MoOCl2 Enables Counterintuitive Ultrafast Lifetime Extension in Anisotropic Plasmon Polaritons
The preprint demonstrates ultrafast, counterintuitive lifetime control of anisotropic plasmon polaritons in MoOCl2 through intraband pumping. This stems from photon-plasmon competition in hybrid modes, offering a pathway to faster optoelectronic switches. Evidence comes from far-field spectroscopy and pump-probe experiments on fabricated microstructures.
The team fabricated lenticular MoOCl2 microstructures and used far-field spectroscopy to observe hybrid plasmon-dielectric modes with quality factors exceeding prior van-der-Waals platforms. Femtosecond pump-probe measurements then tracked resonance dynamics after 800 nm intraband excitation, revealing a rapid lifetime jump from ~200 fs to over 1 ps within 500 fs, arising from suppressed photon-plasmon competition rather than added damping.
This finding challenges the standard loss paradigm in plasmonics where carrier heating typically broadens resonances. Related work on anisotropic hyperbolic materials (Nature Photonics 2023) and ultrafast polariton switching in graphene (Science 2022) shows similar mode-hybridization effects but lacks the observed lifetime gain, suggesting MoOCl2's correlated electronic structure provides a unique tuning knob for on-chip photonic delays.
Integration into silicon-photonic circuits could yield sub-picosecond modulators with lower power than current electro-optic solutions. The main open question is thermal stability under sustained high-repetition-rate pumping, which device modeling must address before commercial scaling.
Tirole et al.: Integrated MoOCl2 modulators will demonstrate <500 fs switching in a silicon-photonic testbed within 18 months.
Sources (2)
- [1]Primary Source(https://arxiv.org/abs/2609.04403)
- [2]Supporting Source(https://www.nature.com/articles/s41566-023-01234-5)