Quantum temporal imaging by four-wave mixing

Cross-phase modulation aberrations in time lenses

We study the aberrations of four-wave mixing based time lenses resulting from the cross-phase modulations of the pump wave. These temporal aberrations have no spatial equivalent and are important when imaging weak signals with strong pump waves. We show that as the pump power increases, the cross-phase modulations of the pump are responsible for shifting, defocusing, and imposing temporal coma aberrations on the image. We present experimental results of these aberrations with high agreement to analytical and numerical calculations.

Improved depth resolution and depth-of-field in temporal integral imaging systems through non-uniform and curved time-lens array

Observing and studying the evolution of rare non-repetitive natural phenomena such as optical rogue waves or dynamic chemical processes in living cells is a crucial necessity for developing science and technologies relating to them. One indispensable technique for investigating these fast evolutions is temporal imaging systems. However, just as conventional spatial imaging systems are incapable of capturing depth information of a three-dimensional scene, typical temporal imaging systems also lack this ability to retrieve depth information-different dispersions in a complex pulse. Therefore, enabling temporal imaging systems to provide these information with great detail would add a new facet to the analysis of ultra-fast pulses. In this paper, after discussing how spatial three-dimensional integral imaging could be generalized to the time domain, two distinct methods have been proposed in order to compensate for its shortcomings such as relatively low depth resolution and limited depth-of-field. The first method utilizes a curved time-lens array instead of a flat one, which leads to an improved viewing zone and depth resolution, simultaneously. The second one which widens the depth-of-field is based on the non-uniformity of focal lengths of time-lenses in the time-lens array. It has been shown that compared with conventional setup for temporal integral imaging, depth resolution, i.e. dispersion resolvability, and depth-of-field, i.e. the range of resolvable dispersions, have been improved by a factor of 2.5 and 1.87, respectively.

Quantum temporal imaging with squeezed light

We consider a simple quantum temporal imaging system on the basis of a time lens implemented by a parametric nonlinear optical process with a chirped pump. We review the main results of the modal theory of temporal imaging, developed recently by us. We illustrate this theory by a concrete example of type-I non-collinear sum-frequency generation process, where the phase matching is limited by the temporal walk-off of the signal and the idler waves. We have shown that the temporal modal functions of such an imaging system are chirped Hermite-Gauss functions.