This dissertation has tried to answer some of the questions related to photomechanical actuation of carbon nanotubes, investigate the photon-induced actuation in nanotube-polymer systems, develop models for photomechanical actuation and develop applications that are compatible with CMOS and MEMS processes. The intriguing photomechanical responses were studied for pure carbon nanotube ensembles and nanotube-polymer systems for both single and multi-wall nanotubes in both multilayer and nanocomposite actuators to compare their photon-induced actuation properties. Classical affine deformation model was employed to relate the observed macroscopic optical actuation to the microscopic photo-response of individual nanotubes. Several possible physical mechanisms responsible for the observed photomechanical responses of carbon nanotubes were discussed. Following investigations into the photomechanical responses of carbon nanotubes, this dissertation has developed a new carbon nanotube patterning technique to integrate nanotube ensembles in micro systems acting as both functional materials and structural materials. This technique is completely compatible with CMOS and MEMS processes. Combining the patterning technique and the novel photomechanical properties of carbon nanotubes, a new concept of carbon nanotube based micro-opto-mechanical system (CNT-MOMS) has been developed. By exploring the in-plane actuation mechanism of the CNT-MOMS, novel MOM grippers were developed for micromanipulation. By exploring the out-of-plane actuation mechanism, novel MOM rotating mirrors were developed. Both the grippers and rotating mirrors showed comparable performance to their electrostatic MEMS counterparts while offering remote controllability. To address the controllability of nanotube based optical systems, optical filters were employed which was effective to realize wavelength selective control and modulation. The results in this dissertation suggest that it is possible to construct "smart" micro or nano actuation systems with multiple functionalities with many degrees of freedom based on photomechanical actuation of carbon nanotubes, while only powered by light.