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.

我们报告了失谐傅里叶域锁模（FDML）激光器中各种强度模式类型的形成，并确定了相应的工作条件。这种模式是复杂的激光动力学的结果，是研究潜在物理过程以及进行模型验证的理想工具。通过数值模拟，我们推断出图案的形成与瞬时激光线形相对于扫频带通滤波器的透射窗的光谱位置有关。线形的光谱特性由相位偏移的长期累积确定，由于腔内带通滤波器狭窄以及半导体光放大器的响应时间短，导致时域中的高振幅强度快速波动获得中等。