedicine, material processing, optoelectronic countermeasure, and information communication due to their ultrashort pulse width and extremely high peak power. However, due to the wide spectral characteristics of ultrashort pulses, their spectral resolution in the application of microscopy imaging technology is poor, which greatly limits the performance of the microscopy imaging system. Therefore, it is usually necessary to compress the spectral width of ultrashort pulses through some technical means.

[0003] At present, the methods for realizing spectral compression mainly include two types. One is to use the comb structure of single-mode fiber cascaded with highly nonlinear fiber to realize spectral compression, and the other is to use the structure of dispersion fiber cascaded with a phase modulator to realize spectral compression.

[0004] Disadvantages of the prior art: First, in the comb structure of single-mode fiber cascaded with highly nonlinear fiber, the highly nonlinear fiber is relatively fixed, and the fiber cost and the requirements for fiber splicing technology are relatively high, resulting in a large problem of system signal light transmission loss. Second, the structure of dispersion fiber cascaded with a phase modulator is relatively complex, with high hardware requirements, requiring an external driving power supply, and the spectral compression ratio is relatively limited. Content of the Utility Model

[0005] The purpose of the utility model is to provide an optical fiber type spectral compressor to solve the problems put forward in the above background technique.

[0006] To achieve the above purpose, the utility model provides the following technical solution: An optical fiber type spectral compressor includes an optical fiber circulator 1, an optical fiber Bragg grating, an optical fiber circulator 2, an optical fiber collimator 1, a half-wave plate 1, a polarization beam splitter prism, a grating 1, a grating 2, a Faraday rotator, a dielectric film mirror, a half-wave plate 2, an optical fiber collimator 2, a ytterbium-doped fiber amplifier, and an optical fiber mirror;

[0007] Signal light is input into port a of the first optical fiber circulator. Port b of the first optical fiber circulator is connected to an optical fiber Bragg grating. Port c of the first optical fiber circulator is connected to port a of the second optical fiber circulator. Port b of the second optical fiber circulator is connected to a first-stage compression module. Port c of the second optical fiber circulator is connected to a second-stage compression module. The first-stage compression module and the second-stage compression module both include a first optical fiber collimator, a half-wave plate 1, a polarization beam splitter prism, a first grating, a second grating, a Faraday rotator, a dielectric film mirror, a half-wave plate 2, a second optical fiber collimator, a ytterbium-doped fiber amplifier, and an optical fiber mirror. The first optical fiber collimator, the half-wave plate 1, the polarization beam splitter prism, the first grating, the second grating, the Faraday rotator, and the dielectric film mirror are connected in sequence and are correspondingly arranged.

[0008] The dielectric film mirror, the Faraday rotator, the second grating, the first grating, the polarization beam splitter prism, the half-wave plate 2, the second optical fiber collimator, the ytterbium-doped fiber amplifier, and the optical fiber mirror are connected in sequence and are correspondingly arranged.

[0009] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0010] First, since negative chirp is introduced by setting a pair of gratings, the amount of negative chirp introduced by the pulse can be controlled by flexibly adjusting the spacing between the pair of gratings, thereby optimizing the spectral compression effect.

[0011] Second, the setting of the ytterbium-doped fiber amplifier enables the improvement of the signal light power while completing the spectral width compression, effectively solving the problem of signal light transmission loss during the spectral compression process.

[0012] Third, the design of double-pass amplification improves the output power of the signal light and the stability of spectral compression, and a higher spectral compression ratio can be achieved by simply cascading multiple spectral compression modules, having high device flexibility.

[0013] Fourth, the present utility model does not require the setting of special optical fibers and modulation devices, having the advantages of simple structure and low cost. Description of the Drawings

[0014] Figure 1 It is a schematic structural diagram of the present utility model.

[0015] In the figure: 1. The first optical fiber circulator; 2. Optical fiber Bragg grating; 3. The second optical fiber circulator; 4. The first optical fiber collimator; 5. Half-wave plate 1; 6. Polarization beam splitter prism; 7. First grating; 8. Second grating; 9. Faraday rotator; 10. Dielectric film mirror; 11. Half-wave plate 2; 12. The second optical fiber collimator; 13. Ytterbium-doped fiber amplifier; 14. Optical fiber mirror. Detailed Embodiments

[0016] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0017] Please refer to Figure 1 , the present invention provides a technical solution: an optical fiber spectral compressor, including an optical fiber circulator 1, an optical fiber Bragg grating 2, an optical fiber circulator 3, an optical fiber collimator 4, a half-wave plate 5, a polarization beam splitter prism 6, a grating 7, a grating 8, a Faraday rotator 9, a dielectric film mirror 10, a half-wave plate 11, an optical fiber collimator 12, a ytterbium-doped fiber amplifier 13, and an optical fiber mirror 14;

[0018] Signal light is input into port a of the optical fiber circulator 1. Port b of the optical fiber circulator 1 is connected to the optical fiber Bragg grating 2. Port c of the optical fiber circulator 1 is connected to port a of the optical fiber circulator 3. Port b of the optical fiber circulator 3 is connected to the first-stage compression module. Port c of the optical fiber circulator 3 is connected to the second-stage compression module. Both the first-stage compression module and the second-stage compression module include an optical fiber collimator 4, a half-wave plate 5, a polarization beam splitter prism 6, a grating 7, a grating 8, a Faraday rotator 9, a dielectric film mirror 10, a half-wave plate 11, an optical fiber collimator 12, a ytterbium-doped fiber amplifier 13, and an optical fiber mirror 14. Moreover, the optical fiber collimator 4, the half-wave plate 5, the polarization beam splitter prism 6, the grating 7, the grating 8, the Faraday rotator 9, and the dielectric film mirror 10 are connected in sequence and are correspondingly arranged;

[0019] The dielectric film mirror 10, the Faraday rotator 9, the grating 8, the grating 7, the polarization beam splitter prism 6, the half-wave plate 11, the optical fiber collimator 12, the ytterbium-doped fiber amplifier 13, and the optical fiber mirror 14 are connected in sequence and are correspondingly arranged.

[0020] In the present utility model, the signal light reaches the fiber Bragg grating through the input port of the optical fiber circulator 1. The fiber Bragg grating has a relatively narrow reflection bandwidth. Therefore, after the signal light is reflected by the fiber Bragg grating, spectral filtering is achieved, and the output spectral width is determined by the reflection bandwidth of the fiber Bragg grating. After the signal light that has undergone spectral filtering is output through the collimator, it sequentially passes through a half-wave plate and a polarization beam splitter prism and then reaches the grating pair. After passing through the grating pair, a negative chirp is introduced to the signal light. Then, after being reflected by the dielectric film mirror and the polarization beam splitter prism in sequence, it is coupled into the fiber collimator and enters the ytterbium-doped fiber amplifier through the fiber collimator. During the amplification process, the negative chirp pulse compensates with the positive chirp introduced by the self-phase modulation effect (SPM), achieving spectral compression. The setting of the ytterbium-doped fiber amplifier effectively compensates for the loss of the signal light during transmission, achieving power improvement while realizing spectral compression. In addition, by cascading spectral compressors with the same structure, efficient compression of the ultrashort pulse spectrum can be achieved.

[0021] The utility model: The signal light is input from port a of the optical fiber circulator 1, reaches the fiber Bragg grating 2 after passing through port b, realizes spectral filtering after being reflected by the fiber Bragg grating 2, and then is input to the circulator 2 3 through port c. After passing through port b, it is output to the space by the optical fiber collimator 1 4. By adjusting the half-wave plate 1 5, the linear polarization direction of the signal light is changed, so that the signal light input before the polarization beam splitter prism 6 is p-state linearly polarized light. After the p-state polarized signal light passes through the polarization beam splitter prism, it reaches the Faraday rotator 9 after being diffracted by the grating 1 7 and the grating 2 8 in sequence. After passing through the Faraday rotator, the linear polarization direction of the signal light rotates by 45°. Then, after being reflected by the dielectric film mirror 10, it passes through the Faraday rotator 9 again. At this time, the signal light becomes s-state linearly polarized, and then passes through the grating 2 8 and the grating 1 7 again and reaches the polarization beam splitter prism 6. After the s-state linearly polarized signal light is reflected by the polarization beam splitter prism, it is coupled into the optical fiber collimator 2 12 after passing through the half-wave plate 2 11. After passing through the optical fiber collimator 2 12, it enters the ytterbium-doped fiber amplifier 13. After the signal light is amplified for the first time, it reaches the optical fiber mirror 14. After being reflected by the optical fiber mirror 14, it enters the ytterbium-doped fiber amplifier 13 again. After the signal light is amplified for the second time, it is output to the space by the optical fiber collimator 2 12. The negative chirp pulse compensates with the positive chirp introduced by the self-phase modulation effect SPM during the amplification process, realizing the first-stage spectral compression. The signal light output by the optical fiber collimator 12 reaches the polarization beam splitter prism 6 after passing through the half-wave plate 2 11. After being reflected by the polarization beam splitter prism, it passes through the grating 1 7 and the grating 2 8 in sequence. The signal light diffracted by the grating 2 8 reaches the Faraday rotator 9. After passing through the Faraday rotator 9, it reaches the dielectric film mirror 10. After being reflected by the dielectric film mirror 10, it reaches the Faraday rotator 9 again. After the signal light passes through the Faraday rotator 9 again, it becomes p-state linearly polarized light, and then passes through the grating 2 8 and the grating 1 7 in sequence and reaches the polarization beam splitter prism 6. After passing through the polarization beam splitter prism 6, it reaches the half-wave plate 1 5, and then is coupled into the optical fiber collimator 1 4, and is output from port c of the optical fiber circulator 2 to the second-stage spectral compression module. The second-stage compression module has the same structural device as the first-stage compression module, and the spectral compression principle is also the same, that is, a negative chirp is introduced by the grating pair, and it compensates with the positive chirp introduced by the self-phase modulation effect SPM during the amplification process of the ytterbium-doped fiber amplifier, realizing the second-stage spectral compression.

[0022] The content not detailed in this specification belongs to the prior art well-known to those skilled in the art. Although the embodiments of the present utility model have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present utility model. The scope of the present utility model is defined by the appended claims and their equivalents.

Claims

1. An optical fiber spectrum compressor, characterized in that: It comprises a fiber circulator (1), a fiber Bragg grating (2), a fiber circulator (3), a fiber collimator (4), a half-wave plate (5), a polarization beam splitter (6), a grating (7), a grating (8), a Faraday rotator (9), a dielectric film reflector (10), a half-wave plate (11), a fiber collimator (12), an ytterbium-doped fiber amplifier (13) and a fiber reflector (14); The port a of the optical fiber circulator 1 (1) is input with signal light, the port b of the optical fiber circulator 1 (1) is connected to the optical fiber Bragg grating (2), the port c of the optical fiber circulator 1 (1) is connected to the port a of the optical fiber circulator 2 (3), the port b of the optical fiber circulator 2 (3) is connected to the first-stage compression module, the port c of the optical fiber circulator 2 (3) is connected to the second-stage compression module, and the first-stage compression module and the second-stage compression module both include an optical fiber collimator 1 (4), a half-wave plate 1 (5), a polarization A polarization beam splitter prism (6), a grating 1 (7), a grating 2 (8), a Faraday rotator (9), a dielectric film reflector (10), a half wave plate 2 (11), a fiber collimator 2 (12), an ytterbium-doped fiber amplifier (13) and a fiber reflector (14), and the fiber collimator 1 (4), a half wave plate 1 (5), a polarization beam splitter prism (6), a grating 1 (7), a grating 2 (8), a Faraday rotator (9) and a dielectric film reflector (10) are connected in sequence and arranged accordingly; The dielectric film reflector (10), Faraday rotator (9), grating 2 (8), grating 1 (7), polarization beam splitter (6), half wave plate 2 (11), optical fiber collimator 2 (12), ytterbium-doped optical fiber amplifier (13) and optical fiber reflector (14) are connected in sequence and arranged accordingly.

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