Multi-wavelength selective crossbar switch

Abstract

When I started out at UC Santa Barbara as a PhD student in 2015, there was no funding until the AIM project proposal got accepted. Without funding no work gets done, so first I am grateful to Prof. Rod Alferness for funding me for the first year and Prof. John Bowers for funding me for the rest of my PhD. To John, thanks for giving me complete freedom at work without which I could not have explored so many different areas in research. I enjoyed our conversation in the monthly meetings with Rod, John and Adel. For the first few months of my PhD I spent a lot of time with Adel doing a literature survey, it was an exciting journey in a new field. To Adel, thanks for filtering out the unsound ideas and helping me frame my thoughts. I enjoyed our white board discussions. To Roger, Clint, Takako and Andy at the Datacom meetings for discussions and helpful feedback. To Tin, for the fun we had at the New York Training conference. To Alex, Warren, Eric and Andy for the excellent office environment. To Alex, for inspiring me to get Scuba certified and also for tips on cooking Thai cuisine. To Aranya, for being my climbing buddy. To Sean, Simran Lawrence, Wilson and many others, for the fun time we had at UCSB badminton intramural. To Chirag, for providing helpful advice when needed. Thanks to Nicolas, Geza, Christos, Sarat, Aditya for helpful discussions. I would also like to thank Minh, Tony, Paolo, Yuan and Alan for their helpful advice. Special Thanks to Songtao for help with high speed measurements. Thanks to my Pappa, Mamma and Sairaj for the support during my PhD and for recharge time in India. Finally I would also thank Jeremiah Hebding, Brett Attaway, and SUNY for their foundry services. v

Flex-LIONS: A Silicon Photonic Bandwidth-Reconfigurable Optical Switch Fabric

“…The number of cascaded MRRs on the path of the reconfigured channels in a Flex-LIONS with the Beneš MZS network is two while that of a Flex-LIONS with multi-wavelength MRR crossbar is three, so that the bandwidth-narrowing effect is reduced. Table 1 compares Flex-LIONS with various state-of-theart wavelength-and-space selective reconfigurable switching fabrics, including indium phosphide (InP) AWGRs + semiconductor optical amplifier (SOA) gates [13], silicon (Si) echelle gratings + (micro-electro-mechanical system) MEMS arrays [14], and multi-wavelength selective crossbar [15]. In particular, the comparison study takes into account the port count, on-chip loss, and the number of switching elements.…”

“…[13] architecture to scale up to high radix. Reference [14] architecture suffers not only from the high number of switching elements (N 3 ) but also from high on-chip insertion loss since the number of waveguide crossings increases by ∼ N 2 , while the number of waveguide crossings in Flex-LIONS increases by ∼ N. Reference [15] architecture also has the issue of a high number of switching elements which makes the control plane more complex and limits the scalability. Compared with Flex-LIONS with multi-wavelength MRR crossbar, Flex-LIONS with the Beneš MZS network exhibits a lower number of switching elements and reduced bandwidth-narrowing effect at the expense of higher on-chip insertion loss and a more complex control mechanism due to the rearrangeable non-blocking nature of this solution.…”

“…At the physical layer, optical interconnects are becoming the dominant communication technology in HPC and datacenters driven by the ever-increasing bandwidth scaling pushed by the widespread adoption of the cloud and emerging applications. In the past few years, we have witnessed a number of different integrated reconfigurable wavelength routing and space switching solutions that allow redefining the connectivity in both spectral and spatial domains, dynamically [6]- [15] Among these works, in [7] we proposed and demonstrated SiPh Flex-LIONS (silicon photonic flexible low-latency interconnect optical network switch), a reconfigurable photonic interconnect architecture that leverages both wavelength routing and spatial switching to spatially and temporarily steer and increase the communication bandwidth between specific node pairs (a comparison between Flex-LIONS and other existing approaches is presented in Sect. 2.2).…”

Scalable Microring-Based Silicon Clos Switch Fabric With Switch-and-Select Stages

“…The first demonstration of a μm-scale silicon ring resonator by Xu et al stimulated the research of MRR-based photonic integrated circuits [20]. There have been a number of demonstrations of microringbased optical switch fabrics, scaling from 2 to 8 ports [9], [17], [18], [21]- [26]. Table I summarises notable demonstrations of microring-based optical switching circuits chronologically.…”

“…Key metrics, such as port count, insertion loss, crosstalk, and optical power penalty are highlighted and compared. This type of switch tends to utilize the MRR element as a 1 × 2 spatial adddrop unit assembled in certain topologies, such as the hitless [17] and five-port [21] routers, the crossbar switches [9], [23], [26], and the Omega switch with dual-ring intersections [18]. In these configurations, while each 1 × 2 elementary cell is only traversed by one signal, the crosstalk leakage gets aggregated with adjacent channels.…”