title: Compact spatial multiplexers for mode division multiplexing.
abstract: Spatial multiplexer (SMUX) for mode division multiplexing (MDM) has evolved from mode-selective excitation, multiple-spot and photonic-lantern based solutions in order to minimize both mode-dependent loss (MDL) and coupler insertion loss (CIL). This paper discusses the implementation of all the three solutions by compact components in a small footprint. Moreover, the compact SMUX can be manufactured in mass production and packaged to assure high reliability. First, push-pull scheme and center launch based SMUXes are demonstrated on two mostly-popular photonic integration platforms: Silicon-on-insulator (SOI) and Indium Phosphide (InP) for selectively exciting LP01and LP11modes. 2-dimensional (2D) top-coupling by using vertical emitters is explored to provide a coupling interface between a few-mode fiber (FMF) and the photonic integrated SMUX. SOI-based grating couplers and InP-based 45° vertical mirrors are proposed and researched as vertical emitters in each platform. Second, a 3-spot SMUX is realized on an InP-based circuit through employing 45° vertical mirrors. Third, as a newly-emerging photonic integration platform, laser-inscribed 3D waveguide (3DW) technology is applied for a fully-packaged dual-channel 6-mode SMUX including two 6-core photonic lantern structures as mode multiplexer and demultiplexer, respectively.
authors.forename: Haoshuo
authors.initials: H
authors.lastname: Chen
authors.forename: Roy
authors.initials: R
authors.lastname: van Uden
authors.forename: Chigo
authors.initials: C
authors.lastname: Okonkwo
authors.forename: Ton
authors.initials: T
authors.lastname: Koonen
mesh_terms: D003195:Computer Communication Networks / Q000295:instrumentation*; D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005336:Fiber Optic Technology / Q000295:instrumentation*; D008904:Miniaturization; D008962:Models, Theoretical; D055096:Optical Devices; D020349:Surface Plasmon Resonance / Q000295:instrumentation*; D018511:Systems Integration; D013685:Telecommunications / Q000295:instrumentation*