Reconstruction of dynamic structures of experimental setups based on measurable experimental data only

Nowadays,massive amounts of data have been accumulated in various and wide fields,it has become today one of the central issues in interdisciplinary fields to analyze existing data and extract as much useful information as possible from data.It is often that the output data of systems are measurable while dynamic structures producing these data are hidden,and thus studies to reveal system structures by analyzing available data,i.e.,reconstructions of systems become one of the most important tasks of information extractions.In the past,most of the works in this respect were based on theoretical analyses and numerical verifications.Direct analyses of experimental data are very rare.In physical science,most of the analyses of experimental setups were based on the first principles of physics laws,i.e.,so-called top-down analyses.In this paper,we conducted an experiment of"Boer resonant instrument for forced vibration"(BRIFV)and inferred the dynamic structure of the experimental set purely from the analysis of the measurable experimental data,i.e.,by applying the bottom-up strategy.Dynamics of the experimental set is strongly nonlinear and chaotic,and it's subjects to inevitable noises.We proposed to use high-order correlation computations to treat nonlinear dynamics;use two-time correlations to treat noise effects.By applying these approaches,we have successfully reconstructed the structure of the experimental setup,and the dynamic system reconstructed with the measured data reproduces good experimental results in a wide range of parameters.

Preparation of Bi_(2)Te_(3) Based on Saturable Absorption System and Its Application in Fiber Lasers

Fiber laser is a fundamental component of laser systems and is of great significance for development of laser technology.Its pulse output can be divided into Q-switched and mode-locked.Achieving ultrashort pulse with narrower pulse duration and higher power is the focus of current research on mode-locked lasers.As an important component of fiber laser systems,saturable absorber(SA) can modulate losses in the optical cavity and generate pulses,enabling the laser system to achieve pulse output under long-term normal operating conditions better.Therefore,expanding the selection range of materials with better saturable absorption properties to improve the quality of pulse output is an important topic in current research.Here,the second generation topological insulator Bi_(2)Te_(3) single crystal is prepared,and a ring fiber laser system is built with the Bi_(2)Te_(3) SA.The mode-locked pulse with a pulse duration of 288 fs and a signal-to-noise ratio of 80.202 dB is realized.This result verifies that Bi_(2)Te_(3),as a member of topological insulator,has good saturable absorption characteristics,and has broad prospects for the application research in lasers.