| A single erbium-doped laser has advantages of the long fluorescence lifetime and the high quantum efficiency,which is an ideal resource for obtaining the 2?m-laser.Its output band is widely used in lidar,laser ranging,laser medical and meteorological monitoring.Due to the single-doped erbium-doped quasi-three-level system with a small emission cross section of Tm3+-level,this type of laser is seriously affected by the thermal effect,which restricts the generation of high-performance 2?m-lasers.It can be shown in recent years that the bonding technology of crystals can effectively alleviate the thermal effect caused by thermal deposition inside the rods.In this paper,the thermal effects and continuous light output characteristics of a single-doped erbium laser are studied by designing two different types of multi-segment bonded Tm:YAG crystals.In theory,based on the quasi-three-level model of a single erbium-doped laser,the optimal concentration length range of the Tm:YAG crystal has been discussed to detemine the parameters of the multi-stage bonded rods.Subsequently,two types of multi-segment bonded crystal structures are introduced.The results show that: the multi-section bonded crystals are beneficial to mitigate the thermal effects through establishing thermal models of these two and analyzing the thermal effects according to the heat conduction equation.In addition,the optimal parameters of multi-segment bonded crystals are proved in simulation.Combined the solution of the Type-I crystal's thermal focal length and the ABCD matrix,the range of stability zone can be obtained,which provides a basis for subsequent experiments.In order to verify a hypothesis that multi-segment bonded crystals can effectively alleviate thermal effects,in comparision of the stimulation of multi-segment bonded and conventional crystals,the experiments of single-ended LD pumped double-ended bonding/multi-segment bonding/ double rod tandem Tm:YAG lasers are carried out to indicate that:a maximum output power of 7.08 W is obtaind in LD single-ended pumped double-ended bonded Tm:YAG laser obtained,with the optical-optical conversion efficiency of 34.14%,the LD single-ended pumped multi-segment bonded Tm:YAG laser gains a maximum output power of 6.11 W,and its optical-to-optical conversion efficiency is 28.1%;the one with a double rod tandem laser indicates a maximum output power of 3.03 W,its opticaloptical conversion efficiency is 25.2% in addition.The same parameters in corresponding double-ended lasers are of 11.55 W,13.3W,4.05 W with the maximum output powers and of37.5%,32%,20.4% in optical-to-optical conversion efficiency.The experimental results point that: the use of multi-segment bonding technology has the great effect of mitigating the thermal effects in Tm: YAG crystals. |
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