The capture, hold and forward release of an optical pulse from a dynamic photonic crystal nanocavity.

We develop a silicon photonic crystal nanocavity device capable of performing targeted optical pulse capture and release via distinct ports on demand, based on dynamic Q factor control. The capture of 4 ps pulses and their release up to 332 ps later is directly observed by time-resolved measurements of the energy behaviour in both the nanocavity and emitted from the release port. We also discuss how the behaviour of excited free carriers dictates the performance of such dynamic devices.

Time-resolved catch and release of an optical pulse from a dynamic photonic crystal nanocavity.

We perform time-domain measurements of the interaction between light and silicon photonic crystal nanocavities under dynamic Q factor control. Time-resolved evidence of optical pulse capture and release on demand is demonstrated and compared for samples with dynamic Q ranges from ~3,000 to 26,000 and from 18,500 to 48,000. Observing the energy behaviour in response to dynamic control provides insight not available with time-integrated measurements into factors influencing device performance such as carrier absorption and pulse capture efficiency.

Reaction of 2-methoxy-3H-azepine with NBS: efficient synthesis of 2-substituted 2H-azepines.

[reaction: see text] The reaction of 2-methoxy-3H-azepines, in the presence or absence of a nucleophile, with N-bromosuccinimide (NBS) gave a regioselective 1,4-adduct from which the corresponding 2H-azepine derivatives were formed via base-promoted hydrogen bromide elimination, generally in moderate to quantitative yield. Competitive formation of 4-bromo-2-methoxy-3H-azepine by electrophilic substitutuion or 3H-azepin-2-yl 2H-azepin-2-yl ether by transetherification was minimized at lower reaction temperatures. Quantitative substitution of 2-(2',4',6'-trichlorophenoxy)-2H-azepine derivatives, formed in moderate yield from the respective 3H-azepine and NBS in the presence of 2,4,6-trichlorophenol (TCP), by various nucleophiles gave the corresponding 2-substituted 2H-azepine. Among these nucleophiles were alkanethiol and alkylamine that are not tolerated in the reaction of 3H-azepine and NBS.