Variable Optical Attenuator Based on Long-Range Surface Plasmon Polariton Multimode Interference Coupler

Xiaoqiang Sun,Daming Zhang,Ying Xie,Fei Wang,Changming Chen,Tong Liu

doi:10.1155/2014/394976

Abstract

The fabrication and characterization of a thermal variable optical attenuator based on long-range surface plasmon polariton (LRSPP) waveguide with multimode interference architecture were investigated. The surface morphology and waveguide configuration of Au stripe were studied by atomic force microscopy. The fluctuation of refractive index of poly(methyl-methacrylate-glycidyl-methacrylate) polymer cladding was confirmed to be less than3×10-4within 8 h curing at120°C. The end-fire excitation of LRSPP mode guiding at 1550 nm along Au stripe indicated that the extinction ratio of attenuator was about 12 dB at a driving power of 69 mW. The measured optical rise time and fall time are 0.57 and 0.87 ms, respectively. These favorable properties promise potentials of this plasmonic device in the application of optical interconnection.

Highlights

Surface plasmon polariton (SPP) is a wave of longitudinal charge oscillations of the conduction electrons at the metal surface
Research works about the long-range SPP (LRSPP) waveguide applications for integrated optical components, such as S-bends, Y-junctions, multimode interference (MMI) couplers, and Mach-Zehnder interferometers (MZIs), have been reported [5,6,7,8,9,10]
The optical loss of proposed LRSPP waveguide with symmetrical polymer claddings is induced by different issues, including ohmic loss of metal, scattering loss coming from the imperfect configuration of metal stripe, and intrinsic absorption loss of cladding material

Summary

Introduction

Surface plasmon polariton (SPP) is a wave of longitudinal charge oscillations of the conduction electrons at the metal surface. It leads to a transverse magnetic (TM) polarized optical surface waves that propagate along the interface between a metal and a dielectric. The attenuation can be significantly reduced by changing a metal-dielectric interface to a symmetrical structure and constructing metal waveguides with finite width and thickness. This will result in the propagation of a lowloss fundamental symmetric mode and an increase in the propagation length, known as the long-range SPP (LRSPP) [4]. Research works about the LRSPP waveguide applications for integrated optical components, such as S-bends, Y-junctions, multimode interference (MMI) couplers, and Mach-Zehnder interferometers (MZIs), have been reported [5,6,7,8,9,10]

Methods

Results

Conclusion