A structure for controlling electric field distribution in an optoelectronic device

An optical device comprises an optoelectronic device (300) formed on a substrate (302), wherein the substrate (302) includes a recess (330) formed beneath the optoelectronic device (300). A surface of the recess (330) is coated with a layer of an electrically conducting material (316) so that the spatial distribution of electrical energy (318) in the optical device is preferentially determined by the electrically conducting material (316). The optical device may be a laser diode, an optical amplifier, an optical modulator, an optical switch or a photodetector. The recess which may be called a "backtub" preferably, controls the electric field distribution in an optoelectronic device, or array of devices.