A novel scheme for ultrashort terahertz pulse generation over a gapless wide spectral range: Raman-resonance-enhanced four-wave mixing

Jiaming Le; Yudan Su; Chuanshan Tian; A H Kung; Y Ron Shen

doi:10.1038/s41377-023-01071-z

A novel scheme for ultrashort terahertz pulse generation over a gapless wide spectral range: Raman-resonance-enhanced four-wave mixing

Light Sci Appl. 2023 Feb 2;12(1):34. doi: 10.1038/s41377-023-01071-z.

Authors

Jiaming Le^#¹, Yudan Su^#², Chuanshan Tian^{3

4}, A H Kung¹, Y Ron Shen^{5

6}

Affiliations

¹ Department of Physics, State Key Laboratory of Surface Physics and Key Laboratory of Micro- and Nano-Photonic Structure (MOE), Fudan University, Shanghai, 200433, China.
² Department of Physics, University of California, Berkeley, CA, 94720, USA.
³ Department of Physics, State Key Laboratory of Surface Physics and Key Laboratory of Micro- and Nano-Photonic Structure (MOE), Fudan University, Shanghai, 200433, China. cstian@fudan.edu.cn.
⁴ Collaborative Innovation Center of Advanced Microstructures, Nanjing, 210093, China. cstian@fudan.edu.cn.
⁵ Department of Physics, State Key Laboratory of Surface Physics and Key Laboratory of Micro- and Nano-Photonic Structure (MOE), Fudan University, Shanghai, 200433, China. yrshen@berkeley.edu.
⁶ Department of Physics, University of California, Berkeley, CA, 94720, USA. yrshen@berkeley.edu.

^# Contributed equally.

Abstract

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 >20 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 0.5-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.

Abstract

Grants and funding