title: Coherent nonlinear optical imaging: beyond fluorescence microscopy.
abstract: The quest for ultrahigh detection sensitivity with spectroscopic contrasts other than fluorescence has led to various novel approaches to optical microscopy of biological systems. Coherent nonlinear optical imaging, especially the recently developed nonlinear dissipation microscopy (including stimulated Raman scattering and two-photon absorption) and pump-probe microscopy (including excited-state absorption, stimulated emission, and ground-state depletion), provides new image contrasts for nonfluorescent species. Thanks to the high-frequency modulation transfer scheme, these imaging techniques exhibit superb detection sensitivity. By directly interrogating vibrational and/or electronic energy levels of molecules, they offer high molecular specificity. Here we review the underlying principles and excitation and detection schemes, as well as exemplary biomedical applications of this emerging class of molecular imaging techniques.
authors: Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
authors: Wei
authors: W
authors: Min
authors: Christian W
authors: CW
authors: Freudiger
authors: Sijia
authors: S
authors: Lu
authors: X Sunney
authors: XS
authors: Xie
mesh_terms: D000042:Absorption; D005453:Fluorescence; D008856:Microscopy, Fluorescence / Q000379:methods; D020527:Microscopy, Scanning Probe / Q000295:instrumentation*; D057054:Molecular Imaging / Q000295:instrumentation*; D017711:Nonlinear Dynamics; D055095:Optics and Photonics / Q000295:instrumentation*; D056951:Photoelectron Spectroscopy / Q000295:instrumentation*; D017785:Photons; D012680:Sensitivity and Specificity; D013059:Spectrum Analysis, Raman / Q000295:instrumentation*; D041623:Tomography, Optical Coherence / Q000379:methods*; D014732:Vibration