Brillouin Stokes Lines Research Articles

Investigation on the effect of EDFA location in ring cavity Brillouin-Erbium fiber laser

We have investigated the characteristics of Brillouin-Erbium fiber laser (BEFL) with variation of Erbium-doped fiber amplifier (EDFA) locations in a ring cavity configuration. Three possible locations of the EDFA in the laser cavity have been studied. The experimental results show that the location of EDFA plays vital role in determining the output power and the tuning range. Besides the Erbium gain, Brillouin gain also contributes to the performance of the BEFL. By placing the EDFA next to the Brillouin gain medium (dispersion compensating fiber), the Brillouin pump signal is amplified thereby generating higher intensities of Brillouin Stokes line. This efficient process suppresses the free running self-lasing cavity modes from oscillating in cavity as a result of higher Stokes laser power and thus provide a wider tuning range. At the injected Brillouin pump power of 1.6 mW and the maximum 1480 nm pump power of 135 mW, the maximum Stokes laser power of 25.1 mW was measured and a tuning range of 50 nm without any self-lasing cavity modes was obtained.

Brillouin-Erbium fiber laser with enhanced feedback coupling using common Erbium gain section

We demonstrate an enhanced architecture of Brillouin-Erbium fiber laser utilizing the reverse-S-shaped fiber section as the coupling mechanism. The enhancement is made by locating a common section of Erbium-doped fiber next to the single-mode fiber to amplify the Brillouin pumps and the oscillating Stokes lines. The requirement of having two Erbium gain sections to enhance the multiple Brillouin Stokes lines generation is neglected by the proposed fiber laser structure. The mode competitions arise from the self-lasing cavity modes of the fiber laser are efficiently suppressed by the stronger pre-amplified Brillouin pump power before entering the single mode fiber section. The maximum output power of 20 mW is obtained from the proposed fiber laser with 10 laser lines that equally separated by 0.089 nm spacing.

Tunable range enhancement of Brillouin-erbium fiber laser utilizing Brillouin pump preamplification technique

We demonstrate an enhanced multiwavelength L-band Brillouin-erbium fiber laser (BEFL), in which the Brillouin pump is pre-amplified before entering the single-mode fiber. The Brillouin pump pre-amplification provided by the Erbium-doped fiber has created higher intensity of Brillouin Stokes line generated in the single-mode fiber that leads to the homogenous gain saturation. Thus the built-up of self-lasing cavity modes is suppressed in a wider wavelength range. In contrary to the conventional linear-cavity BEFL, the number of output channels is enhanced within the same tuning range.

Flat amplitude multiwavelength Brillouin-Raman comb fiber laser in Rayleigh-scattering-enhanced linear cavity

We investigate the amplitude flatness of Rayleigh-assisted Brillouin-Raman comb laser in a linear cavity in which feedbacks are formed by high-reflectivity mirror. The optimization of Brillouin pump power and wavelength is very crucial in order to obtain a uniform power level between Stokes lines. The Brillouin pump must have a relatively large power and its wavelength must be located closer to the Raman peak gain region. The flat-amplitude bandwidth is also determined by the choice of Raman pump wavelengths. A flat-amplitude bandwidth of 30.7 nm from 1527.32 to 1558.02 nm is measured when Raman pump wavelengths are set to 1435 and 1450 nm. 357 uniform Brillouin Stokes lines with 0.086 nm spacing are generated across the wavelength range. The average signal-to-noise ratio of 17 dB is obtained for all the Brillouin Stokes lines.

160-line multiwavelength generation of linear-cavity self-seeded Brillouin-Erbium fiber laser

We have demonstrated a novel multiwavelength Brillouin-erbium fiber laser (BEFL), in which the Brillouin pump is self-excited within the linear cavity, instead of the injection from the external cavity or direct generation in the intracavity. By using this simple scheme, the generation of more than 160 Brillouin Stokes lines has been experimentally demonstrated, which is the largest one achieved in BEFLs to the best of our knowledge. Also, the single longitudinal mode operation and the low noise performance of output wavelength line have been confirmed. Meanwhile, the experiment demonstrates that the BEFL performs good stability on both the operating wavelengths and the output power of each wavelength.

Flat amplitude equal spacing 798-channel Rayleigh-assisted Brillouin/Raman multiwavelength comb generation in dispersion compensating fiber

We demonstrate a simple method of generating evenly spaced multiwavelength Brillouin comb by employing dispersion compensating fiber both for Brillouin Stokes generation and Raman amplification. Multiwavelength output of 798 Brillouin Stokes lines with average channel power of -17 dBm has been obtained with excellent flatness. Channel spacing corresponds to the Brillouin Stokes shift in dispersion compensating fiber and is estimated to be 9.4 GHz with the heterodyne detection method. Coupled interaction of Brillouin, Raman, and Rayleigh scattering explains the unique feature of proposed structure.