We present a widefield microscopy system for imaging super-paramagnetic nanoparticles (SPNs), and propose to use it
as a bio-sensing system wherein SPNs are used as tags. Potential advantages of magnetic tags over conventional
fluorescent tags include the elimination of noise from auto-fluorescence, optical isolation of the biological system from
the measurement apparatus, and the potential for magnetic removal of non-specifically bound material. The microscope
magnetic sensing surface is composed of a thin layer of nitrogen-vacancy defect centers in the top 200 nm of a diamond
substrate. Nitrogen-vacancy centers in diamond have been shown to be suitable for use as highly sensitive
magnetometers due to their long spin-coherence time at room temperature. Furthermore, spin-dependent
photoluminescence allows for simple far-field optical readout of the spin state, which in turn allows for opticallydetected
magnetic resonance measurements. We will present our results detecting a single, lithographically defined 50
nm diameter by 100 nm thick iron nanodot. With the current sensitivity of 9 μT⋅Hz-1/2, we expect to be able to detect single 20 nm magnetite SPNs, our proposed tags, in less than one minute. By further optimizing the sensor surface, we predict DC magnetic sensitivities as low as 1 μT⋅Hz-1/2.
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.
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