CN101303452B

CN101303452B - Bundling optical fiber pulse delay overlapped shaper

Info

Publication number: CN101303452B
Application number: CN200810053630XA
Authority: CN
Inventors: 柴路; 王清月; 胡明列
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2008-06-25
Filing date: 2008-06-25
Publication date: 2010-06-23
Anticipated expiration: 2028-06-25
Also published as: CN101303452A

Abstract

The invention discloses a pulse delay and superposition reshaper of cluster optical fiber, which pertains to the technical field of laser. The pulse delay and superposition reshaper of the invention comprises a single high-power pulse laser, an aspheric collimating beam expander or a micro-lens array, a cluster single mode optical fiber retarder, an aspheric focusing lens or the micro-lens array and a multi-head single mode optical fiber. After being reshaped by the collimating beam expander, a flat roof-typed large mode field laser beam outputted by the laser is coupled and enters the cluster single mode optical fiber retarder; splitting beam pulses form a pulse sequence with the fixed-time delay and the same pulse energy and the pulse sequence is coupled in a single mode optical fiber by passing through a converging lens and the aspheric focusing lens and then superposed and reshaped to form a nanosecond rectangular pulse to be output. The pulse delay and superposition reshaper of the invention has the advantages of small size, low manufacturing cost, high stability, more splitting beams, uniform pulse energy, etc.

Description

Bundling optical fiber pulse delay overlapped shaper

Technical field

The present invention relates to a kind of bundling optical fiber pulse delay overlapped shaper, belong to laser technology field.

Background technology

Shape in optical communication field and laser inertial confinement nuclear fusion field to seed laser pulse has special requirement, often needs to have the rect.p. than long duration (ns magnitude).The method that adopts mainly contains: frequency domain filtering method, time domain delay-and-sum method.

The technology of comparative maturity has two kinds in the time domain delay-and-sum method at present: the one, the picosecond magnitude pulse of many fiber lasers and line output is introduced time delay through different time delay lines respectively, and then the rect.p. of the nanosecond order of the formation that stacks up; The 2nd, the rect.p. of the nanosecond order that adopts separate unit laser instrument output carrying out serial repeatedly to stack up again after the beam splitting to form.

There is significant disadvantages in above technology, promptly can not isolate more pulse (general＜10).This be because: adopt the parallel superimposed pulse of the every increase of export technique of many fiber lasers will increase a laser instrument in the method 1, therefore cause expense, power consumption, complicacy, the volume of total system all to increase fast; Though the quantity of laser instrument does not increase in the method 2, the pulse energy after the serial beam splitting decays, i.e. beam splitting pulse energy reduces step by step, and the stack building-up process is brought difficulty.

Summary of the invention

The present invention is intended to propose a kind of bundling optical fiber pulse delay overlapped shaper, this superimposed pulses reshaper has advantages such as volume is little, cost is low, stability is high, beam splitting is many, pulse energy is even, and therefore the pulse after the synthetic shaping of stack has higher pulse quality.

The present invention is realized by the following technical programs, a kind of bundling optical fiber pulse delay overlapped shaper, it is characterized in that, this reshaper comprises separate unit high power large mode area pcf mode-locked laser or separate unit high power solid pulse laser or separate unit high power semiconductor pulsed laser 1, aspheric mirror collimator and extender device or micro lens array I2, boundling single-mode fiber delayer 3, aspheric surface condenser lens or micro lens array II4 and single single-mode fiber 5, the annexation of each parts is in the device, the space distribution of laser instrument output is that the big mould field laser beam of flat-head type is coupled into boundling single-mode fiber delayer after by the shaping of aspheric mirror collimator and extender device collimator and extender, has the set time delay through the beam splitting pulse shaping behind the boundling single-mode fiber delayer, the pulse train that pulse energy is identical, then all pulse trains are coupled in the single-mode fiber through the aspheric surface condenser lens, stack is shaped to the rect.p. output of nanosecond order.

Above-mentioned high power large mode area pcf mode-locked laser is made of the polarization faraday isolator between oscillator stage and amplifier stage and oscillator stage and the amplifier stage, oscillator stage covers the photonic crystal gain fibre by the double-contracting of mixing ytterbium ion or er-doped ion of big mould field, semiconductor saturable absorbing mirror and polarization rotation (NPE) mix mode locker, oscillator stage grating pair or big negative dispersion optical fiber dispersion compensator constitute, wherein, the core diameter of photonic crystal gain fibre is the 10-50 micron, numerical aperture (NA) is 0.02-0.06, surrounding layer diameter 200-400 micron, numerical aperture (NA) is 0.4-0.8, length is 1-10m, and the cladding pumping source is the high-power laser diode of 5-30W; Amplifier stage covers photonic crystal gain fibre, amplifier stage grating pair or big negative dispersion optical fiber dispersion compensator by the double-contracting of mixing ytterbium ion or er-doped ion of big mould field and constitutes, wherein, the core diameter of photonic crystal gain fibre is the 20-70 micron, numerical aperture (NA) is 0.02-0.06, surrounding layer diameter 200-400 micron, numerical aperture (NA) is 0.4-0.8, and length is 1-10m, and the cladding pumping source is the 20-100W high-power laser diode.

Above-mentioned aspheric mirror collimator and extender device is the Galileo telescope system, and expanding beam ratio is with respect to 1 of the effective mode field diameter of boundling single-mode fiber delayer: 2-10, and perhaps focal length is the micro lens array that is of millimeter magnitude.

Above-mentioned boundling single-mode fiber delayer is the boundling of the Transmission Fibers of the general single mode fiber (SMF) of different length or other types, bundling optical fiber one end and neat back are fixing, bundling optical fiber other end length time delay is as required selected length, and successively decreases step by step to arrange according to central optical fiber to the outer fibers length of fibre bundle and constitute.

Above-mentioned aspheric surface convergent lens is that focal length is the microcobjective of 5-20mm, and perhaps focal length is the micro lens array of millimeter magnitude.

The invention has the advantages that: (1) adopts separate unit high power large mode area pcf lock laser instrument as the seed pulse source, all obviously reduces on operating cost, power consumption, complicacy and volume no matter these many mode of a lower powered general single mode fiber laser instrument and line output than present employing; (2) adopt the optical fiber pulse-delay unit of cluster type, to the incident pulse delay that walk abreast, than original technical pattern simply and pulse decay little; (3) adopt the middle part that long optical fibers is placed boundling, the mode that shortens is gradually from inside to outside constructed the pulse-delay line of bundling optical fiber formula, can revise the energy difference of the stronger pulse beam splitting of introducing of the general intermediate distribution of seed pulse spatial light intensity easily; (4) can repeated using bundling optical fiber formula pulse-delay line, the output pulse that is about to every optical fiber in the one-level bundling optical fiber formula pulse-delay line is coupled in the secondary bundling optical fiber formula pulse-delay line once more, form the dendritic morphology of parallel cascade, increase beam splitting quantity fast and do not increase complicacy.

Description of drawings

Fig. 1 is the structured flowchart of bundling optical fiber pulse delay overlapped shaper of the present invention.

Among the figure: 1 is high power pulsed laser; 2 is aspheric surface collimator and extender reshaper or micro lens array I; 3 is beaming type single-mode fiber delayer; 4 aspheric surface condenser lenses or micro lens array II; 5 bull single-mode fibers.

Fig. 2 is the structural representation of beaming type single-mode fiber delayer 3 among Fig. 1.

Fig. 3 is the high power large mode area pcf mode-locked laser structural representation that high power pulsed laser adopts among Fig. 1.

Among the figure: 1-1 is the oscillator stage pumping source; 1-2 is an oscillator stage large mould field photon crystal gain fibre; 1-3 is that semiconductor saturable absorbing mirror and polarization rotation (NPE) mix mode locker; 1-4 is oscillator stage grating pair or big negative dispersion optical fiber dispersion compensator; 1-5 is the polarization faraday isolator; 1-6 is an amplifier stage large mould field photon crystal gain fibre; 1-7 is amplifier stage grating pair or big negative dispersion optical fiber dispersion compensator; 1-8 is the pumping source of amplifier stage.

Embodiment

Integrated optical fiber pulse delay overlapped shaper of the present invention as shown in Figure 1, specific embodiment is as follows:

High power pulsed laser adopts high power large mode area pcf mode-locked laser shown in Figure 3, the gain media of oscillator stage wherein adopts the big mould field double-contracting of mixing Yb to cover polarization-maintaining photonic crystal fiber 1-2,25 microns of core diameters, NA is 0.03, and 250 microns of surrounding layer diameters, NA are 0.5, length is 3.5m, cladding pumping is directly carried out through subsiding and polishing the oblique angle in two ends, or welds the SMF that goes up suitable length, by the pumping of WDM mode; Oscillator stage adopts the LD1-1 of 10W to carry out single or double cladding pumping form, one end of resonator cavity is taked semiconductor saturable absorbing mirror and polarization impeller locked mode 1-3 and as output port, adopts grating pair or big negative dispersion optical fiber dispersion compensator 1-4 to carry out dispersion compensation and pulse compression at the other end of resonator cavity; The gain media of amplifier stage adopts the big mould field double-contracting of mixing Yb to cover polarization-maintaining photonic crystal fiber 1-6,40 microns of core diameters, NA is 0.03,270 microns of surrounding layer diameters, NA is 0.6, and length is 1.5m, and cladding pumping is directly carried out through subsiding and polishing the oblique angle in two ends, or weld the SMF that goes up suitable length, by the pumping of WDM mode; Adopt the LD1-8 of high power 30W to carry out single or double cladding pumping form, place polarization faraday isolator 1-5 at the input end of this resonator cavity and return oscillator stage, carry out dispersion compensation and pulse compression at the output terminal employing grating pair or the big negative dispersion optical fiber dispersion compensator 1-7 of resonator cavity to prevent laser; High power pulsed laser 1 also can be any other high power pulsed laser.Selecting for use non-spherical lens constitute to expand beam ratio among aspheric surface collimator and extender device or the micro lens array I2 is 1: 5 Galileo telescope system; Perhaps adopt micro lens array that the direct focusing of 1 output is advanced in each fibre core of beaming type single-mode fiber delayer.Beaming type single-mode fiber delayer 3 as shown in Figure 2,19 SMF are integrated a branch of, and the shortest single SMF gets 20mm, and every of all the other SMF increase 11mm successively, single-ended parallel boundling is divided into the pulse train that 19 time delay intervals are about 56ps with the ultrashort pulse of the 1550nm wave band of incident; And adopting the middle part that long optical fibers is placed boundling, the mode that shortens gradually from inside to outside is configured to cluster type optical fiber pulse-delay unit.Aspheric surface condenser lens II4 is that focal length is the microcobjective of the non-spherical lens formation of 10-20mm, and perhaps adopting the focal length corresponding with the fibre core of beaming type single-mode fiber delayer is the micro lens array of millimeter magnitude.Bull single-mode fiber 5 adopts many general single mode fibers of (corresponding with 3 output terminals) separately to carry out and restraint, fiber lengths 0.2m, and the output pulse is the rect.p. of the synthetic ns magnitude of 19 ultrashort pulses.If the output pulse through every optical fiber behind the beaming type single-mode fiber delayer 3 is repeated beaming type single-mode fiber delayer 3 processes again, the quantity of branch type increase pulse beam splitting fast then.

Claims

1. bundling optical fiber pulse delay overlapped shaper, it is characterized in that, this reshaper comprises separate unit high power large mode area pcf mode-locked laser or separate unit high power solid pulse laser or separate unit high power semiconductor pulsed laser (1), aspheric mirror collimator and extender device (2), boundling single-mode fiber delayer (3), aspheric surface condenser lens (4) and single single-mode fiber (5), wherein, described high power large mode area pcf mode-locked laser is made of the polarization faraday isolator between oscillator stage and amplifier stage and oscillator stage and the amplifier stage, oscillator stage covers the photonic crystal gain fibre by the double-contracting of mixing ruthenium ion or er-doped ion of big mould field, semiconductor saturable absorbing mirror and polarization rotation mix mode locker, oscillator stage grating pair or big negative dispersion optical fiber dispersion compensator constitute, wherein, the core diameter of photonic crystal gain fibre is the 10-50 micron, numerical aperture is 0.02-0.06, surrounding layer diameter 200-400 micron, numerical aperture is 0.4-0.8, length is 1-10m, and cladding pumping is the high-power laser diode of 5-30W; Amplifier stage covers photonic crystal gain fibre, amplifier stage grating pair or big negative dispersion optical fiber dispersion compensator by the double-contracting of mixing ytterbium ion or er-doped ion of big mould field and constitutes, wherein, the core diameter of photonic crystal gain fibre is the 20-70 micron, numerical aperture is 0.02-0.06, surrounding layer diameter 200-400 micron, numerical aperture is 0.4-0.8, and length is 1-10m, and cladding pumping is the 20-100W high-power laser diode; The annexation of each parts is in this reshaper, the space distribution of laser instrument output is that the big mould field laser beam of flat-head type is coupled into boundling single-mode fiber delayer after by aspheric mirror collimator and extender device collimator and extender, has the pulse train that the set time postpones, pulse energy is identical through the beam splitting pulse shaping behind the boundling single-mode fiber delayer, then all pulse trains are coupled in the single-mode fiber through the aspheric surface condenser lens, stack is shaped to the rect.p. output of nanosecond order.

2. by the described bundling optical fiber pulse delay overlapped shaper of claim 1, it is characterized in that it is Galileo telescope that the aspheric mirror collimation expands device, expanding beam ratio is with respect to 1 of the effective mode field diameter of boundling single-mode fiber delayer: 2-10.

3. by the described bundling optical fiber pulse delay overlapped shaper of claim 1, it is characterized in that, boundling single-mode fiber delayer is the boundling of the general single mode fiber of different length, bundling optical fiber one end and neat back are fixing, bundling optical fiber other end length time delay is as required selected length, and successively decreases step by step to arrange according to central optical fiber to the outer fibers length of fibre bundle and constitute.

4. by the described bundling optical fiber pulse delay overlapped shaper of claim 1, it is characterized in that the aspheric surface condenser lens is that focal length is the microcobjective of 5-20mm.