Classical imaging with undetected photons using four-wave mixing in silicon core fibers

Abstract

Undetected-photon imaging allows for objects to be imaged in wavelength regions where traditional components are unavailable. Although first demonstrated using quantum sources, recent work has shown that the technique also holds with classical beams. To date, however, all the research in this area has exploited parametric down-conversion processes using bulk nonlinear crystals within free-space systems. Here, we demonstrate undetected-photon-based imaging using light generated via stimulated four-wave mixing within highly nonlinear silicon fiber waveguides. The silicon fibers have been tapered to have a core diameter of ∼ 915 nm to engineer the dispersion and reduce the insertion losses, allowing for tight mode confinement over extended lengths to achieve practical nonlinear conversion efficiencies ( ∼ − 30 dB ) with modest pump powers ( ∼ 48 mW ). Both amplitude and phase images are obtained using classically generated light, confirming the high degree of spatial and phase correlation of our system. The high powers ( > 10 nW ) and long coherence lengths ( > 4 km ) associated with our large fiber-based system result in high contrast and stable images.

Fifteen years of nonlinear semiconductor optical fibers: a review of past, present, and future

“…This includes several demonstrations based on four-wave mixing (FWM) such as parametric amplification (see Fig. 1(a) [44]), wavelength conversion of high-speed data signals [45,46], and undetected photon imaging [47]. More recently, by extending the fiber lengths, we have also observed Raman amplification using a low power CW pump (see Fig.…”

Nonlinear Interferometry: A New Approach for Imaging and Sensing

“…In this section, we focus on the quantum domain (low-gain regime), but it is worth mentioning that imaging with undetected light also has been implemented classically. [60,61]…”

“…Another approach to boost the signal and sensitivity of imaging with undetected light by seeding the input of the first crystal. [155] Since the seed is inducing emission through a coherent classical state, this technique is sometimes also referred to as "classical imaging with undetected light" and imaging experiments have been performed, [60,61] also in a ZWM-type of setup. [156] Similar to the unseeded case, gain unbalancing can be used for loss compensation and phase uncertainty below some Heisenberg-type scaling for the SU(1,1) geometry has been demonstrated.…”