For Review Only > REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER (DOUBLECLICK HERE TO EDIT) < 1 ! " !! # ! $ " % !&! " ! ! " $’( ! ! " $)((* + ,! ! ! " )- ! ! ! " . ! ! " ’/ 0/$ . ! ! ! !! ! " 1" ! ’ ’+ 2 " ! ! I. INTRODUCTION HE increasing bandwidth and connectivity requirements in datacenters, computer and telecommunications has led to a considerable interest in optical interconnects and space and wavelength selective switching [1, 2]. The ability to arbitrarily map data paths between many multiwavelength ports is particularly important for highdegree reconfigurable optical adddrop multiplexers. Currently deployed technologies use the combination of separate wavelength selective switches and broadband photonic switches [3] but the underlying MEMS optical engines require complex assembly, and are not fast enough to accommodate future packetbased traffic at the optical layer. Optoelectronic switching has been proposed for scalable, packetcompliant optical switching systems [48]. However these approaches have so far been prototyped using hundreds of discretely packaged components. Integrated optoelectronic Manuscript received August 9, 2013. This work is supported by the Dutch Technology Foundation, Stifting voor Technische Watenschappen (STW). The Authors are with the COBRA Research Institute, Eindhoven University of Technology, 5600 MB, Eindhoven, The Netherlands (email: r.stabile@tue.nl). circuit technology offers a radical reduction in physical size and assembly complexity. Research into scalable integrated optoelectronic switch circuit technology has focused on three classes of switch: • Photonic or space switches have come to represent wavelengthindependent circuits and these have received the most sustained research attention over the past two decades [89]. In the last four years, considerable advances have been made by scaling the connectivity to tens of outputs for single input 1×N circuits [1011], and up to 16 outputs for N×N circuits [1213]. • Wavelength conversionbased switches offer the prospect of bandwidth reallocation at the optical layer. This has led to considerable research in terms of systems design, but this class of switch has proved more challenging to integrate. The 8×8 MOTOR circuit integrating eight wavelength converters and one cyclic router is a notable exception [14]. Channel bandwidths as high as 40 Gbit/s [14] and 80 Gbit/s [15] have been realized with integrated approaches. • Wavelength selective switches allow arbitrary combinations of wavelengths to be routed from one input to one or more outputs. This offers massive bandwidth without compromising granularity. The early integrated circuit implementations have enabled 1×1 channel blockers which operate on up to 100 wavelengths [16]. This approach has been used in combination with broadband photonic switches to enable fast reconfiguration for telecom nodes [17]. The integration of 2×2 photonic switches within de/mux pairs has also allowed the first prototypes for high speed monolithic ROADMs [18]. This concept has been used for 1×2 wavelength selective switches operating on tens of wavelengths [19] [20]. Recently we proposed a new monolithic architecture for broadband photonic and wavelength selective crossconnection within one multipleinput, multipleoutput, monolithic circuit. Our first implementation of a fourinput, fouroutput, four wavelength (4×4×4λ) circuit is described in [21]. Recently we have scaled each of these dimensions to create the first 8×8×8λ monolithic circuit [22]. In this paper we present a detailed description of the design, fabrication and implementation for this first integrated 8×8 space and wavelength crossconnect. The switch design and fabrication are presented in section II. Section III presents an analysis for the connectivity for the full range of paths through the circuit. Representative paths are assessed in terms of noise performance and data integrity in section IV. Switching Monolithically Integrated 8×8 Space and Wavelength Selective CrossConnect R. Stabile, A. Rohit, and K.A. Williams T Journal of Lightwave Technology