Gigatera Ag

Lukas Krainer

Ursula Keller

Kurt J Weingarten

Gabriel J Spuehler

Rüdiger Paschotta

Rudiger Paschotta

A passively mode-locked solid-state laser is designed to emit a continuous-wave train () of electromagnetic-radiation pulses, the fundamental repetition rate of the emitted pulses exceeding 1 GHz, without Q-switching instabilities. The laser includes an optical resonator (), a solid-state laser gain element () placed inside the optical resonator (), a device () for exciting said laser gain element () to emit electromagnetic radiation having the effective wavelength, and a device () for passive mode locking including a saturable absorber. The laser gain element () is a laser material with a stimulated emission cross section exceeding 0.8&#xd7;10cmat the effective wavelength, and is made of Nd:vanadate. The saturable absorber () is preferably a semiconductor saturable absorber mirror (SESAM) device. Even higher repetition rates are achieved by operating the laser in the soliton regime. For use in fiber-optical telecommunication, the laser wavelength is preferably shifted to 1.5 &#x3bc;m by use of an optical parametric oscillator. The laser is simple, robust, compact, efficient, and low-cost. It generates a relatively large average power of 100 mW and higher, which is useful for a number of optical probing and detection applications, in a beam () that is substantially a fundamental spatial mode.

High-repetition-rate passively mode-locked solid-state laser

An optically pumped laser with an Er:Yb: doped solid state gain element is disclosed, which is passively mode-locked by means of a saturable absorber mirror. The laser is designed to operate at a fundamental repetition rate exceeding 1 GHz and preferably at an effective wavelength between 1525 nm and 1570 nm. Compared to state of the art solid state pulsed lasers, the threshold for Q-switched-mode-locked operation is substantially improved. Thus, according to one embodiment, the laser achieves a repetition rate beyond 40 GHz. The laser preferably comprises means for wavelength tuning and repetition rate locking.

Pulse-generating laser

A &ldquo;low field enhancement&rdquo; (LFR) semiconductor saturable absorber device design in which the structure is changed such that it has a resonant condition. Consequently, the field strength is substantially higher in the spacer layer, resulting in a smaller saturation fluence and in a higher modulation depth. However, the field in the spacer layer is still lower than the free space field or only moderately enhanced compared to the field in the free space. According to one embodiment, the absorber device is a Semiconductor Saturable Absorber Mirror (SESAM) device. In contrast with SESAMs according to the state of the art, a structure including the absorber and being placed on top of a Bragg reflector is provided, which essentially fulfills a resonance condition whereby a standing electromagnetic wave is present in the structure. In other words, the design is such that the field intensity reaches a local maximum in the vicinity of the device surface.

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Zurich, Switzerland

Lukas Krainer