Black phosphorus has been the subject of growing interest due to its unique band structure that is both layer dependent and anisotropic. While many have studied the linear optical response of black phosphorus, the nonlinear response has remained relatively unexplored. Here we report on the observation of third-harmonic generation in black phosphorus using an ultrafast near-IR laser and measure χ(3) experimentally for the first time. It was found that the third-harmonic emission is highly anisotropic, dependent on the incident polarization, and varies strongly with the number of layers present due to signal depletion and phase-matching conditions.
Bibliographical noteFunding Information:
This work was supported by the Air Force Office of Scientific Research (Award No. FA9550-14-1-0277) and the National Science Foundation (Award No. ECCS-1351002). Device fabrication was carried out at the University of Minnesota Nanofabrication Center, which receives partial support from the NSF through the National Nanotechnology Coordinated Infrastructure (NNCI) program. The authors also used resources at the Characterization Facility, which is a member of the NSF-funded Materials Research Facilities Network via the NSF MRSEC program.
- Black phosphorus
- Nonlinear optics
- Third-harmonic generation
- Two-dimensional materials