Intensity pattern types in broadband Fourier domain mode-locked (FDML) lasers operating beyond the ultra-stable regime
Intensity pattern types in broadband Fourier domain mode-locked (FDML) lasers operating beyond the ultra-stable regime
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DOI：
10.1007/s00340-021-07600-1
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发表时间：
2020-12
期刊：
影响因子：
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通讯作者：
M. Schmidt;C. Grill;S. Lotz;T. Pfeiffer;R. Huber;C. Jirauschek
中科院分区：
文献类型：
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作者：
M. Schmidt;C. Grill;S. Lotz;T. Pfeiffer;R. Huber;C. Jirauschek
我们报告了失谐傅立叶域锁模 (FDML) 激光器中各种强度图案类型的形成，并确定了相应的操作条件。这些图案是复杂激光动力学的结果，是研究底层物理过程以及模型验证的理想工具。通过数值模拟，我们推断图案的形成与瞬时激光线形相对于扫频带通滤波器的传输窗口的光谱位置有关。线形的光谱特性是由相位偏移的长期积累决定的，由于窄腔内带通滤波器和半导体光放大器增益介质的快速响应时间，导致时域中快速的高振幅强度波动。此外，我们通过在主要形成倾角的区域运行激光，呈现强度轨迹中倾角持续时间的分布，并深入了解它们在大量往返过程中的演变。
We report on the formation of various intensity pattern types in detuned Fourier domain mode-locked (FDML) lasers and identify the corresponding operating conditions. Such patterns are a result of the complex laser dynamics and serve as an ideal tool for the study of the underlying physical processes as well as for model verification. By numerical simulation we deduce that the formation of patterns is related to the spectral position of the instantaneous laser lineshape with respect to the transmission window of the swept bandpass filter. The spectral properties of the lineshape are determined by a long-term accumulation of phase-offsets, resulting in rapid high-amplitude intensity fluctuations in the time domain due to the narrow intra-cavity bandpass filter and the fast response time of the semiconductor optical amplifier gain medium. Furthermore, we present the distribution of the duration of dips in the intensity trace by running the laser in the regime in which dominantly dips form, and give insight into their evolution over a large number of roundtrips.