A light source provided with a laser element that emits a laser beam emits a laser beam for synchronization control. The invention is also a toughened dielectric polymer comprising benzocyclobutene-based monomers or oligomers, ethylenically unsaturated polymer additive, and, optionally, a photoactive compound. In addition the amplifier is provided with a transconductance gain. for a time period of between 30 minutes and 1 hour to consolidate the defects; applying a second defect enlargement heat treatment to the substrate at a temperature of between 900\xb0 C. This arrangement minimises delay before retransmission of data, and improves the robustness of the system.