Optical frequency combs based on mode-locked lasers have revolutionized many areas of science and technology, such as precision metrology, optical frequency synthesis, and telecommunications. In recent years, a particular kind of frequency comb has been observed in edge-emitting semiconductor lasers where the phase difference between longitudinal laser modes is fixed but not zero. This results in a linearly chirped output in the time domain with nearly constant intensity. Here, by using coherent beatnote spectroscopy, we show that such a comb regime can also exist in vertical-external-cavity surface-emitting lasers, as evidenced for a specific part of the laser spectrum. Our findings may not only lead to a better understanding of the physics of frequency-modulated combs but also enable comb applications with high optical power per comb line and flexible emission wavelengths.

中文翻译：

---

VECSEL中调频梳的签名

基于锁模激光器的光频率梳彻底改变了许多科学技术领域，例如精密计量，光频率合成和电信。近年来，在边缘发射半导体激光器中观察到一种特殊类型的频率梳，在该激光器中，纵向激光器模式之间的相位差是固定的，但不是零。这样会在时域中产生线性chi声输出，强度几乎恒定。在这里，通过使用相干节拍谱，我们显示出这种梳理也可以存在于垂直外腔表面发射激光器中，这是针对激光光谱的特定部分所证明的。