Self-polarization emission based on coherent combination of intracavity eigenmodes in Nd:YAG/Cr^(4+):YAG lasers

The behavior of self-polarization emission in Nd∶Y_(3)Al_(5)O_(12)(YAG)=Cr^(4+)∶YAG lasers has been proved in some cases.However,the degree and direction of polarization were often sensitive and unstable.We experimentally observed different beam profiles versus the angle of the polarizer relative to the polarization direction of the laser.In order to explore the polarization mechanism,the dynamics of intracavity polarized eigenmodes was analyzed theoretically.Simulative results were well consistent with our experimental observations.It indicated that the linear self-polarization emission was a composite state rather than an intrinsic state.This study contributed to the improvement of the polarization stability in Nd∶YAG=Cr^(4+)∶YAG passively Q-switched lasers.

Stable self-polarization in lead-free Bi(Fe_(0.93)Mn_(0.05)Ti_(0.02))O_(3)thick films

The BiFeO3-based film is one of the most promising candidates for lead-free piezoelectric film devices.In this work,the 1μm-thick Bi(Fe_(0.93)Mn_(0.05)Ti_(0.02))O_(3)(BFMT)films are grown on the ITO/glass substrate using a sol-gel method combined with spin-coating and layer-by-layer annealing technique.These films display a large saturated polarization of 95μC/cm^(2),and a rema­nent polarization of 70μC/cm^(2).Especially,the films are self-poled caused by an internal bias field,giving rise to asymmetric polarization-electric field(P-E)loops with a positive shift along the x-axis.A stable self-polarization state is maintained during the applied electric field increasing to 1500 kV/cm and then decreasing back.The weak dependence of P-E loops on frequency(1-50 kHz)and temperature(25-125°C)indicate that the internal bias field can be stable within a certain frequency and tempera­ture range.These results demonstrate that the self-polarized BFMT thick films can be integrated into devices without any poling process,with promising applications in micro-electro-mechanical systems.

A Robust Numerical Method for Generalized Coulomb and Self-Polarization Potentials of Dielectric Spheroids

By utilizing a novel quasi-harmonic three-layer dielectric model for the interface between a dielectric spheroid and the surrounding dissimilar dielectric medium,a robust numerical method for calculating the generalized Coulomb and self-polarization potentials of the dielectric spheroid is presented in this paper.The proposed numerical method can not only overcome the inherent mathematical divergence in the self-polarization energy which arises for the simplest step-like model of the dielectric interface,but also completely eliminate the potential numerical divergence which may occur in other treatments.Numerical experiments have demonstrated the convergence of the proposed numerical method as the number of the steps used to discretize the translation layer in a general three-layer dielectric model goes to infinity.

Textured CsPbI_(3) nanorods composite fibers for stable high output piezoelectric energy harvester

The utilization of piezoelectric nanogenerator(PENG)based on halide perovskite materials has demonstrated significant promise for energy harvesting applications.However,the challenge of synthesizing halide perovskite materials with both high output performance and stability using a straightforward process persists as a substantial obstacle.Herein,we present the fabrication of CsPbI_(3) nanorods(NRs)exhibiting highly uniform orientation within polyvinylidene fluoride(PVDF)fibers through a simple texture engineering approach,marking the instance of enhancing PENG performance in this manner.The resultant composite fibers showcase a short-circuit current density(I_(sc))of 0.78μAcm^(-2) and an open-circuit voltage(V_(oc)) of 81V,representing a 2.5 fold increase compared to the previously reported highest value achieved without the electric poling process.This outstanding output performance is ascribed to the orientation of CsPbI_(3) NRs facilitated by texture engineering and dipole poling via the self-polarization effect.Additionally,the PENG exhibits exceptional thermal and water stability,rendering it suitable for deployment in diverse and challenging environmental conditions.Our findings underscore the significant potential of textured CsPbI_(3) NRs composite fibers for powering low-power consumer electronics,including commercial LEDs and electronic watches.

Large piezoelectric property of Bi(Fe_(0.93)Mn_(0.05)Ti_(0.02))O_(3) film by constructing internal bias electric field

BiFeO_(3)(BFO),Mn-doped-BFO(BFMO),Ti-doped-BFO(BFTO),and(Mn,Ti)-codoped-BFO(BFMTO)thin films are fabricated on the Pt/TiO_(2)/SiO_(2)/Si substrates via a sol–gel method combined with spin-coating and the subsequent layer-by-layer annealing technique.Compared with BFO film,the BFMTO film exhibits the lowest leakage current density(-10^(-4) A/cm^(2)@290 kV/cm).Notably,the polarization–electric field(P–E)loop of BFMTO film exhibits a positive displacement along the x-axis due to the existence of internal bias electric field,which is in agreement with the results of the PFM phase and amplitude curves.Especially,a very prominent inverse piezoelectric constant of d_(33)-160 pm/V was obtained,which overcomes other related thin films.The internal bias electric field of BFMTO film can be caused by the different work functions of the thin film and the bottom electrode,accumulation of oxygen vacancies and the formation of defect dipoles.Besides,the internal bias electric field of BFMTO film has a good stability at the same electric field after experiencing the test cycle from low electric field to high electric field(400–1900 kV/cm).These results indicate that self-polarized BFMTO film can be integrated to devices without additional polarization process,and have a wide range of application in microelectromechanical systems.