Abstract: A dispersion compensating fiber (DCF), which is an amplification medium of an S-band discrete Raman amplifier (RA), has a trapezoid core, an inner cladding surrounding the trapezoid core; and an outer cladding surrounding the inner cladding. A ring is disposed between the inner cladding and the outer cladding. The refractive index plotted across the diameter of the trapezoid core as a function of distance is substantially trapezoidal in shape. The difference in refractive index between the trapezoid core and the outer cladding is 1.2 to 1.6%; between the inner cladding and the outer cladding is 0.4 to 0.8%; and between the ring and the outer cladding is 0.2 to 0.6%. The thickness of the ring is 0.8 to 1.2 times the radius of the trapezoid core, and the thickness of the inner cladding is 1 to 3 times the radius of the trapezoid core.

Abstract: An optical transponder which can be reconfigured in accordance with various types of client networks is provided. A client network interface transceiver includes a connector comprising a first connection terminal providing a unit transmitting and receiving a plurality of first clock signals, a plurality of second clock signals, and a plurality of data signals to and from the digital wrapper; a second connection terminal providing a unit transmitting and receiving a supervision/control signal and a CPU-related signal to and from the supervision/controlling unit; and a power source terminal providing a unit to which a power source is supplied. The client network interface transceiver multiplexes a client signal transmitted from the client network or demultiplexes a signal transmitted from an optical transmission network, outputs the client signal and the signal, and can be replaced through a front panel of the optical transponder line card in accordance with types of client networks.

Abstract: The present invention provides an apparatus and method for compensating for the variation of a gain spectrum attributable to the temperature variation of a fiber amplifier, and a long-wavelength band dispersion-compensating hybrid amplifier equipped with the gain spectrum compensating apparatus. The apparatus includes a DCF located between a first amplification stage and a second amplification stage to compensate for dispersion of an optical signal output from the first amplification stage and perform Raman amplification of the optical signal using input pumping light; at least one pumping light provision means for providing forward or backward pumping light to the DCF; first and second temperature detection means for detecting temperature variations of the first and second amplification stages, respectively; and control means for controlling intensity of the pumping light of the pumping light provision means according to the detected temperature variations.