Method and apparatus for measuring single mode fiber mode field radius.

摘要

The fundamental-mode field radius 'w' is a key parameter in characterizing optical fibers. 'w' is a function of P, theta and lambda where P is the far-field power passing through a circular aperture subtending a solid angle of 2 theta at the fiber end face and lambda is the center wavelength of transmitted light. 'w' is derived by moving a fixed diameter aperture (20) along an axis extending between the test fiber end surface and a photodetector (24) so as effectively to vary theta . At each location the power P incident on the photodetector (24) and the corresponding acceptance angle theta are measured. A microprocessor (28) is programmed to compute from the range of measured values of theta and P, the value of mode field radius for a particular transmission wavelength lambda .