Multispectral photoacoustic microscopy uses a wavelength-dependent absorption difference as a contrast mechanism to image the target molecule. In this paper, we present a novel multispectral pulsed fiber laser source, which selectively alternates the excitation wavelengths between green and red colors based on the stimulated Raman scattering (SRS) effect for imaging. This laser has a high pulse repetition rate (PRR) of 300 kHz and high pulse energy of more than 200 nJ meeting the real-time requirements of optical-resolution photoacoustic microscopy imaging. By switching the polarization state of the pump light and optical paths of the pump light, the operating wavelengths of the light source can be selectively alternated at the same fast PRR for any two SRS peak wavelengths between 545 and 655 nm. At 545 nm excitation wavelength, molecular photoacoustic signals from both blood vessels and gold nanorods were obtained simultaneously. However, at 655 nm, the photoacoustic signals of gold nanorods were dominant because the absorption of light by the blood vessels decreased drastically in the spectral region over 600 nm. Thus the multispectral photoacoustic system designed using the novel laser source implemented here could simultaneously monitor the time-dependent fast movement of two molecules independently, having different wavelength-dependent absorption properties at a high repetition rate of 0.49 frames per second (fps).

多光谱光声显微镜使用波长依赖的吸收差异作为对目标分子成像的对比机制。在本文中，我们提出了一种新颖的多光谱脉冲光纤激光光源，该光源根据成像的受激拉曼散射（SRS）效应在绿色和红色之间选择性地交替激发波长。该激光器具有300 kHz的高脉冲重复频率（PRR）和超过200 nJ的高脉冲能量，可满足光学分辨率光声显微镜成像的实时要求。通过切换泵浦光的偏振态和泵浦光的光路，对于545至655 nm之间的任何两个SRS峰值波长，光源的工作波长可以有选择地以相同的快速PRR进行交替。在545 nm激发波长下，同时获得了来自血管和金纳米棒的分子光声信号。然而，在655 nm处，金纳米棒的光声信号占主导地位，因为在600 nm以上的光谱区域中，血管吸收的光急剧下降。因此，使用此处实现的新型激光源设计的多光谱光声系统可以同时监视两个分子的时间相关的快速移动，并以0.49帧/秒（fps）的高重复速率具有不同的波长相关的吸收特性。金纳米棒的光声信号占主导地位，因为在600 nm以上的光谱区域中，血管对光的吸收急剧下降。因此，使用此处实现的新型激光源设计的多光谱光声系统可以同时监视两个分子的时间相关的快速移动，并以0.49帧/秒（fps）的高重复速率具有不同的波长相关的吸收特性。金纳米棒的光声信号占主导地位，因为在600 nm以上的光谱区域中，血管对光的吸收急剧下降。因此，使用此处实现的新型激光源设计的多光谱光声系统可以同时监视两个分子的时间相关的快速移动，并以0.49帧/秒（fps）的高重复速率具有不同的波长相关的吸收特性。