title: Surface Optical Rectification from Layered MoS2Crystal by THz Time-Domain Surface Emission Spectroscopy.
abstract: Surface optical rectification was observed from the layered semiconductor molybdenum disulfide (MoS2) crystal via terahertz (THz) time-domain surface emission spectroscopy under linearly polarized femtosecond laser excitation. The radiated THz amplitude of MoS2has a linear dependence on ever-increasing pump fluence and thus quadratic with the pump electric field, which discriminates from the surface Dember field induced THz radiation in InAs and the transient photocurrent-induced THz generation in graphite. Theoretical analysis based on space symmetry of MoS2crystal suggests that the underlying mechanism of THz radiation is surface optical rectification under the reflection configuration. This is consistent with the experimental results according to the radiated THz amplitude dependences on azimuthal and incident polarization angles. We also demonstrated the damage threshold of MoS2due to microscopic bond breaking under the femtosecond laser irradiation, which can be monitored via THz time-domain emission spectroscopy and Raman spectroscopy.
authors.affiliation: Shaanxi Joint Lab of Graphene, State Key Lab Incubation Base of Photoelectric Technology and Functional Materials, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics and Photon-Technology, Northwest University , Xi'an 710069, China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Shaanxi Joint Lab of Graphene, State Key Lab Incubation Base of Photoelectric Technology and Functional Materials, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics and Photon-Technology, Northwest University , Xi'an 710069, China.
authors.forename: Lipeng
authors.initials: L
authors.lastname: Zhu
authors.affiliation: Shaanxi Joint Lab of Graphene, State Key Lab Incubation Base of Photoelectric Technology and Functional Materials, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics and Photon-Technology, Northwest University , Xi'an 710069, China.
authors.forename: Qiyi
authors.initials: Q
authors.lastname: Zhao
authors.affiliation: Shaanxi Joint Lab of Graphene, State Key Lab Incubation Base of Photoelectric Technology and Functional Materials, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics and Photon-Technology, Northwest University , Xi'an 710069, China.
authors.forename: Yaohui
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Shaanxi Joint Lab of Graphene, State Key Lab Incubation Base of Photoelectric Technology and Functional Materials, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics and Photon-Technology, Northwest University , Xi'an 710069, China.
authors.forename: Zhaoyu
authors.initials: Z
authors.lastname: Ren
authors.affiliation: Shaanxi Joint Lab of Graphene, State Key Lab Incubation Base of Photoelectric Technology and Functional Materials, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics and Photon-Technology, Northwest University , Xi'an 710069, China.
authors.forename: Jintao
authors.initials: J
authors.lastname: Bai
authors.affiliation: Shaanxi Joint Lab of Graphene, State Key Lab Incubation Base of Photoelectric Technology and Functional Materials, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics and Photon-Technology, Northwest University , Xi'an 710069, China.
authors.forename: Xinlong
authors.initials: X
authors.lastname: Xu
keywords: femtosecond laser; molybdenum disulfide (MoS2); optical rectification; second-order susceptibility; terahertz (THz) time-domain surface emission spectroscopy