20.500.12556/DiRROS-28307 Quasi-phase-matched spontaneous parametric down-conversion in chiral ferroelectric nematic liquid crystals For high-intensity photon pair generation via spontaneous parametric down-conversion, phase matching or quasi-phase-matching must be realized. The most common method is to use periodically poled crystals, where quasi-phase-matching is achieved through the periodic modulation of the nonlinear susceptibility. In contrast to solid-state materials typically employed, an alternative approach is demonstrated here by using chiral ferroelectric nematic liquid crystals (FNLCs). It involves the spontaneous formation of a twisted periodic arrangement of liquid crystal molecules that depends only on the concentration of chiral dopants. This enables the rapid and scalable fabrication of nonlinear optical media with a tunable periodicity of the structure. We show that within only 20µ⁢m, we can enhance the signal by 2 orders of magnitude compared to the maximal achievable rate for the non-phase-matched case. This process enables us to achieve a significantly enhanced photon pair generation rate of over 1200 Hz/mW in a very short interaction length while simultaneously maintaining a high degree of polarization entanglement. These results establish chiral FNLCs as a versatile, reconfigurable, and low-cost platform for nonlinear and quantum photonics. ferroelectric liquid crystals optical second-harmonic generation photon pairs parametric down-conversion feroelektrični tekoči kristali true false true American Physical Society ZDA Angleški jezik Slovenski jezik Neznano 2026-03-13 12:45:58 2026-03-13 12:45:58 2026-03-14 04:25:54 0000-00-00 00:00:00 2026 0 0 Nasl. z nasl. zaslona; Opis vira z dne 13. 3. 2026; str. 013119-1-013119-7 iss. 1, [article no.] 013119 Vol. 8 Feb./Apr. 2026 0000-00-00 Zaloznikova Objavljeno NiDoloceno 2025-07-21 2025-12-16 2026-02-02 53 2643-1564 10.1103/wgb3-clj5 271600643 https://journals.aps.org/prresearch/abstract/10.1103/wgb3-clj5 1 375c6864-1ed2-11f1-acf8-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=41796 RAZ_Kavcic_Aljaz_2026.pdf RAZ_Kavcic_Aljaz_2026.pdf 1 CD20C11E963A6132963FA72BD8D42EAF fcd2c3f233a2d95bfef2d7aff9eab3cdc825127dd37ea973c150f0a297adc68d 851265f2-1ed2-11f1-acf8-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=41798 Institut Jožef Stefan 0 0 0