ABSTRACT
We demonstrate a new, to the best of our knowledge, method of generating mid-infrared pulses by difference frequency mixing the Stokes pulse generated by four-wave mixing in a photonic crystal fiber with the remaining pump pulse. The Stokes pulses generated by four-wave mixing are inherently overlapped temporally and spatially with the pump pulse at the output of the fiber. Focusing this output into a nonlinear crystal phase matched for difference frequency generation between the pump and Stokes pulses results in a simple method of generating mid-infrared pulses. With a pump source at 1.064 µm, and a photonic crystal fiber engineered to generate Stokes pulses at approximately 1.65 µm, we generate 160 mW of mid-infrared light at approximately 3 µm through difference frequency generation.
ABSTRACT
We demonstrate a simplified set-up for STED microscopy with a straightforward alignment procedure that uses a single spatial light modulator (SLM) with collinear incident excitation and depletion beams to provide phase modulation of the beam profiles and correction of optical aberrations. We show that this approach can be used to extend the field of view for STED microscopy by correcting chromatic aberration that otherwise leads to walk-off between the focused excitation and depletion beams. We further show how this arrangement can be adapted to increase the imaging speed through multibeam excitation and depletion. Fine adjustments to the alignment can be accomplished using the SLM only, conferring the potential for automation.
