The temporal resolutions of the ultrafast imaging technologies based on nonlinear optics

Abstract

We theoretically study some ultra-fast imaging technologies based on nonlinear optical switching effect sampling, and derive the expressions of switching functions based on nonlinear process sampling methods such as second harmonic (SH), optical Kerr effect and optical parametric amplification (OPA). For the first time, we propose a new concept, named equivalent exposure time (EET), which is used to describe accurately the actual gating time during ultrafast imaging. By using the ultra-fast rotating light fields as the targets, the simulations show that the EET of the ultrafast imaging based on SH is equivalent to the sampling laser pulse width, but the EET of the ultrafast imaging based on optical Kerr effect is 0.7 times of the sampling pulse width, while for the ultrafast imaging based on OPA, the EET depends on both the sampling pulse width and the gain. The higher the gain is, the shorter the EET, thus the higher the temporal resolution. The EET is reduced to half of the sampling pulse width when the OPA gain is 1 000. This research provides an effective way to improve the temporal resolution of the ultrafast imaging via the nonlinear optical switches.