27,279 research outputs found
Mechanism of high-energy pulse generation without wave breaking in mode-locked fiber lasers
No full textThe mechanism and intrinsic conditions of high-energy wave-breaking-free pulse generation in fiber lasers mode-locked by a nonlinear polarization rotation technique are investigated numerically and experimentally. Both numerical and experimental results show that the pulses along the two orthogonal polarization axes of the fiber have a large difference in pulse energy. The numerical simulations show that the ratio of the energy of two components is limited and ranges from about 8 to about 65. The slope of the instantaneous frequency at the central position of the pulse decreases rapidly with the increase of the pulse duration and energy, whereas the slope at the pulse edge changes slightly. The accumulation of instantaneous frequency throughout the pulse width approaches a constant in a higher pulse energy regime. Understanding the mechanism and intrinsic conditions of the wave-breaking-free pulse generation could be useful in generating high-energy pulses delivered from fiber lasers
Liu Kang
No full textLiu Kang: Essays on Art and Culture is a testament to the inexorable passion of an artist who knew no boundaries. This collection of essays, which Liu Kang wrote over 44 years, offers an insight into the artist’s myriad interests as well as his contributions as a first generation Nanyang artist and art educator. Translated into English for this volume, Liu Kang’s essays are accompanied by commentaries and photographs of the artist-author and his subjects
Pulse evolution without wave breaking in a strongly dissipative-dispersive laser system
No full textWe report on pulse evolution without wave breaking in a strongly dissipative-dispersive laser system where pulses encounter significant amounts of positive and negative dispersions. In contrast to conventional soliton, dispersion-managed soliton, and self-similar pulse evolutions, a different type of pulse shaping in mode-locked lasers is theoretically investigated and experimentally observed. The pulses of this laser have very low frequency chirp and exhibit as the quasirectangle temporal and Gaussian spectral profiles, and the spectral width is almost independent of the pumping strength. The temporal and spectral widths fluctuate as low as similar to 3% of the relative fluctuation throughout the laser cavity. Both numerical and experimental results show that the pulses exist with energies much greater than can be tolerated in self-similar pulse shaping
Beam dynamics in disordered PT-symmetric optical lattices based on eigenstate analyses
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Wave functions will experience a localization process when evolving in disordered lattices. Here, we have demonstrated the effects of disordered PT-symmetric potentials on wave- function characteristics in optics based on eigenstate analyses. In weak- disorder cases, by using the tight-binding approximation method, a conclusion is obtained that the increasing of the imaginary part of potential can enhance the diffraction, while the increasing disorder will block the diffraction and lead to localization. In the general case, band theory is used for band-structure analysis of three bands. We find that the disorder has a smaller effect on the higher- order band, which is proved by the beam evolutions. Our work may be instructive for realizing beam path control by manipulating the strengths of disorder and gain and/ or loss of lattice.</p
Tunable multiple phase-coupled plasmon-induced transparencies in graphene metamaterials
No full textWe demonstrate the existence of multiple electromagnetically induced transparencies (EIT)-like spectral responses in graphene metamaterials consisting of a series of self-assembled graphene Fabry-Perot (FP) cavities. By exploiting the graphene plasmon resonances and phase-coupling effects, the transfer matrix model is established to theoretically predict the EIT-like responses, and the calculated results coincide well with numerical simulations. It is found that high-contrast (similar to 90%) multiple EIT-like windows are observed over a broad range of mid-infrared. Additionally, these optical responses can be efficiently tuned by altering the Fermi level in graphene and the separations of FP cavities. The proposed scheme paves the way toward control of the multiple EIT-like responses, enabling exploration of the on-chip multifunctional electro-optic devices including multi-channel-selective filters, sensors, and modulators. (C) 2014 Optical Society of Americ
MoS2-clad microfibre laser delivering conventional, dispersion-managed and dissipative solitons
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Molybdenum disulfide (MoS2), whose monolayer possesses a direct band gap, displays promising applications in optoelectronics, photonics, and lasers. Recent researches have demonstrated that MoS2 has not only a significant broadband saturable absorption performance, but also a higher optical nonlinear response than graphene. However, MoS2 shows much lower optical damage threshold owing to the poorer thermal conductivity and mechanical property. Here, we exploit a MoS2-clad microfibre (MCM) as the saturable absorber (SA) for the generation of ultrashort pulses under different dispersion conditions. The improved evanescent field interaction scheme can overcome the laser-induced thermal damage, as well as take full advantage of the strong nonlinear effect of MoS2. With the MCM SA, conventional, dispersion-managed, and dissipative solitons are generated around 1600 nm in Er-doped fibre lasers with anomalous, near-zero, and normal cavity dispersions, respectively. Our work paves the way for applications of 2D layered materials in photonics, especially in laser sources.</p
Phoebus 10: A Journal of Art History
No full texttableOfContents: Homage to the Past: The Art of Yin Xiaofeng by Ralph Gabbard and Liu Liu.. pages 5-1
Nonlinear Saturable and Polarization-induced Absorption of Rhenium Disulfide
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Monolayer of transition metal dichalcogenides (TMDs), with lamellar structure as that of graphene, has attracted significant attentions in optoelectronics and photonics. Here, we focus on the optical absorption response of a new member TMDs, rhenium disulphide (ReS2) whose monolayer and bulk forms have the nearly identical band structures. The nonlinear saturable and polarization-induced absorption of ReS2 are investigated at near-infrared communication band beyond its bandgap. It is found that the ReS2-covered D-shaped fiber (RDF) displays the remarkable polarization-induced absorption, which indicates the different responses for transverse electric (TE) and transverse magnetic (TM) polarizations relative to ReS2 plane. Nonlinear saturable absorption of RDF exhibits the similar saturable fluence of several tens of mu J/cm(2) and modulation depth of about 1% for ultrafast pulses with two orthogonal polarizations. RDF is utilized as a saturable absorber to achieve self-started mode-locking operation in an Er-doped fiber laser. The results broaden the operation wavelength of ReS2 from visible light to around 1550 nm, and numerous applications may benefit from the anisotropic and nonlinear absorption characteristics of ReS2, such as in-line optical polarizers, high-power pulsed lasers, and optical communication system.</p
Cultural exploitation in chinese politics: Reinterpreting liu sanjie
No full textLiu Sanjie is a typical Chinese legendary figure, adapted from folk custom and transformed during many historical and political stages. By comparing the musical film Liu Sanjie with the landscape performing art Impression Liu Sanjie, this paper explores how Liu Sanjie is reconstructed in the Impression to be in accord with contemporary demands (shidaixing). In the film, made during the 1960s, Liu Sanjie was promoted as a heroine fighting against the privileged classes, but in the Impression, her class struggle has been erased and only a harmonious and abstract legend remains. Her ethnicity is promoted by Han elites as not exclusive Zhuang, but shared equally with Han, Miao and Dong ethnicity in an imagined community to propagate a sense of ethnic harmony and unified Chineseness. Her transformation from a realistic character, full of a rebelling spirit, to an abstract and disembodied ‘sense of harmony’, is a complete reinterpretation of a Chinese historical legend. Utilizing a term from Wang Ban (1997), ‘the sublime figure of history’, which refers to an ideology aestheticized by the party state for securing its governance, this paper refers to the bold artistic treatment of Liu Sanjie for cultural exploitation as ‘Liu Sanjie’s sublime’. The paper explores the evolutionary progress of Liu Sanjie from class revolution to art revolution in response to political requirements. The author is a stage-trained performing artist, specialized in both Western opera and Chinese classical and folk singing and dance. He is also a critic and art consultant in the Chinese landscape performing arts industry. These professional roles have allowed privileged access to the top people in this industry
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