Mohammed Hayder Al-Mansoori

Seamless tuning range based-on available gain bandwidth in multiwavelength Brillouin fiber laser.

We experimentally demonstrate a simple widely tunable multiwavelength Brillouin/Erbium fiber laser that can be tuned over the entire C-band, thereby greatly improving the tuning range limitation faced by the previous Brillouin-erbium fiber laser architectures. Tuning range of 39 nm from 1527 nm to 1566 nm, which is only limited by the amplification bandwidth of the erbium gain was successfully achieved. At Brillouin pump wavelength of 1550 nm and 1480 nm laser pump and Brillouin pump powers of 130 mW and 2 mW respectively, all the generated output channels have peak power above 0 dBm, with the first output channel having a peak power of 8.52 dBm. The experimental set up that consists of only 4 optical components, is simple, devoid of the complex structure employed previously to enhance the tunability and feedback mechanism normally associated with multiwavelength Brillouin-erbium fiber laser sources. The generated output channels are stable, rigidly separated by 10 GHz (0.08 nm).

Intelligent Dynamic Bandwidth Allocation Algorithm in Upstream EPONs

An upstream access scheme for Ethernet passive optical networks, called the intelligent fuzzy-logic-based dynamic bandwidth allocation algorithm (IFLDBA) has been proposed. The algorithm provides the allotment of bandwidth between optical network units (ONUs) and within ONUs. Fuzzy logic is used to improve the bandwidth allocation within each ONU. We compare the IFLDBA algorithm with the existing broadcast polling algorithm. The results show that IFLDBA has bandwidth utilization of up to 21% better and lower delay than the broadcast polling algorithm.

Broadly tunable multiple wavelength Brillouin fiber laser exploiting erbium amplification

We experimentally demonstrate a highly stable and flawless-tuning-range multiple wavelength Brillouin fiber laser incorporating an erbium gain block. Free-running cavity modes that inherently circulate in the cavity of a Brillouin/erbium fiber laser, which limits wavelength tunability, are completely suppressed. At a Brillouin pump power of 2 mW and 130 mW of 1480 nm pump power, we obtained seven output channels. The tunability of the generated channels is only limited to 35 nm by the amplification bandwidth of the erbium gain used in the experiment. The first four channels have an output power each above 1.6 dBm with the first and the seventh channels having a peak power of 8.19 dBm and −8.30 dBm.

Ring cavity multiwavelength Brillouin-erbium fiber laser with a partially reflective fiber Bragg grating

Utilization of a partially reflective fiber Bragg grating in the development of a multiwavelength Brillouin-erbium fiber laser is proposed. A ring cavity with a preamplified Brillouin pump configuration is implemented to demonstrate much better performance in comparison with the previously reported results obtained with different configurations. The combination of a 7 km long single-mode fiber and a 10 m long erbium-doped fiber ultimately yields the generation of up to twenty-one Brillouin Stokes lines. The laser configuration provides a greater tuning range of 21 nm at a Brillouin pump power of 2 mW and 980 nm pump power of 20 mW, and requires a much lower pump power to initiate lasing.

Threshold Reduction of Stimulated Brillouin Scattering in Photonic Crystal Fiber

A simple configuration for the reduction of stimulated Brillouin scattering threshold in photonic crystal fiber is presented. The threshold reduction is contributed by the bidirectional pumping scheme through the reflection of transmitted Brillouin pump back to the gain medium. The pump recycling scheme has greatly reduced the Brillouin threshold of a 200-m long of photonic crystal fiber from 50 to 30 mW of Brillouin pump power.

Optimization of output coupling ratio on the performance of a ring-cavity Brillouin-erbium fiber laser.

The operation of a single-wavelength Brillouin-erbium fiber laser (BEFL) system with a Brillouin pump preamplified technique for different output coupling ratios in a ring cavity is experimentally demonstrated. The characteristics of Brillouin Stokes power and tunability were investigated in this research. The efficiency of the BEFL operation was obtained at an optimum output coupling ratio of 95%. By fixing the Brillouin pump wavelength at 1550 nm while its power was set at 1.6 mW and the 1480 pump power was set to its maximum value of 135 mW, the Brillioun Stokes power was found to be 28.7 mW. The Stokes signal can be tuned within a range of 60 nm from 1520 to 1580 nm without appearances of the self-lasing cavity modes in the laser system.

Double Brillouin frequency shift through circulation of odd-order Stokes signal

We demonstrate a simple configuration for generating a double Brillouin frequency shift through the circulation of an odd-order Brillouin Stokes signal. It is operated based on cascaded Brillouin scattering in single-mode optical fibers that behave as the Brillouin gain media. A four-port circulator is incorporated into the setup to circulate the odd-order Brillouin Stokes signal in the fiber. It thus initiates a higher order Brillouin Stokes signal, which is double Brillouin frequency downshifted from the input signal. For the 5 km long fiber, the Brillouin pump power at 23 mW gives a clean output spectrum with 30 dB sideband suppression ratio. The output signal is 0.174 nm or approximately 21.7 GHz downshifted from the input signal.

Efficient dynamic bandwidth allocation algorithm for upstream EPON

In this paper, an efficient dynamic bandwidth allocation (DBA) algorithm based fuzzy logic for upstream Ethernet passive optical networks (EPON) is proposed. The algorithm provides the allotment of bandwidth for inter optical network unit (ONU) and intra ONU. We compared the performance of DBA algorithm based fuzzy logic and DBA algorithm without fuzzy logic in terms of bandwidth utilization and delay. The results shows that the usage of fuzzy logic improve the bandwidth utilization up to 20% and about 50% reduction on the system delay is achieved.

Pressure sensing utilizing linear cavity erbium-doped fiber laser

In this paper, we report a fiber laser pressure sensor based on linear cavity erbium-doped fiber laser. The fiber laser structure comprises of an erbium-doped fiber amplifier, a circulator, an optical coupler and a fiber Bragg grating (FBG) which acts simultaneously as a lasing wavelength selecting components as well as a pressure sensor. The FBG is fitted to the shock tube where the pressure is applied. The fiber laser pressure sensor has a low threshold power of 7 mW, an output power of 2.28 mW and an optical signal to noise ratio over 55 dB. The proposed fiber laser sensor is expected to be an attractive choice for long-distance pressure monitoring.

A stabilized tunable dual wavelength erbium-doped fiber laser with equal output power

Tunable dual-wavelength erbium-doped fiber laser with good stability is experimentally demonstrated. Output power of as high as +5.26 dBm is obtained in dual ring configuration. Both laser output can be tuned to as closed as 0.8 nm spacing between each other, with tuning range of 31.33 nm. The stability of both outputs was tested that results in less than ±0.8 dB and ±0.01 nm in power and wavelength fluctuation, respectively.