Optical multiplexing techniques and their marriage for on-chip and optical fiber communication:a review

Herein,an attention-grabbing and up-to-date review related to major multiplexing techniques is presented which in-cludes wavelength division multiplexing(WDM),polarization division multiplexing(PDM),space division multiplexing(SDM),mode division multiplexing(MDM)and orbital angular momentum multiplexing(OAMM).Multiplexing is a mech-anism by which multiple signals are combined into a shared channel used to showcase the maximum capacity of the op-tical links.However,it is critical to develop hybrid multiplexing methods to allow enhanced channel numbers.In this re-view,we have also included hybrid multiplexing techniques such as WDM-PDM,WDM-MDM and PDM-MDM.It is prob-able to attain N×M channels by utilizing N wavelengths and M guided-modes by simply utilizing hybrid WDM-MDM(de)multiplexers.To the best of our knowledge,this review paper is one of its kind which has highlighted the most prom-inent and recent signs of progress in multiplexing techniques in one place.

Highly Sensitive Refractive Index Sensor Based on Plasmonic Bow Tie Configuration

We propose a highly refractive index sensor based on plasmonic Bow Tie configuration.The sensitivity of the resonator design is enhanced by incorporating a nanowall(NW)in a modified Bow Tie design where sharp tips of V-junction are flattened.This approach provides high confinement of electric field distribution of surface plasmon polariton(SPP)mode in the narrow region of the cavity.Consequently,the effective refractive index(neff)of the mode increases and is highly responsive to the ambient medium.The sensitivity analysis of the SPP mode is calculated for six resonator schemes.The results suggest that the NW embedded cavity offers the highest mode sensitivity due to the large shift of effective index when exposed to a slight change in the medium refractive index.Moreover,the device sensitivity of the proposed design is approximated at 2300 nm/RIU which is much higher than the sensitivity of the standard Bow Tie configuration.

Polarization-Insensitive Hybrid Plasmonic Waveguide Design for Evanescent Field Absorption Gas Sensor

We propose a polarization-insensitive design of a hybrid plasmonic waveguide(HPWG)optimized at the 3.392µm wavelength which corresponds to the absorption line of methane gas.The waveguide design is capable of providing high mode sensitivity(Smode)and evanescent field ratio(EFR)for both transverse electric(TE)and transverse magnetic(TM)hybrid modes.The modal analysis of the waveguide is performed via 2-dimension(2D)and 3-dimension(3D)finite element methods(FEMs).At optimized waveguide parameters,Smode and EFR of 0.94 and 0.704,can be obtained for the TE hybrid mode,respectively,whereas the TM hybrid mode can offer Smode and EFR of 0.86 and 0.67,respectively.The TE and TM hybrid modes power dissipation of~3 dB can be obtained for a 20-µm-long hybrid plasmonic waveguide at the 60%gas concentration.We believe that the highly sensitive waveguide scheme proposed in this work overcomes the limitation of the polarization controlled light and can be utilized in gas sensing applications.