The rapidly growing global internet traffic requires ever faster data transfer within computer networks. Photonic integrated circuits can pave the way to accelerated signal transmission and increase bandwidth of optical interconnects in a compact way. One of the key building blocks for photonic integrated circuits is an on-chip nanolaser. In this dissertation, we explore ways to reduce resistance and the Joule heating of the nanolasers We experimentally demonstrated an electrically pumped nanolaser by incorporating a tunnel junction. The resistance is reduced, so as the threshold voltage and joule heating. Besides nanolasers, an optically controlled microwave switch is another essential component in photonic integrated circuits. We designed and demonstrated a Monolithic Optically Reconfigurable Integrated Microwave Switches (MORIMSs) as a more efficient and integrated photoconductive switch. The two devices we explore in this dissertation have the potential to be essential building blocks for photonic integrated circuits in the future.