An ammunition cartridge including a case, an ignitable material within the case and an optical primer for igniting the ignitable material. The optical primer includes a conductive cylindrical cup electrically coupled to the case and a circular conductive button including a top button portion positioned in the cup and a bottom button portion extending through an opening in the cup, where the button and the cup are electrically isolated. The optical primer further includes a first bracket electrically coupled to the button, a second bracket electrically coupled to the cup, and a pair of laser diodes electrically coupled in a reverse parallel direction and being electrically coupled to the first and second brackets, where one of the laser diodes generates a laser beam that ignites the ignition material in response to a current flow in either direction through the case, the cup and the button.