Cut-Off Wavelength

In filter terminology, the wavelength at which the transmission decreases to 50% throughput in a shortpass filter. In fiber optics, the shortest wavelength at which a fiber transmits in single mode. Below the cut off several modes will propagate and the fiber is no longer single-, but multimode. In detector technology, the wavelength at which the detector response falls to a set percentage (usually 20 or 50 percent).