Abstract: An apparatus and a method is provided for frequency identification and laser locking by sending optical signals of a laser through a set of optical filters. The signal power transmitted by the filters is measured and the resulting set of powers normalized with respect to a reference power. The multidimensional measurement output curve of the set of filters is nondegenerate. The set of measurements is compared to a set of points in a calibration table or constellation, which results in the identification of the frequency of the laser.

Abstract: Attenuation of an optical fiber is measured by transmitting an optical signal having a predetermined wavelength to the fiber, and FSK modulating the optical signal with information identifying the wavelength and transmitted power of the optical signal. At a receiver, the optical signal is detected and the information is recovered by demodulation. Wavelength-dependent sensitivity information for the detector is read from a store in dependence upon the wavelength information and used to control the gain of an amplifier for amplifying a subsequently transmitted continuous wave optical signal used for attenuation measurement. The received power level of this optical signal is converted into a digital value and used with the transmitted power information to determine the fiber attenuation at the predetermined wavelength. Reference power levels are determined by connecting a jumper between a port and an external detector.