Eur. Phys. J. D (2022) 76: 88
https://doi.org/10.1140/epjd/s10053-022-00411-9

Regular Article – Optical Phenomena and Photonics

Potassium upconversion violet light generation under two-color two-photon excitation to 4D, 6S level

¹ North China Research Institute of Electro-Optics, 100846, Beijing, China
² Institute of North Electronic Equipment, 100191, Beijing, China
³ Key Laboratory of Chemical Lasers, Dalian Institute of Chemical Physics, Chinese Academy of Science, 116023, Dalian, China

^g hushu@dicp.ac.cn

Received: 12 January 2022
Accepted: 2 May 2022
Published online: 17 May 2022

Abstract

Two-color nanosecond dye lasers were used to excite potassium vapor cell, and 404-nm violet beam output was observed. This violet beam owns good collimation and transient properties, and its wavelength matches with the transition from potassium 5²P_3/2,1/2 doublet to the ground state. An analysis process shows that the violet light mechanism is attributed to two-photon-induced 4²S_1/2 → 4²P_3/2 → 4²D_3/2,5/2/6²S_1/2 transition, 4²D_3/2,5/2/6²S_1/2 → 5²P_3/2,1/2 SHRS (stimulated hyper-Raman scattering), and FWM (four-wave-mixing) processes; this is a third-order nonlinear optics process. Violet light doublet-line intensity ratio was found to change while fine scanning of excitation wavelength; this shifting was thought related to the FWM resonant degree. Potassium violet light is expected to become new tunable light source.