Single-wavelength ring-cavity fiber laser employed pre-amplification technique to reduce threshold by circulating spontaneous brillouin scattering

<span>In this paper, two types of ring-cavity fiber laser structures that operate as a single wavelength laser were investigated on the threshold performance. The two structures are namely Brillouin fiber laser and Brillouin erbium fiber laser. In the first structure, the Brillouin pump signal was amplified before being injected into the laser cavity which namely as Brillouin fiber laser. Meanwhile, for second structure respectively, the Brillouin pump signal was pre-amplified in the laser cavity which namely as Brillouin Erbium fiber laser. We found that the stimulated Brillouin scattering threshold power was lowered significantly by circulating the spontaneous Brillouin scattering in the gain medium utilizing the pre-amplification technique. The optimum stimulated Brillouin scattering threshold power was about 1.4 mW, and this was achieved at optimum output coupling ratio of 95%. By comparing to the first structure in which the Brillouin pump signal was amplified before entering the laser cavity, stimulated Brillouin scattering threshold power was only achieved at 2.62 mW at a similar wavelength. The pre-amplification technique proposed in this paper has been shown to improve the performance of single-wavelength ring-cavity fiber lasers via significant reduction of the stimulated Brillouin scattering threshold power which was around 1.22 mW.</span>

Phase-Coded and Noise-Based Brillouin Optical Correlation-Domain Analysis

Correlation-domain analysis has enabled distributed measurements of Brillouin gain spectra along optical fibers with high spatial resolution, up to millimeter-scale. The method relies on the joint modulation of counter-propagating Brillouin pump and signal waves so that their complex envelopes are correlated in select positions only. Brillouin optical correlation-domain analysis was first proposed nearly 20 years ago based on frequency modulation of the two waves. This paper reviews two more recent variants of the concept. In the first, the Brillouin pump and signal waves are co-modulated by high-rate binary phase sequences. The scheme eliminates restricting trade-offs between the spatial resolution and the range of unambiguous measurements, and may also suppress noise due to residual Brillouin interactions outside the correlation peak. Sensor setups based on phase coding addressed 440,000 high-resolution points and showed potential for reaching over 2 million such points. The second approach relies on the amplified spontaneous emission of optical amplifiers, rather than the modulation of an optical carrier, as the source of Brillouin pump and signal waves. Noise-based correlation-domain analysis reaches sub-millimeter spatial resolution. The application of both techniques to tapered micro-fibers and planar waveguides is addressed as well.

Lasing threshold characteristics of multi-wavelength Brillouin–erbium laser in the L-band region assisted by delay interferometer

This paper reports the simulation of L-band multi-wavelength Brillouin–erbium fiber laser that utilizes delay interferometer as a comb filter. The simulation is performed using OptiSystem. The structure exhibits threshold power in terms of Erbium doped fiber amplifier (EDFA) gain of 10[Formula: see text]mW at a very low Brillouin pump power of 0.00316[Formula: see text]mW for the generation of first Stokes. Thirty one output channels were produced with minimum EDFA gain of 1[Formula: see text]W at Brillouin pump power of 0.00316[Formula: see text]mW. In line with theory, it has been observed that higher Brillouin pump power requires low threshold gain and vice versa to generate the Brillouin Stokes.

Optimization of Output Coupling Ratio for Multi-Wavelength Brillouin Fiber Laser Employing FBG and DCF as Gain Medium

A ring-cavity multi-wavelength Brillouin fiber laser by employing a fiber Bragg grating and dispersion compensating fiber was experimentally demonstrated. The multi-wavelength Brillouin fiber laser has been analyzed at different output coupling ratios at 1550 nm of Brillouin pump wavelength. A ring-cavity multi-wavelength Brillouin fiber laser has been designed with a 16 km long of dispersion compensating fiber which acts as gain medium for stimulated Brillouin scattering effect. Dispersion compensating fiber is designed to have small core size and has higher nonlinear coefficient. As a result, 8 Brillouin Stokes signals were produced at maximum Brillouin power of 21 dBm and output coupling ratio of 80%. The best performance of output coupling ratio was determined by 70% with the highest of signal to noise ratio at 38.39 dB.

Correlation of Brillouin Stokes Signals and Optical-Signal-to-Noise-Ratio in Multi-Wavelength Brillouin Fiber Laser with Additional Fiber Bragg Grating

We experimentally demonstrate unidirectional propagation of multi-wavelength Brillouin fiber laser system with additional fiber Bragg grating. The configuration is arranged in a ring resonator by utilizing five different Brillouin gain mediums. In this experiment, the input Brillouin pump power was varied in order to maximize the generated Brillouin Stokes signals based on the respective fiber lengths. The influence of these controllable parameters leads to the correlation between of Brillouin Stokes signals and optical-signal-to-noise-ratio. In this case, at 10 km of single mode fiber the maximum of 38 Brillouin Stokes signals were generated together with 15.07 dB of average optical-signal-to-noise-ratio when the 17 dBm Brillouin pump power was launched into the ring resonator.