Abstract: The present invention provides an apparatus for generating L-band light source and an optical signal amplifier, specifically, relates to an apparatus for generating L-band light source by increasing amplification gain against an L-band light to execute a stable resonating operation, and to an optical amplifier which amplifies L-band light signal efficiently. That is, it is possible to use the output light of the first optical fiber amplifier 10 as a pumping light of the second optical fiber amplifier 20 by connecting the first optical fiber amplifier 10 for supplying a maximum amplification gain against an input light having a wavelength of 1530 nm to 1560 nm with the second optical fiber amplifier 20 for supplying a maximum amplification gain against an input light having a wavelength of 1570 nm to 1610 nm in series, thus securing a satisfied amplification gain against a L-band light and to generate a desirable light source.

Abstract: Disclosed relates to an L-band optical fiber amplifier which amplifies an L-band optical signal of 1570 nm to 1610 nm. In general, when a pumping light of 980 nm for example, output from a pumping light generating laser diode, is supplied to an erbium doped fiber EDF, an amplified spontaneous emission ASE having a bandwidth of 1530 nm to 1560 nm, namely, C-band is generated. The L-band optical fiber amplifier of the invention is configured in a manner that ASE transmitted in the backward direction, or a predetermined wavelength light selected from the bandwidth of 1530 nm to 1560 nm is reflected by a reflecting means and re-injected to EDF. A fiber bragg grating FBG or a reflecting mirror is applied as the reflecting means. The reflected light from the reflecting means is re-injected to EDF and acts as the pumping light, thus increasing the amplification gain for the L-band input light remarkably.