A method for providing, on a carrier (40), an insulative spacer layer (26) which is patterned such that a cavity (27) is formed which enables connection of an optical semiconductor element (41) to the intended conductor structure (22) when placed inside the cavity (27). The cavity (27) is formed such that it, through its shape, extension and/or depth, accurately defines a location of an optical element (45; 61) in relation to the optical semiconductor element (41). Through the provision of such a patterned insulative spacer layer, compact and cost-efficient optical semiconductor devices can be mass-produced based on such a carrier without the need for prolonged development or acquisition of new and expensive manufacturing equipment.