We study theoretically the propagation of a step-modulated optical field as it passes through a dispersive dielectric made up of a dilute collection of oscillators characterized by a single narrow-band resonance. The propagated field is given in terms of an integral of a Fourier type, which cannot be evaluated even for simple models of the dispersive dielectric. The fact that the oscillators have a low number density (dilute medium) and have a narrow-band resonance allows us to simplify the integrand. In this case, the integral can be evaluated exactly, although it is not possible using this method to separate out the transient part of the propagated field known as optical precursors. We also use an asymptotic method (saddle-point method) to evaluate the integral. The contributions to the integral related to the saddle-points of the integrand give rise to the optical precursors. We obtain analytic expressions for the precursor fields and the domain over which the asymptotic method is valid. When combined to obtain the total transient field, we find that the agreement between the solutions obtained by the asymptotic and the exact methods is excellent. Our results demonstrate that precursors can persist for many nanoseconds and the chirp in the instantaneous frequency of the precursors can manifest itself in beats in the transmitted intensity. Our work strongly suggests that precursors have been observed in many previous experiments.
Pulse generation with ultra-superluminal pulse propagation in semiconductor heterostructures by superradiant phase transition enhanced by transient coherent population gratings
Optical Neural Networks from Coherent Transient Dynamics in Waveguide QED
School of Physics, Sun Yat-sen University（中山大学物理学院）；Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education, Hunan Normal University（湖南师范大学低维量子结构与量子控制教育部重点实验室）；Center for Quantum Computing, RIKEN（理化学研究所量子计算中心）；Department of Physics, University of Michigan（密歇根大学物理系）；State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University（中山大学光电材料与技术国家重点实验室）
Laser-induced transient opacity in helium nanodroplets probed by single-shot coherent diffraction
ETH Zurich（苏黎世联邦理工学院）；University of Rostock（罗斯托克大学）；Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy（马克斯·玻恩非线性光学和超快光谱研究所）；Technical University of Berlin（柏林工业大学）
