System and method of estimating beam mode content for waveguide alignment

摘要

Alignment of a multimode waveguide to a source of light or another waveguide is evaluated using a multi-wavelength light source and a modal decomposition processing of an intensity profile of a waveguide output beam, wherein inter-modal interference is averaged out over wavelength. Fitting a superposition of mode intensity profiles to a wavelength-averaged intensity profile of the output beam provides information about the modal composition of the output beam, which may be used to assess the alignment of the multimode waveguide with respect to the input light beam, and to provide a feedback for guiding a waveguide alignment process.

主权项

1. A method comprising:
a) launching a plurality of light wavelengths into an input end of a first waveguide using a multi-wavelength light source, wherein the first waveguide is capable of supporting a plurality of waveguide modes; b) receiving an output light beam from an output end of the first waveguide with a photodetector array (PDA) for generating electrical signals carrying beam image data; c) using a computer operationally coupled to the PDA to obtain a multi-wavelength beam intensity profile for the output light beam from the beam image data, wherein the multi-wavelength beam intensity profile comprises contributions from each of the plurality of light wavelengths; and, d) estimating, with the computer, a relative contribution of a selected waveguide mode from the plurality of waveguide modes into an optical power of the output light beam based on the multi-wavelength beam intensity profile and one or more mode intensity profiles corresponding to one or more waveguide modes of the first waveguide; wherein the plurality of light wavelengths launched into the first waveguide spans a wavelength range that is sufficiently broad so as to average out contributions from phase-dependent inter-modal interference at the plurality of light wavelengths into the multi-wavelength beam intensity profile.