The mechanism of the SiH 3 + SiH 3 reaction was studied by means of time resolved mass spectrometry. SiH 3 radical was generated by the ArF laser photolysis of C 2 Cl 4 in SiH 4 /He mixtures, and the products were detected by a low-energy electron impact ionization mass spectrometer. The rate constant derived from the decay rate of SiH 3 agreed well with that obtained from the rise rate of Si 2 H 6 . The overall rate constant of the reaction at 297 ( 2 K was determined to be (9.5 ( 3.5) × 10 -11 cm 3 molecule -1 s -1 . H 2 could also be detected as a product of the SiH 3 + SiH 3 reaction, and the yield of H 2 was measured to be 11 ( 4%. The other major product of the SiH 3 + SiH 3 reaction was SiH 2 , which rapidly reacts with SiH 4 to form Si 2 H 6 . It was confirmed by the addition of a large amount of H 2 as a SiH 2 -trapping reagent that Si 2 H 6 detected at p ) 5 Torr was exclusively produced via the SiH 2 + SiH 4 reaction. On the basis of these observations, the branching ratios for the decomposition of vibrationally excited Si 2 H 6 produced by the SiH 3 + SiH 3 reaction were estimated. These results were compared with conventional RRKM calculations.
Carrier-injection-based efficient polarization controller with a strained InGaAsP multiple-quantum-well (MQW) layer is demonstrated on a regrowth-free InP platform. We employ a straight-line device configuration by cascading an asymmetric polarization rotator (PR) to provide a fixed polarization conversion and a polarization-dependent phase shifter (PD-PS) to enable tunable polarization rotation. Based on a novel design concept, both the PR and PD-PS sections are integrated monolithically without active-passive integration. Using the fabricated device, we experimentally demonstrate efficient polarization conversion over the entire Poincaré sphere with a total current of less than 40 mA. With the capability of monolithically integrating other InP-based active components, the demonstrated scheme should be attractive for various applications, such-as low-cost coherent communication, microwave photonics, and quantum key distribution.
Integrated reconfigurable optical unitary converters (OUCs) are crucial in realizing all-optical spatial mode demultiplexing for mode-division-multiplexed transmission systems and programmable photonic processing for optical neural networks. In this work, we present the first experimental demonstration of 4×4 OUC monolithically integrated on InP. To avoid the difficulty of integrating a large number of Mach-Zehnder interferometer couplers on the InP platform, we apply the concept of multi-plane light conversion and use cascaded stages of 4-port multimode interference couplers, which are more scalable and easier to fabricate on InP. By optimizing the phase shifters, we demonstrate reconfigurable 4-mode sorting as well as error-free switching of 40-Gbit/s signal.
Carrier-injection-based polarization controller with strained MQW layer is demonstrated. Based on novel design concept, both polarization-rotating and phase-shifting sections are integrated monolithically on regrowth-free InGaAsP/InP platform to achieve efficient conversion over the entire Poincaré sphere.
Experimental studies on astrophysical reactions involving radioactive isotopes (RI) often accompany technical challenges. Studies on such nuclear reactions have been conducted at the low-energy RI beam separator CRIB, operated by Center for Nuclear Study, the University of Tokyo. We discuss two cases of astrophysical reaction studies at CRIB; one is for the 7Be+n reactions which may affect the primordial 7Li abundance in the Big-Bang nucleosynthesis, and the other is for the 22Mg(α, p) reaction relevantin X-raybursts.
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