The coefficient of absorption of a pre-selected region of a glass sheet is preferentially increased. The glass sheet may thereafter be sealed to a substrate using a sealing laser. In one embodiment, the coefficient of absorption sheet is increased by irradiating the glass sheet at a wavelength of about 248 nm, preferably through a mask, to produce an irradiated pattern on the glass sheet having a pre-determined shape. The glass sheet is then heat treated, placed over a substrate and sealed to the substrate by exposing the irradiated pattern to a sealing laser light having a wavelength in the range between about 355 nm and 532 nm to produce a glass envelope. The method disclosed herein is useful, inter alia, for manufacturing electro-luminescent devices, such as light emitting diodes (LEDs) and in particular organic light emitting diodes (OLEDs).