State Key Laboratory of Pulsed Power Laser Technology of China

ShuShan District, China

State Key Laboratory of Pulsed Power Laser Technology of China

ShuShan District, China
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Hu Y.,State Key Laboratory of Pulsed Power Laser Technology of China | Nie J.,State Key Laboratory of Pulsed Power Laser Technology of China | Sun K.,State Key Laboratory of Pulsed Power Laser Technology of China | Ye Q.,State Key Laboratory of Pulsed Power Laser Technology of China | Wang L.,State Key Laboratory of Pulsed Power Laser Technology of China
Optics Communications | Year: 2017

The spatiotemporal dynamics of femtosecond filamentation were investigated numerically to evaluate various intensity distributions of zero-order Mathieu beams without the phase alteration for adjacent lobes. The side filaments are formed due to constructive interferences of the light fields of the side lobes. For the beam with appropriate lobes, the whole length of filament can be extended. The diffraction-free characteristic can still be retained in the femtosecond filamentation area, even when ignoring the phase alternation of adjacent lobes. Thus, several high peak intensity spikes behind the continuous clamping segment were illuminated by the remaining energy of side filaments. For the spectrum, intensity distribution with a suitable number of lobes enhances the supercontinuum (SC) emission on both the blue and red sides. © 2017 Elsevier B.V.


Li Z.-M.,State Key Laboratory of Pulsed Power Laser Technology of China | Wang X.,Electronic Engineering Institute
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2017

An investigation of silicon melting occurring under femtosecond laser irradiation has been presented, The two-temperature model and photoionization model are introduced to calculate the free-carrier intensity's evolution with time. In both models, the electrons density's evolution under laser fluence 2 F0 = 0.2,0.3,0.5J/cm are performed. The maximum density reaching the threshold density for SPP excitation by these two model are discussed. For both single pulse and double pulse, according to the simulation data, the two temperature model have a more agreement with the experiment results. © 2017 SPIE.


Hu Y.,State Key Laboratory of Pulsed Power Laser Technology of China | Nie J.,State Key Laboratory of Pulsed Power Laser Technology of China | Sun K.,State Key Laboratory of Pulsed Power Laser Technology of China | Wang L.,State Key Laboratory of Pulsed Power Laser Technology of China
Optics Communications | Year: 2017

The spatial and temporal features of femtosecond laser filamentation, which are induced by a laser with power several times higher than the critical power, influenced by strong air turbulence at various propagation distances have been studied numerically. First, a strong turbulence occurring right before focal lens induces a few counter-balanced energy spikes which prevent the filament generation. Second, with the turbulence right before the filamentation, side filaments formed in the periphery towards the outside area leads the filament to be slightly short. Third, with the turbulence right after the lens, numerous energy spikes of the wave profile arise, but they will merge into one filament gradually, leading to a delayed filamentation onset and a shorter filamentation length. The deformation of temporal pulse shape become more sensitive and the supercontinuum (SC) can be weakened more significantly when strong turbulence takes place in air more previously. © 2016 Elsevier B.V.


Hu Y.,State Key Laboratory of Pulsed Power Laser Technology of China | Nie J.,State Key Laboratory of Pulsed Power Laser Technology of China
Journal of the Optical Society of America B: Optical Physics | Year: 2017

Nonlinear dynamics of femtosecond filamentation with accelerating parabolic beams are numerically investigated for the first time. The parabolic trajectory of filaments can be formed in the main lobes. For a zero-order accelerating parabolic beam which contains one wing of sidelobes, the accelerating characteristics of filaments are similar to that of the Airy beam. When it comes to the first-order accelerating parabolic beam which consists of two wings of sidelobes with a certain angle between each other, the accelerating action takes place after two main lobes blend together and it can be more obvious with the increase of initial peak intensity. Multiple filaments (MFs) which are formed in the first-order accelerating parabolic beam can benefit the accelerating action of filaments and enhance the length of the parabolic trajectory. In addition, MFs also raise the possibility for pulse splitting of the main lobe in the temporal domain. © 2017 Optical Society of America.


Hu Y.,State Key Laboratory of Pulsed Power Laser Technology of China | Nie J.,State Key Laboratory of Pulsed Power Laser Technology of China | Sun K.,State Key Laboratory of Pulsed Power Laser Technology of China
Optics Communications | Year: 2017

The nonlinear dynamics of multiple filaments in self-accelerating actions by using corrected accelerating parabolic beams (CAPBs) are numerically investigated. By increasing the number of main lobes, the curved filaments can be elongated, leading to a longer displacement. The replenished energy originating from curved multiple filaments (MFs) that constructively interfere with the central one plays a crucial role in the phenomenon. At the bifurcation position, a beam pattern in which secondary lobes tightly follow the main lobes is formed, which is beneficial for the accelerating action of MFs. A new curved filament is generated due to the merging of side-curved MFs, and its accelerating strength decreases gradually with further propagation. Moreover, a special spatiotemporal profile that enhances the possibility of acceleration is also formed. The use of the accelerating beam with the appropriate amount of main lobes provides a new approach to elongate curved filaments. © 2017


Hu Y.,State Key Laboratory of Pulsed Power Laser Technology of China | Nie J.,State Key Laboratory of Pulsed Power Laser Technology of China
Optics Express | Year: 2017

We propose theoretically various kinds of filaments via the Mathieu modulation. Our results indicate curved filaments, in-phase and out-of-phase quasi-solitons and nonlinear light bullets can be formed successfully in air. Through calculated initial Mathieu accelerating beam (MAB), curved filament is able to propagate along a predesigned elliptical trajectory. By transforming the MAB into an axial symmetrical structure with in-phase and out-of-phase modulations, we obtain two kinds of quasi-solitons in air, respectively. The latter case can even propagate in a breathing fashion. With a ring structure of MAB, we successfully form a light bullet in air that generates a chain of intensity peaks over extended distances. These unique filaments can offer significant advantages for numerous applications, such as micro engineering of materials, THz radiation generation and attosecond physics. © 2017 Optical Society of America.


Hu Y.,State Key Laboratory of Pulsed Power Laser Technology of China | Nie J.,State Key Laboratory of Pulsed Power Laser Technology of China | Sun K.,State Key Laboratory of Pulsed Power Laser Technology of China | Bian J.,State Key Laboratory of Pulsed Power Laser Technology of China | And 2 more authors.
Journal of the Optical Society of America B: Optical Physics | Year: 2016

We have numerically studied femtosecond laser filament array generation in air by using two-dimensional acousto-optic modulation (AOM). Similar regular filament distributions have been achieved compared with filamentation by using a microlens array (MLA) in air. The overall length of filamentation with the same onset can be prolonged almost triple that generated in the case of a single lens. The modulation frequency, namely, acoustic period, has a great effect on the elongation. For the supercontinuum (SC), more efficient enhancement on the blue side, especially the visible spectrum, can be obtained with higher frequency of acousto-optic modulation, but at the cost of weaker redshift. The energy evolution process is different from the case with an MLA due to the sinusoidal phase modulation, which interprets distinguishes between these two cases. The AOM offers a convenient way to control the filamentation and SC emission, which can be a valid substitute of an MLA. © 2016 Optical Society of America.


Hu Y.,State Key Laboratory of Pulsed Power Laser Technology of China | Nie J.,State Key Laboratory of Pulsed Power Laser Technology of China | Sun K.,State Key Laboratory of Pulsed Power Laser Technology of China
Journal of the Optical Society of America B: Optical Physics | Year: 2017

We theoretically demonstrate the formation and control of novel snake filaments in air. In particular, the snake filaments can be elongated with large input beam size in the phase modulation direction, and they share almost the same zigzagging fashion during propagation. The specific fields of satellite lobes make great contributions on alternating the accelerating direction of the main lobe, namely, the snake filament. As a result, the filament accelerates in a certain transverse area within two-phase boundaries that are called phase wells. Furthermore, for the spatiotemporal dynamics, a strip structure is sustained during the filamentation process of snake filaments. Results presented here are expected to have a significant impact on a wide range of fields in nonlinear optics. © 2017 Optical Society of America.


Hu Y.,State Key Laboratory of Pulsed Power Laser Technology of China | Nie J.,State Key Laboratory of Pulsed Power Laser Technology of China | Ye Q.,State Key Laboratory of Pulsed Power Laser Technology of China | Bian J.,State Key Laboratory of Pulsed Power Laser Technology of China | And 2 more authors.
Optik | Year: 2016

Filamentation processes with different atmospheric pressure gradients are investigated numerically both in spatial and temporal regimes. The filamentation position and length are very sensitive to the pressure gradient. With the positive pressure gradient from low pressure to the standard pressure, the plasma density may still keep increasing with the intensity decreasing. The temporal profiles are also influenced by the pressure gradients dramatically. For supercontinuum (SC) emission, the red shift is dominated by the average atmospheric pressure while the blue shift is enhanced in the low pressure. Moreover, the positive pressure gradient is slightly good for the blue shift. © 2016 Elsevier GmbH

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