Enhancing coupling efficiency and propagating length for surface plasmon polaritons.

A high coupling efficiency and long propagating length technique is suggested for surface plasmon polaritons (SPPs). An attenuated total reflection (ATR) mode is employed to enhance the coupling efficiency by SPPs resonating with the incident light in the SPP launching zone. In the SPP transmitting zone, a step-metal film is embedded in a dielectric to decrease the radiation and absorption losses. Simulated results reveal that an SPP transmitting length of several hundred micrometers can be achieved with high energy. Besides, analyzed results indicate that the fabrication of the device is easy because of its simple structure and large tolerances.