CORNING, N.Y., Nov. 16 -- Corning Inc. and Oak Industries Inc. have signed a definitive merger agreement, which has been approved unanimously by the boards of both companies. The agreement calls for Corning to exchange .83 shares of its common stock for each share of Oak Industries common stock. Corning said the merger with Oak Industries would extend Corning's product portfolio into new market segments. Corning pointed specifically to Oak Industries' Lasertron Inc. subsidiary, a developer of active fiber-optic devices for telecommunications, which Corning expects to enhance its photonic technology product offering and development activities. Lasertron manufactures pump lasers -- the key active component in optical amplifiers -- and is one of a handful of companies with both internal laser chip-making capability and expertise in packaging. In addition, Lasertron produces transmission lasers and receivers aimed at the rapidly growing metropolitan transmission market.