The double-clad couplers developed by Castor combine single-mode light transmission with multimode light transfer. Light transmission in the core is quasi-lossless from Port A to Port S, and again from Port S to Port A (see diagrams below). In the inner cladding of the double-clad fiber, light transfer occurs either from the inner cladding of Port S to the multimode branch called Port B in couplers designed for light collection OR from the Port J to the inner cladding of Port S, for couplers designed for injection.
In the multimode regime, our coupler work for all wavelength between 400nm up to 1600nm, with a flat spectral response.
In the single-mode regime, the operating wavelength range for the core of the double-clad fiber is bound by the cutoff wavelength, defined as the smallest wavelength for which we can guarantee single-mode operation. Below that wavelength - indicated below for each coupler - the core of the double-clad fiber still transmits light, but not in the single mode regime.
Our couplers may be inserted in your fiber optics assembly through the use of connectors or through fusion splicing with other optical fibers. At Castor, we know our couplers inside-out: we also provide custom integration with single mode fibers, double-clad fibers, and multimode fibers for applications requiring the highest level of sensitivity.