Photonic integrated circuits

Recent progress in InGaAsP-InP photonic integrated circuits (PICs) is reviewed with emphasis on the versatility afforded by metalorganic chemical vapor deposition (MOCVD)-based quantum-well growth and etch-stop fabrication techniques. These include the ability to form interconnected optical elements employing (1) buried heterostructure guides where carefully controlled current injection or low capacitance field application is required, such as quantum-well gain regions, quantum-well modulators, or photodetectors, (2) a variety of precisely defined, low-loss semi-insulating-InP-clad weak buried rib guides where carefully controlled phase characteristics are required, such as directional couplers, switches, power combiners, and splitters, and (3) grating filters and reflectors where required. PICs incorporating these features can be fabricated with self-aligned guide connections between different guide types and no additional growth stages beyond those required for the semi-insulating-blocked buried-heterostructure lasers employed in the circuits.