The overall performance of modern computing systems is increasingly determined by the characteristics of the interconnection network used to provide communication links between on-chip cores and off-chip memory. Photonic technology has been proposed as an alternative to traditional electronic interconnects because of its advantages in bandwidth density, latency, and power efficiency. Circuit-switched photonic interconnect topologies take advantage of the optical spectrum to create high-bandwidth transmission links through the transmission of data channels on multiple parallel wavelengths; however, this technique suffers from low path diversity and high setup time overhead, which induces high network resource contention, unfairness, and long latencies. This work improves upon the circuit-switching paradigm by introducing the use of on-chip wavelength-selective spatial routing to produce multiple logical communication layers on a single physical plane. This technique yields higher path diversity in photonic interconnection networks, demonstrating as much as 764% saturation bandwidth improvement with synthetic traffic and as much as 89% improvement in execution time and energy dissipation for traffic from scientific application traces.