Silicon photonics is a disruptive technology that is poised to revolutionize number of application areas such as data centres, high performance computing and sensing. The key driving force behind silicon photonics is its compatibility with CMOS fabrication, high volume production and low cost. The optical modulator is one of the key elements in the transmission of data in short and long reach optical interconnects. With ever increasing numbers of integrated components on a chip, the total power budget for modulation becomes more demanding. This report outlines two promising approaches based on phase modulation of light for reducing the energy requirements which can be implemented in integrated optical communication systems in foreseeable future. The first involves light recycling through an MMI and utilizing the present thermal gradient/carriers to accumulate additional phase change. Another approach utilizes actuation of suspended slot waveguide-based structures to achieve the phase change by modifying the structure geometry when actuated electrically.