Towards Maximum Energy Efficiency in Nanophotonic Interconnects with Thermal-Aware On-Chip Laser Tuning

Abstract

Nanophotonic is an emerging technology considered as one of the key solutions for future generation on-chip interconnects. However, silicon photonic devices are highly sensitive to temperature variation. Under a given chip activity, this leads to a lower laser efficiency and a drift of wavelengths of optical devices (on-chip lasers and microring resonators (MRs)), which results in a higher Bit Error Ratio (BER). In this paper, we propose to jointly tune the on-chip lasers and and MRs in order to align the wavelengths of the emitted signals with the resonant wavelengths of the MRs. Our method allows significant improvements of the power consumption with regard to the related methods, while meeting the BER requirement. Compared to methods for which laser tuning is not possible, results show that a combined tuning of laser and MRs leads to 53% energy reduction when the uniform chip activity decreases from 20% to 5%. BER-energy tradeoffs have been explored and allow strategies to be defined to minimize either the energy, or the BER. As a key result, we have shown that, under specific chip activities, increasing the laser power consumption allows both energy and BER to be improved. This trend has been observed for a MWSR channel interconnecting 12 interfaces.

Key issues in exascale computing

“…研究者已经提出许多片上光网的方案, 例如, 波长寻址的片上全光网 λ-Router [61] , Snake 和 Folded Crossbar [62] , 基于预约寻址的片上全光网 QuT [63] 和 Amon [64] , 基于时分复用的片上光网 Corona [65] , FlexiShare [66] , Channel Borrowing [67] 和 SUOR [68] , 兼有电网络和光网络优点的光电混 合网络 Meteor [69] , Atac [59] 和 Firefly [70] 等. 文献 [ (1) 节点操作系统要充分考虑众核特点.…”

Energy and Performance Trade-off in Nanophotonic Interconnects using Coding Techniques

“…This approach has been extended in [8] by considering the laser thermal sensitivity and the crosstalk to evaluate the BER. However, the authors did not investigate the use of ECC for data transmission.…”

“…Finally, the minimum laser output power OP laser is estimated using the transmission model proposed in [8]. In this model, the authors evaluate the total signal transmission in a MWSR channel by taking into account the transmission in each MR (i.e.…”

“…The temperature of the VCSEL depends on i) the optical power to be emitted (OP laser ) and ii) the activity of the electrical layer. Following the methodology detailed in [8], the laser power consumption P laser is estimated assuming 25% chip activity. As illustrated in Figure 4, P laser linearly increases within the 0 − 500µW optical power range but follows an exponential trend for larger values.…”

A Reliability-Aware Joint Design Method of Application Mapping and Wavelength Assignment for WDM-Based Silicon Photonic Interconnects on Chip

“…As a result, the OSNR of the expected signal would decrease, and thus the communication reliability would get worse, especially when many wavelengths are used for communication. In the worst case, the received signal might not be good enough for the correct communication [6], which leads to more laser power consumption [7], [8] for re-transmitting or more cost for signal correction. In the meantime, the scalability of photonic interconnect architecture is limited under a given laser power budget.…”