Servo-controlled light coupling between a light-emitting component and an optical fiber

Claim 1

Optical module comprising: an optoelectronic transmitter for emitting a beam of light, an optical fiber terminated by an end face on which is defined a core region surrounded by a second region having a reflection factor higher than that of the core region, adjustable coupling means for adjustably positioning the light beam from the optoelectronic light transmitter relative to the end face of the optical fiber, wherein the position of the light beam relative to the core region is adjusted to an optimum position in which a central portion of the light beam is coupled into the optical fiber with minimum loss, and control means responsive to an electrical control signal for adaptively adjusting the coupling means to maintain said optimum position, said control means further comprising: a detector having at least two opposing sectors fixedly positioned relative to said end face such that when said light beam is in said optimum position, approximately equal peripheral portions of said light beam are reflected onto each of said sectors from said second region, and such that as the reflected light beam portions shift in a first predetermined direction from a first sector to an opposing second sector, less of the reflected peripheral light beam portion incident on the first sector is reflected from said higher reflectivity region and more of said incident light beamm portion is reflected from the lower reflectivity core region, and means for generating said electrical control signal in response to the intensity of the reflected light beam portions incident on said opposing sectors, whereby any differences between the electrical outputs from two opposing sectors resulting from movement of a reflected light beam portion from a first position incident the first sector to a second position incident on the second sector is magnified by said reflectivity differences of the two end face regions, and whereby as a particular portion of the light beam which is reflected onto a particular sector moves from a first position such that it is reflected from the higher reflectivity second region to a second position where it is reflected off the lower reflectivity core region, a control signal representative of such movement is obtained from the sectors.