Haichang Guo's research investigates phonon and thermal transport spanning micro-to-macro scales. Micro/nano techniques include suspended thermal bridges, FDTR, and optothermal Raman spectroscopy, along with phonon engineering. Macro-scale efforts develop thermally conductive composites, TIMs, and 3D-printed architectures with graphene/BN fillers, enabling efficient anisotropic heat dissipation for various electronic packaging and advanced thermal management.