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We experimentally demonstrate tunable, phase-matched difference frequency generation fully covering the spectral regime below 15 THz using 4H-SiC as nonlinear crystal. The material is also exploited as a broadband detector for electro-optic sampling.
We investigate the nonlinear optical properties of single resonant plasmonic antennas fabricated from heavily-doped Germanium films. Excitation with intense and ultrashort mid-infrared pulses at 10.8 μm wavelength produces emission at 3.7 μm via third-harmonic generation.
The detection and amplification of molecular absorption lines from a mustard gas simulant is demonstrated using plasmonic antennas fabricated from n-Ge epitaxially grown on Si. Approaches to integrated sensors will be presented along with a review of n-Ge compared to other mid-infrared plasmonic materials.
Label-free optical microscopy plays an important role in biological research. Coherent Raman microscopy combines three-dimensional resolution and fast image acquisition with molecular selectivity based on the vibrational spectrum of the sample. During the last years stimulated Raman scattering (SRS) microscopy has become an important technique in this framework since it does not display an electronic...
By accessing the nonperturbative strong-field regime, light-matter interaction is governed by the electric field transient of light as opposed to multiphoton effects. In our experiments, we illuminate a circuit with a nanoscale open junction (Fig. 1(a)) with intense ultrashort pulses at high repetition rate. With this setup, we are able to coherently drive electronic currents at optical frequencies...
The frequency range between 5 THz and 15 THz is a spectral region of particular interest since it includes various fundamental excitations in condensed-matter systems such as phonons in solids, molecular vibrations and low-energy collective modes of correlated materials. However, the generation and coherent detection of highly stable THz transients for ultrafast experiments in this spectral interval...
Generation of ultrashort and intense laser pulses is the primary motive in ultrafast and nonlinear science. Unfortunately, only a limited number of active media allows for scaling ultrashort pulses to energies greater than a few mJ at kHz repetition rate. For this reason, the available wavelengths are extremely restricted. To drive ultrafast processes in novel frequency domains, the ideal approach...
Recent advances in semiconductor film deposition allow for the growth of heavily-doped germanium with effective plasma frequencies above 60 THz, corresponding to wavelengths below 5 μm. This technology paves the way for mid-infrared nanoplasmonics with application in integrated telecommunication systems and enhanced molecular sensing in the so-called vibrational fingerprint spectral region [1].
Optical nanoantennas are excellent tools for accessing the nonlinear response of noble metals owing to the strong enhancement of light-matter interaction occurring in the near-field. For example, excitation of gold nanostructures with intense radiation triggers both coherent and incoherent phenomena such as third-harmonic generation (THG) [1] and multi-photon photoluminescence (MPPL), respectively...
Generation of optical harmonics is an appealing research area due to the prospect of table-top light sources in the extreme ultraviolet and generation of attosecond pulses [1]. Excitation of harmonics in solids shows intrinsic differences compared to the process in gases and has yet to be fully explained [2]. In addition, such experiments are likely to provide fundamental insights into the electronic...
We demonstrate carrier-envelope phase control of even and odd harmonics in solids up to fifth order with intense 2.3-cycle pulses from a near-infrared optical parametric amplifier operated at 10 MHz repetition rate.
Combined Er/Yb:fiber and Yb:thin-disk technology produces 615 fs pulses at 1030 nm with an energy of 17 mJ at 3 kHz repetition rate. The sub-ps duration allows efficient white-light generation and optical parametric amplification.
We exploit the carrier-envelope phase of near-infrared 1.4-cycle pulses with picojoule-level energy to drive and control single-electron transport across the 8 nm tunneling gap of a gold nanoantenna.
We explore the nonlinear optical properties of plasmonic semiconductor antennas resonant in the mid infrared. The nanostructures are fabricated on silicon substrates from heavily doped germanium films with a plasma frequency of 30 THz, equivalent to a wavelength of 10 μm. Illumination with ultrashort pulses at 10.8 μm produces coherent emission at 3.6 μm via third-harmonic generation.
We demonstrate an ultrastable Yb:fiber amplifier delivering 145 fs pulses with 6 μJ energy at 10 MHz repetition rate. The Er:fiber seed laser provides inherently synchronized broadband continua whose power is boosted via optical parametric amplification.
Germanium nanoantennas are activated by triggering a mid-infrared plasma response via ultrafast interband excitation. Femtosecond control of the intrinsic semiconductor allows complete activation of the plasmonic resonance for hundreds of picoseconds.
We demonstrate ultrafast temporal slicing of phase-locked multi-THz pulses using a photoinduced electron-hole plasma in germanium. This approach enables us to extract single-cycle transients with a peak electric field of 10 MV/cm from a multi-cycle waveform at a carrier frequency of 24 THz.
Ultrafast thermalization of electrons in metal nanostructures is studied by means of pump-probe spectroscopy. We track in real-time the plasmon resonsance evolution, providing a tool for understanding and controlling gold nanoantennas non-linear optical response.
In artificial light harvesting systems the conversion of light into charges or chemical energy happens on the femtosecond time scale and is thought to involve the incoherent jump of an electron from the optical absorber to an electron acceptor. Here we investigate the primary process of electronic charge transfer dynamics in a carotene-porphyrin-fullerene triad, a prototypical elementary component...
The generation of ultrafast optical pulses that are used for many applications is increasingly based on Er:fiber lasers. The inherent advantages of this technology are compactness, stability, and turn-key operation. Tm- and Yb-doped fiber systems are promising candidates for reaching microjoule pulse energies [1,2,3].
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