An EDFA with integrated input and output modules is presented. The
integrated input module has a packaged pump laser diode mounted to the
metal EDFA package to provide a heat sink for the pump laser diode which
sends the pump laser light over a optical fiber section connected to the
amplifying erbium-doped optical fiber section. The fiber section is
formed from an optical fiber which better matches the transmission modes
in the erbium-doped optical fiber section and has an end subsection of
the single mode fiber for a larger numerical aperture. Collimating lenses
also increase the coupling efficiency of the laser diode to the
erbium-doped fiber section. The integrated output module has a photodiode
with a tap filter to monitor the output power of the EDFA, an optical
isolator to prevent interference in the erbium-doped optical fiber
section. With a twin optical isolator, the integrated input and output
modules can be arranged in different ways and combinations with the
erbium-doped optical fiber section. The resulting EDFAs can be
manufactured relatively inexpensively into an very small packages
compared to current EDFA packages.