Preferred embodiments of the invention include a thyristor core that is single biased by a source, such as a power source (or a portion thereof) that is being switched through the thyristors. An optically activated transistor that is preferably a minority carrier device is in series with the thyristor core. The thyristor core has an optically activated gate. The turn-off of the thyristor can be accelerated by the turn-on (conduction state) of a gate switch, which ensures a unity gain turn-off of the core thyristor.