Silicon Electronic Photonic Integrated Circuits for High Speed Analog to Digital Conversion

Abstract: Integrated optical components on the silicon platform and optically enhanced electronic sampling circuits are demonstrated that enable the fabrication of a variety of electronic-photonic A/D converter chips surpassing currently available technology in sampling speed and resolution

Infrared frequency selective surfaces fabricated using optical lithography and phase-shift masks

A frequency selective surface (FSS) structure has been fabricated for use in a thermophotovoltaic system. The FSS provides a means for reflecting the unusable light below the bandgap of the thermophotovoltaic cell while transmitting the usable light above the bandgap. This behavior is relatively independent of the light's incident angle. The fabrication of the FSS was done using optical lithography and a phase-shift mask. The FSS cell consisted of circular slits spaced by 1100 nm. The diameters and widths of the circular slits were 870 nm and 120 nm, respectively. The FSS was predicted to pass wavelengths near 7 {micro}m and reflect wavelengths outside of this pass-band. The FSSs fabricated performed as expected with a pass-band centered near 5 {micro}m

High speed analog-to-digital conversion with silicon photonics

Sampling rates of high-performance electronic analog-to-digital converters (ADC) are fundamentally limited by the timing jitter of the electronic clock. This limit is overcome in photonic ADC's by taking advantage of the ultra-low timing jitter of femtosecond lasers. We have developed designs and strategies for a photonic ADC that is capable of 40 GSa/s at a resolution of 8 bits. This system requires a femtosecond laser with a repetition rate of 2 GHz and timing jitter less than 20 fs. In addition to a femtosecond laser this system calls for the integration of a number of photonic components including: a broadband modulator, optical filter banks, and photodetectors. Using silicon-on-insulator (SOI) as the platform we have fabricated these individual components. The silicon optical modulator is based on a Mach-Zehnder interferometer architecture and achieves a V[subscript pi]L of 2 Vcm. The filter banks comprise 40 second-order microring-resonator filters with a channel spacing of 80 GHz. For the photodetectors we are exploring ion-bombarded silicon waveguide detectors and germanium films epitaxially grown on silicon utilizing a process that minimizes the defect density.Defense Advanced Research Projects Agency (contracts W911NF-04-1-0431 and HR0011-05-C-0155)Department of the Air Force (Air Force Contract FA8721-05-C-0002