[PDF]    http://dx.doi.org/10.3952/lithjphys.47316

Open access article / Atviros prieigos straipsnis

Lith. J. Phys. 47, 279–288 (2007)


NUMERICAL TREATMENT OF THE TEMPERATURE DISTRIBUTION IN END-PUMPED COMPOSITE LASER RODS
A.S. Dement’eva, A. Jovaišaa, K. Račkaitisa, F. Ivanauskasb, and J. Dabulytė-Bagdonavičienėb
aLaboratory of Nonlinear Optics and Spectroscopy, Institute of Physics, Savanorių 231, LT-02300 Vilnius, Lithuania
E-mail: aldement@ktl.mii.lt
bDepartment of Computer Science, Vilnius University, Naugarduko 24, LT-03225 Vilnius, Lithuania

Received 20 June 2007

Analytical and numerical studies of the thermal characteristics of conventional and composite laser rods in laser-diode end-pumped geometry are reported in detail using Nd:YAG rods as an example. It has been shown that taking into account the temperature dependence of the heat conductivity, the change of the temperature in the active element can be significantly higher compared to the data for the temperature-independent heat conductivity coefficient. It has been found that the dependence of heat conductivity on temperature causes the non-parabolic heat distribution even in the region inside the pump beam with the top hat intensity distribution. It has also been shown by direct numerical simulations that the undoped entrance section of the composite rod significantly reduces the peak temperature rise inside the crystal.
Keywords: diode-pump solid-state lasers, composite rod, thermal effects
PACS: 42.15.Eq, 42.55.Rz, 42.60.By, 44.10.+i


TEMPERATŪROS SKIRSTINIO IŠILGINIO KAUPINIMO KOMPOZITINIUOSE LAZERIO STRYPUOSE SKAITINIS TYRIMAS
A.S. Dement’eva, A. Jovaišaa, K. Račkaitisa, F. Ivanauskasb, J. Dabulytė-Bagdonavičienėb
aFizikos institutas, Vilnius, Lietuva
bVilniaus universitetas, Vilnius, Lietuva

Analitiškai bei skaitmeniškai modeliuojami šiluminiai reiškiniai išilgai kaupinamuose Nd:YAG lazerių paprastuose ir kompozitiniuose aktyviuosiuose elementuose. Naudojant sukurtą skaitinę modeliavimo programą, įmanoma stebėti temperatūros skirstinį įvairios formos aktyviuosiuose elementuose bei, esant įvairioms kraštinėms sąlygoms, galima parinkti skirtingas aušinimo temperatūras, šilumos pernašos koeficientus arba kaupinimo sritis. Parodyta, kad dėl šilumos laidumo koeficiento priklausomybės nuo temperatūros lazerio aktyviajame elemente blogiau perduodama šiluma ir temperatūra jame tampa aukštesnė nei lazerio kristale su nepriklausančiu nuo temperatūros šilumos laidumu. Pastebėta, kad, kaupinant lazerio pluoštu su stačiakampiu erdviniu intensyvumo pasiskirstymu, šilumos laidumo priklausomybė nuo temperatūros sukelia neparabolinį šilumos pasiskirstymą net ir kaupinamoje aktyviojo elemento srityje. Dėl to aktyviajame elemente susidaro stipriai aberuotas šiluminis lęšis, kuris blogina generuojamo arba stiprinamo lazerio pluošto kokybę. Tiesioginiu skaitiniu modeliavimu parodyta, kad priekinė kompozitinio elemento dalis be aktyviųjų jonų gali žymiai sumažinti aukščiausią temperatūrą jo centre.


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