摘要
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.
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.20K15197
Grant-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.
