We demonstrated a yellow laser source emitting at 577nm externally pumped by 1029 nm Q-switched laser. With the proper combination of Raman and frequency doubling medium, a maximum output of 9mW is achieved.
Nanocrystalline LiYF4:Pr promises exciting design opportunities for composite photonic devices. Here, we present an in-depth spectroscopic investigation on monodispersed colloidal LiYF4:Pr nanocrystals of 10nm size. We observed an unexpected yet intense emission with comparably long lifetimes. These results
pave the way for applications in quantum optics or biomedicine.
A compact laser head emitting a linearly polarized radiation at wavelength 1342 nm was designed and constructed. This laser was based on a separate Nd:YAP gain part and V:YAG saturable absorber. Q-switched pulses 12 ns long with energy up to 0.1 mJ were generated with repetition rate 500 Hz.
The influence of the pump wavelength on the heat load and efficiency of Nd:YVO4 crystals is investigated with a specially designed crystal mount. The measurements indicate that the change in heat load in the crystal can be solely ascribed to the difference of quantum defects and no further non-radiative effects.
We report on the cryogenic laser performance of a new “mixed” Yb:LuYAG garnet crystal in the continuous-wave and pulsed regimes. We determined an optimum temperature of 140 K for efficient laser operation. A maximum output of 10.65 W with a slope efficiency of 56% was achieved.
A theoretical model is built for scattering loss from the planar waveguide with multilayer substrate and experimentally validated with good agreement. Our work shows that substrate layer interference can significantly suppress scattering loss.
We introduce a novel nonlinear multi-pass cell configuration comprising a concave-convex geometry. In a proof-of-principle experiment, 260 fs, 15 $\mu$J pulses are broadened and compressed to approximately 50 fs with 90 % efficiency with excellent spatio-spectral homogeneity. A compact design for 0.5 J and 1 ps laser is also presented.
We demonstrate enhanced spectral broadening in Nitrogen, Nitrous Oxide filled multipass cells. Contrast to atomic gases, molecular gases have stronger effective nonlinearity leading to red-shifted broadband spectrum. For comparison, the spectral span of Argon, Nitrogen and Nitrous Oxide recorded is 45, 106 and 265 nm at 15 $\mu$J input energy.
We have frequency doubled an entirely passive dual-comb thin-disk oscillator to perform spectroscopy of iodine at 515nm. Simultaneous measurement of iodine and acetylene (1034nm) helps to evaluate the jitter characteristics at both wavelengths. It indicates that the approach can be extended to higher harmonics in the deep UV spectral range.
A continuous-wave all-fibered single-oscillator thulium-doped fiber laser is developed. Taking advantage of a high absorption at 793 nm (8.42 dB/m), the source exhibits 260 W of maximum output power at 1.94 µm and a slope efficiency of 59 %. Rate equations are applied to numerically study the cavity.
Temperature measurements inside electrolysis cells pose a challenge for conventional sensors. Since up-conversion-nanocrystals exhibit a temperature dependent emission, we attached such nanocrystals to a fiber facet and applied it as nanothermometer in an electrolysis cell. This approach will yield new insights into the performance of these cells.
The phase transition in fully-connected, multimode equal-coupling photonic networks is studied via numerical simulations and by using methods from statistical mechanics. Finite-size scaling is used to estimate critical points and exponents, yielding a phase diagram in a relevant parameter plane, and confirming mean-field behavior as for the planar XY model.
An important aspect of optical satellite communication technology is the power consumption of the laser systems. We present a high-efficiency all-fiber amplifier for a WDM communication system. 10 channels combined in a polarization-
maintaining fiber can be efficiently amplified up to a total power level of 100W in the 1 $\mu$m wavelength-range.
We present a polarization-maintaining all-normal dispersion fiber with flat dispersion profile over the range of 1200-2100 nm. The fiber possesses the solid core of an elliptical shape that enables high birefringence (with polarization extinction ratio of > 22 dB) and also allows for low-loss fusion splicing to conventional Panda fiber.
We present a Mamyshev regenerator setup with electrically controlled acousto-optic switch. This setup allows the injection of
a long, poor quality pulse through one of the switch inputs. After a few tens of regeneration cycles occur the input pulse is shaped into high quality ultrashort light pulse.
The melanoma incidence is rising for all skin types. While being responsible for 75 % of deaths from skin cancer, melanoma is highly curable at early stages. We demonstrate a multimodal device for the early detection of melanoma that comprises non-contact dermoscopy, 3D measurement technology and Mueller matrix polarimetry.
We demonstrate high quality, short period QPM structures in KTP and RKTP, produced through coercive field engineering using a new ion exchange based on Ba2+ ion indiffusion. We show advantages of using this method over the previously established coercive field engineering method using Rb+ ions.
Tapered multicore fibers (MCFs) are numerically analyzed in the context of high power MCF lasers using Beam Propagation Method. These simulations facilitate taper design to avoid mode mixing and intercore crosstalk. MCF tapers with active fibers enable scalable fundamental-mode operation in large multimode waveguide cores.
We investigated inversion dependent fluorescence quenching of Tb3+ via a Z-scan technique. Analysis with an analytical model yielded parameters describing the strength of energy transfer upconversion and energy migration between Tb3+ ions. This allows optimizing the quantum efficiency of the emitting ^5𝐷_4-level in Tb3+-based lasers by optimized composition
Previously we have demonstrated an all-fiber-integrated, alignment-free NALM PM Yb: fiber oscillator with sub-fs timing jitter. Here we report on the next steps in engineering this all-fiber compact oscillator. We developed a method to repeatably assemble lasers at a repetition rate required by DESY’s FEL facilities.
An easily fabricated planar polymer optical waveguide sensor with metal-organic framework coating for carbon dioxide sensing is demonstrated. The proposed device exhibits good sensitivity, excellent reversibility and rapid response, which are significant towards the further development of gas sensing products for real-world applications such as environmental monitoring and gas detection.
A scalable fabrication approach for aperiodic and twisted multicore fibers is presented, which will enable next-generation lens-less endoscopy for 3D imaging deep inside tissue. Particularly, an aperiodic fiber with 1281 cores was developed, which is single-mode throughout the visible spectrum. The design process was supported by in-depth numerical design studies.
We study spectral broadening of sub-picosecond telecom wavelength pulses in periodically-poled thin-film lithium niobate waveguides that results from cascaded nonlinear interaction. We experimentally investigate the effect of phase mismatching on spectral broadening and compare the results with simulations based on a split-step Fourier method.
We report that the modulation of the heat-load in fibre laser systems significantly mitigates the transverse mode instability when carefully choosing the modulation parameters. It is possible to suppress the higher-order modes by inducing a permanent energy transfer from the higher-order modes to the fundamental
mode.
We demonstrate a design for a monolithic, multi-gigahertz soft-aperture Kerr-lens mode-locked Ti:Sa laser. First experiments did not show mode-locking but cw laser operation with power fluctuations of less than 0.04% rms. We discuss possible obstacles to mode-locking in monolithic lasers like spatial-hole burning or a standing-wave of the pump beam.
Here, the beat signal detection towards carrier-envelope phase stabilization of a 110 MW Kerr-lens mode-locked thin-disk oscillator delivering 140 fs-long pulses is presented. The implementation of an f-2f interferometer is demonstrated using an octave-spanning spectrum from a cascade with a multi-pass
cell and photonic-crystal fiber.
Ion traps are a promising platform for the realization of high-fidelity quantum information processors. To scale the systems to a large number of qubits, integrated photonic components are crucial for guiding and manipulating laser light on a chip-scale level. We will present our first design of surface-electrode ion-trap chips with integrated optics.
We investigate the suitability of vertical-cavity surface-emitting lasers (VCSEL) as highly sensitive distance sensors for topography measurement. The concept relies on the light reflected from a moving sample into the VSCEL resonator inducing a measurable change of operating current and emission wavelength to detect motion of a few nm only.
Recently there has been renewed interest in rare-earth ion doped low-phonon crystals and glasses as gain media for possible compact mid-IR lasers. In this work, mid-IR fluorescence characterization of Ho3+ doped low-phonon energy crystals (NaYF4, CsCdCl3) and glasses (Ga2Ge5S13) were explored.
