Patent ID: 6826326
Filing Date: 2004-11-30
Classification: H04J

Abstract:
A method for performing add/drop functioning, comprising:adjusting a first tunable filter to a desired wavelength &lgr;x by introducing a reference signal into a first circulator, wherein the reference signal is reflected by the first tunable filter to be dropped from the first circulator to determine a control signal most suitably for the first tunable filter; and scanning a second tunable filter to the desired wavelength &lgr;x with a signal having K wavelengths &lgr;1&lgr;2&lgr;3 . . . &lgr;xâˆ’1&lgr;x&lgr;x+1 . . . &lgr;K, wherein the wavelengths &lgr;1&lgr;2&lgr;3 . . . &lgr;xâˆ’1 are reflected by the second tunable filter before the second tunable filter is turned to the desired wavelength &lgr;x, and the wavelengths &lgr;x+1 . . . &lgr;K pass through the second tunable filter after the second tunable fitter is turned to the desired wavelength &lgr;x; wherein a first optical path includes the first tunable filter and a second optical path includes the second tunable filter, both of the first and second optical paths are coupled to tho first circulator such that the wavelengths &lgr;1&lgr;2&lgr;3 . . . &lgr;xâˆ’1 transmit through the first optical path and the wavelengths &lgr;+1 . . . &lgr;K transmit through the second optical path.