Оптимізація макрологістичних мереж

We report on a Laser source, emitting in the mid-IR spectral range. A mode-locked Nd: YVO Laser is used as a pump Laser, followed by two nonlinear frequency conversion steps (OPG, DFG). The broad-band output beam is tunable between 9 ?m and 13 ?m, with average powers up to 10 mW. Further extension of the tuning range is possible

Исследование влияния температуры на процесс восстановления ацетилдифенила изопропилатом алюминия

We present a compact module, emitting nearly diffraction limited green laser light at 531 nm at an average output power of more than 500 mW. As pump source for the second harmonic generation a DBR tapered laser with a total length of 6 mm was used. The RW section had a length of 2 mm including a 1 mm long passive DBR section. The devices were mounted p-side up on a copper block. For this mounting scheme, the device reaches up to 7 W maximal output power. At the power level of about 3.8 W used in the presented experiment, a wavelength of 1062.6 nm with a line-width below 0.02 nm (FWHM) was determined. More than 80% of the emitted power is originated within the central lobe of the beam waist profile illustrating the nearly diffraction limited beam quality. Using a 30mm long MgO-doped periodically poled LiNbO3 bulk crystal, the second harmonic wave is generated in a single-pass setup. Due to precise alignment and beam shaping based on the results of numerical simulations and a properly temperature control of the PPLN crystal, a maximum optical conversion efficiency of more than 14% (3.7%/W) was achieved. The fluctuation of the output power is far below 1%

1.95 μm-pumped OP-GaAs optical parametric oscillator with 10.6 μm idler wavelength

We report on an optical parametric oscillator that generates output idler wavelengths around 10.6 μm. On the basis of orientation-patterned gallium arsenide (OP-GaAs) as a nonlinear medium and a 1.95 μm ns-pulsed pump laser, a signal-resonant bow-tie resonator was designed in order to maximize the output power at moderate intensities well below the damage threshold of the optical components. With this setup, the average idler output power at 50 kHz and 100 ns idler pulse length was more than 800 mW, which corresponds to a pulse energy of 16 μJ. The maximum quantum conversion efficiency of 36.8% is the highest value measured so far for comparable setups to the best of our knowledge

High efficient difference frequency generation of tunable visible light in a self-controlled process

Generating the difference frequency of a frequency-doubled, widely tunable Ti:Al2O3 laser and a Nd:YAG laser provides tunable laser radiation in the visible spectrum range. The generated wavelength region closes the spectral gap between the fundamental and the second harmonic of the Ti:Sapphire laser. A prototype has being developed with a fully automated wavelength tuning, i.e. the wavelength tuning of the Ti:Sapphire laser, the angel tuning of the nonlinear crystals and the tuning of the temporal delay between the Ti:Sapphire and the Nd:YAG laser operate self-controlled. Design, theoretical modeling and experimental characterization of the system are closely discussed. At a repetition rate of one kilohertz, the frequency-doubled Ti:Sapphire laser provides pulses of approximately 20 ns, a spectral line width of 20 GHz. a nearly diffraction limited beam quality and pulse energies of up to 850 J. The tuning range reaches from 340 nm to 510 nm. For the three wave interact ion process in a 8 mm long BBO crystal the Ti:Sapphire pulses (pump wave) are mixed with 3.5 mJ pulses of a Nd:YAG laser (signal wave). The generated idler wave has pulse energies of up to 280 J and pulse durations of approximately 10 ns in the spectral range between 510 nm and 680 nm. This yields to a conversion efficiency of about 33% and a quantum conversion efficiency of more than 50%. To our knowledge, this clearly exceeds the values that has been obtained with comparable setups so far. Further increase of the efficiency is currently under investigation

High performance widely tunable Ti:Sapphire laser with nanosecond pulses

Design, theoretical modeling, and experimental characterization of a widely tunable Ti:Sapphire laser with nanosecond pulses and high pulse peak power is presented. The laser provides a continuous tuning range of from 675 nm to 1025 nm with no exchange of optics required. At a pulse rate of one kilohertz it delivers pulse energies of up to 2.5 mJ, pulse durations of around 20ns, a spectral bandwidth of 10 GHz and an almost diffraction-limited beam quality of M2 < 1.2 with a smooth characteristic of these parameters over the full wavelength range. This clearly exceeds the performance data published so far with our previous designs. Effects, which lent to provoke spectral gaps in the past, are totally understood and definitely suppressed by a modified resonator design. The presentation contains a detailed description and discussion of performance determining design aspects, i.e. pump scheme and pump beam shaping, resonator design and the comparison of different tuning elements. As a main prerequisite of an appropriate resonator design thermal lensing in Ti:Sapphire crystals is discussed on the basis of experimental and theoretical results. This includes the wavelength dependency of the focal length, the astigmatism in end-pumped Ti:Sapphire crystals with Brewster-cul end faces, the influence of the pump-light distribution and different cooling schemes

High-power optical parametric frequency converters with addressable wavelengths in the infrared

Based on established short pulse lasers with an output wavelength around 1 μm optical parametric frequency converters open up the spectral range between 1.4 and 4.0 μm for the first time in a power range of interest to laser material processing. The systems can be flexibly adapted as regards wavelength, pulse parameters and spectral properties to the requirements of various applications. We will discuss technical implementation and characterization of different optical parametric generators (OPG) based on periodically poled Lithium Niobate (PPLN) to show the parameter flexibility of this approach as well as current technical limits. Actual design examples will address output wavelengths between 1.6 μm and 3.4 μm with output powers ranging from several watts to tens of watts. The pulse parameters of these lasers range from a pulse duration of 9 ps with a repetition rate of 86 MHz to 1.5 ns and 100 kHz. The spectral bandwidth of the OPG examined can be very large. In particular, spectral bandwidths of about 100 nm are measured at the degenerated point, where the output wavelength is equal to twice the pump wavelength. Even beyond this point, a spectrum of typically a few tens of nanometers width generally accompanies a large conversion efficiency (>50 %). For applications that require a narrower spectrum, the OPG can be operated in a seeded mode, where only a few milliwatts of power from a continuously emitting laser diode are sufficient to seed a pulsed high power OPG efficiently and reduce the bandwidth to few nanometers

Nanospectroscopy of infrared phonon resonance enables local quantification of electronic properties in doped SrTiO3 ceramics

Among the novel materials for electronic applications and novel device concepts beyond classical Si‐based CMOS technology, SrTiO3 represents a prototype role model for functional oxide materials: It enables resistive switching, but can also form a 2D electron gas at its interface and thus enables tunable transistors. However, the interplay between charge carriers and defects in SrTiO3 is still under debate. Infrared spectroscopy offers the possibility to characterize structural and electronic properties of SrTiO3 in operando, but is hampered by the diffraction‐limited resolution. To overcome this limitation and obtain nanoscale IR spectra of donor‐doped Sr1‐xLaxTiO3 ceramics, scattering‐type scanning near‐field optical microscopy is applied. By exploiting plasmon–phonon coupling, the local electronic properties of doped SrTiO3 are quantified from a detailed spectroscopic analysis in the spectral range of the near‐field ‘phonon resonance’. Single crystal‐like mobility, an increase in charge carrier density N and an increase in ε∞ at grain boundaries (µ≈ 5.7 cm2 V−1s−1, N = 7.1 × 1019 cm−3, and ε∞ = 7.7) and local defects (µ≈ 5.4 cm2 V−1s−1, N = 1.3 × 1020 cm−3, and ε∞ = 8.8) are found. In future, subsurface quantification of defects and free charge carriers at interfaces and filaments in SrTiO3 can be envisioned