EDFA and EDFL Review

In this chapter, I propose a comprehensive study of erbium-doped fiber amplifier (EDFA) and erbium doped fiber laser (EDFL). The chapter is based on three principal levels: the first is at the atomic level, where it is evident and meaningful to give general and deep studies on erbium spectra at theoretical background angle. The important part that needs to be understood in the erbium is its energy level splitting and lasing. The second level is based on the EDFA and EDFL critical, where many research papers have been reviewed to show and clarify their strong and weak side at different views. To specify the weakness of the classical EDFA and EDFL, and to describe the future generations and its characteristics, it is very important to review the recent published papers and books. At the experimental level a full investigation is given. Vast and new designs were invented showing high-gain and low-noise-figure (NF) utilizing a new technique called double pass with filter. An efficient amplification occurs at the signal wavelength of 1550 nm when it travels along the design quadruple pass double stages with filter amplifier (QPDSF). The highest gain of 62.56 dB with a low NF of 3.98 dB was achieved for an input signal power of -50 dBm and pump powers of 10 and 165 mW in the second and first stage amplifiers respectively. This important result shows also, a large difference of 40 dB gain between the QPDSF and the single stage single pass (SPSS) EDFA configuration. This design is used to show high gain of 62.56 dB compared to SPSS which records only 20 dB. A higher power and wider spectrum of ASE is observed for the double pass compared with single pass. A comparative investigation is presented and analyzed for various configurations. At the end, a high output power EDFL configuration is reported. It incorporates a double stages linear cavity with fiber loopback and a tunable bandpass filter TBF. The configuration increases the output power by suppressing the amplified spontaneous emission and achieves a highly stable output power of more than 18 dBm at 1560 nm. A standard spectrum is attained with TBF adjustment.