Defect-induced ultimately fast volume phonon-polaritons in the wurtzite Zn0.74Mg0.26Se mixed crystal

H. Dicko (1) , O. Pagès (1) , M. B Shoker (1) , F. Firszt (2) , K. Strzałkowski (2) , A. Maillard (3) , A. Polian (4) , Y. Battie (1) , L. Broch (1) , A. En Naciri (1) , A. V Postnikov (1) , W. Paszkowicz (5) , J.-P. Itie (6)

1 LCP-A2MC - Laboratoire de Chimie et Physique - Approche Multi-échelle des Milieux Complexes
2 Institute of Physics [Toruń]
3 LMOPS - Laboratoire Matériaux Optiques, Photonique et Systèmes
4 IMPMC - Institut de minéralogie, de physique des matériaux et de cosmochimie
5 Institute of Physics, Polish Academy of Sciences
6 SSOLEIL - Synchrotron SOLEIL

Volume-phonon-polaritons (VPP’s) propagating at a light-in-vacuum-like speed are identified in the wurtzite-type Zn0.74Mg0.26Se mixed crystal by near-forward Raman scattering. Their detection is selective to both the laser energy and the laser polarization, depending on whether the ordinary (n0) or extraordinary (ne) refractive index is addressed. Yet, no significant linear birefringence (n0 ≃ ne) is observed by ellipsometry. The current access to ultrafast VPP’s is attributed to the quasi-resonant Raman probing of an anomalous dispersion of n0 due to impurity levels created deep in the optical band gap by oriented structural defects. The resonance conditions are evidenced by a dramatic enhancement of the Raman signals due to the polar modes. Hence, this work reveals a capacity for the lattice defects’ engineering to “accelerate” the VPP’s of a mixed crystal up to light-in-vacuum-like speeds. This is attractive for ultrafast signal processing in the terahertz range. On the fundamental side we provide an insight into the VPP’s created by alloying ultimately close to the center of the Brillouin zone.

Mots clés: Polaritons; Semiconductors

Domaines: Physique [physics]; Matière Condensée [cond-mat]

H. Dicko, O. Pagès, M. B Shoker, F. Firszt, K. Strzałkowski, et al.. Defect-induced ultimately fast volume phonon-polaritons in the wurtzite Zn0.74Mg0.26Se mixed crystal. Scientific Reports, 2019, 9, pp.7817 (2019). ⟨10.1038/s41598-019-44273-5⟩. ⟨hal-02156595⟩