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Hybrid lead halide perovskites, such as methylammonium lead halides CH3NH3PbX3 (MAPbX3, X = I, Br, Cl), are emerging as an excellent class of materials for various optoelectronic applications including solar cells, light-emitting diodes, lasers, and photodetectors [1,2]. As for these perovskite-based devices, deep understanding of transport properties of excitons and charge carriers in perovskite...
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 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...
Lithium niobate (LN) is a key material in electronic and photonic technology and, besides this, can be considered as a prototype system among polar oxides characterized by a strong spontaneous polarization and pronounced couplings between the different thermodynamic fields that describe its macroscopic state. In particular the illumination of LN containing some Fe impurities triggers the onset of...
Surface plasmon polaritons (SPPs) in plasmonic metal waveguides can excite a third-order nonlinear response [1] much akin the well-known self-phase modulation (SPM) and two-photon absorption seen in light propagating in dielectric waveguides. In metals, the nonlinearity mainly arises as a self-acting effect: after absorption of the incident light the nonlinearity arises due to hot-electron contributions...
The Optical Frequency Comb (OFC) represents a cornerstone of precision metrology, because it provides a clockwork to down-convert hundreds of THz of optical frequency standards to the countable and traceable radio frequency (RF) domain. In particular, for a future redefinition of the Coordinated Universal Time by an optical atomic transition [1], it will be an essential ingredient. Nowadays, narrowband...
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...
In the past decade, CW fiber lasers have revolutionized industrial material processing because of their high efficiency, robustness and diffraction-limited beams obtained in kW regimes. However, the output power from a single fiber laser is limited by phenomena such as non-linear effects or excessive heating. To overcome these issues, incoherent beam combining (IBC) of multiple independent fiber lasers...
Owing to their high beam quality and enormous power scalability, Yb-doped fiber lasers and amplifiers are currently employed for many scientific and industrial applications. However, photodarkening losses and high operating temperatures can limit their performance or even destroy the laser itself. PD loss reduces the laser efficiency during run-time of fiber laser. Technically, this problem can be...
We report on the realization of quantum-dot (QD) micropillar lasers based on a buried stressor growth approach [1]. This method allows for the site-controlled growth and device integration of QDs with high optical quality [2, 3]. Compared to other concepts for site-controlled QD growth, this approach has the important advantage that the number of QDs within a small ensemble located in the center of...
Nonlinear photonic crystals such as 2D-PPLT (periodically-poled lithium tantalite) are of great interest for multi-wavelengths frequency conversion thanks to the contribution of different reciprocal lattice vectors (RLV) [1]. Such characteristics facilitates optical parametric generation (OPG), second harmonic generation (SHG), sum-frequency generation (SFG) or difference frequency generation (DFG)...
Rapid development of ultrafast laser systems led to the generation of laser pulses with several PW peak power in table top arrangements [1]. Most of these systems rely on amplification using Ti:Sapphire (Ti:Sa), which has exceptional spectral and thermal properties [2]. Reaching ultrahigh peak power pulses at high repetition rates, which is favorable for many applications, is however still a great...
Strong light-matter interaction leads to the appearance of new states, i.e. exciton-polaritons, with photophysical properties rather distinct from their constituents. Recent developments in fabrication techniques allow us to make metallic structures with strong electric field confinement in nanoscale mode volumes, allowing for a facile assembly of strongly coupled systems at room temperature based...
Non-oxide nonlinear crystals are of great significance in the advancement of optical parametric sources in the mid-infrared (mid-IR) beyond 4 μm. The newly developed semiconductor material, orientation-patterned gallium phosphide (OP-GaP), holds promise as the next-generation quasi-phase-matched (QPM) crystal, offering high nonlinearity (d14=70.6 pm/V), wide transparency up to ∼12 μm, and significantly...
Fiber Bragg gratings (FBGs) are key elements for fiber lasers or sensors to measure strain or temperature. Using femtosecond laser pulses for inscription provides high temperature stable modifications [1]. Point by point inscription enables very flexible control of the Bragg wavelength however at the expense of coupling to cladding modes [2, 3]. In contrast a phase mask technique, where the interference...
We demonstrate an optomechanical system with quantum cooperativity Cq = 4g2/κγ >> 1 already at moderate cryogenic temperature [1]. It is realised as a membrane-in-the-middle system [2] with a high-stress silicon nitride membrane. Here, y = kBT/ħQ is the quantum decoherence rate of the mechanical system due to its thermal bath at temperature T∼4 K, and Q∼107 the mechanical quality factor. In...
High-order harmonic generation (HHG) in clusters (instead of separate gas atoms) is of high promise due to expanded options for quasi-phase matching and because clusters appeared to offer an increased optical nonlinearity [1]. To verify the latter, we investigate HHG from noble gas clusters in a supersonic gas jet. To identify a possible dependence of HHG on the average cluster size, we change the...
When a photosensitive (PS) fiber is exposed to UV-irradiation, a permanent refractive index change is induced in the core. As a result, according to Kramers-Kronig relations, the absorption coefficient (α) is also increased. This increment of the absorption can lead to a significant heating of the fiber when it is illuminated by a moderate optical power. Thermal effects may produce spectral changes...
Since the first theoretical prediction by Yang [1] and the first experimental realization [2] interband cascade lasers (ICL) became more and more established for gas sensing applications. The ICL combines the cascading of several active stages known from the quantum cascade laser (QCL) and the interband transition of the diode lasers (DL) enabled by the semimetallic interface between InAs and GaSb...
High power laser systems suffer from optical materials overheating by laser radiation. For optical absorptance testing laser calorimetry is widely used [1]. Its main part is temperature kinetics measurement of the sample exposed to laser radiation. Temperature is measured mostly by indirect methods with sensors adjusted to the sample surface. However, absorption of scattered radiation can induce additional...
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