本文介紹了高功率、高重複率的諧波鎖模Yb:YAG雷射。我們分別使用不同長度的Yb:YAG晶體作為增益介質以得到不同重複率的鎖模脈衝輸出。實驗結果顯示，使用相同晶體下，改變不同的光學腔長可以得到不同的諧波脈衝重複率。當使用光學厚度為1.87毫米的Yb:YAG晶體，我們可以在吸收功率為8.3 W、光學腔長為6.91毫米下，得到輸出功率為4.6 W而脈衝重複率為2.4次兆赫茲（240 GHz）的諧波鎖模脈衝輸出，此時脈衝寬度為0.629 ps；當使用光學厚度為1.00毫米的Yb:YAG晶體時，我們可以提升輸出重複率至4.5次兆赫茲（450 GHz），此時輸出功率為1.75 W，脈衝寬度為0.653 ps。此外，藉由引進簡併共振腔的概念，我們可以進一步提升脈衝重複率至6次兆赫茲（600 GHz）。

We demonstrated a high-power and high pulse repetition rate harmonic-made-locked laser with Yb:YAG as the gain medium. Yb:YAG crystals with different crystal lengths were used for mode-locked operations with different repetition rates. The experimental results showed that different mode-locked repetition rate pulses can be attained with various optical cavity lengths using the same Yb:YAG crystal. By employing the Yb:YAG crystal with the optical length of 1.87 mm, we can obtain mode-locked pulses with the repetition rate of 240 GHz and the pulse duration of 0.629 ps. The average output power was 4.6 W under the absorbed pump power of 8.3 W. On the other hand, mode-locked pulses at the repetition rate of 450 GHz and with pulse duration of 0.653 ps can be achieved via using gain crystal with optical thickness of 1.00 mm. Under the pump power of 3.08 W, average output power of 1.75 W was obtained. Besides, we can further scale up the repetition rate to 600 GHz by using the scheme of degenerate cavity.