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Introduction
Publications
Publications (86)
Entropy and energy had not yet been introduced to physics by the time Carnot wrote his seminal Réflexions. Scholars continue to discuss what he really had in mind and what misconceptions he might have had. Actually, his work can be read as a correct introduction to the physics of heat engines when the term calorique is replaced by entropy and entro...
Quantum technologies have outgrown mere fundamental research in laboratories over recent years, and will facilitate more and more potentially disruptive applications in a wide range of fields in the future. In foresight, qualification opportunities need to be implemented in order to train qualified specialists, referred to as the future quantum wor...
We report an exploratory interview study into students’ conceptions of photons developed by learners introduced to a QED model of photons as part of an introductory course in quantum physics at the secondary school level. By combining qualitative and quantitative research methods, we extract types of students’ imaginations about photons. Furthermor...
No consensus has been reached so far concerning the key topics on quantum physics suitable for secondary school teaching, despite comprehensive research. We identified the variety of associations with quantum physics among professionals as a potential cause. From an explorative mind map study with N = 29 physics researchers, we derive six subject-s...
Physics teachers are often faced with the challenge of having to set up difficult experiments, or they have to consciously manipulate parameters in order to be able to demonstrate a phenomenon convincingly. Comprehensive laboratory courses are standard procedure in any study program for prospective physics teachers. However, many students, even aft...
Jüngste Ergebnisse der Beforschung gängiger Modellvorstellungen zu Elektronen in der Atomhülle von Ubben und Heusler legen zwei unabhängige Faktoren des Modellverständnisses Lernender nahe: die Gestalttreue und die Funktionalitätstreue. Mit diesen beiden Faktoren wird die Beschreibung von Typen des physikalischen Modellverständnisses ermöglicht. In...
Background: Quantum physics is both a highly topical and challenging topic of physics education. Learning quantum physics is inherently difficult because it is unimaginative, counterintuitive and fundamentally different from what learners know from their everyday life and classical physics. The results of recent studies underline that students are...
Analogiebildung ist ein methodisches Werkzeug zur Förderung naturwissenschaftlicher Lernpro-zesse. Für das Erlanger Unterrichtskonzept zur Quantenoptik wurde zur Vermittlung des Lernbereichs Einzelphotonendetektoren eine Analogie erarbeitet. Die Funktionsweise der Einzelphotonendetektoren wird dabei mit dem Entstehen und Abgehen von Schneelawinen v...
In der empirischen Unterrichtsforschung wird im Kontext von Testentwicklung oft von der Validierung eines Testinstruments gesprochen. Die Debatte über das Testgütekriterium Validität führte zu einer Verschiebung der Auffassung von Validität. Heute ist weniger von der Validität als Eigenschaft eines Tests die Rede. Vielmehr steht eine valide Testwer...
Mit dem Erlanger Unterrichtskonzept zur Quantenoptik wird das Ziel verfolgt, eine moderne Sichtweise auf die Quantenphysik zu vermitteln. Lernende sollen anschlussfähiges Wissen bis hin zu den Wesenszügen der Quantenphysik aufbauen. Im Rahmen einer summativen Evaluation mit Schülerinnen und Schülern der gymnasialen Oberstufe wird das Konzept evalui...
In this article, an approach to integrate contemporary quantum physics into secondary school teaching is presented. The Erlanger concept on quantum optics provides an experimental-based guideway to aspects of modern quantum physics. We avoid the traditional historical approach in order to overcome the lack of modern concepts of quantum physics. In...
Evaluation eines Unterrichtskonzepts zur Quantenoptik mit Einzelphotonenexperimenten -Ergebnisse einer Pilotstudie
Quantenphysik unterscheidet sich von der klassischen Physik fundamental: Während Beobachtungen mechanischer Vorgänge
einfach möglich sind und sich durch den Beobachtungsprozess kein Einluss auf den Vorgang ergibt, sind vergleichbare Beobachtungen in der Quantenphysik nicht möglich, da jeder Messprozess den Zustand eines Quantensystems ändert . Weil...
A rotor of 12 cm diameter is attached to a precision electric motor, used as a generator, to make a model wind turbine. Output power of the generator is measured in a wind tunnel with up to 15 m s−1 air velocity. The maximum power is 3.4 W, the power conversion factor from kinetic to electric energy is c p = 0.15. The v 3 power law is confirmed. Th...
The electrical circuit of the jumping ring experiment based on discharging a capacitor is optimized. The setup is scoop proof at 46 V and yet the ring jumps more than 9 m high. The setup is suitable for both lectures and student laboratory work in higher education.
A high standard of living causes a large number of irreversible processes, which generate entropy. Energy flow is necessary to remove entropy from the location of generation; commonly this is called energy consumption. The usefulness of an energy flow is defined by its capability of removing entropy from an irreversible process. Fossil energy sourc...
An ultra-capacitor in parallel with the output of a dc power supply reduces the source resistance and yields an electrical current of up to 900A through a low resistance load. The magnetic field of wires is made visible with iron filings over a large area.
We present an experiment for education which demonstrates random transmission or reflection of heralded single photons on beam splitters. With our set-up, we can realize different quantum random experiments by appropriate settings of polarization rotators. The concept of entanglement is motivated by correlated randomness. The experiments are suitab...
Single photons are used for fundamental quantum physics experiments as well as for applications. Originally being a topic of advance courses, such experiments are increasingly a subject of undergraduate courses. We provide interactive screen experiments (ISE) for supporting the work in a real laboratory, and for students who do not have access to a...
A digital SLR camera with a standard lens (50 mm focal length, f/1.4) on a fixed tripod is used to obtain photographs of the sky which contain stars up to 8m apparent magnitude. The angle of view is large enough to ensure visual identification of the photograph with a large sky region in a stellar map. The resolution is sufficient to observe the mo...
Colour science is based on the sensation of monochromatic light. In contrast to that, surface colours are caused by reflection of wide sections of the daylight spectrum. Non-spectral colours like magenta and purple appear homologous to colours with spectral hue, if the approach of mixing monochromatic light is abandoned. It is shown that a large re...
The simultaneous sound of several voices or instruments requires proper tuning to achieve consonance for certain intervals and chords. Most instruments allow enough frequency variation to enable pure tuning while being played. Keyboard instruments such as organ and piano have given frequencies for individual notes and the tuning must be based on a...
We report on a 1064nm pumped, 10kHz noncollinear PPLN-OPO. It generates 5.8ns pulses at 1566nm with an average power of 3.6W. The tilted QPM grating improves substancially the signal beam quality (M2 < 1.2).
We characterize a 1064 nm pumped, 10 kHz seminoncollinear PPLN-OPO. The crystal had a parallel grating tilted by 60/spl deg/ to its x-axis. The OPO provides an efficiency of 35% and compared to a collinear PPLN-OPO an improved beamquality (M/sup 2/<1.2) due to reduced backconversion.
A synchronously pumped femtosecond optical parametric oscillator based on congruent MgO-doped periodically poled lithium niobate
(c-MgO:PPLN) is reported. The system, operating at room temperature, was pumped by a mode-locked Ti:sapphire laser. The wavelengths
of the signal and idler waves were tuned from 870nm to 1.54μm and 1.58 to 5.67μm, respect...
The properties of all-optical phase-coherent frequency division by 3,
based on a self-phase-locked continuous-wave (cw) optical parametric
oscillator (OPO), are investigated theoretically and experimentally. The
frequency to be divided is provided by a diode laser master-oscillator
power-amplifier system operated at a wavelength of 812 nm and used...
We present a novel technique for tuning an optical parametric oscillator (OPO) through electro-optically induced shape variations of the parametric gain spectrum in quasi-phase-matched lithium niobate (LN). The diode-pumped, triply resonant continuous-wave OPO is based on a 58-mm-long LN crystal that consists of three equally long sections, the out...
We report on an injection-seeded 9.5-W 82-MHz-repetition-rate picosecond optical parametric generator (OPG) based on a 55mm
long crystal of periodically poled lithium niobate (PPLN) with a quasi-phase-matching (QPM) grating period of 29.75μm. The
OPG is excited by a continuously diode pumped mode-locked picosecond Nd:YVO4 oscillator-amplifier syste...
This paper reports on the pulse-to-pulse wavelength tuning of a multiwatt narrow-linewidth nanosecond optical parametric generator
(OPG). The OPG consists of a 55mm long periodically poled lithium niobate (PPLN) crystal with a domain period of 29.75μm.
Excited by 5.7W of 1064nm laser pulses (duration: 10ns, repetition rate: 10kHz, spatial beam qual...
We explore the potential of a new laser resonator design that uses an intracavity Fourier transformation and allows for multi-color operation, gain extension and intracavity second harmonic generation (SHG). First, purely electronically controlled wavelength tuning is demonstrated using liquid crystal displays (LCDs) and digital mirror devices. Mor...
We present a cw single-frequency laser source with what is to our knowledge the largest emission range ever demonstrated, from the green to the mid-IR range. It employs a cw optical parametric oscillator with subsequent resonant frequency doubling. Typical output powers are 30–500 mW, with 160 mW at 580 nm. Mode-hop-free oscillation, high absolute...
We present and analyze a new concept for a semiconductor laser with a
Fourier-transform external cavity that allows for purely electronically
operated wavelength tuning, simultaneous control of multiple gain media
within one shared external cavity, and simultaneous multi-wavelength
emission from one laser diode only. We investigate the new setup wi...
We introduce a new concept for a wavelength-tunable frequency-doubled laser diode with a single control parameter. The concept is based on intracavity frequency doubling in an external resonator geometry with spatial separation of the spectral components. The use of a fan-structured periodically poled LiTaO 3 crystal permits tuning of both the fund...
Summary form only given. We report on an experimental investigation of MgO:PPLN synchronously pumped OPOs (SPOPOs) excited by two different fs-laser sources. The used fs-laser sources were a Kerr-lens-mode-locked Ti:sapphire laser or an additive-pulse-mode-locked Yb:YAG laser. Mode-locked Ti:sapphire lasers are reliable sources for fs-laser pulses...
We demonstrate a method that enables in situ modification of the spectral shape of the parametric-gain profile in quasi-phase-matching crystals. In our experiment we used the electro-optic effect to modify the phase-matching profile for second-harmonic generation in a 57-mm-long nonuniformly poled LiNbO 3 crystal. In the direction of beam propagati...
We demonstrate a novel scalable and engineerable approach for the frequency-doubling of ultrashort pulses. Our technique is based on quasi-phase-matching and simultaneously provides tailored dispersion and nonlinear frequency conversion of few-cycle optical pulses. The method makes use of the spatial localization of the conversion process and the g...
Fabrication of periodically poled lithium tantalate (PPLT) with periods as short as 1.3μm for second harmonic generation
(SHG) in the UV range and for optical parametric oscillators pumped at 532nm is reported. Both the maximum crystal size of
up to 40mm and the minimum poling period of 1.3μm are improvements on earlier results, achieved by optimiz...
We demonstrate the generation of sub-6-fs pulses centered at 405 nm by frequency doubling of 8.6-fs Ti:sapphire laser pulses. The frequency doubling is carried out in a nonlinearly chirped quasi-phase-matching grating fabricated in a lithium tantalate substrate. This device simultaneously provides frequency conversion and pulse compression of the p...
The tuning properties of pulsed narrowband THz radiation generated via optical rectification in periodically poled lithium niobate have been investigated. Using a disk-shaped periodically poled crystal tuning was easily accomplished by rotating the crystal around its axis and observing the generated THz radiation in forward direction. In this way n...
Summary form only given. We report on increased power scalability
for generation of 772 nm and 386 nm radiation using second harmonic (SH)
generation in periodically poled KTP (PPKTP) and LiTaO<sub>3</sub>
(PPLT). We have demonstrated the power-up scalability of 772 nm PPKTP
based source to 3.5 W average power level, and of 386 nm PPLT based
source...
Summary form only given. The spectral shape of
quasi-phase-matching (QPM) profiles of poled crystals can be designed to
control the duration of ultra-short pulses or to optimize multi-channel
wavelength conversion. After a crystal is manufactured, however, the
shape of the phase-matching profile is fixed, and no in situ
optimization is possible. He...
Summary form only given. We have presented a novel and scalable approach to the frequency-doubling of sub-10-fs laser pulses, which uses quasi-phase-matching (QPM) SHG pulse compression in a nonlinearly-chirped grating. A first experimental demonstration of this method has led to sub-6-fs SH pulses. To our knowledge, these are the shortest pulses i...
Long-term stable single-frequency emission from the green to the mid-IR is achieved with a singly-resonant OPO with external resonant idler SHG. It exhibits up to 500 mW output, up to 38 GHz continuous frequency tuning, and < 50 kHz signal linewidth
Summary form only given. Photonic band gap (PBG) materials consist of dielectric media in which the refractive index varies periodically in space. The PBG gives rise to the exciting possibility that all linear optical properties of the material, such as the transmission and reflection can be defined by the manufacturing process. Also, the phase and...
Summary form only given. We give an overview on selected examples of diode pumped OPOs. We report on diode pumped triply and doubly-resonant CW OPOs with low threshold powers in the range of about 100 μW to 100 mW. Such OPOs are of interest, e.g. for a phase-coherent all-optical frequency division, such as in a self-phase-locked degenerate OPO. We...
We generated 56 mW of average power at 384 nm in periodically poled lithium tantalate by use of a visible fiber source based on a variable-pulse format seeded Yb–Er amplifier and frequency upconversion in periodically poled KTP. The feasibility of high-average-power, wide ultraviolet wavelength–range fiber-based sources is evaluated.
We have studied the effect of various proton exchange (PE) processes on ferroelectric domain structure in periodically poled lithium tantalate using a selective chemical etching technique. We show that proton exchange carried out using the highly diluted melt can produce waveguides in periodically poled lithium tantalate without any erasure of doma...
We report on the first realization of an all-optical frequency-by-three divider. The frequency to be divided is generated by a single-frequency diode master-oscillator power-amplifier (MOPA) system emitting at a wavelength of 812 nm. By-three-division is achieved with a continuous-wave (CW) optical parametric oscillator (OPO) based on a periodicall...
We describe the wavelength tunability and conversion efficiency of 532-nm pulse pumped optical parametric oscillators (OPOs) using periodically pulsed lithium tantalate (PPLT). The OPOs reported here used PPLT crystal lengths of 1,2 and 4 cm with signal wavelengths between 660 and 950 nm. These OPO's were pumped with a pump pulse energy of 100 (mu)...
We report on the first realization of an all-optical frequency-by-three
divider. The frequency to be divided is generated by a single-frequency
diode master-oscillator power-amplifier (MOPA) system emitting at a
wavelength of 812 nm. By-three-division is achieved with a
continuous-wave (CW) optical parametric oscillator (OPO) based on a
periodicall...
Fabrication and characterisation of different ferroelectric materials for quasi-phasematching is reported. Optical phase coherent frequency division is observed in an optical parametric oscillator based on a segmented periodically poled LiNbO<sub>3</sub> crystal
Periodically poled nonlinear crystals are of particular advantage for realizing efficient optical parametric oscillators (OPOs). These materials provide high nonlinearity and quasi-phase-matched (QPM) frequency conversion within the range of optical transparency. So far, different materials have been investigated and compared. But none of these mat...
Summary form only given. Phase coherent division of optical frequencies by three using continuous wave optical parametric oscillators (cw-OPOs) is of interest for precision metrology spanning wide optical ranges. We believe we report on the first all-optical frequency-by-three divider OPO proving that its signal and idler frequency are phase-locked...
Summary form only given. We report on a nanosecond optical parametric generator (OPG) of periodically poled lithium niobate (LiNbO 3) (PPLN). The average output power (signal and idler wave) of the OPG is 2.9 W at 10 kHz repetition rate. The linewidth of the OPG radiation was reduced to 300 MHz by injection seeding with the radiation of a DFB diode...
In the last years, laser-based spectroscopic techniques for trace gas detection on the ppb level have received increasing attention. Cavity leak-out spectroscopy (CALOS) is a fast, accurate and universal method for online measurement of absolute trace gas concentrations,e.g., the concentration of small hydrocarbons in ambient air samples. The sampl...
A highly efficient ultraviolet source based on two-stage up frequency conversion in periodically poled KTP and Lithium Tantalate using versatile, variable pulse format, seeded Yb/Er fiber source is proposed and demonstrated. It is shown that up to a watt average power ultraviolet source is feasible.
We report an efficient, visible, nanosecond optical parametric generator of periodically poled lithium niobate pumped at 532 nm by a frequency-doubled, diode-pumped, passively Q -switched, single-mode Nd:YAG laser with 90 ‐ µ J pulse energy. The signal radiation is tunable from 637 to 593 nm. The maximum signal-conversion efficiency is 23%. Optical...
We describe a cw optical parametric oscillator (OPO) with multigrating periodically poled LiTaO 3 . Pumped by a single-frequency 532-nm laser, the OPO emits single-frequency radiation at wavelengths from 0.77 to 1.73 µ m with as much as 60 mW of output power. Mode-hop-free operation for as long as 50 min, a low frequency drift < 70 MHz / h , and as...
We report on the observation of self-injection-locking of the signal wave of an optical parametric oscillator (OPO) with the intracavity frequency doubled idler wave. The two-mirror OPO is based on a periodically poled LiNbO3 (PPLN) crystal and pumped with a grating stabilized, continuous-wave (CW) single-frequency diode master-oscillator power-amp...
We report on what is believed to be the first singly resonant cw optical parametric oscillator (SRO) that is directly pumped by a diode laser. The SRO consists of a 38-mm-long periodically poled LiNbO 3 crystal in a four-mirror signal-resonant ring cavity. Pumped by 2.5 W of 925-nm diode-laser radiation, the SRO generates 480 mW of single-frequency...
We report on the fabrication and characterization of quasi-phase-matched potassium niobate crystals for second-harmonic generation. Periodic 30 ‐ µ m -pitch antiparallel ferroelectric domains are fabricated by means of poling in an electrical field. Both birefrigence and periodic phase shift of the generated second harmonic contribute to phase matc...
Summary form only given. We report on an efficient visible
nanosecond optical parametric generator (OPG) of periodically poled
lithium niobate (PPLN). This material is well suited for realizing an
efficient OPG because of the high gain which can be achieved at pump
intensities well below the crystal's damage threshold. In our
experiments we used as...
Summary form only given. Singly-resonant continuous-wave (CW) optical parametric oscillators (SROs) have favourable properties in respect to power stability and wavelength tunability. A disadvantage is, however, the high pump power at threshold. The operation of singly resonant CW OPOs thus requires multiwatt laser radiation in a beam of good spect...
ions in CaWO4, LaSc3(BO3)4, and YLiF4 crystals are presented. The spectra were measured by a continuous-wave pump and probe technique. It is shown that ESA is
a negligible loss mechanism in cw lasers emitting at 1.06μm. In contrast, the effective emission cross sections in Nd:CaWO4 and Nd:LaSc3(BO3)4 around 1.35μm are considerably diminished.
Summary form only given. We investigated the single pass second harmonic generation of a passively mode-locked Nd:YAlO3 laser operating at λ = 930 nm in a bulk periodically poled LiTaO3 (PPLT) crystal. The Nd:YAlO3 laser was passively mode-locked with a semiconductor saturable absorber mirror (SESAM) in a V-shaped cavity
Summary form only given. We present a diode-pumped optical parametric oscillator (OPO) based on periodically poled (LiTaO<sub>3 </sub>) lithium tantalate (PPLT). This OPO offers wide temperature tuning of the signal and idler wavelengths for a fixed quasi phase matched (QPM) grating period and an appropriate, fixed pump wavelength
We report on a diode-laser pumped cw optical parametric oscillator (OPO) based on quasi-phase-matched periodically poled lithium tantalate. Pumped by the 2.3-W single-frequency, nearly diffraction-limited 925-nm output of an InGaAs diode master-oscillator power amplifier, the pump and signal resonant OPO generates a single-frequency idler wave with...
Luminescence concentration quenching and upconversion have been quantitatively investigated in neodymium-doped LaSc 3 ( BO 3 ) 4 (LSB) and GdVO 4 (GVO) laser crystals. The microparameter of cross relaxation (self-quenching) was determined in Nd:GVO as 3.6 × 10 - 40 cm 6 / s . It is shown that, in Nd:LSB, upconversion is static, with the upconversio...
We describe electric-field poling of fine-pitch ferroelectric domain gratings in lithium tantalate and characterization of nonlinear-optical properties by single-pass quasi-phase-matched second-harmonic generation (QPM SHG). With a 7.5 - µ m -period grating, the observed effective nonlinear coefficient for first-order QPM SHG of 532-nm radiation is...
First Page of the Article
This paper demonstrates a Nd:LaSc3(BO3)4 (Nd:LSB) microchip laser passively Q-switched by an antiresonant Fabry-Perot saturable absorber (A-FPSA), and have achieved the shortest reported pulses from a passively Q-switched solid-state laser. It measures single-frequency, TEM00, 180-ps FWHM pulses with 0.1-μJ pulse energy at a repetition rate of 110...
We passively Q switched a Nd:LaSc3(BO3)4 microchip laser with an antiresonant Fabry–Perot saturable absorber (A-FPSA) and achieved single-frequency, 180-ps pulses with 0.1 μJ of pulse energy at a repetition rate of 110 kHz. Because of the compactness and scaling possibilities offered by the A-FPSA, the pulse width can be varied from 180 ps to 30 ns...
We passively {ital Q} switched a Nd:LaScâ(BOâ)â microchip laser with an antiresonant FabryâPerot saturable absorber (A-FPSA) and achieved single-frequency, 180-ps pulses with 0.1 μJ of pulse energy at a repetition rate of 110 kHz. Because of the compactness and scaling possibilities offered by the A-FPSA, the pulse width can be varied from 180 ps...
Neodymium-doped lanthanum scandium borate [Nd:LaSc3(BO3)4] is a new material for efficient and compact diode-pumped solid-state lasers. A simple plane–plane 3-mm-long resonator is formed by a coated Nd(10%):LaSc3(BO3)4 crystal and a coated potassium titanyl phosphate (KTP) crystal. The second-harmonic output power at 531 nm is 522 mW at 2.05-W inci...
A TEM00 single-frequency, diode-pumped microchip laser of Nd(25%):LaSc3(BO3)4 is operated with an output power of 180 mW. For best performance the laser was pumped by the 450 mW diffraction-limited single-frequency radiation of an injection-locked AlGaAs diode-laser array and cooled to the temperature of liquid nitrogen. The active and passive loss...
We have carried out a detailed spectroscopic characterization of Nd: GdVO4, a new laser crystal with high effective absorption and emission cross sections. The accidental degeneracy of the upper4
F
3/2 laser level decreases the number of emission lines and creates -together with the anisotropic crystal field - high emission cross sections (7.6 10–1...
We report on the spectroscopic properties and laser performance of
Czochralski-grown LaSc<sub>3</sub>(BO<sub>3</sub>)<sub>4</sub> (LSB)
crystals with high neodymium concentrations up to 2.5·10<sup>21
</sup> cm<sup>-3</sup>. The low-concentration quenching of the upper
laser level of neodymium and the polarization dependence of the spectra
indicate...
Laser diode end pumped CW laser action in disordered crystal BaLGa 3 O 7 :Nd (BLGO:Nd) has been investigated. Optical slope efficiency exceeding 50% has been recorded. The process of excited state absorption in this material has been discussed
Laser diode end pumped CW laser action in disordered crystal BaLaGa3O7:Nd (BLGO:Nd) has been investigated. Optical slope efficiency exceeding 50% has been recorded. The process of excited state absorption in this material has been discussed.
The tetravalent vanadium ion (V4+) is isoelectronic to Ti3+ and therefore has promising aspects for tunable solid state lasers. V4+ fluoresces strongly throughout the red and yellow spectral region. The crystal growth and spectroscopic characterization of V4+ -doped Al2O3 and YAlO3 are presented. Loss mechanisms due to the unstable valency of V4+ a...
