Fellinger Jakob, Winkler Georg, Mayer Aline S, Steidle Laurin R, Heckl Oliver H
Opt Express. 2019 Feb 18;27(4):5478-5486. doi: 10.1364/OE.27.005478.
We present a versatile method to generate a dual-color laser from a single fiber laser cavity by spectral subdivision using a tunable mechanical filter. As a proof-of-principle, we implement the concept in a nonlinear polarization evolution (NPE)-mode-locked ytterbium (Yb)-fiber laser. The division into two independent spectral regions is achieved by inserting a narrow blade-shaped beam block into the free-space grating compressor section of the cavity, where the spectrum is spatially dispersed. By mode-locking both spectral regions, two pulse trains, with different repetition rates around 23 MHz, are generated. Each pulse train has a FWHM of ~10 nm. The method presented here enables tuning of the difference in repetition rate as well as the spectral separation of the two independent pulse trains. The difference in repetition rates originates from intracavity dispersion and can be tuned over a large range (650 Hz - 3 kHz in this setup) by changing the length of the grating compressor. By changing the effective width of the beam block the spectral separation can be dynamically adjusted. This approach's simplicity holds great promises for the development of single-cavity dual-comb lasers featuring tunable sampling rates.
我们提出了一种通用方法，通过使用可调谐机械滤波器进行光谱细分，从单个光纤激光腔中产生双色激光。作为原理验证，我们在非线性偏振演化（NPE）锁模镱（Yb）光纤激光器中实现了这一概念。通过将一个窄的叶片形光束阻挡器插入腔的自由空间光栅压缩器部分来实现将光谱分为两个独立的光谱区域，在该部分光谱在空间上被色散。通过对两个光谱区域进行锁模，产生了两个重复频率约为23MHz的不同脉冲序列。每个脉冲序列的半高宽约为10nm。这里提出的方法能够调节重复频率的差异以及两个独立脉冲序列的光谱分离。重复频率的差异源于腔内色散，并且通过改变光栅压缩器的长度可以在很大范围内（在此设置中为650Hz - 3kHz）进行调节。通过改变光束阻挡器的有效宽度，可以动态调整光谱分离。这种方法的简单性为开发具有可调采样率的单腔双梳状激光器带来了巨大希望。
