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Generation and use of orbital angular momentum (OAM) of light is finding more and more interest in a wide variety of fields of photonics: communications, optical trapping, quantum optics, and many more [1]. In the investigation of such behavior, twisting of photonic crystal fibers shows interesting physical phenomena [2]. We previously reported the ability to create helical hollow fibers by mechanically...
Quantum cascade lasers (QCLs) are compact and powerful sources that cover a wide spectral range from infrared to terahertz (THz) radiation. The emission characteristics of QCLs depend on design parameters such as layer thickness, material composition and doping. Therefore, the material system has to be chosen accurately. Most commonly used material systems for THz QCLs are GaAs/AlGaAs and InGaAs/InAlAs...
The helium-neon (HeNe) laser with its characteristic wavelength of 633 nm is one of the most well-known and successful laser systems. Although it was already invented in 1961 [1], the HeNe laser is still the basis for many optical metrology techniques and has found many applications in the fields of manufacturing, medicine and quantum optics. However, the range of implementations for emission at this...
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...
Compact monolithic single-mode red emitting diode lasers are still not readily available for many wavelengths in the visible spectrum. Strontium lattice and Calcium clocks are some of the most widely investigated optical clocks worldwide and the pertinent transitions wavelengths required are in the red and blue wavelength spectral region. The current state of the art in laser technology employs external...
The rising demand in ultrafast radiation sources has boosted the search for high power and high stability mode-locked fiber lasers, particularly at telecom wavelengths. In this work, we demonstrate the first ultrafast mode-locked fiber laser relying on InN as saturable absorber, centered at 1.5μm. The saturable absorber consists of a 1-μm-thick InN grown on a GaN-on-sapphire template deposited by...
Nonlinear Polarization Evolution (NPE) — a passive mode-locking technique — is successfully used in many all-fiber ultrafast oscillators. It is based on a temporal filtration of the pulse polarization state affected by a self-action due to the instantaneous Kerr nonlinearity. To work properly, most of NPE based architectures of fiber lasers contain pieces of standard optical fibers or bulk optical...
In the past years rare-earth-doped fiber lasers have emerged as attractive and power scalable solid-state laser concept due to the outstanding thermo-optical properties of an actively doped fiber. The large ratio of surface to active volume of such a fiber ensures excellent heat dissipation, furthermore the beam quality is defined by the refractive index profile of the active core and is therefore...
Intense, ultra-broadband terahertz (THz) pulses can drive major advances in ultrafast dynamics, nonlinear THz optics, and bio-material imaging [1,2]. Single and two-color filamentation of ultrashort laser pulses in gases have been extensively used for the generation of such pulses [3,4]. However, filament formation in gases is hindered by the need of high laser pulse energies, motivating the exploration...
The efficient conversion of photons into matter degrees of freedom is a hallmark of almost all quantum technology. Quantum communication for example relies on storing, retrieval as well as processing of photonic quantum information in matter qubits and quantum sensing is greatly facilitated by converting quantum signals into photon states. The talk will describe a novel matter-photon interface based...
Light is used to modify or control properties in many quantum systems, leading to phenomena such as electromagnetically induced transparency, the generation of slow light or bright coherent XUV radiation. Using light fields, with strengths comparable to the Coulomb field which binds valence electrons in atoms, particularly unusual quantum states can be created which describe a nearly free electron...
There is a growing interest in the use of metal halide perovskites with different compositions as highly efficient light emitters among the whole visible spectral region [1]. Several groups have observed amplified spontaneous (ASE) emission in thin perovskite films. The gain and threshold values for ASE are very promising, motivating the current effort to develop practical devices that lase.
A single pixel Holoscopy for 3D high resolution optical imaging acquisition method is proposed. By using compressive sensing theory in holoscopy, we fully reconstruct the wave field from a single hologram with only 10% sampling ratio.
Fluorescence microscopy is a widely used tool in cell biology to resolve subcellular structures and reveal dynamic processes, such as molecular transport in or between cells. In the last decade, several techniques were developed that have enabled us to overcome the optical diffraction limit and to resolve even finer spatial structures.
Within the last years it has been shown that chemical sensitive linear and non-linear spectroscopy approaches for multi-contrast and multi-parameter imaging of biological and biomedical target structures (e.g. viruses, pathogens, tumor cells, tissue sections, organs etc.) offers great potential for clinical diagnostics and therapy. Here, we review our recent work on transferring spectroscopic approaches...
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...
It is well known that photons carrying momentum ħk exert a positive pressure on an object in vacuum. However, whether photons push or pull an object immersed inside a dielectric medium is not so straightforward due to the century-old debate associated with the definition of photon momentum inside dielectrics [1-2]. This question becomes even more puzzling with the advent of metamaterials, which can...
The photonic crystal (PhC) membrane represents a platform for planar integration of components, where cavities and waveguides may play a key role in realizing compact optical components with classical functionality such as switches, lasers, and amplifiers or quantum optical functionality such as integrated sources of quantum light. By leaving out a row of holes in an otherwise perfect PhC membrane...
Graphene plasmonics is a promising building block for high speed communication devices that takes advantage of strong confinement of the electromagnetic energy at sub-wavelength scales, tunable via charge carrier density through a gate voltage.[1] The fabrication of integrated optoelectronic devices based on graphene plasmons however is extremely challenging, and launching and conveying graphene plasmons...
Two-dimensional transition metal dichalcogenide (MX2) are receiving lot of attention in recent years due to their excellent electronic and optical properties which make them feasible for advanced photonics applications [1]. In particular Molybdenum-Disulfide (MoS2) has shown large exciton binding energy, strong spin-orbit interaction, and high carrier mobilities.
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