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Detection of chemical species using differential absorption lidar is a topic of growing interest for safety in petrochemical facilities, outdoor air quality measurements, greenhouse gases monitoring from space, and standoff detection of toxic chemical plumes. In such a lidar the optical source must combine a high energy (> 10 mJ for range-resolved detection), a wide and arbitrary wavelength tunability,...
Yb:YAG thin-disk (TD) oscillators are able to deliver energetic femtosecond pulses without external amplification at hundreds of watts average power and MHz repetition rates [1, 2]. Such compact, high-power, low-noise sources are beneficial for scientific experiments and industrial micromachining. They also serve as a great starting point for spectral broadening, which allows transferring their power...
Pulse burst generation has important applications in material processing [1], seeding of free electron lasers [2] and coherent pulse stacking [3]. In particular, coherent pulse stacking technique allows further scaling of fiber and solid-state amplifiers by splitting the seed pulse into multiple replicas and stacking them into a single dominant pulse after the amplification. For this task, a pulse...
Satellite-based laser-based remote sensing (lidar) of the atmosphere can be used for meteorology, atmospheric chemistry and climate change but requires high energy (100mJ-class) lasers with precision wavelength control. A high energy Alexandrite laser source is an interesting alternative to Nd:YAG in future Earth Observation missions with its added scientific benefit of broad wavelength tunability...
Fiber and bulk lasers form two distinct classes of solid-state laser, both of which have achieved tremendous success in various arenas, but they are not without their limitations. The long, thin geometry of a fiber allows excellent heat dissipation, which combined with a waveguiding structure provides stronger resilience to thermally-induced mode distortions than in bulk lasers, allowing diffraction-limited...
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.
Terahertz (THz) and sub-THz frequency emitter-detector technology is receiving increasing attention because of key apphcations in several fields. In particular, ultrafast THz receivers are desired for compact, ultrafast spectroscopy and communication systems. While most of the available THz detectors (thermal, FET …) are currently limited in response time by slow thermal processes and/or by the read-out...
Lead halide perovskite semiconductors have recently gained interest for their application in a wide range of different optoelectronic devices, demonstrating impressive performances in solid-state photovoltaic devices [1] with impressive efficiencies exceeding 20% and great potential for lighting and lasing application [2,3]. These materials not only show exceptional primary optoelectronic properties...
The emerging field of topological photonics aims to realize photonic structures which are resilient to fabrication imperfections by utilizing ideas developed in topology[1]. In photonics, the topological phases are defined on the reciprocal space and usually are associated with the formation of topologically protected (TP) defect states within photonic band-gaps. In this endeavor the manipulation...
One of concepts giving opportunities for studying of topological insulators in non-magnetic materials, or creating scattering-immune in optical waveguides is creation of synthetic gauge fields in photonic systems. It was shown that gauge fields shift the band-gaps of optical waves, which can be applied to implement one-way nonreciprocal waveguides, even though both the waveguide core and cladding...
A quantum walk, that is, a synthetic quantum system mainly impremented by photonic systems, whose dynamics is described by a time-evolution operator, provides potential applications for quantum computing and information. It is further interesting that the quantum walk possesses novel topological phases akin to those of Floquet topological insulators, which are topological insulators driven by a time-periodic...
In a biaxial biréfringent crystal there are two directions at which the refractive index surfaces intersect, leading to the phenomenon of conical refraction [1]. These conical intersections are analogs of Dirac points, and are generically present in non-chiral optical materials. One of the most interesting aspects of Dirac points is that they carry an associated topological charge. As such the propagation...
Melanoma skin cancer is one of the most lethal types of cancer due to comparably early development of metastasis. As preventative medical check-up, optical inspection using polarized light (dermoscopy) is the gold standard in medical practise. If a lesion is diagnosed to be suspicious, it is subsequently excised by a surgeon and analysed by means of histopathology. However, optical inspection so far...
Multimode fibers (MMF) recently received considerable attention to realize space-division multiplexed (SDM) transmission systems, in order to increase the capacity of optical transmission systems. The nonlinear signal propagation in MMFs systems can be described by the nonlinear Schrödinger or the Manakov equation [1]. These are commonly solved numerically by applying split-step Fourier methods [2],...
Multi-plane light conversion (MPLC) [1], [2] consists of a series of phase masks separated by a Fourier transform or free-space propagation and is illustrated conceptually in Fig. 1(a). Through this cascaded sequence of phase masks, and the diffraction which occurs between the masks, it is possible to implement arbitrary unitary spatial transformations. That is, any spatial input basis can be converted...
Low phase noise micro — mm waves are critical building blocks for future wireless communications and radar. Micro — mm waves generated by optical frequency combs via optical frequency division can have extremely low phase noise [1], but producible RF carrier frequencies are essentially limited to harmonics of the comb repetition frequency. Actively suppressing phase noise of RF oscillators is a more...
Precision spectroscopy in the mid-infrared (MIR) region is of great importance for many applications including breath diagnosis and astronomical spectroscopy as various molecular vibrational modes exist in this region. A mid-infrared comb combined with a broadband comb-resolved spectrometer can be a promising method to do this since target gas contains multiple molecular species in most applications...
We present results of polarization-resolved differential transmission experiments, in which pump and probe pulses are quasi-resonant with charged and neutral excitons in monolayer WSe2. By selecting co- and cross-circular polarization configurations for pump and probe pulses, the excitations in the K and K' valleys can be individually addressed [1]. From far above the band edge excited pump-probe...
Monolayers of the transition metal dichalcogenides (TMDCs) MoS2, MoSe2, WS2, WSe2 and MoTe2 are a new class of atomically thin, direct band gap semiconductors with extraordinary optical and electronic properties. Due to their unique electronic structure the spin and valley (K+ or K−) of the excitons are locked, which allows for selective, optical addressing of the valleys. These properties render...
Strong interaction between two single photons [1], is a long standing and important goal in quantum photonics. This would enable a new regime of nonlinear optics and unlock several applications in quantum information science, including photon-photon gates and deterministic Bell-state measurements for quantum networking. In the context of quantum networks [2], a particularly important case is to achieve...
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