T. F. Al-Mashhadani

Characteristics of multiwavelength L-band Brillouin–Raman fiber laser under forward and backward pumped environment

We experimentally investigate the performance of L-band multiwavelength Brillouin-Raman fiber laser (MBRFL) under forward and backward pumped environments utilizing a linear cavity. A short length of 1.18 km dispersion compensating fiber is used as a nonlinear gain medium for both Brillouin and Raman gain. Experimental results indicate that the gain in the copumped laser configuration is higher than the gain in the counterpumped configuration. A stable and constant number of Brillouin Stokes lines up to 23 Stokes, with channel spacing of 0.08 nm and more than 20 dB of optical signal to noise ratio, can be generated as well as tuning over 20 nm in the L-band region from 1570 to 1590 nm. The laser generating the Brillouin Stokes lines exhibits flat amplitude bandwidth and high average output power of 0.8 and 1.6 dBm for the copropagation and counterpropagation pumps, respectively. Moreover, the tuning range bandwidth of the MBRFL can be predicted from the oscillated Brillouin pump gain profile.

L-Band Multi-Wavelength Brillouin–Raman Fiber Laser with 20-GHz Channel Spacing

Abstract A tunable multi-wavelength L-band Brillouin–Raman fiber laser with a 20-GHz channel spacing utilizing bidirectional ring cavity is proposed and experimentally investigated. The laser employs a co-pumped dispersion compensating fiber as a gain medium for both Brillouin and Raman gains. With a Raman pump of 425 mW, the laser system can generate up to 12 double-spaced Brillouin Stokes signals. This simple laser configuration provides stable Brillouin Stokes signals in the absence of self-lasing cavity modes with a tuning range exceeding 35 nm without using any filtering mechanism. The Stokes signals have more than 20 dB of optical signal-to-noise ratio.

Raman amplification effects on stimulated Brillouin scattering threshold in multiwavelength Brillouin-Raman fiber laser

We report experimental results demonstrating the stimulated Brillouin scattering threshold (SBSTH) features in multiwavelength Brillouin-Raman fiber laser against Raman pump power (RPP) variation. The reduction of SBSTH is attributed to the Raman amplification on each of oscillated Brillouin pump power (OBP) and generated Stokes signals. The saturation in SBSTH is owing to the RPP depletion, this saturation is coincides with the appearance of Raman peak gain. In addition, the red shift effect became significant at RPP beyond 650mW and led to degradation of the Raman amplification. This degradation appeared as an increase in SBSTH after the saturation region. Moreover, the Brillouin Stokes comb can be generated only at the saturation region of the Raman amplification between 350 to 600 mW of Raman pump.

Simulation and experimental validation of gain-control parallel hybrid fiber amplifier

We demonstrate a simulation of a parallel hybrid fiber amplifier in the C+L-band with a gain controlling technique. A variable optical coupler is used to control the input signal power for both EDFA and RFA branches. The gain spectra of the C+L-band are flattened by optimizing the coupling ratio of the input signal power. In order to enhance the pump conversion efficiency, the EDFA branch was pumped by the residual Raman pump power. A gain bandwidth of 60 nm from 1530 nm to 1590 nm is obtained with large input signal power less than -5 dBm. The gain variation is about 1.06 dB at a small input signal power of -30 dBm, and it is reduced to 0.77 dB at the large input signal power of -5 dBm. The experimental results show close agreement with the simulation results.

Impact of booster section length on the performance of linear cavity brillouin-erbium fiber laser

The impact of booster section length made from passive erbium-doped fiber (EDF) on the L-band multiwavelength Brillouin-Erbium fiber laser (MBEFL) is studied experimentally in this paper. The influence on the performance of MBEFL in term of number of generated Stokes lines, tuning range and lasing threshold were investigated. A comparison was made between MBEFL without a booster section and with booster sections of different lengths. Through comparative study and at fixed BP power and 100mW of 1480 pump power, longer passive EDF length of 5m exhibits the highest average number of Stokes lines of 23 with tuning range of 14nm. In contrast, shorter passive EDF length of 1m shows the highest tuning range of 17nm and an average number of 21 Stokes lines.

Impact of passive EDF length on the performance of linear cavity BEFL

We experimentally demonstrate the impact of a section of passive Erbium doped fiber (EDF) within linear cavity multiwavelength Brillouin Erbium fiber Laser (MBEFL). The influence of such passive EDF section length on the tuning range and the lasing cavity threshold is experimentally presented. The lasing threshold of the MBEFL in case of without and with different passive EDF2 section lengths is presented. A comparison is made between the traditional linear BEFL cavity and the BEFL cavity that utilized different passive EDF lengths of 1m, 3m, and Sm. Different 1480 pump power range (25-150) mW is used in the investigated study. The proposed configuration show significant increment in the tuning range for all passive EDF2 lengths as compared to the conventional BEFL cavity. Sm of passive EDF2 length exhibits higher tuning range of about 28nm at 100mW as compared to the 24.4nm tuning range at the same 1480 pump power using 1m of passive EDF2. All passive EDF2 lengths were compared in term of tuning range at different 1480 pump power range (25-150) mW.

Effect of EDF position on the performance of hybrid dispersion-compensating Raman/EDF amplifier

The effect of the location of the Erbium-doped fiber (EDF) on the performance of the hybrid dispersion compensation of Raman/EDF amplifier is discussed in this study. Two different configuration set-ups were determined according to the position of the EDF amplifier. The setup in which EDF A is positioned before is denoted by type A, while type B denotes the setup in which EDFA is positioned after. In these two amplifier configurations, the Raman gain saturation due to the Stimulated Brillouin scattering (SBS) effect is included. Type B shows a better hybrid fiber amplifier (HF A) performance in terms of overall gain, noise figure (NF), and flatness gain profile. A small signal gain of 33 and 35 dB with a flat gain bandwidth of 40 nm is achieved for types A and B, respectively. In addition, type B exhibits a high peak gain of 23 dB, with gain variation of 3 dB along 70 nm bandwidth for large input signal compared with the 17 dB peak gain of type A with gain variation of 4.4 dB along the same bandwidth.

Modeling of Multi-Wavelength Brillouin Fiber Laser Based on Analytical Solutions in a Linear Cavity

Abstract In this article, an accurate model of multi-wavelength Brillouin fiber laser is developed by analytically solving cascade-stimulated Brillouin scattering equations in a linear cavity. The dependence of Stokes signal power on the incident pump power and the successive reflected transmitted powers is calculated. Furthermore, an analytical approach that can be used to predict the generated Stokes signals power is derived. Finally, this derived model is checked with experimental results that show significant agreement with the analytical solution of the model.

Effect of Cascading Amplification Stages on the Performance of Serial Hybrid Fiber Amplifier

Abstract This study demonstrates simulation and experimental validation of a wideband serial hybrid Raman/erbium-doped fiber amplifier. Two configurations are adopted; in type A, a Raman amplifier is the first stage, and in type B, an erbium-doped fiber amplifier is the first stage. At low input signal power, the average gain level is 20 dB with a flat gain bandwidth of 40 nm for both configurations. The noise figure in type B is dominated by the erbium-doped fiber amplifier and produces lower values and flatter spectra than in type A. The gain of the proposed hybrid amplifiers is affected more by the second amplification stage.

Impact of passive EDF location on the performance of L-band Brillouin-Erbium fiber laser

A simple L-band multiwavelength Brillouin-Erbium fiber laser (MBEFL) that utilizes a passive erbium doped fiber (PEDF) at two different locations within the linear cavity was successfully demonstrated. The impact of the inclusion of such PEDF sections on the number of the generated Stokes lines, laser tunability and the laser cavity threshold are experimentally investigated. The proposed laser structure in which the PEDF was inserted closer to the active EDF exhibits 21 Brillouin Stokes lines and a tuning range of 18nm at 100 mW and 4 mW of 1480 nm pump and Brillouin pump powers, respectively. In addition laser cavity threshold of 10.7mW is recorded at the same Brillouin pump power of 4mW. On the other side, the proposed laser structure in which the PEDF location is changed to be inserted at the far end of the single mode fiber shows 17 Brillouin Stokes lines, a tuning range of 24.4nm and a laser cavity threshold of 10.4mW under the same pump powers conditions. These two different cavity structures are compared with the conventional linear cavity MBEFL as a benchmark.