The growing demand for fast, reliable and low power interconnect systems requires the development of efficient and scalable CMOS compatible photonic devices, in particular optical modulators. In this paper, we demonstrate an innovative electro absorption modulator (EAM) developed on an 800 nm SOI platform; the device is integrated in a rib waveguide with dimensions of a 1.5 μm x 40 μm, etched on a selectively grown GeSi cavity. High speed measurements at 1566 nm show an eye diagram with dynamic ER of 5.2 dB at 56 Gbps with a power consumption of 44 fJ/bit.
The field of silicon photonics is attracting a lot of attention due to the prospect of low-cost and compact circuits that integrate photonic and microelectronic elements on a single chip. Such silicon chips have applications in optical transmitter and receiver circuits for short-distance communications as well as for long-haul optical transmissions. Silicon photonics has proven to be a successful platform for many functional elements such as low-loss waveguides, filters, multiplexers/demultiplexers, optical modulators and Ge-on-Si photodiodes. On-going developments for advanced photonic integrated circuits include compact and energy-efficient silicon modulators, temperature-insensitive passive devices and hybrid III-V on Silicon lasers.
The European COSMICC project gathers key industrial and research partners in the field of silicon photonics, CMOS electronics, printed circuit board packaging, optical transceivers and datacenters, aiming at developing low-cost and low-energy consumption 50 Gb/s 4-wavelength coarse wavelength division multiplexing optical transceivers that will be packaged on-board. Combining CMOS electronics and Si-photonics with innovative high-throughput fiber attachment techniques, the developed solutions will be scalable beyond 1 Tb/s to meet the future data-transmission requirements in data-centers and super computing systems.
Diabetes is a fast growing metabolic disease, where the patients suffer from disordered glucose blood levels. Monitoring
the blood glucose values in combination with extra insulin injection is currently the only therapy to keep the glucose
concentration in diabetic patients under control, minimizing the long-term effects of elevated glucose concentrations and
improving quality of life of the diabetic patients. Implantable sensors allow continuous glucose monitoring, offering the
most reliable data to control the glucose levels. Infrared absorption spectrometers offer a non-chemical measurement
method to determine the small glucose concentrations in blood serum. In this work, a spectrometer platform based on
silicon photonics is presented, allowing the realization of very small glucose sensors suitable for building implantable
sensors. A proof-of-concept of a spectrometer with integrated evanescent sample interface is presented, and the route
towards a fully implantable spectrometer is discussed.
In this paper we discuss silicon-based photonic integrated circuit technology for applications beyond the
telecommunication wavelength range. Silicon-on-insulator and germanium-on-silicon passive waveguide circuits are
described, as well as the integration of III-V semiconductors, IV-VI colloidal nanoparticle films and GeSn alloys on
these circuits for increasing the functionality. The strong nonlinearity of silicon combined with the low nonlinear
absorption in the mid-infrared is exploited to generate picosecond pulse based supercontinuum sources and optical
parametric oscillators that can be used as spectroscopic sensor sources.
In this paper we review our work in the field of heterogeneous integration of III-V semiconductors and non-reciprocal optical materials on a silicon waveguide circuit. We elaborate on the heterogeneous integration technology based on adhesive DVS-BCB die-to-wafer bonding and discuss several device demonstrations. The presented devices are envisioned to be used in photonic integrated circuits for communication applications (telecommunications and optical interconnects) as well as in spectroscopic sensing systems operating in the short-wave infrared wavelength range.
In this paper, we review our work on efficient, broadband and polarization independent interfaces between a silicon-on-insulator photonic IC and a single-mode optical fiber based on grating structures. The high alignment tolerance and the fact that the optical fiber interface is out-of-plane provide opportunities for easy packaging and wafer-scale testing of the photonic IC. Next to fiber-chip interfaces we will discuss the use of silicon grating structures in III-V on silicon optoelectronic components such as integrated photodetectors and microlasers.
Several molecules of interest have their absorption signature in the mid-infrared. Spectroscopy is commonly used for the
detection of these molecules, especially in the short-wave infrared (SWIR) region due to the low water absorption.
Conventional spectroscopic systems consist of a broadband source, detector and dispersive components, making them
bulky and difficult to handle. Such systems cannot be used in applications where small footprint and low power
consumption is critical, such as portable gas sensors and implantable blood glucose monitors. Silicon-On-Insulator
(SOI) offers a compact, low-cost photonic integrated circuit platform realized using CMOS fabrication technology. On
the other hand, the GaSb material system allows the realization of high performance SWIR lasers and detectors.
Integration of GaSb active components on SOI could therefore result in a compact and low power consumption
integrated spectroscopic system.
In this paper, we report the study on thin-film GaSb Fabry-Perot lasers integrated on a carrier substrate. The integration
is achieved by using an adhesive polymer (DVS-BCB) as the bonding agent. The lasers operate at room temperature at
2.02μm. We obtain a minimum threshold current of 48.9mA in the continuous wave regime and 27.7mA in pulsed
regime. This yields a threshold current density of 680A/cm2 and 385A/cm2, respectively. The thermal behaviour of the device is also studied. The lasers operate up to 35 °C, due to a 323 K/W thermal resistance
Mid-infrared spectroscopy has gained significant importance in recent years as a detection technique for
substances that absorb in this spectral region. Traditionally, a spectroscopic system consists of bulky
equipment which is difficult to handle and incurs high cost. An integrated spectroscopic system would
eliminate these disadvantages. GaSb-based active opto-electronic devices allow realizing mid-infrared light
sources and detectors in the 2-3μm wavelength range for such integrated systems. Silicon photonics, based on
Silicon-on-Insulator (SOI) waveguide circuits, on the other hand, is a well established technology based on
high refractive index contrast waveguides, enabling ultra-compact passive integrated photonic circuits.
Moreover, SOI waveguide circuit processing is compatible with CMOS processes. Hence, the integration of
GaSb-based active devices onto SOI passive waveguide circuits potentially allows highly compact
spectroscopic systems with a large degree of freedom in passive device design to improve the system
performance. This approach has a high potential for several applications, e.g. an implantable glucose level
monitor and gas sensing devices.
In this paper, we report our work on the integration of GaSb-based epitaxy onto SOI waveguide circuits. The
heterogeneous integration is based on an epitaxial layer transfer process using the polymer divinylsiloxanebenzocyclobutene
(DVS-BCB) as a bonding agent. The process is performed by transferring the epitaxial
layer to an SOI waveguide circuit wafer through a die-to-wafer bonding process. With this approach, a
bonding layer of 150 nm thickness is easily achievable. We also report our results on the integration of
waveguide-based GaSb p-i-n photodetectors coupled to SOI waveguide circuits using evanescent coupling,
which show a responsivity higher than 0.4A/W. The design of active and passive structures and the overall
fabrication process will also be discussed.