Microchip laser operation of Tm, Ho:KYW crystals with different ho concentrations

摘要

ions were demonstrated. However the study of influence different doping ions concentrations on laser characteristics in the same cavity configuration was not reported for these crystals. Considering complexity of the system where direct and back energy transfer [2], as well as up-conversion processes [4] take place, experimental study of the crystals with different content of doping ions is of high interest.In this work we report laser operation of Ng-cut Tm(5at.%)Ho(0.5at.%):KYW and Tm(5at.%)Ho(1at.%):KYW crystals in microchip cavity configuration. The schematic of the laser setup is shown in Fig.1a. Fiber-coupled (d=120 μm, N.A.=0.15) AlGaAs laser diode (LD) with maximum output power of 1.7 W at 802 nm was used as a pump source. The LD radiation was collimated and focused into the active element to a spot of 180 μm diameter. The lateral sides of the active elements were in thermal contact with the copper heat sink whose temperature was kept at 150C with a thermal electric cooler (TEC). The laser resonator was formed by two plane mirrors which were positioned close to the ends of the active element. The length of the active elements was 2.4 mm and their faces were AR-coated for the pump and laser radiation. In QCW experiment the pump radiation was modulated by chopper with duty cycle of 25%.