We analyze the development of collaborative research in the technological field of laser beam sources (IPC code H01S) that newly emerged in the year 1960. We are able to follow all patent applications in this category with German priority from the emergence of this technology to the year 2005, a period of 45 years. Our main measure of innovative labor division is co-invention as documented by the number of inventors named in a patent application. We find a significant trend towards an increasing share of patent applications in the field of laser beam sources that have several inventors. At the same time, average team size has also increased. Teams are not very stable indicating that the composition of teams is primarily determined by the nature of the respective problem. Constructing networks of inventors for different sub-periods shows an increasing degree of integration particularly at a time when the number of patents approached the peak level. Our analysis confirms the long-term trend towards collaborative research.