Hybrid 2D/3D photonic integration for non-planar circuit topologies

Complex photonic integrated circuits (PIC) may have strongly non-planar topologies that require waveguide crossings (WGX) when realized in single-layer integration platforms. The number of WGX increases rapidly with the complexity of the circuit, in particular when it comes to highly interconnected optical switch topologies. Here, we present a concept for WGX-free PIC that rely on 3D-printed freeform waveguide overpasses (WOP). We experimentally demonstrate the viability of our approach using the example of a $4 \times 4$ switch-and-select (SAS) circuit realized on the silicon photonic platform. We further present a comprehensive graph-theoretical analysis of different $n \times n$ SAS circuit topologies. We find that for increasing port counts $n$ of the SAS circuit, the number of WGX increases with $n^4$, whereas the number of WOP increases only in proportion to $n^2$.

[1]  C. Kuratowski.  Sur le problème des courbes gauches en Topologie , 1930 .

[2]  M. Wegener,et al.  Direct laser writing of three-dimensional photonic-crystal templates for telecommunications , 2004, Nature materials.

[3]  Nobuhiko Nishiyama,et al.  Crystalline/Amorphous Si Integrated Optical Couplers for 2D/3D Interconnection , 2016, IEEE Journal of Selected Topics in Quantum Electronics.

[4]  David S. Johnson,et al.  Crossing Number is NP-Complete , 1983 .

[5]  G. Lo,et al.  Ultralow loss single layer submicron silicon waveguide crossing for SOI optical interconnect. , 2013, Optics express.

[6]  Yi Zhang,et al.  Silicon Photonics: The Next Fabless Semiconductor Industry , 2013, IEEE Solid-State Circuits Magazine.

[7]  Xiaoge Zeng,et al.  Ultra-low-loss CMOS-compatible waveguide crossing arrays based on multimode Bloch waves and imaginary coupling. , 2013, Optics letters.

[8]  Aleksandar Nesic,et al.  Hybrid integration of silicon photonics circuits and InP lasers by photonic wire bonding , 2018, Optica.

[9]  Young-Kai Chen,et al.  Compact, low-loss and low-power 8×8 broadband silicon optical switch. , 2012, Optics express.

[10]  W. Freude,et al.  Connecting Silicon Photonic Circuits to Multicore Fibers by Photonic Wire Bonding , 2015, Journal of Lightwave Technology.

[11]  C. Koos,et al.  Connecting silicon photonic circuits to multi-core fibers by photonic wire bonding , 2014, 2014 Optical Interconnects Conference.

[12]  Geoffrey Exoo,et al.  Crossing Number Graphs , 2009 .

[13]  Ming C. Wu,et al.  Large-scale broadband digital silicon photonic switches with vertical adiabatic couplers , 2016 .

[14]  László A. Székely,et al.  Turán’s Brick Factory Problem: The Status of the Conjectures of Zarankiewicz and Hill , 2016 .

[15]  S. Randel,et al.  3D-Printed Ultra-Broadband Highly Efficient Out-of-Plane Coupler for Photonic Integrated Circuits , 2018, 2018 Conference on Lasers and Electro-Optics (CLEO).

[16]  T. Zwick,et al.  Silicon-organic hybrid devices , 2013, Photonics West - Optoelectronic Materials and Devices.

[17]  Sae Woo Nam,et al.  Multi-planar amorphous silicon photonics with compact interplanar couplers, cross talk mitigation, and low crossing loss , 2017 .

[18]  Kuanping Shang,et al.  Low-loss compact multilayer silicon nitride platform for 3D photonic integrated circuits. , 2015, Optics express.

[19]  G. Lo,et al.  Multilayer Silicon Nitride-on-Silicon Integrated Photonic Platforms and Devices , 2015, Journal of Lightwave Technology.

[20]  R Schmogrow,et al.  Photonic wire bonding: a novel concept for chip-scale interconnects. , 2012, Optics express.

[21]  Etienne de Klerk,et al.  Improved Bounds for the Crossing Numbers of Km, n and Kn , 2004, SIAM J. Discret. Math..

[22]  Yi Zhang,et al.  A CMOS-compatible silicon photonic platform for high-speed integrated opto-electronics , 2013, Microtechnologies for the New Millennium.

[23]  M. Kohtoku,et al.  Waveguide Interconnection in Silica-Based Planar Lightwave Circuit Using Femtosecond Laser , 2009, Journal of Lightwave Technology.

[24]  Alfred Errera.  Un théorème sur les liaisons , 1923 .

[25]  Dominic Goodwill,et al.  Tri-layer silicon nitride-on-silicon photonic platform for ultra-low-loss crossings and interlayer transitions. , 2017, Optics express.

[26]  Wolfgang Freude,et al.  Silicon-organic hybrid phase shifter based on a slot waveguide with a liquid-crystal cladding. , 2012, Optics express.

[27]  Kuanping Shang,et al.  Silicon nitride tri-layer vertical Y-junction and 3D couplers with arbitrary splitting ratio for photonic integrated circuits. , 2017, Optics express.

[28]  Ming Lu,et al.  High-density waveguide superlattices with low crosstalk , 2015, Nature Communications.

[29]  Qixiang Cheng,et al.  Si/SiN Microring-Based Optical Router in Switch-and-Select Topology , 2018, 2018 European Conference on Optical Communication (ECOC).

[30]  Ken Tanizawa,et al.  Ultralow-crosstalk and broadband multi-port optical switch using SiN/Si double-layer platform , 2017, 2017 Opto-Electronics and Communications Conference (OECC) and Photonics Global Conference (PGC).

[31]  Robert A Norwood,et al.  Ultra-low crosstalk, CMOS compatible waveguide crossings for densely integrated photonic interconnection networks. , 2013, Optics express.

[32]  Michael R. Watts,et al.  Large-scale nanophotonic phased array , 2013, Nature.

[33]  Ray T. Chen,et al.  Ultralow-loss silicon waveguide crossing using Bloch modes in index-engineered cascaded multimode-interference couplers. , 2013, Optics letters.

[34]  Tomoya Yoshida,et al.  Vertical silicon waveguide coupler bent by ion implantation. , 2015, Optics express.