Brillouin Stokes Signals Research Articles

Tunable 60 GHz Multiwavelength Brillouin Erbium Fiber Laser

An experimental study of a tunable 60 GHz multiwavelength Brillouin erbium fiber laser is presented in this paper. Two unidirectional ring laser cavities and two pre-amplification laser cavities are used. In the first three cavities, a Brillouin gain medium is presented with a dispersion compensation fiber (DCF) spool, and a single-mode fiber (SMF) spool is used as a Brillouin gain medium in the fourth cavity. Three erbium amplifiers are utilized to supply enough gain to the generated Brillouin Stokes signal and to suppress cavity losses. For these three amplifiers, up to 450 mW (150 mW for each) of a 1480 nm pump power is used. In our proposed configuration, four sextuple Brillouin Stokes signals with a high power of 10 dBm and more than 55 dB as an optical signal-to-noise ratio are achieved. The obtained Brillouin Stokes signals can be tuned over 30 nm (1560–1590 nm) and can be easily used in dense wavelength division multiplexing in optics communication systems.

Enhanced sensitivity temperature sensing based on second order Brillouin slow light

We demonstrate a temperature fiber sensor with enhanced sensitivity based on the second order Brillouin slow light. In this process, the modulated probe wave coincides with the second order Brillouin gain that was generated by circulating the first order Brillouin Stokes signal. Optical delay was induced on the modulated probe wave as it interacts with the second order Brillouin Stokes signal. As the temperature changes, the measured optical delay at the output also changes accordingly. The first order setup has a temperature slope coefficient of 1.126 ns/°C. Compared to the first order setup, the second order setup achieved a coefficient of 1.917 ns/°C, which is almost double the value obtained from the first order experiment.

Wide multiwavelength Brillouin-Raman fiber laser assisted by an arc-shaped fiber attenuator.

A wide bandwidth, single-spacing half-open-cavity multiwavelength Brillouin-Raman fiber laser (MWBRFL) is demonstrated. The laser cavity contains a fiber loop mirror (FLM) with an arc-shaped optical fiber attenuator that is used to control the mirror reflectivity, thereby suppressing gain competition from longitudinal cavity modes. A tuning range of 45 nm with 632 lines at Raman and 1525 nm Brillouin pump powers of 1.2 W and 12 dBm can be achieved using the 10 dB arc-shaped optical fiber attenuator in the cavity. This is in comparison to 433 Stokes lines obtained over a 31 nm tuning range for the half-open MWBRFL cavity without any feedback power optimization. The MWBRFL has low power fluctuations of less than 0.1 dB over a 1 h test period. The inclusion of the arc-shaped optical fiber attenuator in the MWBRFL provides substantial control over the reflectivity of the FLM as well as improving the laser's tuning range to generate a high number of Brillouin Stokes signals.

Influence of bidirectional cavity structure on the Brillouin Stokes signal characteristics in ring BFL

We experimentally demonstrate the effects of Brillouin amplifications on the stimulated Brillouin scattering threshold as well as the generated Stokes power. Brillouin fiber laser (BFL) ring cavity structure is used to show the effect of bidirectional signal propagation on threshold and Stokes power. The laser cavity is tested with conventional technique in which there is no signal circulation take place. Both structures are tested under the same experimental conditions using 5 km SMF length, threshold power for the 1 st Stokes signal is improved and reduced up to 90% in ring cavity structure compared to its value in conventional technique. The threshold is reduced, from the value of 16.2 mW in conventional structure to be 1.67 mW in ring laser cavity. Furthermore, different SMF lengths are tested and exhibits the same threshold reduction ratio. In addition, the 1 st and the 2nd Stokes signals within ring laser cavity are tested in terms of threshold and Stokes signals power. In addition, the induced Brillouin gain effect within a bidirectional ring cavity are studied on the maximum Brillouin Stokes signal power.

Fiber bragg grating assisted cavity loss reduction in the generation of multiwavelength brillouin fiber laser

This work investigates two types of multiwavelength Brillouin fiber laser configurations. These configurations are ring-cavity multi-wavelength Brillouin fiber laser employs fiber Bragg grating and S-shaped multiwavelength Brillouin fiber laser. The two arrangements comprise of 10km long single mode fiber as a gain medium and operate in the C-band region. Replacing the S-Shaped with Bragg grating fiber has led to a loss reduction in the ring-cavity multiwavelength Brillouin fiber laser and subsequently generated higher number Brillouin Stokes (BS) signals. The maximum of 33 BS signals with ∼0.08nm (∼10GHz) spacing is obtained. Optical signal to noise ratio of about 15dB is observed at output coupling ratio of 70%, when 1550nm of Brillouin pump is launched into the ring-cavity multiwavelength Brillouin fiber laser employs fiber Bragg grating. In contrast, due to the limitation of high cavity losses, only 17 BS signals with ∼0.16 (20GHz) spacing are generated from the S-shaped multi-wavelength Brillouin fiber laser. These findings contribute new insights and profiles of the multi-wavelength Brillouin fiber laser employs fiber Bragg grating that has the capability to reduce cavity losses while generating a high number of Brillouin Stokes signals.

Multiple lasing Brillouin Fiber Laser with the implementation of reflective Fiber Bragg Grating in a ring cavity configuration

A multi-wavelength Brillouin fiber laser with the implementation of reflective fiber Bragg grating is developed. In this ring cavity architecture, the fiber laser system is performed by the stimulated Brillouin scattering effect and four-wave mixing process. An improvement in the number Brillouin Stokes signal and average of the optical signal to noise ratio were generated through the reflection process of fiber Bragg grating. Due to the optimization of output coupling ratio from 10% to 60%, the highest Brillouin Stokes signal of 17 and average optical signal to noise ratio of 14.7 dB were recorded at 60% of the output coupling ratio. The amplified Brillouin pump power of 16.5 dBm at 1550 nm of Brillouin pump wavelength was injected into the laser system. A constant line spacing of 0.08 nm at each of the Brillouin Stokes signals was also recorded.

Lasing characteristics of 10 GHz signal spacing in a ring cavity multi-wavelength Brillouin fiber laser employing fiber Bragg grating

This paper experimentally demonstrated a ring cavity multi-wavelength Brillouin fiber laser employing fiber Bragg grating (FBG) that operated in the C-band region. The FBG plays a significant role to reflect signals and filter selected wavelengths. A number of generated Brillouin Stokes (BS) signals and tuning range ability were investigated. A 9[Formula: see text]km length of single mode fiber was utilized to provide a Brillouin gain medium for generating stimulated Brillouin scattering effect. In this work, at optimum output coupling ratio of 90% and Brillouin pump (BP) wavelength of 1550[Formula: see text]nm, up to a maximum of 26 BS signals were recorded by injecting 63.1[Formula: see text]mW of amplified BP powers. The BS signals were also tunable within the ranges of 1544–1556[Formula: see text]nm in accordance with the FBG properties at 3[Formula: see text]dBm bandwidth of 5[Formula: see text]nm.

Single Brillouin frequency shifted S-band multi-wavelength Brillouin-Raman fiber laser utilizing fiber Bragg grating and Raman amplifier in ring cavity

This paper is focusing on simulation and analyzing of S-band multi-wavelength Brillouin–Raman fiber laser performance utilizing fiber Bragg grating and Raman amplifier in ring cavity. Raman amplifier-average power model is employed for signal amplification. This laser system is operates in S-band wavelength region due to vast demanding on transmitting the information. Multi-wavelength fiber lasers based on hybrid Brillouin–Raman gain configuration supported by Raman scattering effect have attracted significant research interest due to its ability to produced multi-wavelength signals from a single light source. In multi-wavelength Brillouin–Raman fiber, single mode fiber is utilized as the nonlinear gain medium. From output results, 90% output coupling ratio has ability to provide the maximum average output power of 43 dBm at Brillouin pump power of 20 dBm and Raman pump power of 14 dBm. Furthermore, multi-wavelength Brillouin–Raman fiber laser utilizing fiber Bragg grating and Raman amplifier is capable of generated 7 Brillouin Stokes signals at 1480 nm, 1510 nm and 1530 nm.

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.

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.

Multi-wavelength Brillouin Fiber Laser with Fiber Bragg Grating Employs Loop Mirror

In this paper, the development of multi-wavelength Brillouin fiber laser with fiber Bragg grating utilizing a loop mirror is successfully demonstrated. A multi-wavelength Brillouin fiber laser configuration employs 11 km length of single mode fiber as the gain medium, while the reflection of fiber Bragg grating is adopted to produce multi-wavelength signals. Based on the experimental results, it shows that the position of the fiber Bragg grating in the Brillouin fiber laser configuration plays an important role in producing the multi-wavelength signals. By using 19.0 dBm of Brillouin pump power, the highest number of Brillouin Stokes signal and tuning range obtained from this formation is about 23 and 4 nm, respectively. Furthermore, 50% output coupling ratio demonstrates the best ratio to produce Brillouin Stokes signal which gives a better performance in the Brillouin fiber laser system.

Fiber Length Optimization of Ring Cavity Multi-Wavelength Brillouin Fiber Laser Utilizing Fiber Bragg Grating

In this paper, we experimentally investigated the performance of ring cavity multi-wavelength Brillouin fiber laser utilizing fiber Bragg grating which operated in the C-band wavelength region. The combination of stimulated Brillouin scattering and selective wavelengths gave a new invention in the optical fiber communication. Five different lengths of single mode fiber are used in order to get the best gain medium for stimulated Brillouin scattering effect. Up to 33 of Brillouin Stokes signals and 31 of anti-Stokes signals were obtained when 10 km fiber length was used in the laser system. The average value optical signal to noise ratio of 15 dB has been achieved. The broadening bandwidth of Brillouin Stokes signals also occurred at the center wavelength of 1550 nm based on the 3 dB bandwidth of 5 nm fiber Bragg grating.

L-band multi-wavelength Brillouin–Raman fiber laser utilizing the reverse-S-shaped section

In this paper, we experimentally demonstrated multi-wavelength Brillouin–Raman fiber laser that operates in the L-band wavelength region. The laser structure utilizes the reverse-S-shaped technique. 35 output Brillouin Stokes signals were generated at the injection of 6.3 mW of Brillouin pump power at wavelength of 1580 nm into the laser cavity together with a Raman pump power of 891.25 mW. The generated output Brillouin Stokes signals are rigidly separated by 0.08 nm (10 GHz). The structure also provides a high tuning range of 25 nm, from 1570 nm to 1595 nm at the injection of 6.3 mW of Brillouin pump signal power with a Raman pump signal power of 795.3 mW. The generated Brillouin Stokes signals also have an average peak power of 1.11 mW. Highest optical signal-to-noise ratio of 21 dB was obtained at Brillouin pump wavelength of 1595 nm.

Frequency switched narrow linewidth microwave signal photonic generation based on a double-Brillouin-frequency spaced fiber laser.

A simple photonic approach to generate microwave frequency switched microwave signal is proposed and experimentally demonstrated. In this scheme, a Brillouin fiber laser with double-Brillouin-frequency spacing is used. The Brillouin ring configuration suppresses incoming Brillouin pump and even-order Stokes signals in the cavity. In addition, it also allows propagation of the odd-order Brillouin Stokes signals from configuration to output coupler. A dual-wavelength optical signal is heterodyned at the high-speed photodetector to produce a microwave signal. Frequency switched microwave signals, at 10.75 and 21.39GHz, respectively, can be obtained through adjusting the polarization controller (PC) and loss of the variable optical attenuator (VOA).

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

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.

20 GHz spacing multi-wavelength generation of Brillouin-Raman fiber laser in a hybrid linear cavity

We demonstrate a tunable multi-wavelength Brillouin-Raman fiber laser with 20 GHz wavelength spacing. The setup is arranged in a linear cavity by employing 7.2 and 11 km dispersion compensating fibers (DCF) in addition to a 30 cm Bismuth-oxide erbium doped fiber. In this experiment, for the purpose of increasing the Stokes lines, it is necessary to optimize Raman pump power and Brillouin pump power together with its corresponding wavelengths. At the specific Brillouin pump wavelength, it is found that the longer length of 11 km DCF with optimized parameters results in larger number of Stokes combs and optical signal to noise ratios (OSNRs). In this case, a total of 195 Brillouin Stokes combs are produced across 28 nm bandwidth at Brillouin pump power of -2 dBm and Raman pump power of 1000 mW. In addition, all Brillouin Stokes signals exhibit an average OSNR of 26 dB.

Influence of a bidirectional recycling residual pump on the Stokes signal characteristics of a linear cavity Brillouin fiber laser

The effect of a bidirectional recycling residual pump on the Brillouin Stokes signal threshold, as well as on its power, is experimentally investigated. The laser cavity is formed with two optical mirrors as the resonator reflectors which allow bidirectional residual pump recycling that causes bidirectional Brillouin gains. These gains significantly reduce the threshold power and increase the Stokes signal power. For the same single mode fiber length, the Brillouin Stokes signal threshold is reduced by up to 75% and 50% in the laser structure compared to its values in conventional and recycling Brillouin threshold reduction techniques, respectively. In addition, the effect of Brillouin gains on the Stokes signal power is illustrated and exhibits no additional gain in the laser cavity as compared with the recycling technique, especially for long fibers >8 km.

A widely tunable double-Brillouin-frequency spaced multiwavelength fiber laser with a 110 nm tuning range

A wideband double-Brillouin-frequency spaced multiwavelength Brillouin–erbium fiber laser (MWBEFL) with 110 nm tuning range is demonstrated. The fiber laser utilizes simple compound-ring cavity structures which confine the odd-order Brillouin–Stokes (BS) signals within the right ring and couple out the initial Brillouin pump signal (BP) and even-order BS signals to generate a 0.176 nm spacing multiwavelength. A wavelength- and bandwidth-tunable optical band-pass filter (TBF) is used to manipulate the location of self-lasing cavity and to get a wideband tuning range. All the generated output channels exhibit good stability.

Widely Tunable C $+$ L Bands Multiwavelength BEFL With Double-Brillouin Frequency Shifts

A wideband multiwavelength Brillouin–erbium fiber laser (BEFL) with double Brillouin frequency spacing is demonstrated. The fiber laser structure utilizes a tunable band-pass filter and a pre-amplified Brillouin pump technique within a ring cavity. An average of six Brillouin–Stokes signals in C <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$+$</tex></formula> L bands with a constant wavelength spacing of 0.174 nm can be turned over a span of 80 nm from 1530 nm to 1610 nm. Total average output power of 8.5 mW from this laser structure was achieved. All the generated Brillouin–Stokes signals exhibit good stability, and high peak power of above <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$-$</tex></formula> 10 dBm per signal was demonstrated.

Double Brillouin frequency spaced multiwavelength Brillouin-erbium fiber laser with 50 nm tuning range

A 50 nm tuning range multiwavelength Brillouin-erbium fiber laser (MWBEFL) with double Brillouin frequency spacing is presented. Two separated gain blocks with symmetrical architecture, consisted by erbium-doped fiber amplifiers (EDFAs) and Brillouin gain media, are used to generate double Brillouin frequency spacing. The wider tuning range is realized by eliminating the self-lasing cavity modes existing in conventional MWBEFLs because of the absence of the physical mirrors at the ends of the linear cavity. The Brillouin pump (BP) is preamplified by the EDFA before entering the single-mode fiber (SMF), which leads to the reduction of threshold power and the generation enhancement of Brillouin Stokes (BS) signals. Four channels with 0.176 nm spacing are achieved at 2 mW BP power and 280 mW 980 nm pump power which can be tuned from 1525 to 1575 nm.