Ghazaleh Mamdoohi

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.

Multi-wavelength Brillouin-Raman fiber laser utilizing enhanced nonlinear amplifying loop mirror design

We demonstrate a single-spacing, multi-wavelength Brillouin-Raman fiber laser utilizing an enhanced cavity of nonlinear amplifying loop mirror. In this structure, the optimization of multi-wavelength lasing is done with proper adjustments of coupling ratio and Brillouin pump power. When setting the Raman pump power to 300 mW, up to 28 channels with an average 17 dB optical signal-to-noise ratio are achieved. In this case, the Brillouin pump power is maintained at -2.6 dBm when the splitting ratio and Brillouin pump wavelength are fixed at 99/1 and 1555 nm, correspondingly. Our achievements present high numbers of Stokes channels with an acceptable optical signal-to-noise ratio at low pump power operation.

Effects of Raman pump power distribution on output spectrum in a multi-wavelength BRFL.

This paper aims to investigate changes in multi-wavelength Brillouin-Raman fiber laser (MBRFL) spectra characteristics that are influenced by variation of Raman pump power distribution along the two fiber-entry points. This is carried out by incorporating a Raman pump source with a set of couplers with various ratios. In this arrangement, the optimization of pumping ratio is properly carried out to achieve high number of lasing lines with 20 GHz spacing which yield the highest peak power discrepancy between odd- and even-order lasing lines and an excellent Stokes optical signal-to-noise ratio (S-OSNR). Employment of 50/50 coupler offers 212 flat amplitude channels with an average 27.5 dB S-OSNR and -10 dBm Stokes peak power when the Brillouin pump wavelength is set at 1543 nm. Achievements such flat and wide bandwidth MBRFL spectrum with 20 GHz spacing and excellent S-OSNR utilizing just a single pump source is significant in terms of simplicity and flexibility.

Realization of microcontroller-based polarization control system with genetic algorithm

Realization of a PIC32 microcontroller-based polarization control system is described. Genetic algorithm is used for control purposes. The controller measures the signal intensity to estimate the genetic value. To reach optimum performance, the code is optimized by using the best genetic parameter to achieve the fastest execution time. This algorithm consumes low size of memory besides providing fast speed. The implementation of microcontroller allows for more economic polarization control solution.

Effects of Raman pump power distribution on output spectrum in a multi-wavelength BRFL: publisher's note.

This publishers note amends the author list and Acknowledgments of a recent publication [Opt. Express23, 25570 (2015)].

Optimization of hybrid Raman-Brillouin-EDF amplification fiber laser in long distance FBG sensor system

We present a hybrid Raman-Brillouin-Erbium Doped Fiber (EDF) amplification based Fiber Bragg Grating (FBG) sensor system capable of transmitting over long reach Single Mode Fiber (SMF). The performance of output spectra has been optimized and realized by the best effective placement of EDF and Raman pump power. An optimized combination of Raman, Brillouin and Erbium gain brings forth an optical signal-to-noise ratio of 16.34 dB in 100 km long distance FBG sensor system.

Effect of double-pass and single-pass architecture in Brillouin-Raman fiber laser

We experimentally investigate effect of double pass and single pass configuration in multi-wavelength Brillouin-Raman fiber laser in a linear cavity. Up to 110 flat amplitude multi-wavelengths Brillouin Stokes with spacing of 0.16 nm within wavelength range of 1554 to 1570 nm in single pass configuration are generated. The generated wavelengths with OSNR 25 dB compared with that of double pass architecture. Single space configuration has a superior performance due to double line spacing, higher OSNR, wider bandwidth and high stability than that of double pass configuration. Lasing lines in double pass has 0.08 nm space due to the increment of Rayleigh scattering in double pass configuration.

Effect of Erbium Doped Fiber location on double spacing multi-wavelength Brillouin-Erbium fiber laser performance

Two different locations of Erbium Doped Fiber (EDF) in dual ring configuration to generate double frequency shifted of multiwavelength Brillouin Erbium fiber laser (BEFL) have been investigated. The experimental results show that the location of EDF has important roles to determine the number of output Stoke signals and tuning range. Beside the Erbium gain, the Brillouin gain also contributes to the performance of BEFL. By putting the EDFA next to the BP, more Stokes lines with wider tuning range were obtained compare by putting the EDF next to the gain medium was observed.

Characterization of Raman gain for different gain medium

By using different fiber types as gain medium such as 500 m HNLF, 215 cm Bi-EDF, 7.2 km DCF, 11 km DCF, 18.2 km DCF, as well as the composition of Bi-EDF with 11 km DCF and finally the composition of Bi-EDF with the 18.2 km DCF, Raman gain was characterized and measured by the same set up as proposed in our study. The results revealed that the composition of Bi-EDF with the 18.2 km DCF provided the highest effective Raman gain among the other fibers investigated.

Enhancement of polarization controller characterization using Genetic Algorithm

We propose and demonstrate characterization of 8-stage LiNbO3 polarization controller (PC) by using Genetic Algorithm. An ability of GA to work efficiently in polarization control system possesses many advantages including easy code construction, consumption low memory and fast control speed. This algorithm is intelligent enough to characterize the PC accurately in 300 µs.