Applied Optics

Progress toward photon-pair efficiency optimization using four-wave mixing in few-mode fibers

Seyedehnajmeh Montazeri, Mina Esmaeelpour

Published Apr 7, 2025• 1 citation

Abstract

Intermodal four-wave mixing (FWM) process in few-mode fibers (FMFs) could be utilized for entangled photon-pair generation. Previous studies mainly performed in single-mode fibers suffered from the significant Raman scattering background from the glass fiber. Therefore, the instantaneous Raman and FWM effects would compete; this could be avoided in FMFs if the modal dispersion is larger than the Raman gain spectra. Utilizing two pumps in different modes in FMFs will generate photon pairs in various modes. Here, we study the effect of pump spectral separation on the intermodal FWM power and bandwidth using a seeding technique. It is concluded that the further the pumps and intermodal FWM idler and signal are from each other spectrally, the smaller the photon efficiency and larger the bandwidth. Experimental results for two FMFs of different differential mode group delay values are presented.

DOI: 10.1364/ao.558793

Related papers

Investigation of Intermodal Four-Wave Mixing for Continuous-Wave Photon-Pair Generation

Seyedehnajmeh Montazeri, Md Abu Zobair, Mina Esmaeelpour

We experimentally demonstrate the various intermodal and intramodal four-wave mixing processes in a few-mode fiber with three modes using non-degenerate pumps. We distinguish the processes by calculating their phase mismatch and identify the intermodal spontaneous four-wave mixing process that generates entangled photon pairs in various modes. We achieve this using continuous-wave beams and the seeding technique due to the low efficiency of the spontaneous four-wave mixing effect in the fiber. We seeded the Stokes and anti-Stokes waves and measured the spectral content of each mode while moving the seed away from the perfect phase-matched condition in the fiber under test. We observe that the closer the seed gets to the pumps, the higher the efficiency of the four-wave mixing process.

IEEE Photonics Technology LettersApr 9, 20240 citations

Optimized entangled photon pair generation via intermodal four-wave mixing in a telecommunication-length few-mode fiber

Seyedehnajmeh Montazeri, Mina Esmaeelpour

We report our recent progress in generating and verifying entangled photon pairs in a telecommunication-length few-mode fiber using spontaneous four-wave mixing in a non-degenerate pump configuration. We demonstrate through seeding the desired four-wave mixing effect for pair production in the presence of a strong mode-coupling when using integrated mode multiplexers known as photonic lanterns. The mode content and phase-matching requirements were validated through computations and experiments. We discuss the challenges and requirements for phase matching and photon visibility without modifying the fiber structure. This work represents our first steps toward an efficient tunable source of entangled photons for space division multiplexing applications.

Quantum Computing, Communication, and SimulationMar 12, 20240 citations

Spectrally indistinguishable intermodal-vectorial four-wave-mixing in birefringent few-mode fibers for spatial-polarization-frequency hybrid-entangled photon-pairs generation

Andrzej Gawlik, Marta Bernaś, Kinga Żołnacz +1 more

In this paper, we use a birefringent few-mode fiber to demonstrate an intermodal-vectorial four-wave mixing process that generates two pairs of spectrally overlapping signal-idler bands. Using phase-matching conditions, we show that the pairs of bands become spectrally indistinguishable when the group refractive indices of the signal and idler modes intersect at the pump wavelength. Our theoretical predictions are confirmed through experimental observations corroborated by numerical simulations. Furthermore, we introduce the two-photon state associated with the overlapping bands, which exhibits hybrid entanglement in spatial-polarization-frequency degrees of freedom. We explain that its degree of entanglement can be manipulated by tailoring the spectral position of the overlapping pairs of bands with respect to the Raman band and varying the excitation ratio of the pump modes. This study introduces a scheme for a fiber-based source of photon pairs with spatial-polarization-frequency entanglement.

arXiv:2412.09214Dec 12, 20241 citation

Towards generation of hybrid entangled photon pairs by spectrally overlapping intermodal-vectorial four-wave mixing bands in optical fibers

Andrzej Gawlik, Marta Bernaś, Kinga Żołnacz +1 more

Optical fiber-based sources of photon pairs with hybrid entanglement across multiple degrees of freedom are essential for a wide range of quantum technologies, while remaining compatible with existing communication networks. In this paper, we use a birefringent few-mode fiber to demonstrate an intermodal-vectorial four-wave mixing process that generates two pairs of spectrally overlapping signal-idler bands. Using phase-matching conditions, we show that the pairs of bands become spectrally indistinguishable when the group refractive indices of the signal and idler modes intersect at the pump wavelength. Our theoretical predictions are confirmed through experimental observations and corroborated by numerical simulations. Furthermore, we introduce the two-photon state associated with the overlapping bands, which simultaneously exhibits entanglement in a single degree of freedom and hybrid entanglement across multiple degrees of freedom. We also explain how the type and degree of entanglement can be controlled by tailoring the spectral overlap between the signal-idler bands. This study presents a promising scheme for a fiber-based source of photon pairs with entanglement spanning the spatial, polarization, and frequency degrees of freedom.

Scientific ReportsNov 27, 20250 citations

Photon-Pair Sources Based on Intermodal Four-Wave Mixing in Few-Mode Fibers

Karsten K. Rottwitt, Jacob G. Koefoed, Erik Nicolai Christensen

Four-wave mixing in optical fibers has been proven to have many applications within processing of classical optical signals. In addition, recent developments in multimode fibers have made it possible to achieve the necessary phase-matching for efficient four-wave mixing over a very wide bandwidth. Thus, the combination of multimode fiber optics and four-wave mixing is very attractive for various applications. This is especially the case for applications in quantum communication, for example in photon-pair generation. This is the subject of this work, where we discuss the impact of fluctuations in core radius on the quality of the heralded single-photon states and demonstrate experimental results of intermodal spontaneous four-wave mixing for photon-pair generation.

FibersMay 21, 201835 citations

Tailoring the spectro-temporal mode of photon pairs generated from interspatial-mode four-wave mixing

Shengjie Zhu, Liang Cui, Xiaoying Li

We investigate the spectro-temporal mode property of the photon pairs generated via interspatial-mode spontaneous four-wave mixing (FWM) in a few-mode fiber (FMF) that supports two linearly polarized spatial modes in the 1550 nm telecom band. The two pulsed pumps for the process are in distinct spatial modes, while the created signal and idler photon pairs are also occupying different spatial modes. By exploiting the unique inter-mode phase matching condition in the FMF, we can tailor the spectro-temporal mode structure of the photon pairs by changing the pulse duration (spectral bandwidth) of the two pumps. Especially, photon pairs with a nearly round-shaped factorable joint spectrum are experimentally realized. The techniques are valuable for generating and manipulating quantum states in multi-mode waveguides and exploiting the spatial degree of freedom in quantum information processing.

Optics LettersJun 3, 20248 citations