2013 Conference on Lasers & Electro-Optics Europe & International Quantum Electronics Conference CLEO EUROPE/IQEC, 2013
ABSTRACT Active Q-switching is a common technique to enforce a fibre laser (FL) to oscillate in t... more ABSTRACT Active Q-switching is a common technique to enforce a fibre laser (FL) to oscillate in the regime of short powerful pulses. It is known that if FL cavity is long enough and rise-time of a Q-switch cell (an acousto-optic modulator, AOM) is comparable or shorter than the photon round-trip time, a Q-switch pulse spreads into multiple sub-pulses (sometimes referred to as “self-mode-locking” operation), which significantly deteriorates the laser performance. To mitigate the multi-pulse structure of Q-switch pulses we propose here two special schemes permitting FL to operate in the regime of lone Q-switch pulses with duration less than AOM's rise-time. In both experimental arrangements, AOM rise-time was fixed (50 ns) whereas the active fiber length was chosen such that spurious lasing (usually arising as the result of small internal reflections from a Q-switch cell) still does not occur, thus making the laser operating in a “pulse-on-demand” regime and in the meantime protecting the laser against turning into one of the nonlinear-dynamics regimes. In either scheme, FL cavity was formed by a pair of highly and lowly reflective fiber Bragg gratings (FBGs).
22nd Congress of the International Commission for Optics: Light for the Development of the World, 2011
ABSTRACT In this paper, we present the results of theoretical and experimental study of the activ... more ABSTRACT In this paper, we present the results of theoretical and experimental study of the actively Q-switched erbium-doped fiber laser realized in symmetric configuration. We extend the traveling wave model to this type of fiber lasers and show that such laser permits one to obtain easily the short giant pulses (17 ns on 3 dB level) with small adjacent subpulses. Our model accounts all point losses including loss on the fiber splices and other intra-cavity devices and also the distributed losses such as the active fiber background loss and loss owing to excited state absorption observed in erbium-doped fibers. We compare the experimental data with the modeling results and reveal their good matching, once the laser parameters are properly accounted in the model.
Abstract A Q-switched Erbium-doped fiber laser with symmetric cavity design is thoroughly investi... more Abstract A Q-switched Erbium-doped fiber laser with symmetric cavity design is thoroughly investigated. It is shown theoretically and verified experimentally that such laser is capable to provide generation of stable giant pulses with smooth temporal shape and maximized peak power (~ 40 W) and minimized duration (~ 30 ns), as compared with an analogous laser having conventional asymmetric cavity. The principle that stands behind this performance is also discussed.
IEEE Journal of Selected Topics in Quantum Electronics, 2000
ABSTRACT We report the results of an experimental study aimed at improving the performance of act... more ABSTRACT We report the results of an experimental study aimed at improving the performance of actively Q-switched fiber lasers. Unlike generic design schemes employing photonic crystal fibers, large modal diameter fibers or double-clad fibers, we demonstrate a high-power, actively Q-switched laser based on standard communication erbium doped fibers with peak irradiance beyond the state-of-the-art at 3.1 GW/cm^{2}. The laser had 2.2 kW peak power, 15.5 ns pulse duration and 36.8 muJ pulse energy. We have also investigated the dynamics of pulse generation and have successfully suppressed pulse instabilities caused by backscattered laser emission reaching the pump laser diodes.
2013 Conference on Lasers & Electro-Optics Europe & International Quantum Electronics Conference CLEO EUROPE/IQEC, 2013
ABSTRACT Active Q-switching is a common technique to enforce a fibre laser (FL) to oscillate in t... more ABSTRACT Active Q-switching is a common technique to enforce a fibre laser (FL) to oscillate in the regime of short powerful pulses. It is known that if FL cavity is long enough and rise-time of a Q-switch cell (an acousto-optic modulator, AOM) is comparable or shorter than the photon round-trip time, a Q-switch pulse spreads into multiple sub-pulses (sometimes referred to as “self-mode-locking” operation), which significantly deteriorates the laser performance. To mitigate the multi-pulse structure of Q-switch pulses we propose here two special schemes permitting FL to operate in the regime of lone Q-switch pulses with duration less than AOM's rise-time. In both experimental arrangements, AOM rise-time was fixed (50 ns) whereas the active fiber length was chosen such that spurious lasing (usually arising as the result of small internal reflections from a Q-switch cell) still does not occur, thus making the laser operating in a “pulse-on-demand” regime and in the meantime protecting the laser against turning into one of the nonlinear-dynamics regimes. In either scheme, FL cavity was formed by a pair of highly and lowly reflective fiber Bragg gratings (FBGs).
22nd Congress of the International Commission for Optics: Light for the Development of the World, 2011
ABSTRACT In this paper, we present the results of theoretical and experimental study of the activ... more ABSTRACT In this paper, we present the results of theoretical and experimental study of the actively Q-switched erbium-doped fiber laser realized in symmetric configuration. We extend the traveling wave model to this type of fiber lasers and show that such laser permits one to obtain easily the short giant pulses (17 ns on 3 dB level) with small adjacent subpulses. Our model accounts all point losses including loss on the fiber splices and other intra-cavity devices and also the distributed losses such as the active fiber background loss and loss owing to excited state absorption observed in erbium-doped fibers. We compare the experimental data with the modeling results and reveal their good matching, once the laser parameters are properly accounted in the model.
Abstract A Q-switched Erbium-doped fiber laser with symmetric cavity design is thoroughly investi... more Abstract A Q-switched Erbium-doped fiber laser with symmetric cavity design is thoroughly investigated. It is shown theoretically and verified experimentally that such laser is capable to provide generation of stable giant pulses with smooth temporal shape and maximized peak power (~ 40 W) and minimized duration (~ 30 ns), as compared with an analogous laser having conventional asymmetric cavity. The principle that stands behind this performance is also discussed.
IEEE Journal of Selected Topics in Quantum Electronics, 2000
ABSTRACT We report the results of an experimental study aimed at improving the performance of act... more ABSTRACT We report the results of an experimental study aimed at improving the performance of actively Q-switched fiber lasers. Unlike generic design schemes employing photonic crystal fibers, large modal diameter fibers or double-clad fibers, we demonstrate a high-power, actively Q-switched laser based on standard communication erbium doped fibers with peak irradiance beyond the state-of-the-art at 3.1 GW/cm^{2}. The laser had 2.2 kW peak power, 15.5 ns pulse duration and 36.8 muJ pulse energy. We have also investigated the dynamics of pulse generation and have successfully suppressed pulse instabilities caused by backscattered laser emission reaching the pump laser diodes.
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