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We show efficient wide-tunable mm-wave-to-optical transduction (20 to 70 GHz at -9 to -18 dBc) using a triple-microring modulator. Integrated monolithically with a 18% bandwidth LNA, it generates sidebands with <−35 dBm RF input. 

We demonstrate a dual-cavity modulator based mm-wave to optical converter on GF45SPCLO platform. An optical energy conversion efficiency at -29.8 dB and a side-band SNR at 30.7 dB are reported. 

We demonstrate a Dual Active-Cavity RF modulator combining T-shaped spoked junction with a novel “half-rib” waveguide in a monolithic electronic-photonic platform. We measure a sideband efficiency of -52 dB at 66 GHz RF carrier frequency. 

We demonstrate a Dual Active-Cavity RF modulator combining T-shaped spoked junction with a novel “half-rib” waveguide in a monolithic electronic-photonic platform. We measure a sideband efficiency of -52 dB at 66 GHz RF carrier frequency. 

Emerging applications of photonic integrated circuits are calling for extremely narrowband and/or low-insertion-loss bandpass filters. Both properties are limited by cavity losses or intrinsic quality factors. However, the choice of inter-cavity and bus couplings establishes trade-offs between these two properties and the passband shape, which have been little explored. Using the widely used second-order resonant system as an example, we present new, to the best of our knowledge, classes of filter passband shapes that provide the lowest insertion loss and the narrowest bandwidth for a given lossQ. A normalized design and novel properties based on a temporal coupled-mode theory model are presented, including a design tool to apply these results. These results may benefit loss-sensitive filtering applications such as quantum-correlated photon pair sources and RF-photonic integrated circuits. 

Electro-optic (EO) transduction of weak radio frequency (RF) and millimeter-wave signals, such as those received by an antenna, onto laser sidebands for processing in the optical domain requires efficient EO modulators. Microrings offer spatial density and efficiency advantages over Mach–Zehnder modulators (MZMs), but conventional single-ring modulators suffer a fundamental trade-off between resonantly enhanced conversion efficiency and the RF carrier frequency that it can accommodate. Dual-cavity “photonic molecule” modulators resolve this trade-off, allowing high efficiency independent of the RF carrier frequency by providing separate resonant supermodes to enhance the laser local oscillator (LO) and the narrowband RF-detuned sideband. However, the RF frequency is fixed at design time by geometry, with efficiency dropping quickly for RF carriers away from the design value. We propose a novel, to the best of our knowledge, triple-cavity configuration with an off-resonant middle ring acting as an effective tunable coupler between two active modulator cavities. This configuration provides wideband tunability of the target RF carrier while maintaining efficient sideband conversion. When the middle ring is passive (highQ), this configuration provides wide RF tunability with no efficiency penalty over the fixed dual-cavity case and could become an important building block for future RF/mm-wave photonic integrated circuits (PICs). 

We use a general theory to show a new class of bandpass filter shapes for coupled-resonator filters that provides the lowest insertion loss and the narrowest bandwidth achievable for a given intrinsic Q and bandwidth. 

We demonstrate a path to scalable, wavelength- multiplexed RF/mm-wave-photonic front-end systems-on-chip for radar and extreme massive MIMO arrays, in 300mm-foundry 45nm RF SOI CMOS. We demonstrate mm-wave-to-optical sensing elements comprising low-noise amplifiers (LNAs) mono- lithically integrated with triply-resonant photonic microring- resonator based modulators. The “photonic molecule” modulator concept breaks the conventional ring modulator conversion efficiency-bandwidth tradeoff and provides optimal performance RF-photonic applications, while supporting high bandwidth den- sities. We show a first experiment with projected noise figure of 24dB at 57GHz (30mW/element, -45dBm RF-input, 6dBm laser LO). The elements are tileable at small pitches, enabling photonic disaggregation of large-scale phased arrays. 

Nanostructured steels are expected to have enhanced irradiation tolerance and improved strength. However, they suffer from poor microstructural stability at elevated temperatures. In this study, Fe–21Cr–5Al–0.026C (wt%) Kanthal D (KD) alloy belonging to a class of (FeCrAl) alloys considered for accident‐tolerant fuel cladding in light‐water reactors is nanostructured using two severe plastic deformation techniques of equal‐channel angular pressing (ECAP) and high‐pressure torsion (HPT), and their thermal stability between 500–700 °C is studied and compared. ECAP KD is found to be thermally stable up to 500 °C, whereas HPT KD is unstable at 500 °C. Microstructural characterization reveals that ECAP KD undergoes recovery at 550 °C and recrystallization above 600 °C, while HPT KD shows continuous grain growth after annealing above 500 °C. Enhanced thermal stability of ECAP KD is from significant fraction (>50%) of low‐angle grain boundaries (GBs) (misorientation angle 2–15°) stabilizing the microstructure due to their low mobility. Small grain sizes, a high fraction (>80%) of high‐angle GBs (misorientation angle >15°) and accordingly a large amount of stored GB energy, serve as the driving force for HPT KD to undergo grain growth instead of recrystallization driven by excess stored strain energy.