Four-wave Mixing In Single-mode Fiber Research Articles

Tomographic reconstruction of time-bin-entangled qudits

We describe an experimental implementation to generate and measure high-dimensional time-bin-entangled qudits. Two-photon time-bin entanglement is generated via spontaneous four-wave mixing in single-mode fiber. Unbalanced Mach-Zehnder interferometers transform selected time bins to polarization entanglement, allowing standard polarization-projective measurements to be used for complete quantum state tomographic reconstruction. Here we generate maximally entangled qubits $(d=2)$, qutrits $(d=3)$, and ququarts $(d=4)$, as well as other phase-modulated nonmaximally entangled qubits and qutrits. We reconstruct and verify all generated states using maximum-likelihood estimation tomography.

Experimental Investigation of Inter-Modal Four-Wave Mixing in Few-Mode Fibers

We experimentally demonstrate nondegenerate four-wave mixing (FWM) between waves belonging to different spatial modes of a 5-km-long few-mode fiber (FMF). Of the three inter-modal FWM (IM-FWM) processes possible, two have been experimentally observed. These IM-FWM processes are found to be phase-matched over very large frequency separations of several Terahertz between the waves. In contrast to FWM in single-mode fibers that require operating near the zero-dispersion wavelength to achieve phase matching, IM-FWM in a FMF can be fully phase matched in the presence of large chromatic dispersion in each spatial mode.

Tailored photon pair preparation relying on full group velocity matching in fiber-based spontaneous four-wave mixing

We study photon pair generation through scalar spontaneous four-wave mixing in single-mode fiber and for frequency-degenerate pumps; we concentrate on source geometries which fulfil full group velocity matching (GVM), i.e. where the pump, signal and idler propagate at identical group velocities. We discuss two experimental techniques which permit the attainment of full GVM, and discuss the resulting two-photon state properties. In particular, we show that full GVM can lead to sources which approach phase-matching unconstrained by dispersion and therefore with a remarkably large bandwidth. We also discuss the generation of nearly-factorable states as an application of full GVM.

Comparison of interchannel pulses four-wave mixing in SMF, NZDSF and HNLF

We systematically analyze the interchannel ultrashort pulses four-wave mixing (FWM) in dense wavelength division multiplexing (DWDM) systems with single-mode fiber (SMF), nonzero dispersion-shifted fiber (NZDSF), and highly nonlinear fiber (HNLF). We investigate the FWM conversion efficiency as functions of channel spacing, fiber length, and signal power. We show that the FWM in DWDM system with HNLF is almost 40 times larger than with NZDSF and 400 times larger than with SMF. We obtain the minima of WDM channel spacings limited by FWM for SMF, NZDSF, and HNLF. The FWM conversion efficiency approaches to a constant as the propagation length increases and is approximately an exponential function of the peak power of incident signals.

Energy coupling by partially degenerate four-wave mixing in multichannel lightwave systems

We investigate the energy coupling among different frequency carriers by partially degenerate four-wave mixing in single-mode fibers. We show that for a multichannel lightwave system operated near the zero-dispersion frequency of the single-mode fiber, four-wave mixing may cause significant signal depletion in a channel whose power acts as a pump in the four-wave mixing process. Analytical solutions are derived and the signal depletion due to four-wave mixing is obtained.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Phase conjugation by four-wave mixing in single-mode fibers

We present an exact solution to the coupled-mode equations, governing four-wave mixing in single-mode fibers, under the perfect phase-matching condition. The solution accounts for pump depletion and fiber absorption. Optimum length of fiber is derived and phase conjugation efficiency is calculated and discussed. The calculated results are in good agreement with the reported experimental results.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>