We present the main results achieved in light source, light manipulation and imaging and sensing in our competitive research program. In light source, we have for the first time developed grapheme mode-locked lasers and dark pause lasers as well as nano-crystal Si based light emitting devices with colour tunable. In light manipulation, loss compensation of surface plasmon polaritons (SPPs) using semiconductor gain media was studied theoretically and demonstrated experimentally and the SPP propagation can be controlled through electrical pumping. Microring resonators based on silicon on insulator and III-V semiconductors technologies have been successfully fabricated and they can be used as filter and switch in the photonic circuit. In imaging and sensing, both SPP and metamaterial based lenses are developed and resolution far beyond diffraction limit in visible range has been realized. Broadband photodetectors based on dilute nitrides are also demonstrated.