Ultrashort energetic terahertz(THz)pulses have created an exciting new area of research on light interactions with matter.For material studies in small laboratories,widely tunable femtosecond THz pulses with peak fiel...Ultrashort energetic terahertz(THz)pulses have created an exciting new area of research on light interactions with matter.For material studies in small laboratories,widely tunable femtosecond THz pulses with peak field strength close to MV cm-1 are desired.Currently,they can be largely acquired by optical rectification and difference frequency generation in crystals without inversion symmetry.We describe in this paper a novel scheme of THz pulse generation with no frequency tuning gap based on Raman-resonance-enhanced four-wave mixing in centrosymmetric media,particularly diamond.We show that we could generate highly stable,few-cycle pulses with near-Gaussian spatial and temporal profiles and carrier frequency tunable from 5 to>2o THz.They had a stable and controllable carrier-envelop phase and carried~15 nJ energy per pulse at 10 THz(with a peak field strength of~1 MV cm^(-1)at focus)from a O.5-mm-thick diamond.The measured THz pulse characteristics agreed well with theoretical predictions.Other merits of the scheme are discussed,including the possibility of improving the THz output energy to a much higher level.展开更多
基金This work was supported by the National Natural Science Foundation of China Grants(No.12125403 and No.11874123)the National Key Research and Development Program of China(No.2021YFA1400503 and No.2021YFA1400202).
文摘Ultrashort energetic terahertz(THz)pulses have created an exciting new area of research on light interactions with matter.For material studies in small laboratories,widely tunable femtosecond THz pulses with peak field strength close to MV cm-1 are desired.Currently,they can be largely acquired by optical rectification and difference frequency generation in crystals without inversion symmetry.We describe in this paper a novel scheme of THz pulse generation with no frequency tuning gap based on Raman-resonance-enhanced four-wave mixing in centrosymmetric media,particularly diamond.We show that we could generate highly stable,few-cycle pulses with near-Gaussian spatial and temporal profiles and carrier frequency tunable from 5 to>2o THz.They had a stable and controllable carrier-envelop phase and carried~15 nJ energy per pulse at 10 THz(with a peak field strength of~1 MV cm^(-1)at focus)from a O.5-mm-thick diamond.The measured THz pulse characteristics agreed well with theoretical predictions.Other merits of the scheme are discussed,including the possibility of improving the THz output energy to a much higher level.
