Gigatera Ag

Time-bandwidth Products Ag

Southampton Photonics Limited

Ruediger Paschotta

Ursula Keller

David Colin Hanna

Gabriel J Spuehler

Lars Johan Albinsson Nilsson

John Douglas Minelly

Juerg Aus Der Au

Reto Haering

A pulsed solid-state thin-disk laser comprises an optical resonator and a solid-state laser gain medium placed inside the optical resonator. The laser gain medium is in the shape of a thin plate or layer with two end faces, the extension of the end faces being greater than a thickness of said plate or layer measured in a direction perpendicular to one of the end faces. One of the end faces comprises a cooling surface, via which the laser gain medium is cooled. A pumping source is provided for exciting the laser gain medium to emit electromagnetic radiation. The thin-disk laser further comprises means for passive mode locking placed inside the optical resonator. The mode-locking means are preferably a semiconductor saturable absorber mirror (SESAM). The laser offers a high average power, a good beam quality, short pulses and a high efficiency. Problems such as thermal lensing, Q-switching instabilities and damages of the mode-locking means are avoided. Moreover, the output power of the laser is scalable, i.e., may be increased without increasing the above-mentioned problems.

Mode-locked thin-disk laser

A passively mode-locked optically pumped semiconductor vertical-external-cavity surface-emitting laser (OPS-EXSEL) is disclosed. The laser is mode locked by a semiconductor saturable absorber mirror (SESAM) which forms part of an external cavity. Both the beam-quality limitations of edge-emitting lasers, and the power restrictions of electrically pumped surface-emitting lasers are overcome. The laser uses a semiconductor wafer in which a stack of quantum wells is grown adjacent to a single Bragg-mirror structure. Light from one or more multi-mode high-power diode lasers is focused onto the face of the wafer and pumps the wells by absorption in the barrier regions. The area of the laser mode on the active mirror can be about 10 times larger than the mode area on the facet of an edge-emitting laser, offering scope for the generation of high average power and large pulse energy. At the same time the external cavity enforces fundamental mode operation in a circular, near-diffraction-limited beam. With the laser, sub-picosecond pulse durations are achievable by eliminating coupled cavity effects and by external pulse compression. Band-gap engineering can be used to shape the pulses, or even integrate gain and saturable absorption within the same wafer. Thus, rugged, efficient pulsed laser sources with high average power in a nearly diffraction-limited beam, sub-picosecond pulse durations and multi-GHz repetition rates, which operate in a broad range of wavelengths accessible by bandgap engineering are made possible.

Passively mode-locked optically pumped semiconductor external-cavity surface-emitting laser

Optical amplifier and light source

Growing community of inventors

Zurich, Switzerland

Ruediger Paschotta