Scalable concept for diode-pumped high-power solid-state lasers
TL;DR: In this article, a very thin laser crystal disc with one face mounted on a heat sink is proposed for diode-pumped high-power solid-state laser systems, which allows very high pump power densities without high temperature rises within the crystal and leads to an almost homogeneous and one-dimensional heat flux perpendicular to the surface.
Abstract: A new, scalable concept for diode-pumped high-power solid-state lasers is presented The basic idea of our approach is a very thin laser crystal disc with one face mounted on a heat sink This allows very high pump power densities without high temperature rises within the crystal Together with a flat-top pump-beam profile this geometry leads to an almost homogeneous and one-dimensional heat flux perpendicular to the surface This design dramatically reduces thermal distortions compared to conventional cooling schemes and is particularly suited for quasi-three-level systems which need high pump power densities Starting from the results obtained with a Ti:Sapphire-pumped Yb:YAG laser at various temperatures, the design was proved by operating a diode-pumped Yb:YAG laser with an output power of 44 W and a maximum slope efficiency of 68% From these first results we predict an exctracted cw power of 100 W at 300 K (140 W at 200 K) with high beam quality from a single longitudinally pumped Yb: YAG crystal with an active volume of 2 mm3 Compact diode-pumped solid-state lasers in the kilowatt range seem to be possible by increasing the pump-beam diameter and/or by using several crystal discs
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TL;DR: Semiconductor lasers for optical pumping and fast optical saturable absorbers, based on either semiconductor devices or the optical nonlinear Kerr effect, have dramatically improved these lasers and opened up new frontiers for applications with extremely short temporal resolution, extremely high peak optical intensities and extremely fast pulse repetition rates.
Abstract: Ultrafast lasers, which generate optical pulses in the picosecond and femtosecond range, have progressed over the past decade from complicated and specialized laboratory systems to compact, reliable instruments. Semiconductor lasers for optical pumping and fast optical saturable absorbers, based on either semiconductor devices or the optical nonlinear Kerr effect, have dramatically improved these lasers and opened up new frontiers for applications with extremely short temporal resolution (much smaller than 10 fs), extremely high peak optical intensities (greater than 10 TW/cm2) and extremely fast pulse repetition rates (greater than 100 GHz).
1,914 citations
Cites background from "Scalable concept for diode-pumped h..."
...So far, the best laser head for power scaling of passively modelocked diode-pumped solid-state lasers is based on a thin-disk lase...
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TL;DR: The root-mean-square charge radius, rp, has been determined with an accuracy of 2 per cent by electron–proton scattering experiments, and the present most accurate value of rp (with an uncertainty of 1 per cent) is given by the CODATA compilation of physical constants.
Abstract: Considering that the proton is a basic subatomic component of all ordinary matter — as well as being ubiquitous in its solo role as the hydrogen ion H+ — there are some surprising gaps in our knowledge of its structure and behaviour. A collaborative project to determine the root-mean-square charge radius of the proton to better than the 1% accuracy of the current 'best' value suggests that those knowledge gaps may be greater than was thought. The new determination comes from a technically challenging spectroscopic experiment — the measurement of the Lamb shift (the energy difference between a specific pair of energy states) in 'muonic hydrogen', an exotic atom in which the electron is replaced by its heavier twin, the muon. The result is unexpected: a charge radius about 4% smaller than the previous value. The discrepancy remains unexplained. Possible implications are that the value of the most accurately determined fundamental constant, the Rydberg constant, will need to be revised — or that the validity of quantum electrodynamics theory is called into question. Here, a technically challenging spectroscopic experiment is described: the measurement of the muonic Lamb shift. The results lead to a new determination of the charge radius of the proton. The new value is 5.0 standard deviations smaller than the previous world average, a large discrepancy that remains unexplained. Possible implications of the new finding are that the value of the Rydberg constant will need to be revised, or that the validity of quantum electrodynamics theory is called into question. The proton is the primary building block of the visible Universe, but many of its properties—such as its charge radius and its anomalous magnetic moment—are not well understood. The root-mean-square charge radius, rp, has been determined with an accuracy of 2 per cent (at best) by electron–proton scattering experiments1,2. The present most accurate value of rp (with an uncertainty of 1 per cent) is given by the CODATA compilation of physical constants3. This value is based mainly on precision spectroscopy of atomic hydrogen4,5,6,7 and calculations of bound-state quantum electrodynamics (QED; refs 8, 9). The accuracy of rp as deduced from electron–proton scattering limits the testing of bound-state QED in atomic hydrogen as well as the determination of the Rydberg constant (currently the most accurately measured fundamental physical constant3). An attractive means to improve the accuracy in the measurement of rp is provided by muonic hydrogen (a proton orbited by a negative muon); its much smaller Bohr radius compared to ordinary atomic hydrogen causes enhancement of effects related to the finite size of the proton. In particular, the Lamb shift10 (the energy difference between the 2S1/2 and 2P1/2 states) is affected by as much as 2 per cent. Here we use pulsed laser spectroscopy to measure a muonic Lamb shift of 49,881.88(76) GHz. On the basis of present calculations11,12,13,14,15 of fine and hyperfine splittings and QED terms, we find rp = 0.84184(67) fm, which differs by 5.0 standard deviations from the CODATA value3 of 0.8768(69) fm. Our result implies that either the Rydberg constant has to be shifted by −110 kHz/c (4.9 standard deviations), or the calculations of the QED effects in atomic hydrogen or muonic hydrogen atoms are insufficient.
1,152 citations
TL;DR: In this paper, the scaling laws for thin-disk laser design have been investigated for continuous-wave (CW) and Q-switched operation as well as for amplification of short (nanosecond, femtosecond) pulses.
Abstract: The principal ideas of the thin-disk laser design will be illustrated and the advantages for operating different laser materials will be explained. The results for continuous-wave (CW) and Q-switched operation as well as for amplification of short (nanosecond) and ultrashort (picosecond, femtosecond) pulses demonstrate the potential of the thin-disk laser design. The scaling laws for this laser design show that the power limit for CW operation is far beyond 40 kW for one single disk and the energy limit is higher than 3 J from one disk in pulsed operation. Also, the applicability of the thin-disk laser concept to optically pumped semiconductor structures will be discussed. When pumping directly into the quantum wells, the energy defect between the pump photon and the laser photon can be smaller than 5%, thus reducing the waste heat generated inside the semiconductor structure. First results demonstrate the potential of this new concept. Finally, a short overview of the industrial realization of the thin-disk laser technology will be given.
530 citations
Cites background from "Scalable concept for diode-pumped h..."
...1 shows the principle of the thin-disk laser design [1]–[4]....
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...Since the first demonstration of the principle in 1993 [1], the output power of one single disk could be increased to more than 5 kW in continuous-wave (CW) operation....
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TL;DR: In this article, the spectroscopic and laser kinetic properties of the trivalent ytterbium ion in various solid-state media are reviewed and compared with four-and quasi-three-level laser architectures, and various architectures suitable for use in high-brightness high-power Yb:YAG lasers are examined.
Abstract: The spectroscopic and laser kinetic properties of the trivalent ytterbium ion in various solid-state media are reviewed. Contrasts between four- and quasi-three-level lasers (e.g., Nd:YAG versus Yb:YAG) are highlighted. Various architectures suitable for use in high-brightness high-power Yb:YAG lasers are examined, and achieved laser performance levels are summarized. The properties of alternative ytterbium-doped laser gain media are reviewed, and early laser results are cited.
425 citations
Cites methods from "Scalable concept for diode-pumped h..."
...[55]–[62] have developed the “thin-disk” design approach, shown schematically in Fig....
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Journal Article•
TL;DR: In this paper, the spectroscopic and laser kinetic properties of the trivalent ytterbium ion in various solid-state media are reviewed and compared with four-and quasi-three-level laser architectures, and various architectures suitable for use in high-brightness high-power Yb:YAG lasers are examined.
Abstract: The spectroscopic and laser kinetic properties of the trivalent ytterbium ion in various solid-state media are reviewed. Contrasts between four- and quasi-three-level lasers (e.g., Nd:YAG versus Yb:YAG) are highlighted. Various architectures suitable for use in high-brightness high-power Yb:YAG lasers are examined, and achieved laser performance levels are summarized. The properties of alternative ytterbium-doped laser gain media are reviewed, and early laser results are cited.
415 citations
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TL;DR: The fractional thermal loading at a 6.5 at.% doped Yb:YAG crystal diode pumped at 0.943 mu m has been measured to be >.
Abstract: The fractional thermal loading, the ratio of heat generated to absorbed energy, at a 6.5 at.% doped Yb:YAG crystal diode pumped at 0.943 mu m has been measured to be >
538 citations
TL;DR: In this article, a model for an end-pumped quasi-three-level laser with population in the lower laser level at equilibrium was developed for transitions to the manifolds4I 9/2 in Nd3+,4I 15/2 and 3H 6 in Tm3+.
Abstract: A model is developed for an end-pumped quasi-three-level laser with population in the lower laser level at equilibrium such as for transitions to the manifolds4I 9/2 in Nd3+,4I 15/2 in Er3+,5I 8 in Ho3+and3H 6 in Tm3+. It is shown that the effect of residual lower laser level population on laser operation can be treated as a saturable loss. Room temperature operation on the4F 3/2 -4I 9/2 transition in Nd:YAG under CW dye laser pumping has been demonstrated with a threshold as low as 11.5 mW incident power and a slope efficiency of 7 percent with 0.3 percent output coupling. Performance is limited by the low output coupling and diffraction loss.
399 citations