Topic
Pulse duration
About: Pulse duration is a research topic. Over the lifetime, 19429 publications have been published within this topic receiving 286507 citations.
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01 Jun 1982
TL;DR: In this paper, the first and second pulse-shaped laser beams are guided and directed into the combustion chamber of the engine and the first laser beam of a high energy density causes the breakdown of the air-fuel mixture in combustion chamber to develop a plasma and the second laser beam further increases the energy of the plasma thereby to ensure the setting fire of the combustion mixture.
Abstract: A laser ignition apparatus includes a laser oscillator which generates at least two successive pulse-shaped laser beams during each compression stroke of the engine. A first pulse-shaped laser beam is generated by a Q switching action of the laser oscillator and thus has a high peak output and a second pulse-shaped laser beam is generated without the Q switching action and has a low peak output but a larger pulse duration than the first laser beam. The first and second pulse-shaped laser beams are guided and directed into the combustion chamber of the engine and the first laser beam of a high energy density causes the breakdown of the air-fuel mixture in the combustion chamber to develop a plasma and the second laser beam further increases the energy of the plasma thereby to ensure the setting fire of the air-fuel mixture.
65 citations
TL;DR: In this article, the formation of laser-induced periodic surface structures upon irradiation of titanium, silicon, and fused silica with multiple irradiation sequences consisting of parallel polarized Ti:sapphire femtosecond laser pulse pairs (pulse duration 50-150fs, central wavelength ∼800-nm) was studied experimentally.
65 citations
TL;DR: In this paper, a first-principles study of ionization and high-order harmonic generation by benzene aligned in the polarization plane of a short circularly polarized laser pulse is presented.
Abstract: We present a first-principles study of ionization and high-order harmonic generation by benzene aligned in the polarization plane of a short circularly polarized laser pulse. Time-dependent density-functional theory within the adiabatic local-density approximation is employed to describe the 30 valence-electron dynamics in three dimensions. The multielectron approach enables us to study the effect of very strong laser fields, 10 14 ‐1 0 15 Wc m 22 , where multiple ionization and high-order harmonic generation interplay. Large ionization currents are formed, causing ionization of 1‐ 4 electron charges, while strong high-order harmonic generation is observed. The well-known recollision mechanism of high-order harmonic generation plays a part for moderate laser intensities but is fully suppressed for strong laser fields. The harmonic generation spectra are characterized by two distinguishable plateaus, where the structure of the first plateau is dominated by the 6k 6 1( k50,1,...) selection rule. The number of harmonics in the second plateau is insensitive to the duration of the pulse. The peaks appear in pairs or in threesomes, depending on the pulse duration.
65 citations
TL;DR: In this paper, passive and hybrid mode-locked InAs-GaAs-based quantum dot lasers with bit error rates below 10−11 at −2 dBm receiver power are demonstrated.
Abstract: For InAs-GaAs based quantum dot lasers emitting at 1300 nm digital modulation with bit error rates below 10–11 at –2 dBm receiver power is demonstrated. Error rates of 10–9 or better are realized between 23 °C and 70 °C without current adjustment. Passive and hybrid mode-locked QD lasers are shown to generate optical pulses with repetition frequencies up to 80 GHz and 40 GHz, respectively, with an ultra-short minimum pulse length of 710 fs at 20 GHz. The minimum root mean square jitter of 40 GHz hybrid mode-locked pulses is found to be 400 fs with a corresponding pulse width of 4 ps.
Quantum dot based 1.3 µm fiber-coupled amplifier modules show 40 Gb/s operation with bit error rates below 10–11. Amplifier chip gain up to 26 dB is demonstrated. 710 fs pulses are amplified without pulse broadening. For all devices we use deeply etched narrow ridge waveguide structures which show excellent current and optical confinement.
Along with suppressed beam filamentation of the fundamental mode, a low α -factor and strongly reduced sensitivity to optical feedback our results demonstrate that QD laser performance is now comparable or even superior to quantum well lasers. These achievements became possible due to systematic devel-opment of self-organized growth technologies. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
65 citations
TL;DR: In this article, the authors presented the first passively modelocked thin disk laser (TDL) with sub-100-fs pulse duration using the broadband sesquioxide gain material Yb:LuScO3 and an optimized SEmiconductor Saturable Absorber Mirror (SESAM).
Abstract: We present the first passively modelocked thin disk laser (TDL) with sub-100-fs pulse duration using the broadband sesquioxide gain material Yb:LuScO3 and an optimized SEmiconductor Saturable Absorber Mirror (SESAM). In this proof-of-principle experiment, we obtained 5.1 W of average power at a repetition rate of 77.5 MHz and a pulse duration of 96 fs. We carefully explored and optimized the different parameters on the soliton pulse formation process for the generation of short pulses. In particular, SESAMs combining fast recovery time, high modulation depth and low nonsaturable losses proved crucial to achieve this result even though they are expected to only play a minor role in soliton modelocking. To our knowledge, these are the shortest pulses ever obtained with a modelocked TDL, reaching for the first time the sub-100-fs milestone. This result opens the door to sub-100-fs oscillators with substantially higher power levels in the near future.
65 citations