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For memory applications and optical control of qubits ultrafast manipulation and high coupling efficiencies are desirable. Ultrafast coherent control can be achieved by the off-resonant Raman scheme [1]. There exist several colour centres with an optically accessible lambda-type energy structure which offer a level splitting large enough for broadband laser pulses.
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...
Squeezed states of light are referred to as non-classical field states and are known to be characterized by strong correlations between photons both in the spectral and spatial domain. For these reasons they are very perspective for many important and interesting practical applications in modern quantum optics including storage and transfer of quantum information. From this point of view multiphoton...
Two novel kinds of anti-resonant polygonal-core fibers are introduced, including a triangular-core fiber-design with surrounding silica-glass webs [1], and a negatively-curved square-core fiber-design.
Mid-infrared (MIR) frequency comb sources enable high-speed and accurate detection of various species, since many molecules possess their fingerprints in this wavelength range. Usually, broadband radiation in this spectral region is obtained from optical parametric oscillators (OPOs), which provide high output power and broad tuning capabilities [1]. However, OpO sources require locking of the cavity...
Two-dimensional electronic spectroscopy (2DES) is a powerful spectroscopic technique for the study of energy and charge flow in biological systems, which has been successfully applied in the visible and infrared ranges. Its extension to the UV range (2DUV) is extremely promising for the study of biomolecules but poses several technical challenges: (i) the requirement of phase-locked pulse pairs; (ii)...
Azobenzene (AB) is a diazene derivative where both hydrogens are replaced by phenyl groups. Under irradiation with UV light, it undergoes ultrafast trans→cis isomerization; the inverse cis→trans isomerization can be driven by light or occurs thermally in dark. AB photochromic properties enable its application as a light triggered switch in numerous molecular devices and functional materials [1]. Here...
We report our advances in development of subwavelength engineered metamaterial structures in silicon waveguides, specifically high-efficiency fiber-chip couplers, ultra-broadband surface grating couplers and nanophotonic beam splitters, evanescent field waveguide sensors and on-chip Fourier-transform spectrometers.
Tunable mid-infrared semiconductor light sources are of particular interest for molecular spectroscopy; for example, CO2 and other atmospheric gases have strong absorption lines in this wavelength range. Currently, to detect multiple gases simultaneously one needs several continuous-wave (CW) operated mid-infrared laser diodes (LDs) with wide tuning range. For a miniaturized gas sensing system, a...
Midinfrared (MIR) hyperspectral imaging has a great potential to be used as a tool for medical diagnostics featuring a combination of imaging and spectroscopy. In hyperspectral imaging, the images of the (biomedical) samples contains both spectral and spatial information.
Passively Q-switched fiber lasers based on low-dimensional saturable absorbers have been extensively developed due to their efficiency, robustness and great simplicity [1]. However, an environmentally stable, industrial class lasers are still lacking. Here, we present a new material for the application as a broadband saturable absorber for large-energy Q-switched ytterbium- and erbium-doped fiber...
Our understanding of the dynamical processes such as light harvesting or single fission crucially relies on ultrafast nonlinear measurement modalities [1,2]. Such techniques are routinely applied to bulk materials but their extension to individual quantum systems in condensed phase at room temperature has thus far remained elusive but is highly sought after due to the ongoing device miniaturisation...
Recent advances in the design of broadband parametric down-conversion (PDC) sources have opened the possibility to attain a regime of high squeezing previously unacessible in the pulsed domain [1]. However, characterising a PDC source is a challenging task when multiple spectral modes are being squeezed simultaneously and one wants to determine the number of squeezers and their relative strengths...
Bessel beams are a class of non-diffracting solution to the propagation equation. They exhibit a constant size of their main lobe over propagation distances that are much longer than the Rayleigh range of Gaussian beams with identical lobe size [1]. Such beam have been widely used for, femto-laser ablation [2], microscopy and optical coherence tomography [3-5].
Engineered manipulation of photon flux in structured semiconductor materials with an aperiodic distribution of nanostructures plays a key role in efficiency-enhanced and industrially viable broadband photonic and plasmonic integrated technologies [1, 2]. The dense Fourier spectra of such aperiodic lattice-embedded nanostructured materials could strongly modulate and enable flexible tailoring of the...
Sum frequency generation (SFG) spectroscopy is a powerful technique for characterization of vibrational bonds of molecules at surfaces and interfaces [1]. The principle of SFG is based on resonant nonlinear mixing of two optical pulses — typically one in MIR range and another visible (VIS). There are two main SFG spectroscopy techniques. Narrowband SFG (NB-SFG) is based on picosecond MIR and picosecond...
Optical frequency comb spectroscopy in the mid-infrared fingerprint region combines broad spectral bandwidth with high detection sensitivity and allows simultaneous detection of trace amounts of many molecular species. We have recently demonstrated a continuous-filtering Vernier spectrometer based on a mid-infrared optical frequency comb and an enhancement cavity for fast and sensitive detection of...
In the visible or near-infrared, dual-comb spectrometer based on mode-locked sources leads to high spectral resolution, low recording time and enhanced sensitivity with not traded off, since massively parallel broadband detection can be performed. One challenge is to transfer the benefit of dual-comb spectroscopy to the mid-infrared where strong fundamental ro-vibrational transitions of various molecules...
Vibrational spectroscopy in the mid-infrared (MIR) molecular fingerprint region (∼2–25 μm) provides information on the molecular composition, structure and conformation, affording tremendous potential for advances in fields ranging from fundamental research over security and environmental applications to biology and medicine. Traditionally, broadband measurements in this spectral region are carried...
Mid-infrared (MIR) spectroscopy is becoming increasingly popular for the study of complex molecules in a number of fields ranging from physics to biology and medicine. While molecular vibrations are usually indirectly probed by Raman-type processes, the direct resonant investigation with IR frequencies ranging from 500–3500 cm−1 provides complementary contrast and far better coupling efficiencies...
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