OPTICAL FIBER AMPLIFIER FOR LONG WAVELENGTH BAND

摘要

PURPOSE: An optical fiber amplifier for long wavelength band is provided to generate pumping light of 1550nm band by using reverse amplification light generated inside an optical fiber amplifier without using an expensive laser diode and use the pumping light as the second pumping light of an erbium doped fiber, so as to improve the amplification gain of long wavelength band light. CONSTITUTION: An input light(S) is applied to the first wavelength division multiplexer(WDM)(3) via the first isolator(1) and the second WDM(11). The first WDM(3) applies a pumping light applied from a pumping laser diode(2) and the input light applied from the second WDM(11) to an erbium doped fiber(EDF)(4). The EDF(4) amplifies the input light by means of rare-earth ions exited by the pumping light, then outputs the amplified input light through the second isolator(5). The portion of the amplified light in the EDF(4) is applied to the second WDM(11) via the first WDM(3) reversely and the second WDM(11) outputs the light applied from the first WDM(3) to a coupler(21). The coupler(21) applies the reverse amplification light applied from the second WDM(11) to a damper(23) via the third isolator(22). The damper(23) damps the signal level of the light inputted from the third isolator(22), then applies the damped light to a tunable filter(24) which tunes the wavelength of the light to 1550nm band. The light output from the tunable filter(24) is applied to the second WDM(11) via the coupler(21) and the light output from the coupler(21) is applied to the EDF(4) via the first WDM(3).