BASIC ANALYSIS OF GAIN IN TERMS OF NOISE FIGURE

Abstract

: One attractive fiber-optic amplifier (FDA) in optical communications systems, and particularly in DWDM
systems, is the EDFA. The EDFA is a fiber segment a few meters long heavily doped with the rare earth element erbium
(and also co-doped with Al and Ge). The erbium ions may be excited by a number of optical frequencies-514, 532, 667,
800, 980, and 1480 nm. The shortest wavelength, 514 nm, excites erbium ions to the highest possible energy level. From
this level, it may drop to one of four intermediate metastable levels, radiating phonons (the acoustical quantum
equivalent of photons). From the lowest metastable level, it finally drops to the initial (ground) level, emitting photons
around 1550 nm in wavelength.
In this paper, here we are analysing the basic effect of EDFA switching on optical amplifier gain and noise figure. A
variable gain erbium-doped fiber amplifier (EDFA) with a wide gain range and a small noise figure (NF) variation is
analyzed numerically and performed on MATLAB.