Ultrahigh-contrast imaging by temporally modulated stimulated emission depletion

Stimulated emission depletion (STED) is the key optical technology enabling super-resolution microscopy below the diffraction limit. Here, we demonstrate that modulation of STED in the time domain, combined with properly designed lock-in detection, can radically enhance the contrast of fluorescent images of strongly autofluorescent biotissues. In our experiments, the temporally modulated STED technique, implemented with low-intensity continuous-wave laser sources, is shown to provide an efficient all-optical suppression of a broadband fluorescent background, allowing the contrast of fluorescent images of mammal brain tissues tagged with nitrogen-vacancy diamond to be increased by five orders of magnitude

Air-guided photonic-crystal-fiber pulse-compression delivery of multimegawatt femtosecond laser output for nonlinear-optical imaging and neurosurgery

Large-core hollow photonic-crystal fibers (PCFs) are shown to enable a fiber-format air-guided delivery of ultrashort infrared laser pulses for neurosurgery and nonlinear-optical imaging. With an appropriate dispersion precompensation, an anomalously dispersive 15-m-core hollow PCF compresses 510-fs, 1070-nm light pulses to a pulse width of about 110 fs, providing a peak power in excess of 5 MW. The compressed PCF output is employed to induce a local photodisruption of corpus callosum tissues in mouse brain and is used to generate the third harmonic in brain tissues, which is captured by the PCF and delivered to a detector through the PCF cladding. © 2012 American Institute of Physics