R. Haring

60-W average power in 810-fs pulses from a thin-disk Yb:YAG laser.

We demonstrate a passively mode-locked diode-pumped thin-disk Yb:YAG laser generating 810-fs pulses at 1030 nm with as much as 60 W of average output power (without using an amplifier). At a pulse repetition rate of 34.3 MHz, the pulse energy is 1.75 microJ and the peak power is as high as 1.9 MW. The beam quality is close to the diffraction limit, with M2 < 1.1.

High-power passively mode-locked semiconductor lasers

We have developed optically pumped passively mode-locked vertical-external-cavity surface-emitting lasers. We achieved as much as 950 mW of mode-locked average power in chirped 15-ps pulses, or 530 mW in 3.9-ps pulses with moderate chirp. Both lasers operate at a repetition rate of 6 GHz and have a diffraction-limited output beam near 950 nm. In continuous-wave operation, we demonstrate an average output power as high as 2.2 W. Device designs with a low thermal impedance and a smooth gain spectrum are the key to such performance. We discuss design and fabrication of the gain structures and, particularly, their thermal properties

Passively Q-switched 0.1mJ fiber laser system at 1.53µm

We demonstrate a passively Q-switched fiber laser system generating pulses with as much as 0.1 mJ pulse energy at 1.53µm and > 1kHz repetition rate. This was achieved with a simple MOPA (master oscillator, power amplifier) scheme with a single pump source, realized with large mode area fiber and multiple reflections on a semiconductor saturable absorber mirror (SESAM).

Eyesafe pulsed microchip laser using semiconductor saturable absorber mirrors

We passively Q-switched a diode-pumped Er/Yb:glass microchip laser at a 1.535 μm wavelength using semiconductor saturable absorber mirrors and demonstrated pulses as short as 1.2 ns. By varying the design parameters of the saturable absorber, the pump power, and the pump spot size, we achieved repetition rates from 300 Hz to 100 kHz with pulse energies up to 4 μJ.

Passively Q-switched microchip laser at 1.5 µm

We demonstrate a compact laser source in the eye-safe wavelength regime (≈1.5 µm) that produces peak powers up to 10.6 kW at pulse durations of 0.84 ns with a repetition rate exceeding 1 kHz. An Er:Yb:glass microchip laser was passively Q-switched with a semiconductor saturable absorber mirror (SESAM). We investigated SESAM damage under Q-switching conditions and developed an improved SESAM design that can withstand microjoule pulses.

Passively mode-locked surface-emitting semiconductor laser with nearly 1 W average power

Summary form only given. We recently demonstrated for the first time passive mode locking of a vertical-external-cavity surface-emitting semiconductor laser (VEC-SEL). The device was pumped with a diode laser and mode-locked with a semiconductor saturable absorber mirror (SESAM) This technology is expected to lead to very powerful and compact pulsed sources, with multi-GHz repetition rates. Compared to previous results, we have now obtained a much higher average output power of 213 mW and at the same time a significantly reduced pulse duration of 3.2 ps. This amounts to a 20-fold enhancement of the peak power, which is now 30 W. Semiconductor laser sources have previously reached such power levels only with amplifier systems or with synchronous pumping of VEC-SELs, using a powerful mode-locked pump source. In edge-emitting semiconductor lasers the average and peak power is limited by the small mode area, which cannot be easily increased. With optically pumped VEC-SELs these constraints are eliminated, and much higher powers are possible with accordingly increased mode areas. Diffraction-limited output, as required for mode locking, is obtained with an external cavity.

Passively mode-locked diode-pumped surface-emitting semiconductor lasers

Summary form only given.We believe we demonstrate the first passively mode-locked surface-emitting semiconductor laser, using a semiconductor saturable absorber mirror (SESAM). We obtained 5-ps pulses with 15.3-mW average power and 2.5-GHz repetition rate or 12-ps pulses at 1.8 GHz with 40 mW. We anticipate that even multiwatt average powers should be achievable with our concept; more than 0.5 W has been demonstrated with a similar device in continuous wave operation. This potential arises from the fact that optically pumped semiconductor vertical-external-cavity surface-emitting lasers, in contrast to edge-emitting semiconductor lasers, allow one to scale up the mode area in order to generate a high average power and high pulse energy, while the external cavity enforces a diffraction-limited output. Multi-GHz repetition rates without Q-switching instabilities are possible. In addition, the broad amplification bandwidth should be sufficient for pulse durations in the subpicosecond regime.

60-W average power in 810-fs pulses from a thin-disk Yb:YAG laser

We demonstrate a passively mode-locked diode-pumped thin-disk Yb:YAG laser generating 810-fs pulses at 1030 nm with as much as 60 W of average output power (without using an amplifier). At a pulse repetition rate of 34.3 MHz, the pulse energy is 1.75 µJ and the peak power is as high as 1.9 MW. The beam quality is close to the diffraction limit, with M 2 < 1.1.

Sub-nanosecond pulses from passively Q-switched microchip lasers at 1.53 /spl mu/m

Summary form only given. We demonstrated the first sub-nanosecond pulses at 1.53 /spl mu/m from a passively Q-switched microchip laser. Peak powers of up to 4.7 kW were generated. We found that the alignment of the output coupler is surprisingly critical for the performance and that significantly shortened pulses can be obtained by deliberately using a small tilt.

Novel high-performance pulse generating lasers from 10 GHz to 160 GHz

This paper discusses both solid state and semiconductor lasers used for optical pulse generation by mode locking in an external cavities.