Opt Lett. 2019 Apr 1;44(7):1580-1583. doi: 10.1364/OL.44.001580.
Strong enhancement of optoacoustic interactions in the micrometer-sized core of a photonic crystal fiber (PCF) enables stable, harmonic mode locking of a soliton fiber laser at GHz frequencies. Here we report that by tapering the PCF during the draw, the optoacoustic gain bandwidth can be broadened to ∼47 MHz, more than 3 times wider than in the untapered fiber. This made possible broad pulse-repetition-rate tuning over 66 MHz (from 2.042 to 2.108 GHz) of an optoacoustically mode-locked soliton fiber laser. Within this tuning range, the harmonically mode-locked pulse trains at the laser output were observed to be quite robust, with better than 40 dB supermode suppression ratio, sub-ps pulse timing jitter, and <0.2%relative intensity noise. This gigahertz-rate, near-infrared soliton fiber laser has remarkable pulse-rate tunability and low noise level, and has important potential applications in frequency metrology, high-speed optical sampling, and fiber telecommunications.
在光子晶体光纤（PCF）的微米级纤芯中实现强的光声相互作用，使孤子光纤激光器能够在 GHz 频率下稳定地进行谐波锁模。在这里，我们报告说，通过在拉丝过程中对 PCF 进行锥形化处理，可以将光声增益带宽拓宽到约 47 MHz，比未锥形化光纤宽 3 倍以上。这使得能够在超过 66 MHz（从 2.042 到 2.108 GHz）的范围内对光声锁模孤子光纤激光器进行宽脉冲重复率调谐。在这个调谐范围内，观察到激光输出处的谐波锁模脉冲串非常稳定，具有超过 40 dB 的超模抑制比、亚皮秒脉冲定时抖动和 <0.2%的相对强度噪声。这种千兆赫速率、近红外孤子光纤激光器具有显著的脉冲速率可调谐性和低噪声水平，在频率计量、高速光采样和光纤通信等方面具有重要的潜在应用。
