Optical connector coupling for reducing unwanted effects associated with high power density

An optical connector ferrule is provided having an standard single mode optical fiber therein whose mode field diameter is approximately 10 mu m along its length. An end portion and the end face of the optical fiber are heated to thermally expanded the mode field diameter to approximately 20 mu m or greater for reducing power density at the end face. By providing an expanded mode field diameter at the end face of the fiber, the power density is lessened, thereby lessening the probability that any dirt or debris at the end face will become heated sufficiently to damage the optical fiber.