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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TL;DR: This work reports, for the first time to the authors' knowledge, femtosecond-pulse operation of a Tm,Ho:NaY(WO(4))(4) laser at around 2060 nm with ion-implanted InGaAsSb quantum-well-based semiconductor saturable absorber mirror.
Abstract: We report, for the first time to our knowledge, femtosecond-pulse operation of a Tm,Ho:NaY(WO(4))(2) laser at around 2060 nm. Transform-limited 191 fs pulses are produced with an average output power of 82 mW at a 144 MHz pulse repetition frequency. Maximum output power of up to 155 mW is generated with a corresponding pulse duration of 258 fs. An ion-implanted InGaAsSb quantum-well-based semiconductor saturable absorber mirror is used for passive mode-locking maintenance.
74 citations
TL;DR: In this article, the authors presented an experimental study on the laser cutting of CFRP plate, 1 1/5mm in thickness by means of 150 W Nd:YAG pulsed laser.
Abstract: Laser cutting is a promising alternative to the traditional methods in CFRP cutting. However, laser cutting is based on thermal interaction that results in thermal damages of both matrix and fibres. The heat affected zone (HAZ) extension is strictly dependent on the adopted laser source and the working parameters. The paper presents an experimental study on the laser cutting of CFRP plate, 1 mm in thickness by means of 150 W Nd:YAG pulsed laser. The cutting region and the influence of process parameters, pulse energy, pulse duration and overlapping, on the kerf geometry and the HAZ were analyzed. Experimental results showed that the adopted laser is able to cut the CFRP plate, up to 10.8 mm/s. However, an accurate selection of the process parameters is necessary in order to obtain the maximum cutting speed and a narrow HAZ. Moreover, a relation between the HAZ extension and the process parameters (average power, cutting speed, pulse frequency and pulse duration) was found.
74 citations
TL;DR: In this paper, Teflon, Mylar and Kapton H are compared from the point of view of charged-area scaling of discharge current pulse properties, and the experimental observations are used to motivate a theory of discharge arc propagation in which the propagation velocity is controlled by the rate of removal of excess charge via wave propagation along a filamentary tunnel filled with an overdense plasma.
Abstract: FEP Teflon, Mylar and Kapton H are compared from the point of view of charged-area scaling of discharge current pulse properties. The properties measured are peak current, pulse duration, released charge and energy dissipated in a load resistor, all for 20 keV incident electrons at a current density of 80 nA/cm2. In general it is found that the three materials are more similar than dissimilar, and furthermore that this similarity extends to discharge damage as well, the damage being identified as a combination of subsurface filamentary tunnels and surface grooves. The experimental observations are used to motivate a theory of discharge arc propagation in which the propagation velocity is controlled by the rate of removal of excess charge via wave propagation along a filamentary tunnel filled with an overdense plasma.
74 citations
TL;DR: Results confirm that the temporal dual-pulse pump technique can effectively suppress PL and TASE and has potential applications in a 10 PW CPA laser system.
Abstract: We report on an experimental and theoretical study of a large-aperture Ti:Sapphire (Ti:S) amplifier pumped with a novel temporal dual-pulse scheme to suppress the parasitic lasing (PL) and transverse amplified spontaneous emission (TASE) for high-energy chirped-pulse amplification (CPA). The pump energy distribution was optimized and the time delay between each pump pulse was controlled precisely. Both the numerical and experimental results confirm that the temporal dual-pulse pump technique can effectively suppress PL and TASE. The maximum output energy of 202.8 J was obtained from the final 150-mm-diameter Ti:S booster amplifier with a pump energy of 320.0 J, corresponding to a conversion efficiency of 49.3%. The compressed pulse duration of 24.0 fs was measured with a throughput efficiency of 64%, leading to a peak power of 5.4 PW. This novel temporal dual-pulse pump technique has potential applications in a 10 PW CPA laser system.
74 citations
Patent•
14 Jul 1998
TL;DR: In this article, an improvement to the method for harmonic imaging including the steps of transmitting ultrasonic energy at a fundamental frequency, and receiving reflected ultrasonic energies at a harmonic of the fundamental frequency is provided.
Abstract: An improvement to the method for harmonic imaging including the steps of transmitting ultrasonic energy at a fundamental frequency, and receiving reflected ultrasonic energy at a harmonic of the fundamental frequency is provided. The transmitting step includes the step of transmitting a waveform comprising at least a sequence of at least a first and second pulse characterized by first and second pulse durations, respectively, where the second pulse duration is different than the first duration. This arrangement can reduce harmonic energy in the waveform. The system (10) includes a transmit beam former (12) that supplies high voltage transmit waveform in a plurality of channels via a TX/RX switch (14) to a transducer array (16).
73 citations