Ultrasmall bullets of light—focusing few-cycle light pulses to the diffraction limit

Abstract

We demonstrate an essentially dispersion-free and diffraction-limited focusing of few-cycle laser pulses through all-reflective microscope objectives. By transmitting 6-fs-pulses from a Ti:sapphire oscillator through an all-reflective 0.5 NA objective, we reach a focus with a beam diameter of 1.0 µm, preserving the time structure of the pulses. The temporal and spatial pulse profile is recorded simultaneously using a novel tip-enhanced electron emission autocorrelator, indicating a focal volume of these pulses of only 1.8 µm3. We anticipate that the demonstrated technique is of considerable interest for inducing and probing optical nonlinearities of individual nanostructures.

Near-field-assisted localization: effect of size and filling factor of randomly distributed zinc oxide nanoneedles on multiple scattering and localization of light

“…This pulse pair is then focused to its diffraction limit onto the ZnO samples using a Cassegrain objective with a numerical aperture of NA = 0.5. By using an allreflective objective, dispersion effects limiting the temporal resolution of our microscope are minimized and a time resolution of 6 fs is reached [34]. An early version of this set-up has been used in [23].…”

“…Beyond these similarities, the three samples differ in terms of their rod reflective Cassegrain focusing objective. The generated light from the sample is collected in reflection geometry as a function of sample position (x, y) at a fixed delay τ between the pulse pair and analysed in a spectrometer [34] dimensions and filling fraction. In Fig.…”

Temporal focusing of ultrashort pulsed Bessel beams into Airy–Bessel light bullets

“…high localization of pulses-both in space and time-is desired. Laser pulses lasting only about one optical cycle have been accomplished [1][2][3][4]. In order to achieve such ultrashort pulses close to the fundamental wave-optical limits, whose spectrum spans over the whole visible region, every optical element is a challenge of its own and requires careful pulse dispersion compensation and compression as well as appropriate measurement methods (see, e.g., reviews [5,6]).…”

Ultrafast Nano‐Focusing for Imaging and Spectroscopy with Electrons and Light

“…The initial experimental setup is schematically shown in Figure 9.10a. An all-reflective Cassegrain objective was used to focus the laser to a spot of 1.5 μm, minimizing temporal dispersion of the incident pulses [129].…”