CMOS plasmonic waveguides co-integrated with LPCVD-based Si3N4 via a butt-coupled interface

Plasmonic technology has attracted intense research interest enhancing the functional portfolio of photonic integrated circuits (PICs) by providing Surface-Plasmon-Polariton (SPP) modes with ultra-high confinement at sub-wavelength scale dimensions and as such increased light matter interaction. However, in most cases plasmonic waveguides rely mainly on noble metals and exhibit high optical losses, impeding their employment in CMOS processes and their practical deployment in highly useful PICs. Hence, merging CMOS compatible plasmonic waveguides with low-loss photonics by judiciously interfacing these two waveguide platforms appears as the most promising route towards the rapid and costefficient manufacturing of high-performance plasmo-photonic integrated circuits. In this work, we present butt-coupled plasmo-photonic interfaces between CMOS compatible 7μm-wide Aluminum (Al) and Copper (Cu) metal stripes and 360×800nm Si3N4 waveguides. The interfaces have been designed by means of 3D FDTD and have been optimized for aqueous environment targeting their future employment in biosensing interferometric arrangements, with the photonic waveguides being cladded with 660nm of Low Temperature Oxide (LTO) and the plasmonic stripes being recessed in a cavity formed between the photonic waveguides. The geometrical parameters of the interface will be presented based on detailed simulation results, using experimentally verified plasmonic properties for the employed CMOS metals. Numerical simulations dictated a coupling efficiency of 53% and 68% at 1.55μm wavelength for Al and Cu, respectively, with the plasmonic propagation length Lspp equaling 66μm for Al and 75μm for Cu with water considered as the top cladding. The proposed interface configuration is currently being fabricated for experimental verification.

[1]  Nikos Pleros,et al.  Plasmonic Stripes in Aqueous Environment Co-Integrated With Si3N4 Photonics , 2018, IEEE Photonics Journal.

[2]  M. Lipson,et al.  Broadband mid-infrared frequency comb generation in a Si3N4 microresonator , 2015, 2015 Conference on Lasers and Electro-Optics (CLEO).

[3]  F. Liu,et al.  Extremely high efficient coupling between long range surface plasmon polariton and dielectric waveguide mode , 2009 .

[4]  O. Heavens.  Handbook of Optical Constants of Solids II , 1992 .

[5]  W. Barnes,et al.  Surface plasmon subwavelength optics , 2003, Nature.

[6]  Shiyang Zhu,et al.  Silicon nitride based plasmonic components for CMOS back-end-of-line integration. , 2013, Optics express.

[7]  H. Avramopoulos,et al.  Interfacing Dielectric-Loaded Plasmonic and Silicon Photonic Waveguides: Theoretical Analysis and Experimental Demonstration , 2012, IEEE Journal of Quantum Electronics.

[8]  Sergey I. Bozhevolnyi,et al.  Experimental demonstration of CMOS-compatible longrange dielectric-loaded surface plasmon-polariton waveguides (LR-DLSPPWs) , 2015, 2015 Conference on Lasers and Electro-Optics (CLEO).

[9]  Fang Liu,et al.  Vertical coupling between short range surface plasmon polariton mode and dielectric waveguide mode , 2009 .

[10]  Fang Liu,et al.  Refractive index sensor based on hybrid coupler with short-range surface plasmon polariton and dielectric waveguide , 2012 .

[11]  Nikos Pleros,et al.  TM grating coupler on low-loss LPCVD based Si3N4 waveguide platform , 2017 .

[12]  Eyal Feigenbaum,et al.  Efficient coupling between dielectric-loaded plasmonic and silicon photonic waveguides. , 2010, Nano letters.

[13]  N. Pleros,et al.  A directional coupling scheme for efficient coupling between Si3N4 photonic and hybrid slot-based plasmonic waveguides , 2017, OPTO.

[14]  N. Pleros,et al.  1 TM Grating Coupler on Low-Loss LPCVD based Si 3 N 4 Waveguide Platform , 2018 .

[15]  S. Papaioannou,et al.  A 320 Gb/s-Throughput Capable 2 $\,\times\,$2 Silicon-Plasmonic Router Architecture for Optical Interconnects , 2011, Journal of Lightwave Technology.

[16]  J Leuthold,et al.  Characterization of CMOS metal based dielectric loaded surface plasmon waveguides at telecom wavelengths. , 2017, Optics express.

[17]  Shiyang Zhu,et al.  Fully CMOS compatible subwavelength plasmonic slot waveguides for Si electronic-photonic integrated circuits , 2011, 2011 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference.

[18]  Nikos Pleros,et al.  Active plasmonics in WDM traffic switching applications , 2012, Scientific Reports.

[19]  Nikos Pleros,et al.  Butt-coupled interface between stoichiometric Si3N4 and thin-film plasmonic waveguides , 2017, OPTO.