阅读说明：本技术 一种基于四波混频效应的涡旋光锁模光纤激光器 (A kind of vortex light mode locked fiber laser based on four-wave mixing effect ) 是由 甘久林 衡小波 杨中民 张智深 林巍 于 2019-07-30 设计创作，主要内容包括：本发明公开了一种基于四波混频效应的涡旋光锁模光纤激光器,所述激光器包括单纵模激光源、波长可调谐激光源、第一光纤耦合器、光放大器、第一偏振控制器、轨道角动量模式产生器、第二光纤耦合器、第二偏振控制器和涡旋光纤。本发明基于四波混频效应,通过调谐注入激光频率和优化腔长,可充分保证锁模激光运转输出。基于涡旋光纤的模式分离和优化设计,采用涡旋光纤器件可确保特定阶轨道角动量模式在谐振腔内和输出端的产生和稳定传输。基于同阶模式泵浦机制,使得腔内同阶轨道角动量模式的信号光获得增益最大化,进而获得涡旋光锁模激光输出。本发明基于谐振腔内单一模式直接谐振机制,输出的涡旋光锁模激光具有模式纯度高和光束质量好等优点。(The invention discloses a kind of vortex light mode locked fiber laser based on four-wave mixing effect, the laser includes single longitudinal mode laser source, wavelength-tunable laser source, the first fiber coupler, image intensifer, the first Polarization Controller, orbital angular momentum mode generator, the second fiber coupler, the second Polarization Controller and vortex optical fiber.The present invention is based on four-wave mixing effects, long by tuning injection laser frequency and optimization chamber, can fully ensure that mode-locked laser operating output.Modal cutoff and optimization design based on vortex optical fiber can ensure that specific rank orbital angular momentum mode is transmitted in resonant cavity with the generation of output end and stabilization using vortex optical fibre device.Based on same order mode pumping mechanism, so that the signal light of intracavitary same order orbital angular momentum mode obtains gain and maximizes, and then the output of vortex light mode-locked laser is obtained.The present invention is based on the direct resonance mechanism of single-mode in resonant cavity, the vortex light mode-locked laser of output has many advantages, such as mode purity height and good beam quality.)

1. a kind of vortex light mode locked fiber laser based on four-wave mixing effect, which is characterized in that the laser includes single Longitudinal mode laser source, wavelength-tunable laser source, the first fiber coupler, image intensifer, the first Polarization Controller, orbital angular momentum Mode generator, the second fiber coupler, the second Polarization Controller and vortex optical fiber；

First fiber coupler has first port, second port and third port；

The orbital angular momentum mode generator has first port and second port；

Second fiber coupler has first port, second port, third port and the 4th port；

The single longitudinal mode laser source is connected to the first port of the first fiber coupler, and the wavelength-tunable laser source is connected to The second port of first fiber coupler, the third port of first fiber coupler are connected to image intensifer, and the light is put Big device is connected to the first port of orbital angular momentum mode generator, and first Polarization Controller is applied to image intensifer and rail On the light of road angular momentum mode generator connection, the second port of the orbital angular momentum mode generator is connected to the second light The third port of the first port of fine coupler, second fiber coupler is connect with the 4th port through vortex optical fiber, described Second Polarization Controller is applied on the optical fiber of connection third port and the 4th port, the second end of second fiber coupler Mouth output vortex light mode-locked laser；

The vortex optical fiber meets high refractive index contrast so that supports in vortex optical fiber is each for the refractive index of fibre core and covering Arrow pattern effective refractive index difference is greater than 1 × 10^-4And then support the optical fiber of orbital angular momentum mode stable transmission；

The orbital angular momentum mode generator and the second fiber coupler are vortex optical fibre device, support orbital angular momentum mould Formula is transmitted in resonant cavity with the generation of output end and stabilization；

Second fiber coupler connects and composes ring resonator through vortex optical fiber, is based on same order mode pumping mechanism, so that The intracavitary direct resonance of same order orbital angular momentum mode, and then acquisition high-purity vortex light mode-locked laser is defeated under four-wave mixing effect Out.

2. a kind of vortex light mode locked fiber laser based on four-wave mixing effect according to claim 1, which is characterized in that The single longitudinal mode laser source is narrow linewidth semiconductor laser or narrow cable and wide optical fiber laser, and line width is lower than 1MHz, single longitudinal mode fortune Turn.

3. a kind of vortex light mode locked fiber laser based on four-wave mixing effect according to claim 1, which is characterized in that The wavelength-tunable laser source is semiconductor laser or optical fiber laser, wavelength tuning range 100nm.

4. a kind of vortex light mode locked fiber laser based on four-wave mixing effect according to claim 1, which is characterized in that First fiber coupler is 1 × 2 coupler made from single mode optical fiber and single mode optical fiber fused biconical taper, first port and second The splitting ratio splitting ratio of port is 50:50.

5. a kind of vortex light mode locked fiber laser based on four-wave mixing effect according to claim 1, which is characterized in that The image intensifer selects the semiconductor optical amplifier of high-gain rare-earth-doped fiber amplifier or corresponding wave band.

6. a kind of vortex light mode locked fiber laser based on four-wave mixing effect according to claim 1, which is characterized in that The orbital angular momentum mode generator is that fusion fiber mode selects coupler, long-period fiber grating or chiral fiber light Grid, mode conversion efficiency are greater than 70%, and mode purity is greater than 80%, and first port uses single mode optical fiber, and second port is using vortex Optical fiber.

7. a kind of vortex light mode locked fiber laser based on four-wave mixing effect according to claim 1, which is characterized in that Second fiber coupler is 2 × 2 couplers made from vortex optical fiber and vortex optical fiber fused tapering, first port, second Port, third port and the 4th port are all made of vortex optical fiber.

8. a kind of vortex light mode locked fiber laser based on four-wave mixing effect according to claim 1, which is characterized in that The vortex optical fiber is the step-refraction index ring core optical fiber for supporting the transmission of orbital angular momentum mode stable, graded index ring core light Fine, gradient index fibre or inverse parabolic refractive index optical fiber.

Technical field

The present invention relates to laser technology fields more particularly to a kind of vortex light modelocked fiber based on four-wave mixing effect to swash Light device.

Background technique

Vortex beams are field distribution with helical phase itemexp(ilφ)A kind of light beam, each photon carries in light beamlhOrbital angular momentum (lFor topological charge number,φFor azimuth,hFor planck constant), there is annular light field distribution and spiral phase The characteristics of position singular point.These unique properties make it be widely used in material processing, optical tweezer, high-resolution imaging, optical fiber biography The fields such as sense and fiber optic communication.But these application prospects are to output peak power, stability, the mode purity of whirlpool light beam More stringent requirements are proposed with bandwidth etc..Mode-locked laser is due to narrow pulse width, high-peak power, wide spectrum The advantages that width, can satisfy such requirement.Meanwhile Mode-locked laser is in material retrofit, high field laser and substance phase The fields such as interaction also have important application, and are applied to wavelength-division multiplex and the following high-capacity and high-speed of Optical Time Division Multiplexing realization One of key technology of fiber optic communication.Mode-locked laser and vortex laser are combined and form mode locking pulse vortex laser, is applied Field will more extensively.Therefore, research vortex light mode-locked laser has a very important significance.

There are two types of common frameworks for mode-locked laser: the space structure based on bulk optical element and the light based on optical fibre device Fine framework.Compared to the former, mode locked fiber laser has apparent advantage, and the cavity configuration of one side optical fiber laser is flexible (linear cavity or annular chamber), intracavitary adjustable parameter is more, convenient for generating mode locking pulse.Another aspect mode locked fiber laser has complete Optical fiber cavity, and optical fiber itself has many distinctive characteristics, such as Self-phase modulation, Cross-phase Modulation, nonlinear polarization rotation Deng rationally pulse quality can be effectively improved using these characteristics.Research about mode locked fiber laser has very much, patent CN105428976A discloses a kind of mode locked fiber laser and pulse laser production method, produces lock using linear cavity configuration Mould pulse.Patent CN106785842A discloses a kind of passive mode-locking fiber laser based on Cadmium arsenide's film, using annular Cavity configuration realizes the output of high pulse energy mode locking pulse.In fact, light wave is when optical fiber transmits, due to the limitation on fibre core boundary, What the Helmholtz equation of solution light wave transmissions obtained is discontinuous solution of electro-magnetic field, and this discontinuous field solution is known as mode, Including fundamental transverse mode and high-order transverse mode.Stablizing the mode of transmission in conventional single mode fiber is fundamental transverse mode.And the vortex light in optical fiber It is to be formed by stacking by the odd mould and even mould of order vectors transverse mode (HE or EH) with pi/2 phase difference, also referred to as orbital angular momentum mode. It will be apparent that the pulse that the mode locked fiber laser of above-mentioned patent disclosure exports is fundamental transverse mode mode locking pulse, it is directly to generate Vortex light mode locking pulse.

Currently, the method for generating vortex light mode locking pulse is to add track angle outside the output end of traditional mode locked fiber laser Momentum Model generator or converter, that is, fundamental transverse mode mode locking pulse is converted into orbital angular momentum mode mode locking pulse, example Such as patent CN105870768A, CN108963734A and CN108988112A.Although this method can also generate orbital angular momentum Mode mode-locked laser, but laser activity depends critically upon the performance of orbital angular momentum mode generator or converter, exports laser Mode purity it is relatively low, beam quality is poor.In addition, most of optical-fiber type orbital angular momentum mode generator or converter are It is made based on single mode optical fiber and traditional less fundamental mode optical fibre or multimode fibre.Conventional single mode fiber only supports the transmission of fundamental transverse mode, tradition Since smooth sea leads the approximate order vectors transverse mode degeneracy linearly polarized mode for making similar propagation constant in less fundamental mode optical fibre or multimode fibre Formula is unable to satisfy the stable transmission in a fiber of orbital angular momentum mode.Therefore, turned by traditional modelocked fiber laser output The orbital angular momentum mode mode locking pulse transmission changed is unstable.Therefore, it is steady to obtain to design a kind of mode locked fiber laser Fixed, height mode purity orbital angular momentum mode mode-locked laser has a very important significance.

Summary of the invention

For the above problems of the prior art, the purpose of the present invention is to provide one kind to be based on four-wave mixing effect Vortex light mode locked fiber laser.It is simple with structure, at low cost, be easy to that fibre system is integrated, output laser rail angular motion Measure mode purity height and the good advantage of stability.

The purpose of the present invention can be achieved through the following technical solutions:

A kind of vortex light mode locked fiber laser based on four-wave mixing effect, including single longitudinal mode laser source, tunable wave length are swashed Light source, the first fiber coupler, image intensifer, the first Polarization Controller, orbital angular momentum mode generator, the second fiber coupling Device, the second Polarization Controller and vortex optical fiber；

First fiber coupler has first port, second port and third port；

The orbital angular momentum mode generator has first port and second port；

Second fiber coupler has first port, second port, third port and the 4th port；

The single longitudinal mode laser source is connected to the first port of the first fiber coupler, and the wavelength-tunable laser source is connected to The second port of first fiber coupler, the third port of first fiber coupler are connected to image intensifer, and the light is put Big device is connected to the first port of orbital angular momentum mode generator, and first Polarization Controller is applied to image intensifer and rail On the light of road angular momentum mode generator connection, the second port of the orbital angular momentum mode generator is connected to the second light The third port of the first port of fine coupler, second fiber coupler is connect with the 4th port through vortex optical fiber, described Second Polarization Controller is applied on the optical fiber of connection third port and the 4th port, the second end of second fiber coupler Mouth output vortex light mode-locked laser.

Orbital angular momentum mode mode locked fiber laser provided by the invention is ring cavity structure, and annular chamber is by vortex optical fiber And the device based on vortex optical fiber connects and composes.Compared to traditional less fundamental mode optical fibre or multimode fibre, the design of this vortex optical fiber is thought Road is the contrast of refractive index for increasing fibre core and covering, and to break arrow pattern degeneracy similar in propagation constant, i.e. optical fiber is supported Each arrow pattern effective refractive index difference be greater than 1 × 10^-4, and then realize orbital angular momentum mode in intracavitary stable transmission. The basic mode light in single longitudinal mode laser source and wavelength-tunable laser source output is dual wavelength base by closing beam after the first fiber coupler Mould light obtains high power dual wavelength basic mode light using image intensifer.It is generated by Polarization Controller and orbital angular momentum mode Device is converted to specific dual wavelength orbital angular momentum mode light beam.Orbital angular momentum mode light enters through the second fiber coupler The annular chamber being made of vortex optical fiber.It, can by adjusting the output wavelength and the second Polarization Controller of wavelength-tunable laser source To realize the multi-stage cascade four-wave mixing process of the direct resonance of orbital angular momentum mode in annular chamber.When tunable wave length laser Source and single longitudinal mode laser source output wavelength difference are with the wavelength interval of annular chamber when consistent or integral multiple, then in the second fiber coupler Second port export vortex light mode-locked laser.

Preferably, the single longitudinal mode laser source is narrow linewidth semiconductor laser or narrow cable and wide optical fiber laser, and line width is low In 1MHz, single longitudinal mode operating.

Preferably, the wavelength-tunable laser source is semiconductor laser or optical fiber laser, and wavelength tuning range is 100nm。

Preferably, first fiber coupler is that single mode optical fiber is coupled with made from single mode optical fiber fused biconical taper 1 × 2 The splitting ratio of device, first port and second port is 50:50.

Preferably, the image intensifer selects the semiconductor of high-gain rare-earth-doped fiber amplifier or corresponding wave band Image intensifer.

Preferably, the orbital angular momentum mode generator is that fusion fiber mode selects coupler, long period optical fiber Grating or chiral fiber grating, mode conversion efficiency are greater than 70%, and mode purity is greater than 80%, and first port uses single mode optical fiber, Second port uses vortex optical fiber.

Preferably, second fiber coupler is that vortex optical fiber is coupled with made from vortex optical fiber fused tapering 2 × 2 Device, first port, second port, third port and the 4th port are all made of vortex optical fiber.

Preferably, the vortex fiber selection supports the step-refraction index ring core light of orbital angular momentum mode stable transmission Fibre, graded index ring core optical fiber, gradient index fibre or inverse parabolic refractive index optical fiber, each arrow pattern of transmission are effective Refringence is greater than 1 × 10^-4。

The present invention compared to the prior art, have it is below the utility model has the advantages that

1, the present invention is based on same order mode pumping mechanisms, are pumped using specific rank orbital angular momentum mode pump light to resonant cavity Pu, so that the direct resonance of signal light of intracavitary same order orbital angular momentum mode, the zlasing mode purity is high of acquisition, beam quality It is good；

2, the present invention obtains orbital angular momentum mode mode-locked laser using four-wave mixing effect, and regulation is simple, output laser pulse Stability is good；

3, the present invention uses all optical fibre structure, has many advantages, such as that stability is good, is easy to fibre system and integrates, improves track angular motion Measure the practicability and reliability of Mode for Laser.

Detailed description of the invention

Fig. 1 is the schematic diagram of the vortex light mode locked fiber laser based on four-wave mixing effect in embodiment 1.

In figure, 1- single longitudinal mode laser source, 2- wavelength-tunable laser source, the first fiber coupler of 3-, the first optical fiber of 301- Coupler first port, the first fiber coupler of 302- second port, the first fiber coupler of 303- third port, 4- light amplification Device, the first Polarization Controller of 5-, 6- orbital angular momentum mode generator, 601- orbital angular momentum mode generator first port, 602- orbital angular momentum mode generator second port, the second fiber coupler of 7-, the second fiber coupler of 701- first port, The second fiber coupler of 702- second port, the second fiber coupler of 703- third port, the second fiber coupler of 704- the 4th Port, the second Polarization Controller of 8-, 9- vortex optical fiber.

Specific embodiment

Present invention will now be described in further detail with reference to the embodiments and the accompanying drawings, but embodiments of the present invention are unlimited In this.