Feedback-Injected Erbium Fiber Laser With Selectable Tunability and Constant Single-Longitudinal-Mode Characteristic

Abstract

In this investigation, a wavelength-selected single-longitudinal-mode (SLM) erbium-doped fiber (EDF) ring laser utilizing C-band EDF based gain medium over a tuning bandwidth of 1524.0 to 1573.0 nm is demonstrated experimentally. A self-injection Rayleigh backscattering (RB) is designed in the EDF ring laser configuration to suppress the multi-longitudinal-mode (MLM) oscillation and narrow the obtained linewidth. Here, the physical output features of the proposed self-injected RB EDF laser are also studied and discussed, such as the optical signal to noise ratio (OSNR), output power, and laser linewidth, respectively. Therefore, the demonstrated EDF laser not only can reach SLM output, but also can produce a flat output spectrum of 1524.0 to 1554.0 nm with 0.2 dB power variation. Moreover, the measured fluctuation of each wavelength can be kept at 0.05 nm based on the presented self-injected RB EDF laser, while the uncertainty issue is also considered.

Use of Simple Octa-Ring Configuration for Tunable Erbium Laser With Single-Mode Output

“…Compared to previous triple-ring fiber lasers, which need three CPRs for construction [10], [11], our simple designed EDF laser can result in octa-ring scheme to cause mode-filter by using three CPRs for mode suppression and achieve high OSNR. Moreover, in our prior work [17], the proposed C-band EDF-based octa-ring fiber laser scheme can not only achieve wide wavelength tunability including C and L bands, but also can obtain high OSNR of > 71.1 dB.…”

“…However, the strong homogeneous line broadening of EDF gain could produce wavelength competition and longer fiber cavity of fiber laser would cause the unstable multi-longitudinal-mode (MLM) oscillation [9]. To achieve stable and wide SLM wavelength output, some related methods have been demonstrated, such as using the compound-fiber-ring structure [10], [11], Mach-Zehnder interferometer (MZI) method [12], [13], Sagnac interferometer (SI) loop [4], [14], saturable absorber (SA) based filter [15], [16], optical injection [17] and ultranarrow bandpass filter [18], [19]. Besides, to obtain a wider wavelengthselection range of EDF laser scheme, the parallel erbiumdoped fiber amplifier (EDFA), hybrid optical amplifiers and…”