Patent ID: 7265840

Claim:
A method for determining an improved optical alignment to couple an optical beam having a high power level into an optical waveguide, the improved optical alignment determined such that a power level of a portion of the optical beam coupled into the optical waveguide is substantially maximized, the method comprising the steps of: a) reducing a power level of the optical beam to a minimum test power level, the minimum test power level being less than about one half of the high power level; b) aligning the reduced-power optical beam in a test alignment such that a beam spot of the reduced-power optical beam is formed on a coupling surface of the optical waveguide; c) measuring a coupled power level of the portion of the optical beam coupled into the optical waveguide; d) increasing the power level of the reduced-power optical beam in predetermined steps to a maximum test power level and repeating step (c) for each power level; e) if the coupled power level measured in step (c) does not saturate and a corresponding coupling efficiency is greater than or equal to a desired coupling efficiency, determining that the current test alignment is the improved optical alignment, completing the method, otherwise: i) reducing the power level of the optical beam to the minimum test power; ii) changing the test alignment to vary at least one of; a size of the beam spot formed on the coupling surface of the optical waveguide; a position of the beam spot formed on the coupling surface of the optical waveguide; an angle of incidence of the reduced-power optical beam on the coupling surface of the optical waveguide; or a cone angle of the reduced-power optical beam; and iii) repeating steps (c), (d), and (e), until a predetermined number of iterations are performed; and f) if the predetermined number of iterations are performed, determining the test alignment having a highest of the corresponding coupling efficiencies to be the improved optical alignment.