Ultra-compact 8 × 8 strictly-non-blocking Si-wire PILOSS switch

Abstract

We report on a path-independent insertion-loss (PILOSS) 8 × 8 matrix switch based on Si-wire waveguides, which has a record-small footprint of 3.5 × 2.4 mm2. The PILOSS switch consists of 64 thermooptic Mach-Zehnder (MZ) switches and 49 low-crosstalk intersections. Each of the MZ switches and intersections employs directional couplers, which enable the composition of a low loss PILOSS switch. We demonstrate successful switching of digital-coherent 43-Gbps QPSK signal.

Silicon Photonics towards Disaggregation of Resources in Data Centers

“…The use of BF-encoded forwarding requires a number of look-up table entries that equals the number of switch outgoing ports, suggesting significant savings in router look-up table memory requirements, while the whole concept can easily be expanded to a larger scale. A single FPGA board can easily control more than 100 Si photonic switches, while large scale Si-pho switches have already been demonstrated in the literature [12][13][14][15][16].…”

“…Silicon photonics arise as a promising technological candidate with high port count photonic fabrics already presented in the literature offering low cost due to their CMOS compatible fabrication processes and fast response time in the µs or even in the ns regime [12][13][14][15][16]. Moreover, they have been recently demonstrated in multi-casting routing schemes [15], as well as in software-programmable setups, exploiting photonic hardware-software co-development efforts [15,[17][18][19][20][21][22] in order to gradually enrich their portfolio towards supporting the increased dynamicity and reconfigurability required in DC environments.…”

Multiport optical switches integrated on Si photonics platform

“…In both the approaches, −40 dB crosstalk and 0.2 dB insertion loss can be achieved. As an approach without the mode expansion, a tilted waveguide crossing [19], a subwavelength structure [20], and a directional coupler [21,22] have been proposed. For the large port count switch, crosstalk and insertion loss are desired to be as low as possible because the switch consists of a cascade of a large number of intersections.…”

“…The drawbacks of using the thick rib waveguides are incompatibility with electric circuits and increase in size due to the weak confinement. Our group presented [22,25] an 8 Â 8 strictly non-blocking PILOSS matrix switch based on silicon wire waveguides with the record-small footprint of 2:4 Â 3:5 mm 2 , which is 1/4 compared with the above mentioned switch with the thick rib waveguides. The silicon wire waveguide is 430-nm wide and 220-nm high.…”

“…The insertion loss is broken down into the fiber-to-chip coupling loss and onchip loss from the MZ switches and crossings. For the 8 Â 8 PILOSS with Si-wire waveguides [22,25], a total insertion loss of 13.7 dB were broken down into a fiber-to-chip coupling loss of 7.2 dB, and an on-chip loss of 6.5 dB including an access waveguide's loss of 1.8 dB. The fiber-to-chip coupling loss will be significantly reduced by using a sophisticated design for the spot size converters [27].…”