The ability to inject, guide, and manipulate light on a subwavelength scale using nanowire components that can be assembled into integrated structures represents a promising pathway towards integrated nanoscale photonic systems. This thesis focuses on light-matter interaction at the single nanowire level and presents key advances in nanowire photonic devices for photonic circuits.

Cadmium sulfide (CdS) semiconductor nanowires are grown using single-source precursors via a nanocluster catalyzed vapor-liquid-solid growth process. CdS nanowires are of interest for photonic applications because they provide high quantum efficiency, a large refractive index, and a large nonlinear coefficient (χ²). The optical properties and lasing mechanism of US nanowires are studied using photoluminescence imaging and spectroscopy.

Light is optically or electrically injected locally into nanowire waveguides. The waveguiding properties are characterized along straight and bent nanowire segments, showing low loss even at sharp bends. In addition, nanowires are integrated into electro-optic modulators to switch optical signals with an applied electric field.

A hybrid approach for photonic systems is presented. This approach combines chemically synthesized single nanowire emitters with lithographically defined photonic crystal and racetrack microresonator structures. The hybrid nanowire structures offer a simple and effective way to couple light into and out of the nanowire.

Finally, semiconductor nanowires are used for nonlinear mixing in a subwavelength waveguide. Second-harmonic generation and optical parametric generation are experimentally measured. A theoretical framework is developed to understand nonlinear processes in a subwavelength waveguide and the importance of the coherence length. The ability to efficiently generate and waveguide nonlinear signals offers new opportunities for coherent all-optical switching in integrated nanoscale photonic systems.