Abstract
Building a large-scale Mach-Zehnder-based silicon photonic switch circuit (LS-MZS) requires an appropriate choice of architecture. In this work, we propose, for the first time to our knowledge, a single metric that can be used to compare different topologies. We propose an accurate analytical model of the signal-to-crosstalk ratio (SCR) that highlights the performance limitations of the main building blocks: Mach-Zehnder interferometers (MZI) and waveguide crossings. It is based on the cumulative crosstalk and total insertion loss of the LS-MZS. Four different architectures: Beneš, dilated Beneš, switch and select, double-layer network were studied for the reason that they are mainly referenced in the literature. We compared them using our developed SCR indicator. With reference to the state-of-the-art technology, the analysis of the four architectures using SCR showed that, on a large scale, a high number of waveguide crossings significantly affects the performance of the switch matrix. Moreover, better performance was reached using the double-layer-network architecture. Then, we presented a 2 × 2 MZI using two electro-optic phase shifters and a waveguide crossing realized in LETI’s silicon photonics technology. Measured performances were quite good: the switch circuit had a crosstalk of −31.3 dB and an insertion loss estimated to be less than 1.31 dB.
Highlights
Data switching networks are facing increasing difficulties in handling the exponential growth of traffic [1]
Optical crosstalk occurs when a portion of the signal power leaks into an unwanted output, could be generated in both Mach-Zehnder interferometer (MZI) and waveguide crossing because of their design. We model these which could be generated in both MZI and waveguide crossing because of their design
We model leakages by a factor m in MZI and x in waveguide crossing
Summary
Data switching networks are facing increasing difficulties in handling the exponential growth of traffic [1]. The comparison of architectures takes into account only the effect of MZIs [3,9] or is mainly based on the calculation of the total insertion loss, without considering any crosstalk [10]. These approaches may not be sufficient to estimate which architecture matrix is the most appropriate for a given technology. For the first time to our knowledge, the two basic performance parameters—optical crosstalk and insertion loss—of both MZIs and waveguide crossings, are considered in one single metric to select the most suitable architecture.
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