Laser spectroscopy of the [Formula: see text], [Formula: see text] transitions in stored and cooled relativistic C[Formula: see text] ions

The [Formula: see text] and [Formula: see text] transitions in Li-like carbon ions stored and cooled at a velocity of [Formula: see text] in the experimental storage ring (ESR) at the GSI Helmholtz Centre in Darmstadt have been investigated in a laser spectroscopy experiment. Resonance wavelengths were obtained using a new continuous-wave UV laser system and a novel extreme UV (XUV) detection system to detect forward emitted fluorescence photons. The results obtained for the two transitions are compared to existing experimental and theoretical data. A discrepancy found in an earlier laser spectroscopy measurement at the ESR with results from plasma spectroscopy and interferometry has been resolved and agreement between experiment and theory is confirmed.

High-energy, ceramic-disk Yb:LuAG laser amplifier

We report the first short-pulse amplification results to several hundred millijoule energies in ceramic Yb:LuAG. We have demonstrated ns-pulse output from a diode-pumped Yb:LuAG amplifier at a maximum energy of 580 mJ and a peak optical-to-optical efficiency of 28% at 550 mJ. In cavity dumped operation of a nanosecond oscillator we obtained 1 mJ at up to 100 Hz repetition rate. A gain bandwidth of 5.4 nm was achieved at room temperature by measuring the small-signal single-pass gain. Furthermore, we compared our results with Yb:YAG within the same amplifier system.

Optimising the efficiency of pulsed diode pumped Yb:YAG laser amplifiers for ns pulse generation

We present a numerical model of a pulsed, diode-pumped Yb:YAG laser amplifier for the generation of high energy ns-pulses. This model is used to explore how optical-to-optical efficiency depends on factors such as pump duration, pump spectrum, pump intensity, doping concentration, and operating temperature. We put special emphasis on finding ways to achieve high efficiency within the practical limitations imposed by real-world laser systems, such as limited pump brightness and limited damage fluence. We show that a particularly advantageous way of improving efficiency within those constraints is operation at cryogenic temperature. Based on the numerical findings we present a concept for a scalable amplifier based on an end-pumped, cryogenic, gas-cooled multi-slab architecture.

High-efficiency, room-temperature nanosecond Yb:YAG laser

Yb(3+)-doped gain media offer favorable properties for diode-pumped laser amplifiers for high-energy ns-pulses. To reach high optical-to-optical conversion efficiencies at room temperature however, very high and often impractical fluences are required both for pumping and extraction. Low temperature operation offers a solution, but the required cryogenic cooling systems add considerable complexity, bulkiness and cost. Multi-passing both pump and extraction beams through the gain medium is an alternative approach to overcome efficiency limitations at room temperature. In this article we present numerical and experimental results to this effect.We demonstrated ns-pulse output from a diode-pumped Yb:YAG amplifier at an energy of 566 mJ and an optical-to-optical efficiency of 20%, which is almost a doubling of the efficiency achieved with ns-lasers employing Yb(3+)-doped gain media at this energy level.

High-energy, diode-pumped, nanosecond Yb:YAG MOPA system

Diode-pumped nanosecond multi-pass laser amplification to the joule level using an Yb:YAG slab crystal has been demonstrated. A maximum output pulse energy of 2.9 J at an optical-to-optical efficiency of 10% has been achieved. The seed pulses with a pulse duration of 6.4 ns were generated in a Q-switched Yb:YAG laser and amplified up to a pulse energy of 200mJ in a multi-pass booster amplifier. A maximum average output power of 15W at a repetition rate of 10 Hz has been measured. We also present a relay imaging semi-stable cavity for multi-pass amplification and a diode-pumping scheme employing horizontally stacked high-power laser diodes.