One of the key challenges in Silicon based optical interconnect system remains to be the efficient coupling of optical signals from the submicron size on-chip waveguides to standard single mode (SM) fibers with low insertion loss (IL) and relaxed alignment tolerance. Large optical alignment tolerance allows optical connectors to be attached to on-chip waveguides passively using standard semiconductor pick-and-place assembly tools that have placement accuracies of 10- 15μm. To facilitate the assembly, optical fiber coupling elements need to be modular and compact. They have to also have low profile to avoid blocking air flow or mechanical interference with other elements of the package. In this paper we report the development of a two-dimensional (2D) SM optical fiber coupling architecture that consists of Si based photonic lightwave circuit (PLC) substrate and a high-density micro-lensed fiber optic connector. The system is compact, efficient and has large optical alignment tolerance. At 1300nm an insertion loss of 2.4dB and 1.5dB was measured for the PLC module and the fiber optic connector, respectively. When the PLC module and connector was aligned together, a total insertion loss of 7.8dB was demonstrated with x,y alignment tolerance of 40μm for 1dB optical loss. The SM optical coupling architecture presented here is scalable, alignment tolerant and has the potential to be manufactured in high volume. To our knowledge, such a system has not been reported in the literature so far.
Electro-optic (EO) polymer cladding modulators are an option for low-power high-speed optical interconnects on a
silicon platform. EO polymers have inherently high switching speeds and have shown 40 Gb/s operation in EO polymer
clad ring resonator modulators (RRM). In EO polymer clad RRM, the modulator’s area is small enough to be treated as
a lumped capacitor; the capacitance is sufficiently low that the modulation speed is limited by the bandwidth of the
resonator. A high Q resonator is needed for low voltage operation, but this can limit the speed and/or require precise
control of the resonator’s wavelength, necessitating power consuming heaters to maintain optimal performance over a
large temperature range. Mach Zehnder modulators (MZM), on the other hand, are not as sensitive to temperature
fluctuations, but typically are relatively long and must employ power consuming terminated travelling wave electrodes.
In this paper, a novel MZM design is presented using an EO polymer clad device. In this device, the electrodes are
broken into short parallel segments and the waveguide folds around them. The segments of the electrode length are
designed to provide good signal integrity up to 20 GHz without termination. The electrodes are driven by a single drive
voltage and provide push-pull modulation. Modulators were designed and fabricated using silicon nitride waveguides
on bulk silicon wafers and were demonstrated at high speed (20 GHz). A VπL as low as 1.7 Vcm is measured on initial
devices. An optimized device could provide 40 Gb/s performance at 1 V drive voltages, ~100 fF total device
capacitance and less than 2 dB optical insertion loss.
Recently conjugated polymers and conjugated organic molecules have drawn a great deal of attention, since they are uniquely suited for thin film, large area, mechanically flexible devices. On the other hand, polymer/inorganic nanocomposite have also been pursued to deliver unique electronic properties in various device applications such as organic light-emitting diodes, organic thin film transistors, and solar cells. Here we demonstrate a nanocomposite based on polyaniline nanofibers decorated with gold nanoparticles and apply this composite into memory devices. The electronic property shows an electric bistable effect in a two terminal sandwiched structure. These two bistable states have different conductivities by three orders of magnitude. The mechanism is likely involving electric-field induced charge transfer between the polymer and nanoparticles. This nanocomposite material provides a unique functionality and possibility to open a new direction for future organic electronics.