2022-07-15, Schönfeld, Christoph, Sulzer, Philipp, Brida, Daniele, Leitenstorfer, Alfred, Kurihara, Takayuki

A single-cycle light source in the near infrared is demonstrated enabling sensitive applications of ultrafast optical field control of electronic transport. The compact Er:fiber system generates passively phase-locked pulses with broadband spectra covering 150 THz to 350 THz at a duration of 4.2 fs and 40 MHz repetition rate. A second output arm is equipped with an electro-optic modulator that switches the arrival time of the pulses by 700 ps at arbitrary frequencies up to 20 MHz, enabling timing modulation of the pump pulse without changing the average intensity. As a benchmark demonstration, we investigate the carrier relaxation dynamics in low-temperature-grown InGaAs using quantum interference currents.

2021-11-19, Kuttruff, Joel, Gabbani, Alessio, Petrucci, Gaia, Zhao, Yingqi, Iarossi, Marzia, Pedrueza-Villalmanzo, Esteban, Dmitriev, Alexandre, Parracino, Antonietta, Strangi, Giuseppe, Brida, Daniele

Active nanophotonics can be realized by controlling the optical properties of materials with external magnetic fields. Here, we explore the influence of optical anisotropy on the magneto-optical activity in nonmagnetic hyperbolic nanoparticles. We demonstrate that the magneto-optical response is driven by the hyperbolic dispersion via the coupling of metallic-induced electric and dielectric-induced magnetic dipolar optical modes with static magnetic fields. Magnetic circular dichroism experiments confirm the theoretical predictions and reveal tunable magneto-optical activity across the visible and near infrared spectral range.

2021, Frigerio, Jacopo, Ciano, Chiara, Ballabio, Andrea, Chrastina, Daniel, Allerbeck, Jonas, Kuttruff, Joel, Zeng, Lunjie, Olsson, Eva, Brida, Daniele, Isella, Giovanni

We present the experimental demonstration of second harmonic generation in the mid-infrared by hole-doped Ge/SiGe asymmetric quantum wells.

2021, Herkert, Ediz, Slesiona, Nicole, Recchia, Martina Elisena, Deckert, Thomas, Garcia-Parajo, Maria F., Pruccoli, Andrea, Chitra Ragupathy, Imaiyan, Zumbusch, Andreas, Brida, Daniele, Borri, Paola

In the quest to decipher the chain of life from molecules to cells, the biological and biophysical questions being asked increasingly demand techniques that are capable of identifying specific biomolecules in their native environment, and can measure biomolecular interactions quantitatively, at the smallest possible scale in space and time, without perturbing the system under observation. The interaction of light with biomolecules offers a wealth of phenomena and tools that can be exploited to drive this progress. This Roadmap is written collectively by prominent researchers and encompasses selected aspects of bio-nano-photonics, spanning from the development of optical micro/nano-spectroscopy technologies for quantitative bioimaging and biosensing to the fundamental understanding of light–matter interaction phenomena with biomolecules at the nanoscale. It will be of interest to a wide cross-disciplinary audience in the physical sciences and life sciences.

2022-04-01, Keller, K. R., Budweg, Arne, Allerbeck, Jonas, Brida, Daniele

In this work we present a compact two-stage optical parametric amplifier (OPA) pumped at degeneracy by the fundamental of a Yb:KGW laser system. The output pulses span from 1.7 to 2.5 µm (120-176 THz) and are compressed to a sub-20 fs duration. This parametric amplifier exploits the broad phase-matching bandwidth at the degeneracy point in bismuth triborate (BiBO) and periodically poled lithium tantalate (PPLT). The result drastically expands the availability of ultrashort pulses with few-microjoule energy from near-infrared (NIR) to even longer wavelengths in the mid-infrared (MIR) spectral region.

2021, Allerbeck, Jonas, Deckert, Thomas, Spitzner, Laurens, Brida, Daniele

Ultrafast spectroscopy employing a sequence of phase-locked pump pulses provides a unique method to precisely track the exciton dynamics in bulk gallium selenide with sub-10 fs temporal and 4 meV (1 THz) spectral resolution.

2021, Kuttruff, Joel, Gabbani, Alessio, Petrucci, Gaia, Zhao, Yingqi, Iarossi, Marzia, Pedrueza-Villalmanzo, Esteban, Parracino, Antonietta, Strangi, Giuseppe, Dmitriev, Alexandre, Brida, Daniele, De Angelis, Francesco, Pineider, Francesco, Maccaferri, Nicolo

We study magnetic circular dichroism of type II hyperbolic nanoparticles. Experiments and numerical simulations reveal a broadband response that is analytically described via coupling of electric and magnetic dipole modes with a static magnetic field.

2021-12-15, Frigerio, Jacopo, Ciano, Chiara, Kuttruff, Joel, Mancini, Andrea, Ballabio, Andrea, Chrastina, Daniel, Allerbeck, Jonas, Brida, Daniele, Virgilio, Michele, Ortolani, Michele

Second-harmonic generation (SHG) is a direct measure of the strength of second-order nonlinear optical effects, which also include frequency mixing and parametric oscillations. Natural and artificial materials with broken center-of-inversion symmetry in their unit cell display high SHG efficiency, however, the silicon-foundry compatible group IV semiconductors (Si, Ge) are centrosymmetric, thereby preventing full integration of second-order nonlinearity in silicon photonics platforms. Here we demonstrate strong SHG in Ge-rich quantum wells grown on Si wafers. Unlike Si-rich epilayers, Ge-rich epilayers allow for waveguiding on a Si substrate. The symmetry breaking is artificially realized with a pair of asymmetric coupled quantum wells (ACQW), in which three of the quantum-confined states are equidistant in energy, resulting in a double resonance for SHG. Laser spectroscopy experiments demonstrate a giant second-order nonlinearity at mid-infrared pump wavelengths between 9 and 12 μm. Leveraging on the strong intersubband dipoles, the nonlinear susceptibility χ⁽²⁾ almost reaches 10⁵ pm/V, 4 orders of magnitude larger than bulk nonlinear materials for which, by the Miller’s rule, the range of 10 pm/V is the norm.

2021, Allerbeck, Jonas, Deckert, Thomas, Kurihara, Takayuki, Brida, Daniele

Noncollinear two-dimensional spectroscopy in the 10-40 THz range enables background-free and phase-sensitive investigation of coherent low-energy dynamics in semiconductors and strongly correlated materials in a perturbative excitation regime. Measurements on bulk indium antimonide explore the capabilities of the setup and pave the way toward the investigation of functional thin film materials and few-layer samples.

2021, Frigerio, Jacopo, Baldassarre, Leonetta, Pellegrini, Giovanni, Fischer, Marco P., Gallacher, Kevin, Millar, Ross W., Ballabio, Andrea, Brida, Daniele, Isella, Giovanni, Napolitani, Enrico

In the last decade, silicon photonics has undergone an impressive development driven by an increasing number of technological applications. Plasmonics has not yet made its way to the microelectronic industry, mostly because of the lack of compatibility of typical plasmonic materials with foundry processes. In this framework, we have developed a plasmonic platform based on heavily n-doped Ge grown on silicon substrates. We developed growth protocols to reach n-doping levels exceeding 10²⁰ cm^-3, allowing us to tune the plasma wavelength of Ge in the 3-15 μm range. The plasmonic resonances of Ge-on-Si nanoantennas have been predicted by simulations, confirmed by experimental spectra and exploited for molecular sensing. Our work represents a benchmark for group-IV mid-IR plasmonics.