Single-frequency microchip lasers have been widely used in differential absorption radars, pulse coherent Doppler radars, pumping optical parametric oscillators, and etc. So theoretical analysis and experimental researches on the LD-pumped 2.09 μm microchip laser have important realistic meaning. According to quasi-three-level Cr, Tm, Ho: YAG(CTH:YAG) laser crystal working characteristics, the theoretical expression and relationship curve between the output optical power and 785nm LD-pumped power are obtained by theoretical calculating based on the pumping rate equation. The CTH:YAG crystal with 4mm diameter and 1 mm thickness is used to do experimental test. The corresponding three kinds of particle concentration are 0.85%, 5.9% and 0.36% respectively. When the crystal temperature is controlled at 10 °C, microchip laser beam output characteristic curve is obtained under different pump spots. The results show that when the pump spot diameter is 75um the maximum single-frequency output power is 32mW and when the pump beam is 100um the maximum single-frequency output power is 30mW. The corresponding optical to optical conversion slope efficiencies are 6.8% and 6% respectively.
Seeded erbium∕ytterbium codoped fibre amplifier source with 87 W of single-frequency output power