CN203688951U - Combined type chirped pulse compressor - Google Patents

Abstract

The utility model discloses a combined type chirped pulse compressor. The compressor comprises at least one set of chirped Bragg gratings, wherein each set comprises four chirped Bragg gratings which are divided into two parts in mirroring arrangement; the two chirped Bragg gratings in each part are arranged in parallel, so that the whole compressor has no space for chirp. The compressor is compact in structure and small in space volume, input and output pulse light beams are coaxial, a module can be packaged, and the purpose of plug and play is achieved. The chirped Bragg gratings are prepared from light heat-sensitive refractive glass, the laser induced damage threshold is high, the compressor can bear the energy density of 10J/cm2, the dispersive power is strong, the compressor can be used for pulse compression of which the pulse width is nanosecond magnitude and below, and the application range of the compressor is wider.

Description

A kind of combined type chirp pulse compressor

Technical field

The utility model belongs to optical pulse compressor and manufactures and designs field, is specifically related to a kind of combined type chirp pulse compressor.

Background technology

Since nineteen sixty Theodore H.Maiman utility model First laser instrument starts, people are just seeking more high-energy, more high-power laser always, and utilize it to find new phenomenon, build new theory as laboratory facilities, development new material, make new unit, the further developing of the fields such as promotion science, medical treatment and engineering.

How to improve output energy and the power of laser, since laser utility model, just got more and more people's extensive concerning always.At the initial stage of laser utility model, adjust the application of Q and mode-locking technique that the peak power of laser pulse is promoted to 10 ⁹w magnitude.The energy of laser is from the particle in inverted status, and these particles are by extraneous pumping, be energized into by ground state that high-energy state gets on, these particles (nanosecond or shorter) energy state transition downwards within the extremely short time subsequently, the stimulated radiation of simultaneously sending forms laser.But in the time that laser power is too high, gain media will be damaged by laser because of nonlinear optical effects such as self-focusings.Therefore, the maximum power density that gain media can be exported just must be lower than the laser damage threshold of this medium, and this is also to adjust Q and mode-locking technique cannot break through 10 ⁹the reason place of W bottleneck.

1985, the chirped pulse in radar is amplified (chirped pulse amplification by the Gerard Mourou of Rochester university and Donna Strickland, being called for short CPA) concept is incorporated into laser field, change this present situation, for the further raising of pulse peak power is laid a good foundation.CPA technology utilize dispersion element (such as diffraction grating, prism etc.) before seed pulse enters gain media by its broadening: the path that the low-frequency component of pulse is walked is than radio-frequency component short (just warbling), therefore its pulsewidth is large when initial, peak power is reduced, just can be by the peak power reduction of pulse under the damage threshold of gain media by the chirp value of dispersion element regulating impulse.Pulse after gain media amplifies is again by dispersion element, just contrary when now the effect of dispersion element is with broadening, i.e. warbling in compensated pulse, and the width by pulse compression to seed pulse, pulse peak power now just can be greatly improved.CPA technology has successfully been evaded the problem of gain media damage threshold, and the Laser Focusing power of generation has even exceeded 10 ²⁰w/cm ²magnitude, becomes the core technology of whole world high power laser system.

One of Primary Component of CPA system is chirp pulse compressor, and the Laser-induced damage threshold of compressor reducer has directly determined the output power density of system; The homogeneity of compressor reducer and Output of laser wavefront distortion are closely bound up.Conventional compressor reducer has: prism is to, optical fiber, chirped mirror and diffraction grating pair, domestic visible a kind of based on the right chirp pulse compressor of diffraction grating, and adopts compound lens to carry out compensating (China Patent No. 200410017495.5) to high-order dispersion; Visible a kind of chirp impulse compression method (China Patent No. 200610076255.1) that utilizes plasma; Visible a kind of chirp pulse compressor (China Patent No. 201210535671.9) based on forbidden band reflection.Prism is to simple in structure, but bandwidth is little, and has larger high-order dispersion; The Laser-induced damage threshold of optical fiber is low, and easily produces and the nonlinear effect such as frequency, difference frequency; Chirped mirror dispersion measure is little; The Laser-induced damage threshold low (approximately several joules/square centimeter) that diffraction grating is right, and mainly obtain large dispersion by increasing grating space, the spatial volume needing is large.

Therefore, in view of above problem, being necessary to propose a kind of novel pulse shortener, be nanosecond order and following pulse compression thereof, and Laser-induced damage threshold is high applicable to pulsewidth, and dispersion measure is large, and compact conformation, spatial volume are little, is convenient to encapsulation and uses.

Utility model content

In view of this, the utility model provides a kind of combined type chirp pulse compressor, be nanosecond order and following pulse compression thereof, and Laser-induced damage threshold is high applicable to pulsewidth, and dispersion measure is large, and compact conformation, spatial volume are little, is convenient to encapsulation and uses.

A kind of combined type chirp pulse compressor proposing according to the purpose of this utility model, comprise at least one group of Chirp Bragg grating, every group comprises four blocks of Chirp Bragg gratings, described four blocks of Chirp Bragg gratings are divided into two parts that mirror image arranges, Part I comprises the first Chirp Bragg grating and the second Chirp Bragg grating that be arranged in parallel, Part II comprises the 3rd Chirp Bragg grating and the 4th Chirp Bragg grating that be arranged in parallel, input pulse is successively through the first Chirp Bragg grating, the second Chirp Bragg grating, output after the 3rd Chirp Bragg grating and the compression of the 4th Chirp Bragg optical grating reflection, form output pulse.

Preferably, described input pulse is coaxial with described output pulse.

Preferably, described Chirp Bragg grating thickness is 1cm-4cm.

Preferably, the incident angle of described input pulse is less than 60 °.

Preferably, described Chirp Bragg grating is phase-type Chirp Bragg body grating.

Preferably, the relational expression of the decrement of described input pulse and incident angle and grating thickness is:

wherein, n is the mean refractive index of Chirp Bragg grating, and d is grating thickness, and c is the light velocity in vacuum, and θ is incident angle.

Compared with prior art, the advantage of the disclosed combined type chirp pulse compressor of the utility model is: this compressor reducer comprises at least one group of Chirp Bragg grating, every group comprises four blocks of Chirp Bragg gratings, and four blocks of Chirp Bragg gratings are divided into two parts that mirror image arranges, two blocks of Chirp Bragg gratings of every part be arranged in parallel, make whole compressor reducer without space chirp, compact conformation, spatial volume are little, and input/output pulse light beam is coaxial, can be encapsulated as a module, realize the object of plug and play.By adopting the quick glass preparation Chirp Bragg grating of selling off of photo-thermal, Laser-induced damage threshold is high, can bear 10J/cm ²energy density, dispersive power is strong, can be used for pulsewidth is nanosecond order and following pulse compression thereof, the scope of application is wider.

Accompanying drawing explanation

In order to be illustrated more clearly in the utility model embodiment or technical scheme of the prior art, to the accompanying drawing of required use in embodiment or description of the Prior Art be briefly described below, apparently, accompanying drawing in the following describes is only embodiment more of the present utility model, for those of ordinary skills, do not paying under the prerequisite of creative work, can also obtain according to these accompanying drawings other accompanying drawing.

Fig. 1 is the structural representation of the disclosed a kind of combined type chirp pulse compressor of the utility model.

The title of the numeral in figure or the corresponding component of alphabetical representative:

10, the first Chirp Bragg grating 20, the second Chirp Bragg grating 30, the 3rd Chirp Bragg grating 40, the 4th Chirp Bragg grating

Embodiment

High at the Chirp Bragg grating Laser-induced damage threshold that photo-thermal is quick to be prepared in selling off glass, nanosecond, damage threshold was up to 10J/cm ²(centre wavelength 1064nm), and dispersion measure is larger, every centimetre of about 100ps/nm of maximum cluster time delay dispersion that Chirp Bragg grating provides, can be the compression of high energy and power chirped laser pulse simpler scheme is efficiently provided, and is a kind of chirp pulse compressor that has at present potentiality.

But be subject to the restriction of existing manufacture craft, the thickness of monolithic Chirp Bragg grating is less than 40mm, be applicable to the pulse compression of hundred psecs and following pulsewidth thereof, helpless to the pulse compression of larger pulsewidth, the scope of application is less.

The utility model, for deficiency of the prior art, provides a kind of combined type chirp pulse compressor, is nanosecond order and following pulse compression thereof applicable to pulsewidth, Laser-induced damage threshold is high, dispersion measure is large, and compact conformation, spatial volume are little, is convenient to encapsulation and uses.

To be clearly and completely described the technical solution of the utility model by embodiment below.Obviously, described embodiment is only the utility model part embodiment, rather than whole embodiment.Based on the embodiment in the utility model, those of ordinary skills are not making the every other embodiment obtaining under creative work prerequisite, all belong to the scope of the utility model protection.

As shown in Figure 1, a kind of combined type chirp pulse compressor, comprise at least one group of Chirp Bragg grating, every group comprises four blocks of Chirp Bragg gratings, four blocks of Chirp Bragg gratings are divided into two parts that mirror image arranges, Part I comprises the first Chirp Bragg grating 10 and the second Chirp Bragg grating 20 that be arranged in parallel, Part II comprises the 3rd Chirp Bragg grating 30 and the 4th Chirp Bragg grating 40 that be arranged in parallel, input pulse is successively through the first Chirp Bragg grating 10, the second Chirp Bragg grating 20, output after the 3rd Chirp Bragg grating 30 and the 4th Chirp Bragg grating 40 reflections.Input pulse is realized and is compressed for the first time A and reflex on the second Chirp Bragg grating 20 through the first Chirp Bragg grating 10, compression pulse is realized and is compressed for the second time B and reflex on the 3rd Chirp Bragg grating 30 through the second Chirp Bragg grating 20 for the first time, compression pulse is realized and is compressed for the third time C and reflex on the 4th Chirp Bragg grating 40 through the 3rd Chirp Bragg grating 30 for the second time, and compression pulse is realized the 4th compression D and reflects output through the 4th Chirp Bragg grating 40 for the third time.This compressor reducer dispersive power is strong, is nanosecond order and following pulse compression thereof applicable to pulsewidth.Chirp Bragg grating is sold off glass preparation and is formed by photo-thermal is quick, can bear 10J/cm ²energy density, Laser-induced damage threshold is high, has increased Laser Focusing power.And by mirror image, two parts grating is set, makes this compressor configuration compactness, space hold volume is little.

The quick glass of selling off of photo-thermal is the polycomponent silicate glass doped with cerium, fluorine, silver, tin and antimony.Chirp Bragg grating is phase-type Chirp Bragg body grating.

Input pulse is coaxial with output pulse.Combined type chirp pulse compressor can be encapsulated as to a module, realize the object of plug and play.

Chirp Bragg grating thickness is 1cm-4cm.Every centimetre of about 100ps/nm of maximum cluster time delay dispersion that Chirp Bragg grating provides, can be according to compressing the thickness that need to regulate grating.

The incident angle of input pulse is less than 60 °.The total decrement of compressor reducer is determined by incident angle and Chirp Bragg grating thickness.The relational expression of the decrement of input pulse and described incident angle and grating thickness is:

$\mathrm{GD}=\frac{2\mathrm{nd}}{c\·\cos \mathrm{\θ}}$

Wherein, n is the mean refractive index of Chirp Bragg grating, and d is grating thickness, and c is the light velocity in vacuum, and θ is incident angle.

Embodiment

Wavelength X centered by input pulse ₀about 1053nm, the about 3nm of bandwidth B, the Gaussian-shaped pulse of the about 1ns of pulsewidth.Plan is by this pulse compression to 200ps, required group delay compensation rate is 800ps, wants four Chirp Bragg grating thickness in combined type chirp pulse compressor to be 2cm, the every compressible 200ps of Chirp Bragg grating.Suppose that it is under 5 ° of conditions that four blocks of Chirp Bragg gratings are all operated in incident angle, center response wave length is 1053nm, responsive bandwidth is 9nm, frequency spectrum chirp rate is 1.5nm/cm, refractive index modulation degree is 600ppm, now Chirp Bragg diffraction efficiency of grating is 100%, and the group delay dispersion of every block of Chirp Bragg grating is about 22.2ps/nm.

Adopt transfer matrix method, the compression effectiveness of combined type chirp pulse compressor is carried out to numerical simulation, result shows: input pulse is after the first Chirp Bragg grating 10 compressions, and pulsewidth is about 762ps, and has certain space chirp; Compression pulse is after the second Chirp Bragg grating 20 compressions for the first time, and pulsewidth is about 558ps, and space chirp is double, for the second time the space chirp maximum of compression pulse; After the 3rd Chirp Bragg grating 30 compression, compression pulse is compressed to 398ps for the third time, and space chirp is now compensated half; After the 4th Chirp Bragg grating 40 compression, pulse is about 201ps, reaches desired value, and space chirp is by full remuneration, and output pulse is without any space chirp.The pulse compression efficiency of whole compressor reducer is greater than 99.7%.

In addition, also can many group Chirp Bragg gratings need to be set according to using and compressing, realize the object of stage compression.

The utility model discloses a kind of combined type chirp pulse compressor, this compressor reducer comprises at least one group of Chirp Bragg grating, every group comprises four blocks of Chirp Bragg gratings, and four blocks of Chirp Bragg gratings are divided into two parts that mirror image arranges, and two blocks of Chirp Bragg gratings of every part be arranged in parallel, make whole compressor reducer without space chirp, compact conformation, spatial volume are little, and input/output pulse light beam is coaxial, can be encapsulated as a module, realize the object of plug and play.

By adopting the quick glass preparation Chirp Bragg grating of selling off of photo-thermal, Laser-induced damage threshold is high, can bear 10J/cm ²energy density, dispersive power is strong, can be used for pulsewidth is nanosecond order and following pulse compression thereof, the scope of application is wider.

To the above-mentioned explanation of the disclosed embodiments, make professional and technical personnel in the field can realize or use the utility model.To be apparent for those skilled in the art to the multiple modification of these embodiment, General Principle as defined herein can, in the situation that not departing from spirit or scope of the present utility model, realize in other embodiments.Therefore, the utility model will can not be restricted to these embodiment shown in this article, but will meet the widest scope consistent with principle disclosed herein and features of novelty.

Claims (6)

1. a combined type chirp pulse compressor, it is characterized in that, comprise at least one group of Chirp Bragg grating, every group comprises four blocks of Chirp Bragg gratings, described four blocks of Chirp Bragg gratings are divided into two parts that mirror image arranges, Part I comprises the first Chirp Bragg grating and the second Chirp Bragg grating that be arranged in parallel, Part II comprises the 3rd Chirp Bragg grating and the 4th Chirp Bragg grating that be arranged in parallel, input pulse is successively through the first Chirp Bragg grating, the second Chirp Bragg grating, output after the 3rd Chirp Bragg grating and the compression of the 4th Chirp Bragg optical grating reflection, form output pulse.

2. combined type chirp pulse compressor as claimed in claim 1, is characterized in that, described input pulse is coaxial with described output pulse.

3. combined type chirp pulse compressor as claimed in claim 1, is characterized in that, described Chirp Bragg grating thickness is 1cm-4cm.

4. combined type chirp pulse compressor as claimed in claim 1, is characterized in that, the incident angle of described input pulse is less than 60 °.

5. combined type chirp pulse compressor as claimed in claim 1, is characterized in that, described Chirp Bragg grating is phase-type Chirp Bragg body grating.

6. combined type chirp pulse compressor as claimed in claim 1, is characterized in that, the relational expression of the decrement of described input pulse and incident angle and grating thickness is:

wherein, n is the mean refractive index of Chirp Bragg grating, and d is grating thickness, and c is the light velocity in vacuum, and θ is incident angle.