Wavelength selective coupler for high power optical communications

DETAILED DESCRIPTION In accordance with the present invention, a wavelength selective optical fiber coupler is provided.
A first substrate has an optical input end for receiving a first optical signal.
A first grating is formed in the first substrate.
A second substrate has an optical input end for receiving a second optical signal.
A second grating is formed in the second substrate.
Means are provided for joining the first and second gratings to transfer energy from the second optical signal to the first optical substrate for combination with the first optical signal.
The combined signals are output from an optical output end of the first substrate.
In a preferred embodiment, the gratings are optimized to pass a specific wavelength of the second optical signal.
In order to effect the energy transfer from the second optical signal to the first substrate, the gratings are formed from lines that are oriented at a nonperpendicular angle with respect to the direction of lightwave propagation through their respective substrates.
At least one of the substrates can comprise an optical fiber.
For substrates that are optical fibers, the gratings are advantageously in-fiber gratings.
In an illustrated embodiment, the optical fibers have a substantially D-shaped cross section with their respective gratings formed in a flat portion thereof.
The joining means mate the flat portions to couple the evanescent fields of the two fibers.
In another illustrated embodiment, at least one of the substrates is a polished optical block.
For example, one of the substrates can comprise a polished optical block with its grating situated on a flat surface thereof.
The other of the substrates can comprise an optical fiber having an in-fiber grating situated in a flat portion of the cross section of the fiber.
The joining means mate the flat portion of the optical fiber with the flat surface of the polished optical block such that the gratings adjoin each other.
Apparatus is also provided for combining a plurality of optical signals for communication via a common transmission path