Tracing attosecond electron emission from a nanometric metal tip.

Solids exposed to intense electric fields release electrons through tunnelling. This fundamental quantum process lies at the heart of various applications, ranging from high brightness electron sources in d.c.

Ultrabroadband suppression of mid-infrared reflection losses of a layered semiconductor by nanopatterning with a focused ion beam.

Moth-eye structures are patterned onto gallium selenide surfaces with sub-micrometer precision. In this way, Fresnel reflection losses are suppressed to below one percent within an ultrabroad optical bandwidth from 15 to 65 THz. We tune the geometry by rigorous coupled-wave analysis.

Passive elimination of correlated amplitude fluctuations in ultrabroadband supercontinua from highly nonlinear fibers by three-wave mixing.

The nonlinear transformation of fluctuations by frequency broadening is found to produce strong anti-correlations in the spectral output. This effect is investigated by dispersive Fourier transform measurements. We exploit the anti-correlations in order to cancel the intensity noise in a subsequent sum-frequency mixing step.

Deterministic Nonlinear Transformations of Phase Noise in Quantum-Limited Frequency Combs.

Optical phase noise of femtosecond lasers is analyzed over various steps of broadband nonlinear frequency conversion. The intrinsic phase jitter of our system originates from quantum statistics in the mode-locked oscillator. Supercontinuum generation by four-wave-mixing processes preserves a noise minimum at the optical carrier frequency.

Ultrabroadband out-of-loop characterization of the carrier-envelope phase noise of an offset-free Er:fiber frequency comb.

Recent demonstrations of passively phase-locked fiber-based combs motivate broadband characterization of the noise associated with the stabilized carrier-envelope offset frequency. In our study, we analyze the phase noise of a 100 MHz Er:fiber system in a wide range spanning from microhertz to the Nyquist frequency. An interferometric detection method enables analysis of the high-frequency output of an f-to-2f interferometer.