同步抽运锁模是一种调制增益的锁模技术,就是调节抽运光的调制频率使之等于激光器纵模间隔的整数倍。通过对抽运光源半导体激光器的驱动电流进行正弦调制,实现了掺镱光纤激光器(YDFL)的同步抽运锁模。通过调整抽运激光器的调制频率,在相应于二次谐波锁模,4阶有理数谐波锁模条件下分别得到了较窄的脉冲输出。对重复频率625 kHz的二次谐波锁模脉冲序列,脉冲宽度小于20 ns,约为抽运光宽度的1/40;平均输出功率2.34 mW,能量转换效率约为5%。

Synchronously pumped mode-locking can be obtained when the frequency for gain switching of the pump-laser is equal to (or an integer multiple of) the cavity mode spacing, corresponding to the harmonic mode-locked status. A synchronously pumped mode-locked yetterbium-doped fiber laser (YDFL) is obtained when the pump semiconductor laser current is modulated sinusoidally at the appropriate frequency. By modulating frequency of the pump laser narrower output pulses are obtained on the second harmonic and rational harmonic mode-locked status and the 4th-order rational harmonic mode-locking status. At the repetition rate of 625 kHz,the pulse width of second harmonic mode-locked pulse train is less than 20 ns, approximately 1/40 of the pump-pulse-width. The average output power is about 2.34 mW and the energy convert efficiency is about 5%.