Self-induced laser line sweeping in double-clad Yb-doped fiber-ring lasers

International audienceExperimental observation of the self-induced laser line sweeping (SLLS) in fiber ring lasers is presented. The SLLS with the same gain fiber is studied in Fabry-Perot cavity for comparison. The SLLS effect manifests itself as a laser wavelength drift with speed of the order of nanometer per second from shorter to longer wavelengths across several nanometers and fast backward jump. Recently, the dynamics of the SLLS in a Fabry-Perot cavity fiber laser was qualitatively described by a dynamic grating induced by spatial-hole-burning in the ytterbium doped fiber where the lifetime of the grating was related to the self-sustained relaxation oscillations. In this paper we address possible discrepancies between the published theoretical model and earlier observations of SLLS, particularly in fiber-ring lasers.We show that the qualitative theoretical model developed for explaining SLLS in the Fabry-Perot cavity can be used also to explain the SLLS effect we observed earlier in fiber-ring lasers

Actively mode-locked Nd:YAP laser

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Nonlinear mirror mode locking of a diode-pumped Nd:YAG laser

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Synchronously Intracavity-Pumped Picosecond Optical Parametric Oscillators for Sensors

The research and development of laser systems for intracavity phase interferometry is described. These systems are based on an intracavity synchronously pumped optical parametric oscillator (OPO), enabling the generation of two trains of picosecond pulses inside a single cavity. In such a configuration, it is possible to measure the beat note frequency between two pulses and to very precisely determine the phase difference between them. The pump source is a diode-pumped passively mode-locked Nd:YVO4 laser. A periodically poled magnesium-doped lithium niobate crystal is used as the optical parametric oscillator crystal coupling the pump and the signal cavities. We designed a synchronously pumped OPO in a linear and ring cavity configuration allowing generation in a dual-pulse regime. By a mutual detuning of both cavity lengths, the quasi-synchronous regime of pumping was achieved and high harmonics of repetition rate frequencies were generated. Such a system can be useful for applications such as pump-probe spectroscopy or for testing telecommunication systems. We also realized the subharmonic OPO cavity as a source of two independent trains of picosecond pulses suitable for intracavity phase interferometry; we also measured the beat note signal

1.443 µm operation of a diode pumped Nd:YAG laser

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Self-mode locked operation of a CW Nd:YAG laser using second-harmonic nonlinear mirror

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4W and 23 ps pulses from a lamp pumped Nd :YAG laser passively mode-locked by polarization switching in a KTP crystal

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Self-induced laser line sweeping and self-pulsing in double-clad fiber Lasers in Fabry-Perot and unidirectional ring cavities

Rare-earth doped fiber lasers are subject to instabilities and various self-pulsed regimes that can lead to catastrophic damage of their components. An interesting self-pulsing regime accompanied with laser wavelength drift with time is the so called self-induced laser line sweeping (SLLS). Despite the early observations of the SLLS in solid-state ruby lasers, in fiber lasers it was first time mentioned in literature only in 2009 where such a laser wavelength drift with time was observed in a relatively broad range of about 1076 -1084 nm in ring ytterbium-doped fiber laser (YDFL). The main characteristic of the SLLS is the scanning of the laser wavelength from shorter to longer wavelength, spanning over large interval of several nanometers, and instantaneous bounce backward. The period of this sweeping is usually quite long, of the order of seconds. This spectacular effect was attributed to spatial-hole burning caused by standing-wave in the laser cavity. In this paper we present experimental investigation of the SLLS in YDFLs in Fabry-Perot cavity and ring cavities. The SLLS was observed also in erbium-doped fiber laser around 1560 nm. We present for the first time observation of the laser wavelength sweep in reverse direction, i.e., from longer towards shorter wavelengths. It was observed in YDFL around 1080 nm