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The discovery of intersubband transitions in III-V semiconductor heterostructures [I] had a huge impact on large parts of the condensed matter physics community and ultimately led to the development of quantum well infrared photodetectors [2] and quantum cascade lasers [3]. One of the main constraints, however, are the strict lattice matching conditions of the heterostructures — limiting the available...
A remarkable progress has recently been achieved in studies of thermodynamics and heat machines, with experiments probing down to micro and nano-scale systems such as the single Brownian particle [1], as well as the single atom [2]. However, despite several theoretical proposals [3, 4], implementation of heat machines in the fully quantum regime remains a challenge. We report on an experimental realization...
Implementation of a quantum network with single atoms as quantum nodes and single photons as channels between the nodes requires their interfacing in receiver mode, whereby the photonic qubit is mapped onto the internal degrees of freedom of the atom [1]. Combining such a receiver interface with a source of entangled photon pairs enables the distribution of entanglement between network nodes. We implemented...
Owing to their wide range of exceptional properties, two-dimensional (2D) materials have emerged as exciting media for the development of highly functional optoelectronic devices. Of these materials, the transition-metal dichalcogenides (TMDCs) are of particular interest as, unlike graphene, they are often semiconductors, and their optoelectronic properties can be tuned quite dramatically by controlling...
Optical rectification of ultrashort laser pulses in electro-optic crystals is an established technique of terahertz generation. In this technique, the pump optical pulse produces a nonlinear polarization that moves with the group velocity of the optical pulse and acts as a source of terahertz radiation. The up-to-date generation schemes based on this principle utilize both the standard collinear phase...
Novel nonlinear optical crystals have attracted considerable interests due to their wide applications in frequency shifting, terahertz generation, optical communications, display, sensing, and so on. Because terahertz radiation is sensitive to free carriers and lattice vibrations in solid states, terahertz time-domain spectroscopy (THz-TDS) has become a pivotal tool in investigating fundamental dynamics...
The nonlinear light-matter interaction lies at the heart of controlling the electronic systems for the purpose of developing ultrafast optical switching and modulation devices [1], and attosecond laser technology [2]. In general, the interaction causes the formation of photon dressed state that is a quantum superposition state with energetically spaced sidebands and enables to generate the phase-locked...
The transition cross sections on the pump and laser wavelength of rare-earth-doped materials are of crucial importance for their performance as amplifiers and lasers and for the understanding of their performance in a rate-equation model. Since typically part of the absorbed pump power is converted to heat, the temperature of the host material increases with increasing pumping. This implies a temperature-dependent...
Inverted Type-I quantum rings (QRs) are a recently developed class of nanostructure in which a lower bandgap material is laterally grown as a crown of same thickness around a higher bandgap nanoplatelet (NPL) core [l·2]· e.g. core/crown CdS/CdSe as shown in Fig. 1(a). For this work, we have colloidally synthesized 3 monolayer (ML) thick CdS/CdSe QR samples using seed-mediated method, by using 3ML...
We investigate the possibility of slowing down terahertz light via intersubband transitions in quantum well heterostructures. The slow-down effect is achieved via tunneling induced transparency [1] in a three level Λ-system by careful engineering of the wave functions [2]. The inherently short coherence times in such solid state media inevitably leads to strong absorption of the signal, which we propose...
Upconversion detection is a promising technology for measurement of IR signals in the 1.5 μm–2 μm region used for lidar remote sensing [1-2]. In comparison to conventional InGaAs detector, the upconversion detector can achieve IR detection with better signal-to-noise ratio (SNR), not only due to lower dark noise directly, but also because of its limited field-of-view and acceptance bandwidth that...
Many trivalent rare earth ions, such as praseodymium (Pr), samarium (Sm), terbium (Tb) and dysprosium (Dy), have radiative transitions in the visible wavelength region, and those visible lasers have been reported [1]. Especially, Pr3+-doped lasers are successful so far as one of the most efficient approaches for visible lasing thanks to the development of indium gallium nitride (InGaN) diode lasers.
Manipulation of perovskite crystallinity in order to obtain the desired optoelectronic properties is a critical issue. Perovskite structural characterization has been carried out applying several tools, which usually interrogate bulky portions of the material, averaging out over the inhomogeneities at the sub-micron scale [1]. Preliminary results obtained through photoluminescence microscopy across...
Laser induced forward transfer (LIFT) has been used in recent years for the rapid 3D-bioprinting of cells. Because of the high transfer rates and superior cell survival rates, this technique has great potential for tissue engineering applications. However, the fact that material from an inorganic sacrificial layer, which is required for energy absorption, is usually transferred to the printed target...
In the last years several proof of principle experiments have demonstrated the advantages of quantum technologies respect to classical schemes in imaging, metrology and sensing. The present challenge is to overcome the limits of proof of principle demonstrations to approach real applications. Here, we present the such an achievement in the field of quantum enhanced imaging. In particular, we describe...
Direct laser writing in photosensitive materials is an emerging technique, allowing fabrication of arbitrary shape high-resolution 3D microstructures. Commonly, the femtosecond laser sources are used for initiating the photopolymerization reactions. Due to limited availability, only certain wavelengths are used for this technology, particularly ∼515, ∼800, and ∼1030 nm. Although the achievable results...
Filamentation of Mid-IR pulses in ambient air is significantly more complicated and challenging as compared to near-IR filaments, due the changing sign of dispersion in the vicinity of 3.6 μm, substantially lower ionization rates and hence plasma density [1], as well as because of the presence of molecular resonances around the atmospheric transparency windows. Experimental observations reveal that...
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...
Lasers emitting around 2 μm (eye-safe spectral range) are of practical importance for remote sensing, spectroscopy and medicine. Such emission is typically achieved from Tm3+ (3F4 →3H6 transition) and Ho3+ ions (5I7 → 5I8 transition). The search for appropriate saturable absorbers (SAs) for passive Q-switching (PQS) of ∼2 μm lasers is still ongoing. While “slow” SAs, e.g. Cr2+:ZnS, are well-established,...
The research of organic semiconductor materials are increasingly investigated for organic light emitting diode (OLED) and the other organic light emitting devices. Recently, a novel scheme of the fluorescence system, “thermally activated delayed fluorescence (TADF)” has been repoted with new several molecular designs that shows very high internal electroluminescence quantum yield of almost 100 % [1,...
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