Wavelength-selective 4×4 nonblocking silicon optical router for networks-on-chip

Abstract

We design and fabricate a wavelength-selective nonblocking 4 × 4 silicon optical router based on microring resonator for use in future integrated photonic interconnection networks. We successfully demonstrate 12 possible I/O routing paths and present 13 nonblocking operating states, including four broadcasting states, with worst-case extinction ratio and cross talk of 21.05 and -21.56 dB, respectively. Thermal tuning is employed to compensate the resonance shift of microring resonators caused by fabrication errors and adjust the resonance to match the International Telecommunication Unit grid with the channel spacing of 100 GHz.

Silicon photonic network-on-chip and enabling components

“…Figures 3(a) and 3(b) show the schematic configuration and micrograph of a demonstrated Si MRR-based wavelength-selective (WS) 4 × 4 non-blocking optical router [66]. The four ports are labeled as North (N), South (S), East (E), and West (W).…”

“…The MRR-based devices demonstrated in refs. [66][67][68] adopt the passive wavelength-selective operating principle. Among them, our device exhibits much lower CT but at the sacrifice of more power consumption.…”

“…However, the free carrier absorption (FCA) effect coexisting with FCD effect in Si is a detrimental behavior that can influence the CT and ER of interference-based optical devices, which caused the CT of the reported EO switches seldom below 20 dB. In [66] order to reduce the CT, we improved the traditional structure and demonstrated a 2×2 MZI-based EO switch [78]. The schematic structure is shown in Figure 4(a), composed of a 2×2 EO switch integrated with a variable optical attenuator (VOA) that is used to remove the undesired optical power.…”

Four-Port Silicon Multi-Wavelength Optical Router for Photonic Networks-on-Chip

“…Unlike the optical crossbar in [10] and [11], only three operating wavelengths are needed to realize communications among the four ports in our device and no paths exist for signals to enter and exit from the same port (U-turn). Compared to the router demonstrated in our previous work [9], this new design offers desirable optical spectra for multi-wavelength routing. Four group wavelengths (in the measured spectral range) with spacing equal to the MRRs' free spectral range (FSR) can be routed simultaneously to increase the aggregate bandwidth of the router, and the number of MRRs of this simple configuration is reduced by half, which leads to a smaller footprint and less power consumption.…”

“…The drawback is that they need additional switching time and power consumption for the optical path pre-configuring. The other one consists of passive add-drop ring filters [9]- [11]. All the paths between input and output ports are fixed and optical signals transmit with assigned wavelengths.…”