Enhanced terahertz wave generation via a Stokes cascade process has been demonstrated using picosecond pulse pumped terahertz parametric generation at 1 kHz repetition rate.Clear cascade saturation of terahertz output...Enhanced terahertz wave generation via a Stokes cascade process has been demonstrated using picosecond pulse pumped terahertz parametric generation at 1 kHz repetition rate.Clear cascade saturation of terahertz output was observed,and the corresponding cascade-Stokes spectra were analyzed.The maximum terahertz wave average power was 22μW under a pump power of 30 W,whereas the maximum power conversion efficiency was 8×10^(-7)under a pump power of 21 W.The THz power fluctuation was measured to be about 1%in 20 min.This THz parametric source with a relatively stable output is suitable for a variety of practical applications.展开更多
A general theory of optical parametric generation that accounts for pump depletion, loss, phase mismatch, group-velocity mismatch among the pump, signal and idler pulses, and intrapulse group-velocity dispersion is pr...A general theory of optical parametric generation that accounts for pump depletion, loss, phase mismatch, group-velocity mismatch among the pump, signal and idler pulses, and intrapulse group-velocity dispersion is proposed for coherent ultrashort pulses with arbitrary shapes and carrier chirps. The coupled differential equations are numerically solved using a symmetric split step beam-propagation method. The general solutions of these equations are obtained and the optical parametric generation process is theoretically investigated. Results show that the major factors, which remarkably affect the optical parametric conversion efficiency and durations of the pulses in phase-matched structure, are the group velocity mismatch and the intrapulse group velocity dispersion.展开更多
Acoustic frequency combs(AFCs)contain equidistant coherent signals with unconventional possibilities on metrology.Previously,implementation of AFCs on mechanical microresonators with large air damping loss is difficul...Acoustic frequency combs(AFCs)contain equidistant coherent signals with unconventional possibilities on metrology.Previously,implementation of AFCs on mechanical microresonators with large air damping loss is difficult,which restricted their atmospheric applications.In this work,we explore the potentials of a composite diamond/silicon microcantilever for parametric generation of AFCs in ambient air.We discover that the diamond layer provides a viable route to reduce the linewidth of the primary flexural mode,yielding a 7.1-times increase of the quality factor.We develop a parametric driving scheme that enables generation of AFCs through injection locking and sequential nonlinear dynamic transitions involving subharmonic synchronization(Arnold tongue),and chaotic dynamics.Ultimately,we realize AFCs with a frequency range extending 800 kHz in the air.This work advances the understanding of AFCs and provides a viable route towards their applications in ambient air for high precision metrology.展开更多
A theoretical model is presented to describe the parametric acoustic field generated by a piston radiator. In the model, the high-frequency primary wave interaction region that is truncated by a low-pass acoustic filt...A theoretical model is presented to describe the parametric acoustic field generated by a piston radiator. In the model, the high-frequency primary wave interaction region that is truncated by a low-pass acoustic filter can be viewed as a cylindrical source within the Rayleigh distance of the piston. When the radius of the piston is much smaller than the length of the parametric region, this model is reduced to the Berketey's End-Fire Line Army model. Comparison between numerical calculations and experimental measurement show that the generated parametric sound field (especially near the axis) agrees well with the experiment results.展开更多
基金funded by the National Natural Science Foundation of China (Grant Nos.U22A20353,U22A20123,62175182,and 62275193)Daheng Atlas (Beijing)Laser Technology Co.Ltd.for their support。
文摘Enhanced terahertz wave generation via a Stokes cascade process has been demonstrated using picosecond pulse pumped terahertz parametric generation at 1 kHz repetition rate.Clear cascade saturation of terahertz output was observed,and the corresponding cascade-Stokes spectra were analyzed.The maximum terahertz wave average power was 22μW under a pump power of 30 W,whereas the maximum power conversion efficiency was 8×10^(-7)under a pump power of 21 W.The THz power fluctuation was measured to be about 1%in 20 min.This THz parametric source with a relatively stable output is suitable for a variety of practical applications.
文摘A general theory of optical parametric generation that accounts for pump depletion, loss, phase mismatch, group-velocity mismatch among the pump, signal and idler pulses, and intrapulse group-velocity dispersion is proposed for coherent ultrashort pulses with arbitrary shapes and carrier chirps. The coupled differential equations are numerically solved using a symmetric split step beam-propagation method. The general solutions of these equations are obtained and the optical parametric generation process is theoretically investigated. Results show that the major factors, which remarkably affect the optical parametric conversion efficiency and durations of the pulses in phase-matched structure, are the group velocity mismatch and the intrapulse group velocity dispersion.
基金the National Science Foundation of China(NSFC)(Grant No.52172296,51472143)the National Key R&D Program of China(NKRD)(2017YFB0405403)the Initiative in Quantum Science of Shandong Provincial Natural Science Foundation(ZR2020LLZ005)for financial support.
文摘Acoustic frequency combs(AFCs)contain equidistant coherent signals with unconventional possibilities on metrology.Previously,implementation of AFCs on mechanical microresonators with large air damping loss is difficult,which restricted their atmospheric applications.In this work,we explore the potentials of a composite diamond/silicon microcantilever for parametric generation of AFCs in ambient air.We discover that the diamond layer provides a viable route to reduce the linewidth of the primary flexural mode,yielding a 7.1-times increase of the quality factor.We develop a parametric driving scheme that enables generation of AFCs through injection locking and sequential nonlinear dynamic transitions involving subharmonic synchronization(Arnold tongue),and chaotic dynamics.Ultimately,we realize AFCs with a frequency range extending 800 kHz in the air.This work advances the understanding of AFCs and provides a viable route towards their applications in ambient air for high precision metrology.
文摘A theoretical model is presented to describe the parametric acoustic field generated by a piston radiator. In the model, the high-frequency primary wave interaction region that is truncated by a low-pass acoustic filter can be viewed as a cylindrical source within the Rayleigh distance of the piston. When the radius of the piston is much smaller than the length of the parametric region, this model is reduced to the Berketey's End-Fire Line Army model. Comparison between numerical calculations and experimental measurement show that the generated parametric sound field (especially near the axis) agrees well with the experiment results.
