OPTICAL AMPLIFICATION DEVICE AND OPTICAL TRANSMISSION SYSTEM

PROBLEM TO BE SOLVED: To provide an optical amplification device where degradation of complex distortion characteristics is effectively reduced, and to provide an optical transmission system using the same. SOLUTION: An optical amplification device which amplifies a light signal generated by direct modulation of semiconductor laser by a frequency multiplication image signal modulated by a predetermined modulation mode, comprises an optical input portion which receives the light signal, an excitation light source which generates an excitation light, a double cladding type optical amplification fiber where an optical amplification substance is added to a core portion, the light signal and the excited light are received, and the light signal is amplified by induction and release and a light output portion for outputting the amplified light signal. The optical amplification fiber is designed so that an absorption and length product expressed as a product of fiber length of the optical amplification fiber and a peak value at a predetermined wavelength band of absorption coefficient will be smaller than a folding point where a rate of reduction of composite distortion characteristics to a reduction in an absorption and length product drastically increases, in a curve showing the relation between the absorption and length product, and the composite distortion characteristics of the amplified light signal. COPYRIGHT: (C)2009,JPO&INPIT