One or more single mode waveguide devices are fiber coupled such that
signals to an optical element affect the coupling of the waveguide device
to an optical fiber. A number of systems and methods are disclosed to
adjust the coupling of the waveguide device to the optical fiber. These
include dithering the tunable optical element at different frequencies
along differing axes and using a lock-in technique to derive an error
signal for each degree of motion, using a beamsplitter to form a
secondary image of the focused beam on a position-sensitive detector, the
use of a chiseled fiber to generate reflections from the angled facets,
using an additional laser for a secondary image, or obtaining a secondary
image from an angled fiber or a parasitic reflection.