Wavelength-selective switches have been proposed for datacenter use to enhance their scalability and to help in meeting ever-increasing traffic demands. We have previously demonstrated a 4 × 4 ring-based crossbar silicon photonic switch in which each cross-point contained three ring pairs to partition the free spectral range (FSR) into three equal regions to reduce wavelength tuning range per ring pair— thereby reducing both the tuning power consumption and stress on the rings—while maintaining full routing flexibility. However, the question of scalability remains for the crossbar switch in which 96 signal pads—routed to each ring—are required to fully control it. The pad count scales by 2𝑀𝑁2 for an 𝑁 × 𝑁 switch with 𝑀 ring pairs. In this paper we present a 4-port silicon photonic ring-assisted Mach-Zehnder interferometer (RAMZI) switch, fabricated in the AIM Photonics process, with multiple-sized rings per switching elements in a Beneš network configuration to reduce the number of electrical pads required to 36 signal pads. The switch is 500μm 3mm in size and is packaged on a custom PCB. In such a switch, the pad count scales by 2𝑀(𝑁 log2 𝑁 − 𝑁). Another advantage the RAMZI switch has over the crossbar switch is that the loss through the switch is not path-dependent due to its balanced path configuration. In the crossbar switch, the difference between the shortest and longest paths is 2(𝑁 − 1) switching elements.
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