Silicon photonics has attracted extensive attention in recent years as a promising solution for next generation high-speed, low energy consumption, and low cost data transmission systems. Although a few experiments indicated board-level and long haul communication capability, major and near-future application of silicon photonics is commonly seen as Ethernet at 100Gb/s and beyond, such as interconnects in data centers, where O-Band (near 1310 nm wavelength) has been standardized for its low fiber dispersion. However, almost all silicon photonics devices demonstrated up to date operate at C-Band (1530 nm to 1560 nm), the fiber loss and erbium amplification window, probably due to the wider availability of lasers and testing apparatus at this wavelength. Typical C-Band devices cannot operate at O-Band, thus the whole device library needs to be redesigned and recalibrated for O-Band applications. In this paper, we present an ultra compact, low loss, and low crosstalk waveguide crossing operating at O-Band. It is designed using the finite difference time domain method coupled with a particle swarm optimization. Device footprint is only 6 μm × 6 μm. The measured insertion loss is 0.19±0.02 dB across an 8-inch wafer. Cross talk is lower than -35 dB. We also report a second waveguide crossing with a 9 μm × 9 μm footprint with 0.017±0.005 dB insertion loss. Finally we summarize the performance of our overall O-Band device library, including low-loss waveguides, high-speed modulators, and photodetectors.
We have developed a CMOS-compatible Silicon-on-Insulator photonic platform featuring active components such as pi- n and photoconductive (MIM) Ge-on-Si detectors, p-i-n ring and Mach-Zehnder modulators, and traveling-wave modulators based on a p-n junction driven by an RF transmission line. We have characterized the yield and uniformity of the performance through automated cross-wafer testing, demonstrating that our process is reliable and scalable. The entire platform is capable of more than 40 GB/s data rate. Fabricated at the IME/A-STAR foundry in Singapore, it is available to the worldwide community through OpSIS, a successful multi-project wafer service based at the University of Delaware. After exposing the design, fabrication and performance of the most advanced platform components, we present our newest results obtained after the first public run. These include low loss passives (Y-junctions: 0.28 dB; waveguide crossings: 0.18 dB and cross-talk -41±2 dB; non-uniform grating couplers: 3.2±0.2 dB). All these components were tested across full 8” wafers and exhibited remarkable uniformity. The active devices were improved from the previous design kit to exhibit 3dB bandwidths ranging from 30 GHz (modulators) to 58 GHz (detectors). We also present new packaging services available to OpSIS users: vertical fiber coupling and edge coupling.