Patent ID: 7457544

Claim:
A group delay compensation equalizer, comprising: a fiber path having a first end and a second end; and a single channel four-port WDM device for compensating a group delay produced from a plurality of wavelengths, the WDM device having a filter comprising a first surface with an infrared coating and a second surface with an infrared coating, a first port connected to an incoming fiber, a second port connected to the first end of the fiber path, a third port connected to the second end of the fiber path, and a fourth port connected to a transmission fiber, wherein, when a composite light signal comprising a plurality of wavelengths enters the first port, a first wavelength in the plurality of wavelengths passes through the filter, and the remaining wavelengths in the plurality of wavelengths are reflected from the filter by the first surface with the infrared coating, pass through the second port to the fiber path, enter the third port and are again reflected from the filter by the second surface with the infrared coating to be combined with the first wavelength and transmitted through the fourth port to the transmission fiber; wherein the fiber path has a fiber length L which is equal to the transmission difference between a first transmission delay experienced by the first wavelength and a second transmission delay experienced by the remaining wavelengths traveling through the fiber path.