A segment of optical fiber is engaged with a fiber groove on a device substrate, which positions the fiber segment for optical coupling with an optical component on the substrate. A fiber retainer maintains the fiber segment in engagement with the groove. The fiber retainer may be secured to the substrate with adhesive means. The adhesive means forms at least one retaining member that at least partially fills at least one recessed region formed on the device substrate or on the fiber retainer. That recessed region is spatially separate from the fiber groove and from an area of the fiber retainer engaged with the fiber.