Tile-and-trim micro-resonator array fabrication optimized for high multiplexing factors.

We present a superconducting micro-resonator array fabrication method that is scalable and reconfigurable and has been optimized for high multiplexing factors. The method uses uniformly sized tiles patterned on stepper photolithography reticles as the building blocks of an array. We demonstrate this technique on a 101-element microwave kinetic inductance detector (MKID) array made from a titanium-nitride superconducting film. Characterization reveals 1.5% maximum fractional frequency spacing deviations caused primarily by material parameters that vary smoothly across the wafer. However, local deviations exhibit a Gaussian distribution in fractional frequency spacing with a standard deviation of 2.7 × 10-3. We exploit this finding to increase the yield of the BLAST-TNG 250 µm production wafer by placing resonators in the array close in both physical and frequency space. This array consists of 1836 polarization-sensitive MKIDs wired in three multiplexing groups. We present the array design and show that the achieved yield is consistent with our model of frequency collisions and is comparable to what has been achieved in other low temperature detector technologies.

On-chip optical interconnects made with gallium nitride nanowires.

In this Letter we report on the fabrication, device characteristics, and optical coupling of a two-nanowire device comprising GaN nanowires with light-emitting and photoconductive capabilities. Axial p-n junction GaN nanowires were grown by molecular beam epitaxy, transferred to a non-native substrate, and selectively contacted to form discrete optical source or detector nanowire components. The optical coupling demonstrated for this device may provide new opportunities for integration of optical interconnects between on-chip electrical subsystems.

Low-noise RF-amplifier-free slab-coupled optical waveguide coupled optoelectronic oscillators: physics and operation.

We demonstrate a 10-GHz RF-amplifier-free slab-coupled optical waveguide coupled optoelectronic oscillator (SCOW-COEO) system operating with low phase-noise (<-115 dBc/Hz at 1 kHz offset) and large sidemode suppression (>70 dB measurement-limited). The optical pulses generated by the SCOW-COEO exhibit 26.8-ps pulse width (post compression) with a corresponding spectral bandwidth of 0.25 nm (1.8X transform-limited). We also investigate the mechanisms that limit the performance of the COEO. Our measurements indicate that degradation in the quality factor (Q) of the optical cavity significantly impacts COEO phase-noise through increases in the optical amplifier relative intensity noise (RIN).

Amplifier-free slab-coupled optical waveguide optoelectronic oscillator systems.

We demonstrate a free-running 3-GHz slab-coupled optical waveguide (SCOW) optoelectronic oscillator (OEO) with low phase-noise (<-120 dBc/Hz at 1-kHz offset) and ultra-low sidemode spurs. These sidemodes are indistinguishable from noise on a spectrum analyzer measurement (>88 dB down from carrier). The SCOW-OEO uses high-power low-noise SCOW components in a single-loop cavity employing 1.5-km delay. The noise properties of our SCOW external-cavity laser (SCOWECL) and SCOW photodiode (SCOWPD) are characterized and shown to be suitable for generation of high spectral purity microwave tones. Through comparisons made with SCOW-OEO topologies employing amplification, we observe the sidemode levels to be degraded by any amplifiers (optical or RF) introduced within the OEO cavity.