OPTICAL AMPLIFIER

摘要

PROBLEM TO BE SOLVED: To provide an optical amplifier of less gain wavelength dependency within a usage environment temperature range. SOLUTION: The optical amplifier comprises an erbium-added optical fiber 3, and a gain flattening filter 2 for reducing the gain wavelength dependency characteristics of the erbium-added optical fiber 3. The gain flattening filter 2 is formed by arranging four crystal etalon filters 1a-1d in non-equilibrium state with an interval while filter surfaces faced each other. Since the gain flattening filter 2 is constituted with the crystal etalon filters 1a-1d whose physical property is different from quartz used as an etalon filter so far, the gain wavelength dependency and temperature dependency of the erbium-added optical fiber 3 are reduced.