Eye-safe Raman Laser Operating In 1.5?m Region Based On YVO₄/Nd:YVO4/YVO₄ Bonded Crystal

DPSSL is a semiconductor laser?LD?as the pump source,laser crystal [1]laser as the gain medium,which has the advantages of light weight,small volume,high efficiency,long life and other advantages,in optical storage,optical information processing,laser processing and other important fields of military application widely,it becomes the main direction of research and development of laser technology.The laser energy is highly concentrated advantage in time and space,a large number of calories,become a bunch of very large beams.Therefore,laser medicine,widely used in information technology,environment and military field,using a laser can directly destroy the target,its lethality is enormous.At present,the most commonly used laser band 1064 nm,however due to its great harm to the human eye to find the laser band less harm is imminent.The structure determines the safety wavelength is 1.4 2 ?m.Of the incident wavelength laser,most of the lens and aqueous are absorpted,only a few reach the retina,these wave are less harmful to our eyes.Among them,1.5 ?m laser wavelength obtained in this paper is the main research direction.Design of a human eye safety laser using stimulated Raman scattering principle,with high output power and conversion efficiency,compact structure,laser beam quality,so this paper used Raman laser,using self Raman characteristics of Nd:YVO₄thus,1.5 micron eye safe laser wavelength.In the process of building the laser medium,energy absorption,lack of quantum efficiency of laser transition process of 1 quantum defects will transformed to non radiative relaxation form into heat and heat and cooling on the surface.The mutual influence,will cause the temperature gradient,and even lead to isotropic media becomes anisotropic.The refractive index change,cause thermal lens and laser beam distortion effect has subsided,it will be affected to varying degrees of the normal work.And the bonding technology,effectively reduce the pumping laser medium and laser emission produced in the process of heat,thus improves the crystal thermal effect,improve the laser output power and stability.1.The all solid state laser,active Q-switched is briefly introduced.Emphatically introduces the eye safe laser wavelength,how to get 1.5 micron wavelength laser,intracavity laser stimulated Raman scattering,the thermal effect of laser crystal,crystal bonding strengths.2.The excellent properties of Nd:YVO₄ crystal are described.Neodymium doped laser medium due to thermal conductivity is consistent with our experimental requirements,large excitation cross section and mature pumping process,is well known.Nd doped laser crystal medium at 0.6 ?m,1.09 ?m,1.3 ?m wavelength is generally research,while 1.5?m band is little research,this paper is focusing on the development the 1.5 ?m wavelength.3.In this paper,the five-bar-bonded Nd:YVO₄ crystal is used for the first time to obtain safe laser in the 1.5-micron wavelength,and the thermal effect of the laser is alleviated.4.The threshold pump power of 5.3W,to obtain a stable laser output,when pump power is19.3W,the output power is 1.76 W,light conversion efficiency is 9.1%,the pulse width is 29.9ns,corresponding to a peak power of 1525 nm 11.7kW laser output.5.The main innovation points: taking multi segment bonding crystal can decrease the crystal thermal effect,improve the pump absorption,and effectively increases the Raman crystal length,is expected to achieve eye safe Raman laser high power output with high conversion efficiency.