Wavelength-tunable high-energy wave band laser and wavelength tuning method thereof

Abstract

The invention discloses a wavelength-tunable high-energy waveband laser and a wavelength tuning method thereof, and belongs to the technical field of fiber lasers. The laser comprises a pumping source capable of outputting pumping light, and the pumping source is sequentially provided with a three-in-one mixing device, an ytterbium-doped optical fiber, a first polarization controller, a polarization sensitive isolator and a second polarization controller in the light emitting direction to form an annular cavity. Pump light enters the annular cavity from the input end of the three-in-one device, is amplified into light with the wavelength of 1030 nm through excited radiation of the ytterbium-doped optical fiber, and then enters the first polarization controller through the HI-1060 single-mode optical fiber. The polarization sensitive isolator forms a nonlinear polarization rotation structure between the polarization controller I and the polarization controller II; the output end of the second polarization controller is connected with a three-in-one mixing device, the output end of the three-in-one mixing device is connected with a single-mode jumper wire to output 20% of light, and after output, the remaining 80% of light continues to be subjected to stimulated radiation amplification in the annular cavity.

Description

Technical Field

[0001] The invention belongs to the technical field of optical fiber lasers, and in particular relates to a high-energy band laser with tunable wavelength and a wavelength tuning method thereof. Background Art

[0002] At present, the wavelength of general mode-locked fiber lasers is single and fixed, such as the common communication band 1550 nm, etc. However, many application fields have a strong demand for the tunability of ultrashort pulse sources. For example, in ophthalmic surgery, femtosecond lasers use a wavelength of 1053 nm, and traditional mode-locked ytterbium-doped fiber lasers with a central wavelength of 1030 nm cannot be well applied. Therefore, the research on multi-wavelength tunable mode-locked ytterbium-doped fiber lasers is of great significance and practical value.

[0003] Therefore, building a multi-wavelength tunable ytterbium-doped fiber laser with good stability, low production cost and high energy to meet the use requirements of mode-locked lasers operating in ultrashort pulses is a topic that urgently needs to be studied and explored in this field. Summary of the invention

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a wavelength-tunable high-energy band laser and a wavelength tuning method thereof, which solves the problems in the prior art.

[0005] The purpose of the present invention can be achieved through the following technical solutions: A wavelength-tunable high-energy band laser comprises a pump source capable of outputting pump light, wherein the pump source is provided with a three-in-one hybrid device, an ytterbium-doped optical fiber, a polarization controller 1, a polarization-sensitive isolator and a polarization controller 2 in sequence along the light emission direction to form a ring cavity; The pump light enters the ring cavity from the input end of the three-in-one device, and is amplified by stimulated emission of ytterbium-doped optical fiber to light with a wavelength of 1030 nm, and then enters polarization controller 1; the polarization-sensitive isolator forms a nonlinear polarization rotation structure between polarization controller 1 and polarization controller 2; the output end of polarization controller 2 is connected to the three-in-one hybrid device, and the output end of the three-in-one hybrid device is connected to a single-mode jumper to output 20% of the light. After the output, the remaining 80% of the light continues to be amplified by stimulated emission in the ring cavity.

[0006] Furthermore, the three-in-one hybrid device includes a wavelength division multiplexer, an optical isolator and a coupler which are sequentially connected along the light emitting direction.

[0007] Furthermore, 20% of the light outputted from the output end of the coupler is used to detect the spectrum, pulse width and signal-to-noise ratio, and its pigtail is a HI-1060 single-mode optical fiber.

[0008] Furthermore, the wavelength division multiplexer model is 980 / 1030nm, its input pump end is 980nm, and its output optical fiber port is 1030nm.

[0009] Furthermore, the optical isolator is a single-pole polarization-insensitive isolator with an isolation degree of 3.5 dB.

[0010] Furthermore, the core diameter of the ytterbium-doped optical fiber is 6 μm, the length is 0.8 m, and the gain coefficient is 250 dB / m.

[0011] Furthermore, the polarization sensitive isolator, polarization controller 1 and polarization controller 2 pigtails are all HI-1060 single-mode optical fibers.

[0012] Furthermore, the single-mode jumper is a HI-1060 single-mode optical fiber.

[0013] The wavelength tuning method of the above-mentioned wavelength tunable high-energy band laser includes: adjusting the power of the pump source and the polarization controller 1 and the polarization controller 2 to make the laser generate dissipative soliton mode-locked pulses and control the polarization direction of the light in the ring cavity.

[0014] A multi-signal pulse emission device comprises the above-mentioned high-energy band laser with tunable wavelength.

[0015] Beneficial effects of the present invention: 1. The laser of the present invention is based on the mode-locked ytterbium-doped fiber laser, and realizes wavelength-tunable laser output by introducing a wavelength selection mechanism. Compared with the fixed-wavelength mode-locked ytterbium-doped fiber laser, the laser of the present invention can realize the output of single-pulse lasers in multiple bands.

[0016] 2. The present invention adopts an all-fiber ytterbium-doped mode-locked laser structure, with large positive dispersion in the cavity, and introduces strong positive chirped pulses, which is conducive to carrying higher pulse energy, which is exactly the purpose of the traditional chirped pulse amplification system to perform multi-stage processing on the laser oscillator. Therefore, the positive chirped pulse fiber laser based on the nonlinear polarization rotation structure can realize a simplified chirped amplification system, and then achieve high-energy pulse output.

[0017] 3. The wavelength tunable method in the prior art is mainly implemented by using devices such as gratings and tunable filters, while the laser of the present invention achieves wavelength tuning by controlling the polarization state in the laser cavity; this solution has the advantages of simple and compact structure and low cost. The low-loss fusion between optical fibers improves the coupling efficiency, and the light is always bound in the optical fiber in the laser cavity, which also largely avoids interference from external factors and improves environmental stability.

[0018] 4. The wavelength tunable laser of the present invention realizes single-pulse laser output that is tunable in three different bands, and can be used in fields such as optical sensing and multi-signal pulse transmitters, and deepens the understanding of dissipative soliton mode locking and multi-wavelength conversion mechanisms in nonlinear science. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 It is a schematic diagram of the overall structure of the laser in the present invention; Figure 2 is a pulse sequence diagram of the laser in the present invention; Figure 3 is a spectrum diagram of the laser in the present invention; Figure 4 It is a spectrum diagram of the central wavelength of the laser in the present invention in the 1035.95 nm band; Figure 5 It is a pulse width diagram of the laser center wavelength in the 1035.95 nm band in the present invention; Figure 6 It is a spectrum diagram of the laser center wavelength in the 1044.58 nm band in the present invention; Figure 7 It is a pulse width diagram of the laser center wavelength in the 1044.58 nm band in the present invention; Figure 8 It is a spectrum diagram of the central wavelength of the laser in the present invention in the 1076.52nm band; Fig. 9 It is a pulse width diagram of the laser center wavelength in the 1076.52nm band in the present invention; In the figure: 1- pump source, 2- three-in-one hybrid device, 3- ytterbium-doped fiber, 4- polarization controller 1, 5- polarization-sensitive isolator, 6- polarization controller 2, 7- pump end of the three-in-one hybrid device, 8- input end of the three-in-one hybrid device, 9- 80% coupling end of the three-in-one hybrid device, 10- 20% output end of the three-in-one hybrid device. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Example 1 like Figure 1 As shown, a wavelength tunable high energy band laser comprises a pump source 1 for outputting pump light, wherein the pump source 1 is provided with a three-in-one hybrid device 2, an ytterbium-doped optical fiber 3, a polarization controller 1 4, a polarization sensitive isolator 5, and a polarization controller 2 6 in sequence along the light emission direction, thereby forming a ring cavity of the laser; The three-in-one hybrid device 2 is a device that integrates a wavelength division multiplexer, an optical isolator, and a coupler. The two ends of the three-in-one hybrid device 2 use dual fiber collimators as the coupler end and the wavelength division multiplexer end respectively. Both ends are micro-device type, and the middle part is the isolator core. The three-in-one hybrid device 2 provides input signal power monitoring, pump / signal multiplexing and isolation functions. The isolator core is a polarization-independent structure, and the pump light direction is forward (forward) pumping; among them, 20% of the light output from the output end of the coupler is used to detect information such as spectrum, pulse width, and signal-to-noise ratio, and its pigtail is HI-1060 single-mode optical fiber; the working center band of the wavelength division multiplexer is 980 / 1030nm, its input pump end is 980nm, and the output fiber port is 1030nm, so that the laser cavity is a ring structure; the optical isolator is a single-pole polarization-insensitive isolator with an isolation of 3.5dB, ensuring that the light circulates unidirectionally clockwise in the ring cavity.

[0023] A pump light with a wavelength of 974 nm is coupled into the ring cavity from the input end of the wavelength division multiplexer, and the pump light passes through the ytterbium-doped fiber 3. The ytterbium-doped fiber 3, as a working medium for realizing stimulated emission light amplification, excites the doped ions to transform into light with a wavelength of about 1030 nm. The signal light output from the ytterbium-doped fiber 3 enters the polarization controller 1 4 via the HI-1060 single-mode fiber. The polarization state of the output light can be changed by adjusting the polarization controller 1 4 and the polarization controller 2 6. The polarization-sensitive isolator 5 forms a nonlinear polarization rotation structure between the polarization controller 1 4 and the polarization controller 2 6. The output end of the polarization controller 2 6 is connected to the three-in-one hybrid device 2. The output of the ring cavity is connected to a single-mode jumper through the output end of the three-in-one hybrid device 2 to output 20% of the light, and the remaining 80% of the light continues to be amplified by stimulated emission in the ring cavity. In this embodiment, the central wavelength band of the pump light output by the pump source 1 is 974 nm.

[0024] The loss of 3-in-1 hybrid 2 is 3.5 dB.

[0025] The laser uses ytterbium-doped optical fiber 3 as the laser gain medium. The core diameter of the ytterbium-doped optical fiber 3 is 6 μm, the gain coefficient is 250 dB / m, and the length used is 0.8 m.

[0026] The polarization sensitive isolator 5 has an operating wavelength of about 1030 nm, and the pigtail is a HI-1060 single-mode optical fiber; the pigtails of the polarization controller 1 4 and the polarization controller 2 6 are both HI-1060 single-mode optical fibers, and are 1 m in length respectively.

[0027] The ring cavity is based on nonlinear polarization rotation technology, with a total cavity length of about 6.4 m and an intracavity group velocity dispersion of about 0.1428 ps. 2 Since the optical fibers in the cavity are all positive dispersion structures with large positive chirp, it is easy to use chirped pulse amplification technology to achieve high-energy ultrashort pulse laser output.

[0028] The pigtails of the three-in-one hybrid device 2, polarization controller 1 4, polarization controller 2 6, and polarization sensitive isolator 5 are all HI-1060 single-mode optical fibers. The single-mode jumper is HI-1060 single-mode optical fiber.

[0029] like Figure 2 As shown, the optical signal is converted into an electrical signal by a photodetector (Thorlabs, 5 GHz), and the basic repetition frequency of the laser output pulse train is measured by an oscilloscope (R&S, RTP, 16 GHz). It is 26.37 MHz and the pulse period is 37.92 ns, corresponding to a ring cavity length of about 6.4 meters.

[0030] like Figure 3 As shown, the spectrum information centered at 26.37 MHz is displayed by a spectrum analyzer (RF, R&S FSW). With the RBW set to 10 Hz, the signal-to-noise ratio is 65 dB and remains stable, indicating that the intensity fluctuation of the pulse is small and that the mode-locked operation of the laser is stable.

[0031] Example 2 The wavelength tuning method of the laser in embodiment 1 includes: By adjusting the power of pump source 1 and polarization controller 1 4 and polarization controller 2 6, the laser generates dissipative soliton mode-locked pulses and precisely controls the polarization direction of light in the ring cavity, thus achieving tunable mode-locked laser output in a wide range near the three bands of 1035.95 nm, 1044.58 nm and 1076.52 nm.

[0032] The following tests are used to verify the description; like Figure 4As shown, a typical approximately rectangular dissipative soliton spectrum was observed by an optical spectrum analyzer (OSA, Yokogawa AQ6370D). The 3 dB spectral bandwidth of the laser at the central wavelength of 1035.95 nm was measured to be 8.18 nm. The spectrum is characterized by a relatively flat middle part and steep edges, and the overall shape is rectangular.

[0033] like Figure 5 As shown, the autocorrelation trajectory at the central wavelength of 1035.95 nm is displayed by the autocorrelator (AC, APE). By using Gaussian fitting, the corresponding pulse width is measured to be 13.38 ps, indicating that the laser can output ultrashort pulse lasers of the picosecond level at the central wavelength of 1035.95 nm.

[0034] like Figure 6 As shown, the polarization state in the fiber cavity is precisely controlled, and the mode-locked laser output in the central wavelength band of 1044.58 nm can be observed through a spectrum analyzer. The 3 dB spectral bandwidth at this central band is 9.56 nm, indicating that the laser has a wider half-maximum full width and a larger positive chirp at the central band of 1044.58 nm, which is beneficial to the generation of femtosecond ultrashort pulse lasers in the process of chirped pulse amplification.

[0035] like Figure 7 As shown, the autocorrelation trajectory at the central wavelength of 1044.58 nm is displayed by the autocorrelator. By using Gaussian fitting, the corresponding pulse width is measured to be 13.26 ps, indicating that the laser can generate ultrashort pulse laser at the central wavelength of 1044.58 nm.

[0036] like Figure 8 As shown, the polarization state in the fiber cavity is continued to be adjusted, and finally the ultrafast pulse laser output with a central wavelength of 1076.52 nm is observed through the spectrum analyzer. The 3 dB spectral bandwidth at this central band is 10.56 nm, indicating that the laser has a wider half-maximum full width and a larger positive chirp at the central band of 1076.52 nm, and pulse compression technology can be used to achieve femtosecond pulse output.

[0037] like Fig. 9 As shown in the figure, the autocorrelator signal with a central wavelength of 1076.52 nm is fitted with a Gaussian signal, and the corresponding pulse width is measured to be 12.08 ps, indicating that the laser can output stable ultrashort pulse lasers at a central wavelength of 1076.52 nm.

[0038] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0039] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A wavelength tunable high energy band laser, comprising a pump source capable of outputting pump light, characterized in that: The pump source is provided with a three-in-one hybrid device, an ytterbium-doped optical fiber, a polarization controller 1, a polarization-sensitive isolator and a polarization controller 2 in sequence along the light emission direction to form a ring cavity; The pump light enters the ring cavity from the input end of the three-in-one device, and is amplified by stimulated emission of ytterbium-doped optical fiber to light with a wavelength of 1030 nm, and then enters polarization controller 1; the polarization-sensitive isolator forms a nonlinear polarization rotation structure between polarization controller 1 and polarization controller 2; the output end of polarization controller 2 is connected to the three-in-one hybrid device, and the output end of the three-in-one hybrid device is connected to a single-mode jumper to output 20% of the light. After the output, the remaining 80% of the light continues to be amplified by stimulated emission in the ring cavity.

2. The wavelength tunable high energy band laser according to claim 1, characterized in that: The three-in-one hybrid device comprises a wavelength division multiplexer, an optical isolator and a coupler which are sequentially connected along the light emitting direction.

3. The wavelength tunable high energy band laser according to claim 2, characterized in that: The output end of the coupler outputs 20% of the light for detecting spectrum, pulse width and signal-to-noise ratio, and its pigtail is HI-1060 single-mode optical fiber.

4. The wavelength tunable high energy band laser according to claim 2, characterized in that: The wavelength division multiplexer model is 980 / 1030nm, its input pump end is 980nm, and its output optical fiber port is 1030nm.

5. The wavelength tunable high energy band laser according to claim 2, characterized in that: The optical isolator is a single-pole polarization-insensitive isolator with an isolation degree of 3.5 dB.

6. The wavelength tunable high energy band laser according to claim 1, characterized in that: The core diameter of the ytterbium-doped optical fiber is 6 μm, the length is 0.8 m, and the gain coefficient is 250 dB / m.

7. The wavelength tunable high energy band laser according to claim 1, characterized in that: The polarization sensitive isolator, polarization controller 1 and polarization controller 2 pigtails are all HI-1060 single-mode optical fibers.

8. The wavelength tunable high energy band laser according to claim 1, characterized in that: The single-mode jumper is a HI-1060 single-mode optical fiber.

9. The wavelength tuning method of a wavelength tunable high energy band laser according to any one of claims 1 to 8, characterized in that: include: The power of the pump source and polarization controller 1 and polarization controller 2 are adjusted to make the laser generate dissipative soliton mode-locked pulses and control the polarization direction of the light in the ring cavity.

10. A multi-signal pulse transmitting device, characterized in that: A wavelength-tunable high-energy band laser comprising the method described in any one of claims 1 to 8.

Images