There are two datasets under Downloads on the left menu.

fNIRS motion artifact dataset I
fNIRS motion artifact dataset (File size: 47 MB) Citation: Part of this dataset has been published in "Reducing motion artifacts for long-term clinical NIRS monitoring using collodion-fixed prism-based optical fibers." Yücel MA et al., NeuroImage. 2014 15;85 Pt 1:192-201. Find the details about the dataset in the paper as well as in the readme.txt in the zip file.

fNIRS motion artifact dataset II
The file includes the resting state data from five different subjects. This dataset has fewer motion artifacts than Dataset I.