Temperature tunable plasmonic and optical response of CdS@ITO core-shell quantum dots in the telecom band

We present a detailed theoretical and numerical study on the temperature-tunable plasmonic and optical behavior of CdS@ITO core-shell quantum dots (CSQDs) embedded in dielectric environments. Utilizing the quasi-static approximation and a thermally adaptive Maxwell-Garnett effective medium approach, we systematically analyze how thermal variation modulates key performance metrics, including localized surface plasmon resonance (LSPR), local field enhancement factor (LFEF), refractive index dispersion, extinction coefficient ( $$\kappa $$ ), and resonance quality factor (Q). Thermal effects are incorporated via a modified Drude model accounting for temperature-dependent carrier density and damping rate in the ITO shell. Simulations reveal LSPR redshifts of over 100 nm with increasing temperature, accompanied by a monotonic decline in LFEF from above 1500 to below 100 across 300–600 K. Quality factors degrade from $$Q \approx 20$$ at room temperature to $$Q < 4$$ at 600 K due to increased electron–phonon scattering. Spectral tunability in the 1300–1550 nm telecom range is demonstrated, with extinction coefficients maintained below 0.06. These results highlight the potential of CdS@ITO CSQDs as thermally responsive, low-loss components for thermally adaptive photonic systems, including nanoscale optical buffers, modulators, and slow-light devices.