CN106785870A - A kind of implementation method of the 2 mu m waveband ASE light sources based on LPFG filtering - Google Patents

Abstract

The invention provides a kind of implementation method of the 2 mu m waveband ASE light sources based on LPFG filtering, first, laser pulse by object lens after 50% spectroscope light splitting by focusing on the output that ASE light sources are realized on thulium doped fiber, then pointwise is carried out to thulium doped fiber using femto-second laser to inscribe to form LPFG, in scribing process monitor in real time is carried out by two CCD of X-axis and Z axis, detect situation about inscribing, after last ASE light sources are filtered by LPFG, grating is observed by spectrometer and transmits spectral pattern, judge filter effect；LPFG is inscribed using femtosecond, grating parameter is strictly controllable, can filtered interval optional；Using LPFG compared to other flat means, good stability, it is easy to operate is simple and convenient；Simple structure, effect is good, reduces cost of manufacture and technology difficulty, it is easy to accomplish industrialization.

Description

A kind of implementation method of the 2 mu m waveband ASE light sources based on LPFG filtering

Technical field

The present invention relates to a kind of 2 μm that LPFG inscribed by femtosecond is filtered of ASE light sources, more particularly to one Plant the implementation method of the 2 mu m waveband ASE light sources based on LPFG filtering.

Background technology

Superfluorescence belongs to the spontaneous radiation (ASE) of amplification, therefore super-fluorescence light source (SFS) is also called ASE light sources.Based on single mode Superfluorescence produced by doped fiber has the advantages that good directionality, environmental stability be high, fluorescence Spectra line width, and it is in Fibre Optical Sensor Increasingly it is widely applied in the fibre optic gyroscope of device, fiber-optical probe and aerospace navigation level.Meanwhile, super-fluorescence light source Compared with laser, with nothing from pulse, without outstanding advantages such as relaxation oscillation, non-mode competition, high time stabilities.Therefore, High-power fiber super-fluorescence light source is considered as that a kind of wide spectrum, high stability have the new of laser characteristics and fluorescent characteristic concurrently High-luminance light fibre source.

Between in the past few years, the research of fiber superfluorescent source achieves the progress for attracting people's attention., the report such as Wang in 2006 1.0 mu m waveband space structures, power output up to 110W wide band super fluorescence light source, the light source using 24/550pm big core Footpath double clad mixes mirror optical fiber as gain media, and the larger core diameter of doped fiber effectively inhibits the generation of laser generation, It is achieved thereby that spectral region is exported for the superfluorescence of 1032^-1120nm, its spectral bandwidth has reached 40nm, and slope efficiency is 68%.In addition in 1.0 mu m wavebands, the high power broadband that Beijing University of Technology realizes the output of all optical fibre structure hectowatt magnitude is super glimmering Radiant, the one way gain amplifier of superfluorescence amplifier has reached nearly 30dBm.2011, Schmidt etc. reported all -fiber knot Structure centre wavelength is the arrowband super-fluorescence light source of 1030nm, super to limit using two Fiber Bragg Grating FBGs of arrowband (FBG) The spectral bandwidth in fluorescent seeds source, by having finally given the arrowband super-fluorescence light source with a width of 12pm after casacade multi-amplifier, most High-output power has reached 697W.And the research report on 2 mu m waveband wide band super fluorescence light sources is less, Shen etc. reports sky Between structure be 2.0 mu m waveband wide band super fluorescence light sources, they use core diameter that optical fiber of dispelling is mixed for the double clad of 25pm as increasing Beneficial medium, centre wavelength is the high power multimode semiconductor laser of 790nm as pumping source, realizes mean power for 11W Wide band super fluorescence output, spectral region is 1930-1988nm.In recent years, because 2.0 mu m waveband wide band super fluorescence light sources are in light The fields such as analysis of spectrum, gas sensing and laser medicine coherent tomographic have important application.

Accordingly, it would be desirable to a kind of implementation method of the 2.0 mu m waveband wide band super fluorescence light sources that can effectively realize high flat degree.

The content of the invention

It is an object of the invention to provide a kind of realization of the 2 mu m waveband ASE light sources based on LPFG filtering Method, by making LPFG by oneself, thulium doped fiber ASE is leached using cardiac wave strong point wherein the characteristics of having depression Spike projection make it more flat.

To reach above-mentioned purpose, technical scheme of the present invention is as follows：First, laser pulse by 50% point Generation ASE light sources on thulium doped fiber are focused on by object lens after light microscopic light splitting, thulium doped fiber is entered using femto-second laser then Row pointwise is inscribed to form LPFG, and monitor in real time is carried out by two CCD of X-axis and Z axis in scribing process, and detection is inscribed Situation, after last ASE light sources are filtered by LPFG, by spectrometer observe grating transmit spectral pattern, sentence Disconnected filter effect, realizes that output spectral line is more flat.

Wherein, multiple LPFG series connection, the ASE light sources to thulium doped fiber output are filtered.

Wherein, in scribing process, LPFG is changed by adjusting the parameters such as inscription cycle, grating length Centre wavelength, i.e., by setting the inscription cycle and grating length obtains different fiber gratings, inscribe depth and breadth of spectrum line, The spike projection of thulium doped fiber ASE is leached the characteristics of having depression using cardiac wave strong point wherein, output spectral line is more put down It is smooth.

Wherein, thulium doped fiber is placed on a D translation platform, as gain media, can be moved.

Wherein, described 50% spectroscopical effect is light splitting, it is to avoid power is too strong.

Wherein, the effect of the femto-second laser is to carry out inscription to thulium doped fiber to form LPFG.

Preferably, the femto-second laser is relevant company's production, and centre wavelength is 800nm, and pulse width is 50fs.

Preferably, the thulium doped fiber is the production of Nufern companies, and absorptivity is 3dB/m.

Preferably, the LD pumping sources are the production of JDSU companies, and centre wavelength is 793nm.

Preferably, the type of the wavelength division multiplexer is 793/2000.

The beneficial effects of the invention are as follows the ASE spectral lines for making 2 μm by the LPFG inscribed with femtosecond more It is flat, LPFG is inscribed using femtosecond, grating parameter (inscribing cycle, grating length) is strict controllable, can filter area Between it is optional；Using LPFG compared to other flat means, good stability, it is easy to operate is simple and convenient；Structure Simply, effect is good, reduces cost of manufacture and technology difficulty, it is easy to accomplish industrialization.

It should be appreciated that foregoing description substantially and follow-up description in detail are exemplary illustration and explanation, should not As the limitation to claimed content of the invention.

Brief description of the drawings

With reference to the accompanying drawing enclosed, the present invention more purpose, function and advantages are by by the as follows of embodiment of the present invention Description is illustrated, wherein：

Fig. 1 schematically shows femtosecond fiber and carves grating system.

Fig. 2 schematically shows the grating transmission spectrum that screen periods are 700 μm.

Fig. 3 schematically shows the grating transmission spectrum that screen periods are 800 μm.

Fig. 4 is the schematic diagram of whole system, and wavelength is the LD pumping sources of 793nm centered on wherein 793nmLD, and VDM is ripple Divide recombiner, TDF thulium doped fibers, LPFG is LPFG.

Fig. 5 show by the filtering of long-period gratings string so that the compares figure that optimizes significantly of 2 μm of fluorescence flatness.

Specific embodiment

By reference to one exemplary embodiment, the purpose of the present invention and function and the side for realizing these purposes and function Method will be illustrated.However, the present invention is not limited to one exemplary embodiment as disclosed below；Can by multi-form come It is realized.The essence of specification is only to aid in various equivalent modifications Integrated Understanding detail of the invention.

Hereinafter, embodiments of the invention will be described with reference to the drawings.In the accompanying drawings, identical reference represents identical Or similar part, or same or like step.

The present invention provides a kind of implementation method of the 2 mu m waveband ASE light sources based on LPFG filtering, by certainly LPFG processed, the spike projection of thulium doped fiber ASE is leached using cardiac wave strong point wherein the characteristics of having depression Make it more flat.

Fig. 1 schematically shows femtosecond fiber and carves grating system.As shown in figure 1, spectroscope light splitting of the laser pulse by 50% Focused on thulium doped fiber by object lens afterwards, then carrying out pointwise to thulium doped fiber using femto-second laser inscribes to form long period Fiber grating, monitor in real time is carried out in scribing process by two CCD of X-axis and Z axis, detects situation about inscribing, last 2 mu m waveband After ASE light sources are filtered by LPFG, grating are observed by spectrometer and transmits spectral pattern, judge filter effect, Realize that output spectral line is more flat.

Implementation method of the invention, is connected using multiple LPFGs, and the ASE to realizing thulium doped fiber is composed Line is filtered.

Thulium doped fiber of the invention is placed on a D translation platform, can be moved.

In scribing process, in changing LPFG by adjusting the parameters such as inscription cycle, grating length Cardiac wave is long, i.e., obtain different fiber gratings by setting inscription cycle and grating length, inscribes depth and breadth of spectrum line, utilizes Cardiac wave strong point the characteristics of having depression leaches the spike projection of thulium doped fiber ASE wherein, makes the output spectral line more flat.

Fig. 2,3 schematically show the grating transmission spectrum that screen periods are 700 μm and 800 μm, and this is by transfer matrix method The spectrogram that simulation to LPFG spectrums is obtained.It is more complicated by coupled mode theory emulation LPFG transmission spectrums, transmission square is described below The simulation that the tactical deployment of troops is composed to LPFG：By LPG homogenous segmentations, each section with a matrix description of 2X2, then by all of matrix phase Multiplied to one matrix of total 2X2 represents total grating.Single matrix is represented by:

So as to the expression formula for drawing global matrix is：

To sum up, by emulating the grating transmission spectrum that screen periods are 700 μm and 800 μm, further checking：Can be by setting Putting inscription cycle and grating length can obtain different fiber gratings, and explanation ought reasonably arrange inscription spacing can be obtained by The LPFG that multiple centre wavelengths differ.Multiple LPFG series connection can be just played to thulium doped fiber Being filtered for ASE spectral lines makes it more flat.

If Fig. 4 is that femtosecond fiber carves grating system operation principle schematic diagram, wherein 793nm pump lights enter from wavelength division multiplexer In system, to ASE light before producing thulium doped fiber, 2 μm of generation of ASE light sources are caused by the filtering of long-period gratings string Its flatness optimizes significantly, as shown in figure 5, Fig. 5 schematically shows causes that 2 μm of fluorescence is put down by the filtering of long-period gratings string It is smooth to spend the compares figure for optimizing significantly, it is more flat by the grating transmission spectral line exported after LPFG filtering.

The present invention is mixed leaching using cardiac wave strong point wherein by making LPFG by oneself the characteristics of having depression The spike projection of thulium optical fiber ASE makes it more flat, long by setting inscription cycle and grating using self-control LPFG Degree can obtain different fiber gratings, and being filtered for ASE spectral lines to thulium doped fiber makes it more flat, good stability, It is easily operated, it is simple and convenient；Simple structure, effect is good, reduces cost of manufacture and technology difficulty, it is easy to accomplish industrialization.

With reference to the explanation of the invention and practice that disclose here, other embodiment of the invention is for those skilled in the art All will be readily apparent and understand.Illustrate and embodiment is to be considered only as exemplary, true scope of the invention and purport are equal It is defined in the claims.

Claims (9)

1. a kind of implementation method of the 2 mu m waveband ASE light sources based on LPFG filtering, comprises the following steps：First, Laser pulse is focused on thulium doped fiber by after 50% spectroscope light splitting by object lens, then using femto-second laser to mixing Thulium optical fiber carries out pointwise and inscribes to form LPFG, and monitor in real time is carried out by two CCD of X-axis and Z axis in scribing process, Situation about inscribing is detected, after last ASE light sources are filtered by LPFG, grating are observed by spectrometer and is transmitted Spectral pattern, judges filter effect, realizes that output spectral line is more flat.

2. implementation method as claimed in claim 1, it is characterised in that：Multiple LPFG series connection, to thulium doped fiber ASE spectral lines be filtered.

3. implementation method as claimed in claim 1, it is characterised in that：In scribing process, by adjusting inscription cycle, grating The parameters such as length change the centre wavelength of LPFG, are filtered the characteristics of having depression using cardiac wave strong point wherein Go out the spike projection of thulium doped fiber ASE, make output spectral line more flat.

4. implementation method as claimed in claim 1, it is characterised in that：Thulium doped fiber is placed on a D translation platform, can Move.

5. implementation method as claimed in claim 1, it is characterised in that：Described 50% spectroscopical effect is light splitting, it is to avoid Power is too strong.

6. implementation method as claimed in claim 1, it is characterised in that：The femto-second laser is relevant company's production, center Wavelength is 800nm, and pulse width is 50fs.

7. implementation method as claimed in claim 1, it is characterised in that：The thulium doped fiber is produced for Nufern companies, is absorbed Rate is 3dB/m.

8. implementation method as claimed in claim 1, it is characterised in that：The LD pumping sources are the production of JDSU companies, center Wavelength is 793nm.

9. implementation method as claimed in claim 1, it is characterised in that：The type of the wavelength division multiplexer is 793/2000.