Spectral non-hermitian quantization line shape controlled by phonon dressing in various phases of Eu 3+ :BiPO 4

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2023-08, Vol.11 (32), p.11001-11009
• Main Authors: Nadeem, Faisal, Usman, Muhammad, Mujahid, Anas, Imran, Muhammad, Hussain, Iqbal, Javed, Usman, Usmani, Muhammad Waqas, Ather, Muhammad Fahad, Li, Bo, Zhang, Yanpeng
• Format: Article
• Language: English
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/D3TC01386C

We report the relationship between phonon dressing and spectral line shape in different phases of Eu 3+ -doped BiPO 4 nanocrystals. We depict how the pure hexagonal phase exhibited a narrow line shape in contrast to mixed phases (more hexagonal phase (HP) with less low-temperature monoclinic phase (LTMP), and less HP with more LTMP). We exhibited spectral-line-shape controllability through non-Hermitian exceptional points, phase-transition phonon dressing and thermal phonon dressing. We observed that the spectral line shape in half HP + half LTMP was approximately 7 times wider at 300 K than at 77 K. We also realized that the line shape of a nonclassical spontaneous four-wave mixing (SFWM) signal could be tuned by changing the phases, time gates, detector position, and lasers. Furthermore, we showed that thermal phonons influence the in-phase SFWM line shape but not the out-of-phase fluorescence line shape. These results imply a spectral notch filter analogy with a maximum bandwidth contrast of about 74.6%.