Ultrafast optical pulse polarization modulation based on the terahertz-induced Kerr effect in low-density polyethylene.

Abstract

Controlling the polarization state of an optical pulse within a short gating time facilitates ultrafast all-optical data processing and recording. Using the innovative all-optical modulation method such as the transient terahertz Kerr effect (TKE), the polarization state of the optical pulse can be switched within the gating time on the sub-picosecond scale. In this work, we use high-frequency single-cycle terahertz (THz) pulses to excite the Kerr effects of materials and explore the potential to shorten the gating time of the polarization modulator. A low-density polyethylene (LDPE) material with good Kerr-related properties is proposed to improve the performance of the TKE-based modulator and the obtained ultrafast gating time (FWHM) can reach 86 fs. Experimental evidence for the thickness dependence of the Kerr response demonstrates that the errors caused by optical transmission factors in the LDPE medium can be ignored, and thus the ultrafast gating modulation is mainly limited by the duration of probe pulse. Compared with common TKE-based materials, we believe that the low-cost LDPE is a good candidate to achieve high-power TKE-based ultrafast pulse switching.