Silicon optical modulators

Optical technology is poised to revolutionize short-reach interconnects. The leading candidate technology is silicon photonics, and the workhorse of such an interconnect is the optical modulator. Modulators have been improved dramatically in recent years, with a notable increase in bandwidth from the megahertz to the multigigahertz regime in just over half a decade. However, the demands of optical interconnects are significant, and many questions remain unanswered as to whether silicon can meet the required performance metrics. Minimizing metrics such as the device footprint and energy requirement per bit, while also maximizing bandwidth and modulation depth, is non-trivial. All of this must be achieved within an acceptable thermal tolerance and optical spectral width using CMOS-compatible fabrication processes. This Review discusses the techniques that have been (and will continue to be) used to implement silicon optical modulators, as well as providing an outlook for these devices and the candidate solutions of the future

Novel method of patterning YBaCuO superconducting thin films

A unique method of patterning YBaCuO thin films based on the inhibition of superconductivity by Si-YBaCuO intermixing has been developed. In the experiment, a thin Si film was first evaporated on a MgO substrate and subsequently patterned using laser direct-write etching. Multilayered YBaCuO thin films were then deposited by e-beam evaporation and annealed in a rapid thermal annealing system for 30-90 s at 980°C. The YBaCuO film deposited on the silicon regions became insulating. Auger depth profiling measurements indicate that Si-YBaCuO intermixing had occurred in these areas. Between the insulating regions, narrow YBaCuO superconducting lines were formed. For both 10-μm-wide, 1-mm-long and 2.5-μm-wide, 80-μm-long lines, the T c was observed above 76 K. The critical current density of the lines was measured to be 300 A/cm2 at 75 K. This patterning technique may be useful for fabrication of high Tc superconducting interconnects and devices.link_to_subscribed_fulltex