CN105896249A - High-power broadband tunable soliton-self-similar pulse mode-locked fiber laser - Google Patents

Abstract

The invention relates to a high-power broadband tunable soliton-self-similar pulse mode-locked fiber laser, including a pump source, a fiber combiner, a first dispersion compensation fiber and a second dispersion compensation fiber, a first collimator and a second collimator The first 1/4 wave plate and the second 1/4 wave plate, 1/2 wave plate, polarization beam splitter, birefringence filter, optical isolator, Er: Yb co-doped double-clad gain fiber An annular cavity connected with the space part. The pump source is connected to the pump end of the fiber beam combiner, the signal end of the beam splitter is connected to the first dispersion compensation fiber, the first fiber coupler and the first collimator in turn, and then the beam passes through the first 1/4 The wave plate, the 1/2 wave plate, the polarization beam splitter prism, the birefringence filter, the optical isolator and the second 1/4 wave plate are coupled into the second collimator, and coupled with the second optical fiber through the second dispersion compensation optical fiber The output end of the second fiber coupler is connected to the Er:Yb co-doped gain fiber, and the final gain fiber is connected to the signal end of the beam coupler.

Description

A high-power broadband tunable soliton-self-similar pulse mode-locked fiber laser

technical field

The invention belongs to the technical field of lasers, relates to a high-power broadband tunable soliton-self-similar pulse mode-locked fiber laser, and belongs to a high-power tunable soliton-self-similar fiber laser realized by using an Er:Yb double-clad fiber.

Background technique

Since the introduction of mode-locking technology in 1964, ultrashort pulse lasers have developed very rapidly. At the same time, with the continuous needs of related application fields, the depth and breadth of femtosecond pulse laser development are also expanding. Due to the important characteristics of high peak power and narrow pulse width, the mode-locked pulsed laser has been widely used in many fields such as biomedicine, terahertz technology, information communication, physics, chemistry and other basic science research, military defense and many other fields. The femtosecond fiber laser has many advantages such as high electro-optical conversion efficiency, good beam quality, compact and simple structure, low price, and easy maintenance, and has become one of the most promising lasers in the world.

The generation of ultrafast mode-locked fiber laser is mainly produced by the complex interaction of gain, dispersion and nonlinear effects. Under the condition of periodic boundary condition and dissipation effect limitation, it is convenient to study the generation mechanism of nonlinear wave experimentally. These characteristics are of great significance to the study of the formation mechanism of nonlinear waves, so the research on ultrafast mode-locked fiber laser has always been one of the hot topics in this field. At present, a large number of literatures have reported optical solitons and optical self-similar pulses as a new class of nonlinear waves. The soliton pulse is formed under the joint action of negative group velocity dispersion and self-phase modulation effect. When the two effects are balanced, the soliton mode-locked fiber laser can be realized. Due to the balance of group velocity dispersion and self-phase modulation effects, the soliton can keep the shape and intensity of the pulse stable in the laser cavity, so its mode-locking threshold is small. When the pulse energy increases, the additional non-linear phase shift leads to the splitting of the soliton, and the phenomenon of multi-pulse or harmonic mode-locking occurs experimentally. Therefore, the single pulse energy obtained by the soliton mode-locked fiber laser is generally relatively low. The self-similar pulse is the asymptotic solution of the nonlinear Schrödinger equation with a constant gain. The pulse does not split during the transmission process, and the energy can be gradually amplified. The pulse transmission satisfies the self-similar feature and forms a self-similar parabolic pulse. Self-similar pulsed fiber laser can ensure that the pulse shape is unchanged during the transmission process, with equal proportional gain; it can tolerate large nonlinear effects, and there is no wave splitting in fiber propagation; it can get shorter pulse width. Based on such characteristics, high-power fiber amplification usually uses self-similar pulsed laser as the seed source.

However, with the deepening of research, femtosecond laser output with a single band and a single nonlinear wave type can no longer meet the increasing application requirements, but as far as the current femtosecond mode-locked fiber laser is concerned, most of them can only output soliton pulses or self-similar Pulse, and the output wavelength is generally a single band, these factors restrict the application range of femtosecond mode-locked fiber laser. For some applications, not only the simultaneous output of soliton-self-similar pulses, but also tunable high-power fiber femtosecond laser output is required. Therefore, the research on high-power broadband tunable soliton-self-similar pulse mode-locked fiber laser is an urgent problem to be solved in many applications.

Contents of the invention

In order to overcome the defects or deficiencies in the above-mentioned prior art, the object of the present invention is to provide a high-power broadband tunable soliton-self-similar pulse mode-locked fiber laser with simple structure, reliable performance and low cost to generate high-power Tuning femtosecond laser output, while ensuring simultaneous output of soliton pulses and self-similar pulses.

For realizing above-mentioned task, the present invention takes following technical solution:

A high-power broadband tunable soliton-self-similar pulse mode-locked fiber laser is characterized in that it includes a pump source and a fiber combiner, a first dispersion compensation fiber and a second dispersion compensation fiber, a first fiber coupler and Second fiber coupler, first fiber collimator and second fiber collimator, first 1/4 wave plate and second 1/4 wave plate, 1/2 wave plate, polarization beam splitter, birefringence filter Chip, optical isolator and Er:Yb co-doped double-clad gain fiber form a laser ring cavity with a single-mode fiber and a spatial optical path;

The pumping source is connected to the pumping port of the fiber combiner, and the signal port of the fiber combiner is sequentially connected through the first dispersion compensation fiber, the first fiber coupler and the first fiber collimator, and the first fiber collimator The output light of the collimator is coupled into the second fiber coupler through the first 1/4 wave plate, 1/2 wave plate, polarization beam splitter, birefringent filter, optical isolator and the second 1/4 wave plate, and then through The second dispersion compensating fiber, the second fiber coupler, Er:Yb co-doped double-clad gain fiber are connected to the signal end of the fiber combiner; its stable femtosecond laser pulse is coupled through the first fiber coupler and the second fiber The output of the three ports of the device and the polarization beam combiner.

According to the present invention, the pumping source is a multimode fiber-coupled semiconductor laser, and its center wavelength is located near 975nm.

The operating wavelength of the described fiber combiner is 980/1550nm, and the pigtail type of the fiber combiner is Er: Yb co-doped double-clad gain fiber matching fiber, the absorption peak of this matching fiber is at 1535nm, and the absorption system is 80dB/m, the numerical aperture of the core is 0.22, and the core diameter is about 8um, providing positive dispersion.

The dispersion compensating fiber adopts positive dispersion fiber.

The first fiber coupler adopts a 5:95 fiber coupler, and the pigtail type of the first fiber coupler is a single-mode fiber; the second fiber coupler adopts a 1:99 fiber coupler, and the second fiber coupler The type of pigtail is single-mode negative dispersion fiber.

The working distance between the first fiber collimator and the second fiber collimator is 200mm-500mm, and the pigtail type is single-mode negative dispersion fiber.

The operating wavelengths of the first 1/4 wave plate, 1/2 wave plate and the second 1/4 wave plate are all 1550±40nm.

The beam splitting ratio of the polarization beam splitting prism is greater than 1000:1, and the working wavelength is 1550±40nm.

The thickness of the birefringence filter adopts the fused silica material of 5 mm to 8 mm.

The optical isolator adopts a polarization-dependent isolator with a central wavelength of 1550nm, and a working bandwidth of ±40nm.

The high-power broadband tunable soliton-self-similar pulse mode-locked fiber laser of the present invention is simple and reliable, easy to maintain, can realize self-starting mode-locking, can output soliton pulse and self-similar pulse at the same time, can realize wavelength tuning output, and has high output pulse power , low cost, and easy operation make the femtosecond mode-locked fiber laser a conventional ultrafast laser, which has more important applications in optical communication, spectral analysis, and precision measurement.

The beneficial technologies brought are:

1. Using Er:Yb co-doped double-clad fiber as the gain medium can realize high-power laser output.

2. Reasonably optimize the length of the first dispersion compensating fiber, the second dispersion compensating fiber and the length of the single-mode negative dispersion fiber, and realize the femtosecond laser with simultaneous output of soliton pulse and self-similar pulse.

3. Effective polarization and wavelength control can be realized simultaneously through the wave plate, effective nonlinear polarization rotation mode-locking can be realized, the thickness and angle of the birefringent filter can be reasonably optimized, and femtosecond pulse output with tunable wavelength can be realized by using its filtering effect .

4. The response time is on the order of femtoseconds and has nothing to do with wavelength, so the use of high-power broadband tunable soliton-self-similar pulse mode-locked fiber lasers can be applied in different wavelength ranges.

5. It has good practicability and operability, its compact structure, suitable for repeated production and assembly, suitable for mass production, low cost, laser unidirectional output, high output power, broadband tunable output, soliton Simultaneous output of pulse and self-similar pulse, high stability and high beam quality, etc., can be widely used in national defense, industry, medical treatment, scientific research and other fields, with good application prospects and commercial value.

Description of drawings

Fig. 1 is a schematic structural diagram of a high-power broadband tunable soliton-self-similar pulse mode-locked fiber laser according to an embodiment of the present invention.

The marks in it represent: 1. pump source, 2. fiber combiner, 3. first dispersion compensating fiber, 4. first fiber coupler, 5. first fiber collimator, 6. first 1/ 4 wave plates, 7, 1/2 wave plate, 8, polarization beam splitter, 9, birefringent filter, 10, optical isolator, 11, second 1/4 wave plate, 12, second fiber collimator , 13, the second dispersion compensation fiber, 14, the second fiber coupler, 15, Er: Yb co-doped double-layer fiber.

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

detailed description

In order to make the purpose, technical solutions and advantages of the present invention clearer, it should be understood that the specific embodiments described here are only used to explain the present invention, and are not intended to limit the present invention.

This embodiment provides a high-power broadband tunable soliton-self-similar pulse mode-locked fiber laser. Optical fiber 3 and second dispersion compensating optical fiber 13, first fiber coupler 4 and second fiber coupler 14, first fiber collimator 5 and second fiber collimator (12), first 1/4 wave plate 6 And the second 1/4 wave plate 11, 1/2 wave plate 7, polarization beam splitter prism 8, birefringence filter 9, optical isolator 10 and Er: Yb co-doped double-clad fiber 15 uses single-mode fiber and space The optical path constitutes a laser ring cavity;

Wherein, the pumping source 1 is connected to the pumping port 2a of the fiber combiner 2, and the signal port 2b of the fiber combiner 2 is connected through the dispersion compensating fiber 3, the first fiber coupler 4 and the first fiber collimator 5 in sequence , the output of the first fiber collimator 5 passes through the first 1/4 wave plate 6, 1/2 wave plate 7, polarization beam splitter prism 8, birefringence filter 9, optical isolator 10 and the second 1/4 wave Plate 11 is coupled into the second fiber coupler 12, then through dispersion compensation fiber 13, second fiber coupler 14, Er:Yb co-doped double-clad gain fiber 15 is connected with the signal end of fiber combiner (2); The stable femtosecond laser pulses are output through three ports A, B, and C of the first fiber coupler 4 , the second fiber coupler 14 and the polarization beam combiner 8 .

The pumping source 1 in this embodiment is a semiconductor laser coupled and output by a multimode fiber, the output wavelength of the pump laser is 975nm, the typical output power is 10W, and the pigtail type is 105/125 multimode fiber;

Fiber combiner 2, in order to couple the pump light into the laser cavity, the type of pigtail at pump end 2a is 105/125 multimode fiber, and the type of pigtail at signal output ends 2b and 2c is double-clad gain fiber matching fiber.

The first dispersion compensating fiber 3 and the second dispersion compensating fiber 13 are positive dispersion compensating fibers with a mode field diameter of 5um.

The first optical fiber coupler 4 has a splitting ratio of 5:95, the second optical fiber coupler 14 has a splitting ratio of 1:99, and the pigtail adopts a single-mode negative dispersion fiber.

The first fiber collimator 5 and the second collimator 12 are for mutual conversion of spatial light and fiber light, and the pigtail type is a single-mode negative dispersion fiber.

The first 1/4 wave plate 6, the 1/2 wave plate 7 and the second 1/4 wave plate 11 are used to change the laser polarization to realize nonlinear polarization rotation mode-locking. membrane;

Polarizing beam splitter prism 8, with an extinction ratio greater than 1000:1, coated with a high-transparency film for laser light at 1500nm to 1600nm;

The birefringence filter 9 is made of fused silica material and has a thickness of 7.5mm;

Spatial optical isolator 10, the working wavelength is 1550±40nm, and the isolation degree is greater than 30dB;

The high-power broadband tunable soliton-self-similar pulse mode-locked fiber laser of this embodiment can realize high-power output by using a multimode pump source and Er:Yb co-doped double-clad fiber; at the same time, the length of the dispersion compensation fiber is reasonably optimized, and the adjustment The dispersion distribution in the cavity ensures simultaneous output of soliton pulses and self-similar pulses; the tuning output of the laser can be effectively realized by adjusting the angle of the birefringent filter. In this way, a high-power broadband tunable soliton-self-similar pulse mode-locked fiber laser is realized.

Finally, it should be noted that although the present invention has been described in detail with reference to the above-mentioned embodiments, those of ordinary skill in the art should understand that the present invention is not limited to the above-mentioned embodiments, and those skilled in the art will The simple modification or equivalent replacement will not depart from the protection scope of the technical solution of the present invention.

Claims (10)

1. A high-power broadband tunable soliton-self-similar pulse mode-locked fiber laser is characterized in that it comprises a pump source (1) and is composed of an optical fiber beam combiner (2), the first dispersion compensating optical fiber (3) and the first Two dispersion compensating fibers (13), the first fiber coupler (4) and the second fiber coupler (14), the first fiber collimator (5) and the second fiber collimator (12), the first 1/ 4 wave plates (6) and the second 1/4 wave plate (11), 1/2 wave plate (7), polarization beam splitter prism (8), birefringence filter (9), optical isolator (10) and Er: Yb co-doped double-clad gain fiber (15) forms a laser ring cavity with a single-mode fiber and a spatial optical path; The pumping source (1) is connected to the pump port of the fiber combiner (2), and the signal port of the fiber combiner (2) passes through the first dispersion compensating fiber (3), the first fiber coupler ( 4) be connected with the first fiber collimator (5), the output light of the first fiber collimator (5) passes through the first 1/4 wave plate (6), 1/2 wave plate (7), polarization beam splitter prism ( 8), birefringence filter (9), optical isolator (10) and the second 1/4 wave plate (11) are coupled into the second optical fiber coupler (12), then through the second dispersion compensating optical fiber (13) , the second fiber coupler (14), Er: Yb co-doped double-clad gain fiber (15) is connected with the signal end of the fiber combiner (2); its stable femtosecond laser pulse passes through the first fiber coupler ( 4), output from the three ports of the second fiber coupler (14) and the polarization beam combiner (8). 2. high-power broadband tunable soliton-self-similar pulse mode-locked fiber laser as claimed in claim 1, is characterized in that, described pumping source (1) is the semiconductor laser of multimode fiber coupling, and its central wavelength is at Around 975nm. 3. high-power broadband tunable soliton-self-similar pulse mode-locked fiber laser as claimed in claim 1, is characterized in that, the operating wavelength of described fiber combiner (2) is 980/1550nm, fiber combiner The pigtail type of (2) is the matched fiber of Er: Yb co-doped double-clad gain fiber (15), the absorption peak of this matched fiber is at 1535nm, the absorption system is 80dB/m, the core numerical aperture is 0.22, and the core diameter is about It is 8um, providing positive dispersion. 4. The high-power broadband tunable soliton-self-similar pulse mode-locked fiber laser as claimed in claim 1, characterized in that the dispersion compensation fiber (3) is a positive dispersion fiber. 5. high-power broadband tunable soliton-self-similar pulse mode-locked fiber laser as claimed in claim 1, is characterized in that, described first fiber coupler (4) adopts 5:95 fiber coupler, the first optical fiber The pigtail type of the coupler (4) is a single-mode fiber; the second fiber coupler (13) adopts a 1:99 fiber coupler, and the pigtail type of the second fiber coupler (13) is a single-mode negative dispersion fiber . 6. high power broadband tunable soliton-self-similar pulse mode-locked fiber laser as claimed in claim 1, is characterized in that, described first fiber collimator (5) and second fiber collimator (12) The working distance is 200mm~500mm, and the pigtail type is single-mode negative dispersion fiber. 7. high power broadband tunable soliton-self-similar pulse mode-locked fiber laser as claimed in claim 1, is characterized in that, described first 1/4 wave plate (6), 1/2 wave plate (7) and The working wavelength of the second 1/4 wave plate (11) is 1550±40nm. 8. The high-power broadband tunable soliton-self-similar pulse mode-locked fiber laser as claimed in claim 1, characterized in that, the beam splitting ratio of the polarization beam splitter (8) is greater than 1000:1, and the operating wavelength is 1550 ± 40nm . 9. The high-power broadband tunable soliton-self-similar pulse mode-locked fiber laser according to claim 1, characterized in that, the thickness of the birefringent filter (9) is fused silica material of 5 mm to 8 mm. 10. high power broadband tunable soliton-self-similar pulse mode-locked fiber laser as claimed in claim 1, is characterized in that, described optical isolator (10) adopts the polarization-dependent isolator that center wavelength is 1550nm, working bandwidth is ±40nm.