Passive laser-fiber alignment by index method

A method for packaging a laser-fiber module was explored in which the critical laser-fiber alignment is carried out not with the usual active means, i.e., with the laser activated, but by a passive method based on the registration principles of photolithography. The method relies on an index scheme in which fiducial marks are lithographically placed on the laser chip and on a fiber carrier. At 850 nm, using the index technique with cleaved multimode fibers, it was possible to achieve the same laser-fiber coupling efficiency as attained by active alignment; with cleaved single-mode fibers about 80% of the active-alignment coupling efficiency was achieved.<>