Jeon Chan-Gi, Zhang Shuangyou, Shin Junho, Kim Jungwon
School of Mechanical and Aerospace Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Korea.
Sci Rep. 2018 Sep 17;8(1):13875. doi: 10.1038/s41598-018-31929-x.
Higher repetition-rate optical pulse trains have been desired for various applications such as high-bit-rate optical communication, photonic analogue-to-digital conversion, and multi-photon imaging. Generation of multi GHz and higher repetition-rate optical pulse trains directly from mode-locked oscillators is often challenging. As an alternative, harmonic injection locking can be applied for extra-cavity repetition-rate multiplication (RRM). Here we have investigated the operation conditions and achievable performances of all-fibre, highly tunable harmonic injection locking-based pulse RRM. We show that, with slight tuning of slave laser length, highly tunable RRM is possible from a multiplication factor of 2 to >100. The resulting maximum SMSR is 41 dB when multiplied by a factor of two. We further characterize the noise properties of the multiplied signal in terms of phase noise and relative intensity noise. The resulting absolute rms timing jitter of the multiplied signal is in the range of 20 fs to 60 fs (10 kHz-1MHz) for different multiplication factors. With its high tunability, simple and robust all-fibre implementation, and low excess noise, the demonstrated RRM system may find diverse applications in microwave photonics, optical communications, photonic analogue-to-digital conversion, and clock distribution networks.
对于诸如高比特率光通信、光子模数转换和多光子成像等各种应用而言，人们一直期望获得更高重复率的光脉冲序列。直接从锁模振荡器产生多吉赫兹及更高重复率的光脉冲序列通常具有挑战性。作为一种替代方法，谐波注入锁定可用于腔外重复率倍增（RRM）。在此，我们研究了基于全光纤、高度可调谐谐波注入锁定的脉冲RRM的工作条件和可实现的性能。我们表明，通过对从激光器长度进行微调，从2到大于100的倍增因子实现高度可调谐的RRM是可能的。当倍增因子为2时，所得到的最大边模抑制比（SMSR）为41 dB。我们进一步从相位噪声和相对强度噪声方面对倍增信号的噪声特性进行了表征。对于不同的倍增因子，所得到的倍增信号的绝对均方根定时抖动在20 fs至60 fs（10 kHz - 1 MHz）范围内。凭借其高可调谐性、简单且稳健的全光纤实现方式以及低过量噪声，所展示的RRM系统可能在微波光子学、光通信、光子模数转换和时钟分配网络中找到多种应用。
