Quantitative understanding of 2D atomic layer interface thermal resistance (R) based on Raman characterization is significantly hindered by unknown sample-to-sample optical properties variation, interface-induced optical interference, off-normal laser irradiation, and large thermal-Raman calibration uncertainties. In this work, we develop a novel energy transport state resolved Raman (ET-Raman) to resolve these critical issues, and also consider the hot carrier diffusion, which is crucial but has been rarely considered during interface energy transport study. In ET-Raman, by constructing two steady heat conduction states with different laser spot sizes, we differentiate the effect of R and hot carrier diffusion coefficient (D). By constructing an extreme state of zero/negligible heat conduction using a picosecond laser, we differentiate the effect of R and material's specific heat. In the end, we precisely determine R and D without need of laser absorption and temperature rise of the 2D atomic layer. Seven MoS 2 samples (6.6−17.4 nm) on c-Si are characterized using ET-Raman. Their D is measured in the order of 1.0 cm 2 /s, increasing against the MoS 2 thickness. This is attributed to the weaker in-plane electron−phonon interaction in thicker samples, enhanced screening of long-range disorder, and improved charge impurities mitigation. R is determined as 1.22−1.87 × 10 −7 K•m 2 /W, decreasing with the MoS 2 thickness. This is explained by the interface spacing variation due to thermal expansion mismatch between MoS 2 and Si, and increased stiffness of thicker MoS 2 . The local interface spacing is uncovered by comparing the theoretical Raman intensity and experimental data, and is correlated with the observed R variation.

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We use the real (Kerr) and imaginary (two photon absorption) parts of a third order optical nonlinearity to tune the long ͑1.6 m͒ and short wavelength ͑1.3 m͒ band edges of a stop gap in a two-dimensional silicon photonic crystal. From pump-probe reflectivity experiments using 130 fs pulses, we observe that a 2 m pulse induces optical tuning of the 1.3 m edge via the Kerr effect whereas a 1.76 m pulse induces tuning of the 1.6 m band edge via both Kerr and Drude effects with the latter related to two-photon induced generation of free carriers with a lifetime of ϳ900 ps.

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