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.
Silicon photonics has emerged as a promising material system for the fabrication of photonic devices as well as
electronic ones. The key advantage is that many electronic and photonic functions that up to now have only been
available as discrete components can be integrated into a single package. We present a silicon photonic platform that
includes low-loss passive components as well as high-speed modulators and photodetectors at or above 30 GHz. The
platform is available to the community as part of the OpSIS-IME MPW service.
Shared shuttle runs are an important factor of the microelectronics business ecosystem, allowing fabless semiconductor
companies to access advanced processes and supporting the development of new tools and processes. We report on the
creation and progress of a shared shuttle program for access to advanced silicon photonics optoelectronic platforms that
we expect will create a similar environment for the field of integrated photonics.
Silicon Photonics taps on the volume manufacturing capability of traditional silicon manufacturing techniques, to
provide dramatic cost reduction for various application domains employing optical communications technology. In
addition, an important new application domain would be the implementation of high bandwidth optical interconnects in
and around CPUs. Besides volume manufacturability, Silicon Photonics also allows the monolithic integration of
multiple optical components on the same wafer to realize highly compact photonic integrated circuits (PICs), in which
functional complexity can be increased for little additional cost. An important pre-requisite for Si PICs is a device library
in which the devices are compatibly developed around a common SOI platform. A device library comprising passive and
active components was built, which includes light guiding components, wavelength-division-multiplexing (WDM)
components, switches, carrier-based Si modulators and electro-absorption based Ge/Si modulators, Ge/Si photodiodes
and avalanche photodiodes, as well as light emitting devices. By integrating various library devices, PIC test vehicles
such as monolithic PON transceivers and DWDM receivers have been demonstrated. A challenge with Si PICs lies with
the coupling of light into and out of the sub-micrometer Si waveguides. The mode size mismatch of optical fibers and Si
waveguides was addressed by developing a monolithically integrated multi-stage mode converter which offers low loss
together with relaxed fiber-to-waveguide alignment tolerances. An active assembly platform using MEMS technology
was also developed to actively align and focus light from bonded lasers into waveguides.
An electro-absorption (EA) modulator holds distinct advantages over the silicon Mach-Zehnder interferometer
(MZI) modulator by having lower energy consumption, a smaller footprint on-chip, and a potentially higher modulation
speed. These are crucial for efficient encoding of optical signals in silicon photonics circuits. Furthermore, the
development of a Group IV-based (i.e. silicon- or germanium-based) EA modulator allows compatibility with standard
complementary metal-oxide-semiconductor (CMOS) processing. In this work, we demonstrate a novel evanescent
germanium (Ge) EA modulator structure. A lateral electric field is employed in the Ge rib to enhance absorption via the
Frank-Keldysh effect. This shifts the absorption edge significantly with applied bias for wavelengths beyond 1600 nm.
A peak extinction ratio of ~15 dB at 1600 nm could be achieved for a <3 V dynamic voltage swing from a 20 μm
modulator. The impact of device dimensions and design structure on optical modulation and insertion loss are also
investigated. In addition, monolithic integration of waveguided Ge-based modulator and photodetector can be simplified
with our proposed EA modulator structure. The results from this work can make a low power and high speed Ge-based
EA modulator viable for future silicon photonics applications.