Attosecondattosecond science;extreme ultraviolet;high-order harmonic generation;Ramsey-type spectroscopy Optical and Ramsey-Type Interferometry by Postgeneration Splitting of Harmonic PulseTime domain Ramsey-type inte...Attosecondattosecond science;extreme ultraviolet;high-order harmonic generation;Ramsey-type spectroscopy Optical and Ramsey-Type Interferometry by Postgeneration Splitting of Harmonic PulseTime domain Ramsey-type interferometry is useful for investigating spectroscopic information of quantum states in atoms and molecules.The energy range of the quantum states to be observed with this scheme has now reached more than 20 eV by resolving the interference fringes with a period of a few hundred attoseconds.This attosecond Ramsey-type interferometry requires the irradiation of a coherent pair of extreme ultraviolet(XUV)light pulses,while all the methods used to deliver the coherent XUV pulse pair until now have relied on the division of the source of an XUV pulse in two before the generation.In this paper,we report on a novel technique to perform attosecond Ramsey-type interferometry by splitting an XUV high-order harmonic(HH)pulse of a sub-20 fs laser pulse after its generation.By virtue of the postgeneration splitting of the HH pulse,we demonstrated that the optical interference emerging at the complete temporal overlap of the HH pulse pair seamlessly continued to the Ramsey-type electronic interference in a helium atom.This technique is applicable for studying the femtosecond dephasing dynamics of electronic wavepackets and exploring the ultrafast evolution of a cationic system entangled with an ionized electron with sub-20 fs resolution.展开更多
The carrier-envelope phase(CEP)of an ultrashort laser pulse is becoming more crucial to specify the temporal characteristic of the pulse's electric field when the pulse duration becomes shorter and attains the sub...The carrier-envelope phase(CEP)of an ultrashort laser pulse is becoming more crucial to specify the temporal characteristic of the pulse's electric field when the pulse duration becomes shorter and attains the subcycle regime;here,the pulse duration of the intensity envelope is shorter than one cycle period of the carrier field oscillation.When this subcycle pulse involves a structured wavefront as is contained in an optical vortex(OV)pulse,the CEP has an impact on not only the temporal but also the spatial characteristics owing to the spatiotemporal coupling in the structured optical pulse.However,the direct observation of the spatial effect of the CEP control has not yet been demonstrated.In this study,we report on the measurement and control of the spatial wavefront of a subcycle OV pulse by adjusting the CEP.To generate subcycle OV pulses,an optical parametric amplifier delivering subcycle Gaussian pulses and a Sagnac interferometer as a mode converter were integrated and provided an adequate spectral adaptability.The pulse duration of the generated OV pulse was 4.7 fs at a carrier wavelength of 1.54μm.To confirm the wavefront control with the alteration of the CEP,we developed a novel f-2f interferometer that exhibited spiral fringes originating from the spatial interference between the subcycle OV pulse and the second harmonic of the subcycle Gaussian pulse producing a parabolic wavefront as a reference;this resulted in the successful observation of the rotation of spiral interference fringes during CEP manipulation.展开更多
基金supported by the Core Research for Evolutional Science and Technology(JPMJCR15N1)of JSTthe Center of Innovation Program(JPMJCE1313)of JST+2 种基金a Grant-in-Aid for Specially Promoted Research(JP15H05696)from MEXTGrants-in-Aid for Scientific Research(19H00869,19H05628,20H00371,26247068,20H05670)from MEXTthe Quantum Leap Flagship Program(JPMXS0118068681,JPMXS0118067246)of MEXT,Japan.
文摘Attosecondattosecond science;extreme ultraviolet;high-order harmonic generation;Ramsey-type spectroscopy Optical and Ramsey-Type Interferometry by Postgeneration Splitting of Harmonic PulseTime domain Ramsey-type interferometry is useful for investigating spectroscopic information of quantum states in atoms and molecules.The energy range of the quantum states to be observed with this scheme has now reached more than 20 eV by resolving the interference fringes with a period of a few hundred attoseconds.This attosecond Ramsey-type interferometry requires the irradiation of a coherent pair of extreme ultraviolet(XUV)light pulses,while all the methods used to deliver the coherent XUV pulse pair until now have relied on the division of the source of an XUV pulse in two before the generation.In this paper,we report on a novel technique to perform attosecond Ramsey-type interferometry by splitting an XUV high-order harmonic(HH)pulse of a sub-20 fs laser pulse after its generation.By virtue of the postgeneration splitting of the HH pulse,we demonstrated that the optical interference emerging at the complete temporal overlap of the HH pulse pair seamlessly continued to the Ramsey-type electronic interference in a helium atom.This technique is applicable for studying the femtosecond dephasing dynamics of electronic wavepackets and exploring the ultrafast evolution of a cationic system entangled with an ionized electron with sub-20 fs resolution.
基金This work was part of CREST study JPMJCR15N1 commissioned by JST and has contributed to the Quantum Leap Flagship Program(Q-LEAP)missions commissioned by MEXT of Japan.Y.-C.L.gratefully acknowledges the financial support from Grant-in-Aid for Early-Career Scientists No.20K15197Grant-in-Aid for Scientific Research No.22K04976 from JSPS,Japan.Y.N.K.M.gratefully acknowledge the financial support from Grants-in-Aid for Scientific Research Nos.26247068,26220606,and 19H05628 from MEXT,Japan.
文摘The carrier-envelope phase(CEP)of an ultrashort laser pulse is becoming more crucial to specify the temporal characteristic of the pulse's electric field when the pulse duration becomes shorter and attains the subcycle regime;here,the pulse duration of the intensity envelope is shorter than one cycle period of the carrier field oscillation.When this subcycle pulse involves a structured wavefront as is contained in an optical vortex(OV)pulse,the CEP has an impact on not only the temporal but also the spatial characteristics owing to the spatiotemporal coupling in the structured optical pulse.However,the direct observation of the spatial effect of the CEP control has not yet been demonstrated.In this study,we report on the measurement and control of the spatial wavefront of a subcycle OV pulse by adjusting the CEP.To generate subcycle OV pulses,an optical parametric amplifier delivering subcycle Gaussian pulses and a Sagnac interferometer as a mode converter were integrated and provided an adequate spectral adaptability.The pulse duration of the generated OV pulse was 4.7 fs at a carrier wavelength of 1.54μm.To confirm the wavefront control with the alteration of the CEP,we developed a novel f-2f interferometer that exhibited spiral fringes originating from the spatial interference between the subcycle OV pulse and the second harmonic of the subcycle Gaussian pulse producing a parabolic wavefront as a reference;this resulted in the successful observation of the rotation of spiral interference fringes during CEP manipulation.
