Multi-port optical coupling system

The invention provides an optical coupling system having a first collimator assembly having a first optical axis, a second collimator assembly having a second optical axis, an optical device, such as a tap coupler, an isolator or a WDM filter, disposed along an optical path between the first and the second collimator assembly, a first sleeve for containing the first collimator assembly, said first sleeve having an angled end face for forming a first angle, and a second sleeve for containing the second collimator assembly, said second sleeve having an end face for abutting the angled end face of the first sleeve such that the first optical axis of the first collimator assembly intersects with the second optical axis of the second collimator assembly at a coupling angle. The first sleeve and the second sleeve are relatively rotatable to each other for changing the coupling angle. Furthermore, the end face of the second sleeve is angled for forming a second angle.