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The recent intense research in the newly founded area of PT-symmetric optics [1,2] has triggered a lot of attention in theoretical and experimental studies of non-Hermitian effects in photonics. In this context of composite photonic systems that contain gain and loss, we recently demonstrated for the first time the existence of so-called “constant-intensity waves” (or CI-waves) [3], which, in the...
The interaction of intense extreme ultraviolet (XUV) pulses with an atom can lead to multi-photon absorption and multiple ionization of the target. By using intense, linearly and circularly polarized XUV pulses of the Free Electron Laser (FEL) FERMI [1], we realized the first experimental demonstration of a quantum mechanically complete experiment (CE) in an ionic system. The quest for a CE, as the...
The peculiar coupling of the spin and the valley degrees of freedom in Transition-Metal Dichalcogenides (TMDs) makes this class of materials very interesting for quantum information and possible valleytronics based devices [1]. In the last year the valley depolarization dynamics in TMDs has been object of an intense study [2, 3, 4, 5].
Semiconductor microcavities can be engineered to produce strong coupling between photons and quantum well excitons leading to the formation of new eigenstates called polaritons. Due to their peculiar dispersion, enabling non-equilibrium Bose-Einstein condensation [1], and their straightforward experimental accessibility, microcavity polaritons have gained considerable interest in recent years. Polariton...
Optical phenomena in disordered media have attracted a lot of interest over the recent years due to their potential use in a wide range of applications. Beyond the careful understanding of light propagation in these media, potential devices such as random lasers have been proposed with several advantages notably in microscopy. Nonlinear processes can also take advantage of random media. Multiphoton...
Second harmonic generation (SHG) is an important tool for the study of plasmonic nanostructures and can open up important sensing applications since the second harmonic (SH) signal has an increased sensitivity to nanostructures shape and environment in comparison with the linear scattering [1,2]. SHG from plasmonic centrosymmetric nanostructures is controlled by two main properties. First, SHG is...
Quantum optics experiments require ultimate control over the propagation of light in linear optical networks to realize programmable photon correlations [1]. Integrated optics provides a robust and low-loss platform for implementing such linear optical networks. However, to achieve ultimate control on the quantum state of light, it is necessary to program the network [2]. Tuning the network for controlled...
Authentication of people or objects using physical keys is insecure against secret duplication. Physical unclonable functions (PUF) are special physical keys that are assumed to be unclonable due to the large number of degrees of freedom in their manufacturing [1]. Opaque scattering media, such as white paint and teeth, comprise of millions of nanoparticles in a random arrangement. Under coherent...
When coherent light propagates through a disordered system, such as white paint or biological tissue, its spatial properties are mixed and the resulting transmitted field forms a speckle pattern. Although the size of a speckle grain is diffraction-limited, this complex interference figure is detrimental for all conventional imaging systems. Over the last decade, wavefront shaping techniques have opened...
Optical imaging through complex media such as biological tissue or white paint remains a daily challenge as spatial information gets mixed because of multiple scattering. Without any ballistic light, common microscopy techniques become useless. Over the last decade, spatial light modulators (SLM) have become the indispensable tool to overcome scattering thanks to their millions of degrees of freedom...
A central problem of diffusive imaging is the detection of a hidden object within a highly scattering medium. Overcoming this challenge has potential applications in numerous fields such as medical imaging, communications and security [1-3]. Here we present experimental results based on a single-photon SPAD array camera that allows picosecond timing: the full spatial and temporal information allows...
Highly resolved distributed monitoring of strain and temperature can be easily achieved by means of fiber-optic Brillouin-based sensors. The majority of available Brillouin systems relies on Brillouin Optical Time Domain Analysis (BOTDA) techniques in which pulsed pump and/or signal waves are exploited, allowing a spatial resolution fundamentally restricted to about 1 meter [1]. Brillouin Optical...
Stimulated Brillouin scattering (SBS) is a phonon-photon interaction in which the energy of an optical pump transfers to a Stokes wave through an acoustic wave. Chalcogenide glass (As2S3) photonic integrated circuits (PIC) are among the most efficient platforms for SBS and have been extensively developed for several applications, including microwave photonic filters, lasers and optical memory. In...
The recent findings of line narrowing in Raman-active continuous-wave-pumped gas [1] showed that the Stokes scattering occurs in a Lamb-Dicke regime and is associated to formation of array of deep subwavelength nanotraps, which resulted in a sub-recoil linewidth Stokes radiation [1]. The results also showed that this nanotrap lattice exhibits a macroscopic motion. Here we present theoretical and numerical...
In the last few years, several authors have reported the observation of a new class of acoustic waves in sub-wavelength diameter tapered optical fibers (TOFs) through Brillouin scattering [1, 2]. These include the observation of surface acoustic waves (SAW), hybrid shear and longitudinal acoustic waves (HAW) associated with anti-crossings (AC). It has also been suggested that these acoustic waves...
High-power single-frequency lasers are very attractive for a wide range of applications such as nonlinear conversion, gravitational wave detection, atom trapping or LIDAR. Power scaling in single-frequency regime is a challenging domain of research. In fact, nonlinear effect such as stimulated Brillouin scattering (SBS) is the primary power limitation in single-frequency amplifiers. To mitigate SBS,...
Low phase noise lasers are used throughout many applications including precision metrology [1], and pure microwave synthesis [2], among others. Stimulated Brillouin scattering (SBS), a coherent interaction between photons and phonons, is capable of spectrally purifying optical sources to sub-Hz levels [3]. Previous demonstrations of Brillouin lasers have been limited to fiber based systems or micro-resonators...
Solar-pumped Nd:YAG lasers are a promising renewable energy source for applications including the magnesium-hydrogen energy cycle, power beaming and satellite technologies [1]. The major issue that limits the performance of these lasers is the weak absorption of solar radiation due to the low overlap between the solar spectrum and the Nd:YAG absorption spectrum. The symmetry and homogeneity of this...
Hybrid perovskite semiconductors have attracted strong scientific interest for optoelectronic applications. Despite the current drive for higher optoelectronic device efficiencies and stabilities, little information exists about the fundamental non-equilibrium interactions of photo-excited charge carriers in these materials. Time-resolved experiments with ultrashort laser pulses have been used to...
The energy-efficient generation of white light has recently become an important societal issue. The technology of white-light emitting diodes (LEDs) is one of the most promising solutions to efficiently generate white light for home, office, and street locations, and even for remote locations without electric power grid [1]. One of the outstanding in the development of LED technology are understanding...
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