ABSTRACT
Integrated microring resonators are well suited for wavelength-filtering applications in optical signal processing, and cascaded microring resonators allow flexible filter design in coupled-resonator optical waveguide (CROW) configurations. However, the implementation of high-order cascaded microring resonators with high extinction ratios (ERs) remains challenging owing to stringent fabrication requirements and the need for precise resonator tunability. We present a fully integrated on-chip second-order CROW filter using silicon photonic microelectromechanical systems (MEMS) to adjust tunable directional couplers and a phase shifter using nanoscale mechanical out-of-plane waveguide displacement. The filter can be fully reconfigured with regard to both the ER and center wavelength. We experimentally demonstrated an ER exceeding 25â dB and continuous wavelength tuning across the full free spectral range of 0.123â nm for single microring resonator, and showed reconfigurability in second-order CROW by tuning the ER and resonant wavelength. The tuning energy for an individual silicon photonic MEMS phase shifter or tunable coupler is less than 22 pJ with sub-microwatt static power consumption, which is far better than conventional integrated phase shifters based on other physical modulation mechanisms.
ABSTRACT
Pulse repetition rate multiplier (PRRM) is an essential component of microwave photonics systems, designed not only to alleviate photodiode saturation but also to provide more frequent pulses. However, the presence of interleaving time errors is known to compromise the advantages of PRRM. In this study, we present a high-sensitivity detection method for identifying these time errors using an electro-optic sampling-based timing detector (EOS-TD). We utilize two EOS-TDs: one for generating precise timing ruler signals and the other as a high-precision timing detector. In comparison to the conventional power ratio comparison method, our approach demonstrates sensitivity improvement by two orders of magnitude. This enhancement facilitates the measurement of femtosecond-level time errors. By enabling higher pulse rates while maintaining the ultralow jitter, this method can be useful for building higher-speed photonic systems.
ABSTRACT
This paper proposes a FMCW radar transceiver with photonic elements. The proposed radar system is efficiently designed by budget analysis, and a wideband signal is generated using photonic elements. To verify the performance of the proposed radar system, field tests including changes in bandwidth are conducted. The results confirm that the resolution of ISAR images improves as the bandwidth increases as expected through the budget analysis.
ABSTRACT
Pomegranate (Punica granatum) seed linolenic acid isomers were evaluated as selective estrogen receptor modulators (SERMs) in vitro. Punicic acid (PA) inhibited (IC(50)) estrogen receptor (ER) alpha at 7.2 microM, ERbeta at 8.8 microM; alpha-eleostearic acid (AEA) inhibited ERalpha/ERbeta at 6.5/7.8 microM. PA (not AEA) agonized ERalpha/ERbeta (EC(50)) at 1.8/2 microM, antagonizing at 101/80 microM. AEA antagonized ERalpha/ERbeta at 150/140 microM. PA and AEA induced ERalpha and ERbeta mRNA expression in MCF-7, but not in MDA-MB-231. Overall, the results show PA and AEA are SERMs.
