We investigate the dynamics of a semiconductor laser subject to coherent delayed filtered optical feedback. A systematic bifurcation analysis reveals that this system supports two fundamentally different types of oscillations, namely relaxation oscillations and external roundtrip oscillations. Both occur stably in large domains under variation of the feedback conditions, where the feedback phase is identified as a key quantity for controlling this dynamical complexity. We identify two separate parameter regions of stable roundtrip oscillations, which occur throughout in the form of pure frequency oscillations.
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http://dx.doi.org/10.1103/PhysRevE.73.055201 | DOI Listing |
A three-sectioned, bidirectionally coupled, tunable, optical comb source is presented. The photonic integrated circuit (PIC) consists of a gain section, a slotted mirror section and a Fabry-Perot (FP) section. Optical frequency combs (OFCs) are produced by gain switching the FP section via a high power radio frequency (RF) signal.
View Article and Find Full Text PDFJ Chem Phys
January 2025
Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
Two-dimensional (2D) vibrational spectroscopy is a powerful means of investigating the structure and dynamics of complex molecules in condensed phases. However, even in theory, analysis of 2D spectra resulting from complex inter- and intra-molecular motions using only molecular dynamics methods is not easy. This is because molecular motions comprise complex multiple modes and peaks broaden and overlap owing to various relaxation processes and inhomogeneous broadening.
View Article and Find Full Text PDFAnn Neurosci
January 2025
National Resource Centre for Value Education in Engineering, Indian Institute of Technology, Delhi, India.
Background: Neural activity and subjective experiences indicate that breath-awareness practices, which focus on mindful observation of breath, promote tranquil calm and thoughtless awareness.
Purpose: This study explores the impact of tristage Ānāpānasati-based breath meditation on electroencephalography (EEG) oscillations and self-reported mindfulness states in novice meditators following a period of effortful cognition.
Methods: Eighty-nine novice meditators (82 males; Mean Age = 24.
ACS Nano
January 2025
Beijing Academy of Quantum Information Sciences, Beijing 100193, P. R. China.
The quantum-well-like two-dimensional lead-halide perovskites exhibit strongly confined excitons due to the quantum confinement and reduced dielectric screening effect, which feature intriguing excitonic effects. The ionic nature of the perovskite crystal and the "softness" of the lattice induce the complex lattice dynamics. There are still open questions about how the soft lattices decorate the nature of excitons in these hybrid materials.
View Article and Find Full Text PDFThe extreme electromagnetic near-field environment of nanoplasmonic resonators and metamaterials can give rise to unprecedented electromagnetic heating effects, enabling large and manipulable temperature gradients on the order of 10-10 K/nm. In this Letter, by interfacing traditional semiconductor quantum dots with industry-grade plasmonic transducer technology, we demonstrate that the near-field-induced thermal gradient can facilitate the requisite population inversion for coherent phonon amplification and lasing at the nanoscale. Our detailed analysis uncovers both the characteristics and parameter sensitivity of inversion and relaxation oscillations in the system, thereby unveiling hitherto unexplored opportunities for leveraging plasmonic near-field effects in the context of quantum thermodynamics and phononics.
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