13C-Optimized HTS NMR RF Coil Design at 21.1 T.

We present the design of a novel high-temperature superconductor double-sided racetrack resonator for a 13C optimized nuclear magnetic resonance (NMR) transmitter/receiver coil. The coils operate in a 21.1 T magnet and accommodate a 3 mm × 6.2 mm cross-section rectangular sample tube. The design includes the incorporation of revised finger lengths to improve the homogeneity of current density across the fingers, a new laser trimming approach for adjusting the resonance frequency, and improved ability to shift higher-order modes for suitability in 1H/13C NMR probes. Resonator design methodology, simulations and experimental results are presented.

Modeling the Resonance Shifts Due to Coupling Between HTS Coils in NMR Probes.

Nuclear magnetic resonance (NMR) probes using thin-film HTS coils offer high sensitivity and are particularly suitable for small-sample applications. Typically, HTS probes are optimized for the detection of multiple nuclei and require several coils to be located within a small volume near the sample. Coupling between the coils shifts coil resonances and complicates coil trimming when tuning HTS probes. We have modeled the magnetic coupling between the coils of a 1.5-mm all-HTS NMR probe with 13C, 1H, and 2H channels. By measuring the magnetic coupling coefficients between individual coils, we solve the general coupling matrix given by KVL for six coupled resonators. Our results indicate that required trims can be accurately predicted by applying single coil trimming simulations to this magnetic coupling model. Use of the magnetic coupling model significantly improves the efficiency of tuning HTS probes.

Grating-enhanced through-wafer optical microprobe for microelectromechanical system high-resolution optical position feedback.

We present modeling and experimental results from the use of a 1310-nm-wavelength through-wafer optical microprobe in conjunction with a microstructure grating to monitor the motion of a lateral comb resonator stage. The optical signal that results from shuttle interaction with the microprobe beam exhibits a peak-to-valley dynamic range that corresponds to 2-microm microstructure displacement, facilitating submicrometer positional resolution on digitization. This signal was used to achieve microstructure positional feedback and effective microsystem model parameter extraction, which are essential for structure control and model-based fault detection.

Fresnel phase plate lenses for through-wafer optical interconnections.

While the advantages of optical over electrical interconnects for conventional 2-D VLSI and wafer-scaleintegrated (WSI) circuits have not been clearly demonstrated, for 3-D interconnection structures such as those necessary for stacked wafer and similar architectures, the trade-off between using optical or electrical methods for vertical links is not straightforward. Current work on fabricating a through-wafer optical interconnect within a hybrid-WSI environment is motivated by the need to obtain experimental data on the overall performance of an optical interconnect so that this trade-off can be clarified inthe case of hybrid-WSI and in the general case at least more well defined. This paper details the design and fabrication of SiO(2) Fresnel phase plate lens arrays for use in the experimental 1.3-microm wavelength through-wafer optical interconnects to be constructed. These 0.8-N.A. lenses have submicron minimum linewidths and are VLSI process compatible. Preliminary results are presented indicating that, with the use of these lens arrays, vertical optical interconnect densities comparable with that of on chip bonding pads ( approximately 250-microm pitch) are obtainable within these architectures.