Photoacoustic microscopy (PAM) is a high‐resolution and non‐invasive imaging modality that provides optical absorption contrast. By employing dual‐ or multiple‐wavelength excitation, PAM extends its capabilities to offer valuable spectroscopic information. To achieve efficient multispectral PAM imaging, an essential requirement is a light source characterized by a high repetition rate and switching rate, a ≈microjoule pulse energy, and a ≈nanosecond pulse duration. However, there exists a notable deficiency in suitable light sources, particularly in the near‐infrared‐II window. In this study, a custom‐built all‐fiber‐based light source is reported that provides >3 µJ, 2 ns pulses with a repetition rate of 200 kHz. Digitally addressed semiconductor seed lasers, followed by stimulated Raman scattering amplification, enabled arbitrary sequences of pulses having wavelengths of either 1168.4 or 1202.1 nm. In a switching mode of operation, a 100 kHz switching rate is used to alternate between these wavelengths in even/odd pulses. Furthermore, a high‐resolution multispectral photoacoustic microscopy of three polymer samples is demonstrated with the proposed light source.

中文翻译：

---

用于多光谱光声显微镜的 NIR-II 区域电子控制双波长可切换 SRS 光纤放大器

光声显微镜（PAM）是一种高分辨率、非侵入性成像方式，可提供光学吸收对比度。通过采用双波长或多波长激发，PAM 扩展了其提供有价值的光谱信息的能力。为了实现高效的多光谱 PAM 成像，一个基本要求是具有高重复率和开关率、约微焦耳脉冲能量和约纳秒脉冲持续时间的光源。然而，合适的光源，特别是近红外-II 窗口，存在明显的缺陷。在这项研究中，报告了一种定制的全光纤光源，可提供 >3 µJ、2 ns 脉冲，重复率为 200 kHz。数字寻址半导体种子激光器，随后进行受激拉曼散射放大，可实现波长为 1168.4 或 1202.1 nm 的任意脉冲序列。在开关操作模式中，使用 100 kHz 开关速率在偶数/奇数脉冲中的这些波长之间进行交替。此外，使用所提出的光源演示了三种聚合物样品的高分辨率多光谱光声显微镜。