Nonlinear op cal imaging, including SRS and SFG, was carried out with an in-house built microscope based on an Olympus FV3000 confocal laser scanning microscope (Olympus, Japan), and described in detail elsewhere . The microscope system features an InSight X3+ (Spectra-Physics, USA) laser and a SF-TRU Timing and Recombina on (Newport, USA) for fast hyperspectral SRS imaging . Laser light was focused on the sample with an Olympus® UPLSAPO 60xW1600 objec ve and collected in transmission direc on with a high NA condenser (Leica, Germany) immersed in the buffer medium if present. SRS signal was detected with an SRS detec on module (APE Angewandte Physik und Elektronik GmbH, Germany) and SFG signal with a PMT1001 photomul plier tube module (Thorlabs, Germany), separately. Instrument and experiment control was a combina on of commercial FV31-SW so ware controlling the Olympus microscope frame, and in-house developed LabView (Na onal Instruments, USA) based user interface controlling the nonlinear op cal imaging instrumenta on.