CN102820609A

CN102820609A - End and side mixed pumping Tm laser

Info

Publication number: CN102820609A
Application number: CN2012103051862A
Authority: CN
Inventors: 金光勇; 陈薪羽; 吴春婷; 王超; 张瑜
Original assignee: Changchun University of Science and Technology
Current assignee: Changchun University of Science and Technology
Priority date: 2012-08-27
Filing date: 2012-08-27
Publication date: 2012-12-12

Abstract

The invention discloses an end and side mixed pumping Tm laser, and relates to a laser, in particular to an end and side mixed pumping Tm<3+>:YLF laser. Pumping light of 792 nm is split into two beams to the side of a crystal from the end by using two 45-degree beam splitters; a 45-degree 792 nm membrane series totally reflecting mirror is adopted to turn a light path of the side pumping light; a pumping spot is reduced through a beam shrinkage mirror to perform pumping on the side of the crystal; and thus, a structure for pumping the end and the side simultaneously by an LD (Laser Diode) is formed. In design of the entire machine, focusing is completely avoided, the cavity length is reduced, and the threshold is favorably reduced. The method is complete and accurate, is suitable for the technical research of Tm<3+>:YLF laser pumping and is applied to the fields such as electro-optical countermeasure, laser radar and laser medical treatment.

Description

A kind of end side surface is mixed the Pumped Tm laser

Technical field

The present invention relates to a kind of end side surface and mix the Pumped Tm laser, especially relate to the Tm that a kind of end side surface is mixed pumping ³⁺: the YLF Lasers device.Be applicable to Tm ³⁺: the research of YLF Lasers device pump technology, application comprises fields such as electrooptical countermeasures, laser radar and laser medicine.

Background technology

Tm ³⁺: the YLF Lasers device is widely used in each field such as electrooptical countermeasures, laser radar and laser medicine.2 mum wavelengths are not only to eye-safe, and the propagation in atmosphere loss is little, and because green vegetation and slowly drained soil etc. are big to its absorption, reflect little, thereby in laser acquisition, help the differentiation of ground target and background.Closely-and middle Tunable Infrared Laser is desirable electrooptical countermeasures interference source, the continuous powerful laser output of 2 mu m wavebands is the basis that obtains optical parametric oscillator (OPO) output 3～5 μ m mid-infrared lasers.With laser operate with common scalpel compare with electric knife have hemorrhage less, healing soon, characteristics such as easy infection not.Output wavelength is that the solid state laser of 2 μ m is the optimal wavelength of laser surgey.And one of effective way that realizes 2 μ m output be laser that to adopt the laser diode-pumped crystal output wavelength of singly mixing the Tm ion of 800nm be 1.9 μ m again the crystal of pumping doping Ho ion obtain 2 μ m output, for example LD Pumped Tm: YLF or Tm:GdVO ₄Export 1.9 μ m pumping Ho:YLF or Ho:YAG again.Therefore, need the 1.9 mum wavelengths output of high light beam quality.The even thermal effect that causes of temperature distributing disproportionation can make beam quality descend in the laser crystal, and then influences the output characteristic of 2 μ m even 3～5 μ m.

Chinese scholars has been carried out a large amount of theories and experimental work for Tm:YLF laser pumping technology; Major side overweights the single-ended pumping of Tm:YLF laser, single LD both-end pumping and two LD both-end pumping; Adopt the laser structure of single-ended pump technology simple, easy to adjust, stability is higher, cost is lower; Interior temperature distributing disproportionation is even but single-ended pumping makes laser crystal, and beam quality is not high, and causes the light light conversion efficiency lower owing to absorbing again; And two LD both-end pumpings make temperature distribution uniform in the crystal, but are very easy to take place the phenomenon of focusing, easily optical fiber and crystal are caused damage; Single LD both-end pumping has reduced the possibility of focusing, but the situation that can not avoid fully focusing takes place.If expect the 2 μ m laser output of high light beam quality, narrow pulsewidth, adopt Tm ³⁺: the YLF crystal can be so that its emission spectra matches with the absworption peak that produces 2 μ m crystal, thereby improves output performance, still, and Tm ³⁺: YLF crystal easy fracture, so adopt the pumping configuration that makes the interior uniformity of temperature profile of crystal and avoid focusing particularly important, for this reason, can adopt the structure of distolateral pump mixing pumping to realize this purpose.

Summary of the invention

The objective of the invention is to focusing to occur, provide that a kind of structure is simple relatively, the long novel end side surface short, better performances in chamber is mixed Pumped Tm to the single LD both-end pumping of existing Tm:YLF laser ³⁺: YLF Lasers device laser.Adopt two beam splitters, first reflectivity to pump light is that 30% transmitance is that 70%, the second reflectivity to pump light is that 50% transmitance is 50%, two light beams telling behind beam expander respectively in two side incidents of the other end of laser crystal.Entire machine design has been avoided focusing fully, and it is long to have shortened the chamber, has reduced threshold value, helps improving the output energy.

A kind of end side surface is mixed the Pumped Tm laser, utilizes two 45 degree beam splitters that the 792nm pump light is told two from end face and restraints crystal on side face, has formed the structure that adopts a LD end face and side to be carried out simultaneously pumping.Its characteristic is two 45 degree beam splitters, between two planoconvex spotlights of convergent lens group, as the beam splitter of two profile pump light; Being provided with 45 degree 792nm films is total reflective mirror, between beam splitter and beam expander, as the light path turner of profile pump light; The bundle device that contracts is between total reflective mirror and the laser crystal at 45 degree 792nm films, as the bundle device that contracts of pump spot.

Described end side surface is mixed the Pumped Tm laser, it is characterized in that it is that 30% transmitance is 70% film that one 45 degree beam splitter is coated with the 792nm reflectivity, and it is that 50% transmitance is 50% film that another 45 degree beam splitter is coated with the 792nm reflectivity.

Described 45 degree 792nm films are total reflective mirror, are coated with the film to the 792nm total reflection.

Described beam expanding lens is coated with the 792nm anti-reflection film.

In the laser design process; The present invention adopts two beam splitters (792nm), four total reflective mirrors (792nm) and two beam-shrinked mirrors (792nm) to realize end face and side mixing pumping configuration; Compare with the single LD both-end pumping structure of generally using; Because two bundle pump lights not all are in crystal end-face incident, so avoided focusing fully; Owing to not be used in the chamber in and to insert 45 of 792nm and 1910nm and spend spectroscopes, so it is long to have shortened the chamber; And then because the long shortening in chamber is known that by Principles of Laser cavity loss reduces, and helps reducing threshold value.

Outstanding effect of the present invention will further explanation in addition in embodiment.

Description of drawings

Fig. 1 mixes Pumped Tm laser device figure for end side surface of the present invention;

Embodiment

For example the present invention is done description in more detail below in conjunction with accompanying drawing:

Laser device of the present invention comprises: 792nm laser diode pumping source 1, and optical fiber coupling output 792nm laser is as the end pumping source of laser; Planoconvex spotlight 2, focal length is 35mm, is coated with the 792nm anti-reflection film, to reduce the loss of pump light; The one 45 degree beam splitter 3, being coated with the 792nm reflectivity is that 30% transmitance is 70% film; The 2 45 degree beam splitter 4, being coated with the 792nm reflectivity is that 50% transmitance is 50% film; Planoconvex spotlight 5, focal length is 75mm, is coated with the 792nm anti-reflection film, to reduce the loss of pump light; The 1910nm film is a total reflective mirror 6, is coated with the anti-reflection film of 792nm laser; Laser crystal 7 buries crystal for mixing the thulium yttrium fluoride, and doping content is 3.5%, and cut direction is a direction of principal axis along the physics definition, and the crystal section is long-pending to be 3mm * 3mm, and length is 14mm; Laser output mirror 8, being coated with the 1910nm transmitance is 26% high transmittance film and to the film that is all-trans of 792nm pump light, the plano-concave mirror, radius of curvature is 300mm; 45 degree spectroscopes 9 are coated with the film that the high 792nm of opposition of 1910nm height is passed through; 45 degree 792nm films are total

reflective mirror

10,11,12 and 13; Contract and

restraint device

14 and 15, be coated with the anti-reflection film to 792nm, it is 5 that contracting of 792nm restrainted multiplying power.

The laser output wavelength of laser device of the present invention is 1910nm.Laser diode pumping source 1 emission 792nm pump light, it is 35mm planoconvex spotlight 2 that the 792nm pump light incides focal length, after planoconvex spotlight 2 focuses on; Incide the one 45 degree beam splitter 3; The one 45 degree beam splitter 3 is coated with 70% of 792nm pump light is seen through 30% reflectance coating, and wherein to reflex to 45 degree 792nm films be total reflective mirror 10 to 70% the 792nm pump light 792nm pump light that is transmitted to the 2 45 degree beam splitter 4,30%; Inciding 45 degree 792nm films after the reflection is total reflective mirror 11; Arrive the bundle device 14 that contracts through reflection again, contract through 5 times and incide crystal on side face after restrainting, 792nm pump light spot center is apart from end face 3mm; Through 70% 792nm pump light of the one 45 degree beam splitter 3 transmissions, inciding the 2 45 degree beam splitter 4, the 2 45 degree beam splitters 4, to be coated with the 792nm reflectivity be that 50% transmitance is 50% film; Wherein, 50% 70%792nm pump light, promptly total 792nm pump light of 35% is transmitted to Jiao and gathers the planoconvex spotlight 5 for 75mm; After planoconvex spotlight 5 focused on, inciding the 1910nm film was on the total reflective mirror 6, and the 1910nm film is the anti-reflection film that total reflective mirror 6 is coated with 792nm laser; Can reduce the loss of pump light, other 50% 70%792nm pump light, that is total 792nm pump light of 35% to reflex to 45 degree 792nm films be total reflective mirror 12; It is total reflective mirror 13 that the reflection back arrives 45 degree 792nm films; Arrive the bundle device 15 that contracts through reflection again, contract through 5 times and incide crystal on side face after restrainting, 792nm pump light spot center is apart from end face 7mm; Process 1910nm film is that the 792nm pump light of 35% on the total reflective mirror 6 incides on the end face of laser crystal 7.Like this; 792nm pump light at laser crystal 7 surface feeding sputterings has only a branch of; Compare with two bundle ends, the two incident pump light structures of single LD both-end pumping Tm laser; Avoided 792nm pump light relative situation of focus in laser crystal 7 fully, and then avoided fully because the uneven thermal stress fracture that produces of the heat distribution that the focusing of 792 pump lights causes.After all 792nm pump lights incided laser crystal 7, laser crystal 7 produced the laser of 1910nm, and 792nm pump light and 1910nm laser incide laser output mirror 8 simultaneously; Like this, in the Tm laserresonator, just need not place 792nm and 45 degree spectroscopes of 1910nm laser in the single LD both-end pumping Tm laser, thereby can make the about 10mm of the long shortening in chamber of laserresonator; Known that by Principles of Laser the chamber is long short more, round trip loss is more little in the chamber; The threshold pump power of laser is also low more; It is 26% high transmittance film and to the film that is all-trans of 792nm pump light that laser output mirror 8 is coated with the 1910nm transmitance, and the 792nm pump light is reflected back toward in the laser crystal 7, and 26% 1910nm laser sees through laser output mirror 8; Incide 45 degree spectroscopes 9; 45 degree spectroscopes 9 are coated with the film that the high 792nm of opposition of 1910nm height is passed through, and behind 45 degree spectroscopes 9, are not seen through 45 degree spectroscopes 9 by a small amount of 792nm pump light of laser output mirror 8 reflected back laser crystals 7; And 1910nm laser is obtained 1910nm laser by 9 reflections of 45 degree spectroscopes.

Claims

1. an end side surface is mixed the Pumped Tm laser, utilizes two 45 degree beam splitters that the 792nm pump light is told two from end face and restraints crystal on side face, has formed the structure that adopts a LD end face and side to be carried out simultaneously pumping.Its characteristic is two 45 degree beam splitters, between two planoconvex spotlights of convergent lens group, as the beam splitter of two profile pump light; Being provided with 45 degree 792nm films is total reflective mirror, restraints between the device, as the light path turner of profile pump light with contracting at beam splitter; Beam-shrinked mirror is between total reflective mirror and the laser crystal at 45 degree 792nm films, as the bundle device that contracts of pump spot.

2. a kind of end side surface as claimed in claim 1 is mixed the Pumped Tm laser; It is characterized in that it is that 30% transmitance is 70% film that one 45 degree beam splitter is coated with the 792nm reflectivity, it is that 50% transmitance is 50% film that another 45 degree beam splitter is coated with the 792nm reflectivity.

3. 45 degree 792nm films as claimed in claim 1 are total reflective mirror, are coated with the film to the 792nm total reflection.

4. beam-shrinked mirror as claimed in claim 1 is coated with the 792nm anti-reflection film.