Mohamad Dernaika

A Switchable Figure Eight Erbium-Doped Fiber Laser Based on Inter-Modal Beating By Means of Non-Adiabatic Microfiber

A switchable multiwavelength figure eight fiber laser effect of multimode interference is proposed and experimentally demonstrated. A narrow bandpass filter of multiple specific wavelengths was created by incorporating a tapered non-adiabatic microfiber of 70 mm length and 2 μm diameter in a Sagnac loop mirror. Spatial mode beating arose due to the modal interference in the non-adiabatic microfiber, and resulted in a comb filter able to suppress mode competition. The proposed laser generated single longitudinal modes having a 3-dB linewidth of less than 0.16 pm, which represents an upper limit measurement imposed by the restrictions of the optical analyzer resolution, and possessed an optical signal-to-noise ratio of 58 dB at 82 mW pumping power. Moreover, nonlinear polarization rotation and strain switching mechanisms are demonstrated for generating single, dual, and triple wavelength over more than 20 nm span. In addition, a description is provided on a new technique of packaging non-adiabatic microfiber that diminishes issues relating to degradation of the microfiber over time and external perturbation.

Coupled Cavity Single-Mode Laser Based on Regrowth-Free Integrated MMI Reflectors

A photonic integrated circuit is demonstrated that couples three Fabry-Pérot (FP) lasers together via an integrated star coupler. The FP lasers rely on a common cleaved facet and individual multimode interference reflectors (MIRs) for lasing operation. The MIRs are monolithically integrated with each FP laser using a single growth step, which allows for epitaxial regrowth-free processing. By suitable independent tuning of each Fabry-Pérot, a single mode operation and a mode selection can be attained from the coupled cavity system. The mode selectivity and side-mode suppression ratios of ~40 dB are demonstrated.

Tunable dual-wavelength thulium-doped fiber laser at 1.8 μm region using spatial-mode beating

This study describes a proposal and experimental demonstration of a tunable thulium-doped fiber laser with a multi-wavelength output operating at 1.8 μm. The introduction of a multi-mode non-adiabatic taper fiber into a single-mode cavity induces spatial-mode beating and a consequent narrow band filter mechanism. The fiber laser can be tuned by changing the state of the polarization in a ring cavity via adjustment of a polarization controller. The resulting outputs for single and dual wavelengths with different spacing are reported in detail.

A tuneable, power efficient and narrow single longitudinal mode fibre ring laser using an inline dual-taper fibre Mach-Zehnder filter

A tuneable single longitudinal mode fibre ring laser with dual-taper fibre filter is proposed and experimentally demonstrated in this paper. The single longitudinal mode operation, and power limitations for a Mach–Zehnder interferometer filter generated from a single mode fibre, are verified for the first time. Incorporating an in-line taper fibre Mach–Zehnder interferometer filter inside the laser ring cavity causes a spatial mode beating interference, resulting in a passive narrow band filter with the ability to generate stable single longitudinal modes. The single longitudinal mode achieves a side mode suppression ratio of more than 60 dB using low pump power. The tuneability of the fibre laser ranges from 1525 to 1562 nm using a passive band pass filter. A study of the stability and limitation of the single longitudinal mode in the Mach–Zehnder tapered fibre is also presented.

Teleoperation Scheduling Algorithm for Smart Grid Communications in LTE Network

This paper investigates the performance of three well-known algorithms namely Proportional Fairness, Exponential Proportional Fairness and Modified-Largest Weighted Delay First in LTE network. This study is based on their performance in three smart grid applications (Sub-Station Automation, Advance Metering Infrastructure and Wide Area Situational Awareness). In addition, a new mathematical model has been developed and proposed to target certain weakness of the above mentioned algorithms.

All-incoherent wavelength conversion in highly nonlinear fiber using four-wave mixing

Abstract. This work describes efficient and polarization insensitive, all-incoherent four-wave mixing wavelength conversion achieved within a short length of highly nonlinear fiber medium, created by using both spectrally sliced pump and probe channels from a single-amplified spontaneous emission source coupled to two narrowband Fiber Bragg grating (FBG) filters. This simple and cost-effective scheme is capable of generating a down-converted probe channel across a 17.2-nm wavelength span, while still maintaining a high conversion efficiency of around −22  dB and an optical-signal-to-noise ratio of ∼21  dB. The effects of pump power, FBG detuning, and polarization are also reported.

Regrowth-free integration of injection locked slotted laser with an electroabsorption modulator

Optical injection locking was used to red shift an integrated semiconductor laser up to 30 nm away from the main free running lasing mode. This injection locking of the laser beyond its band edge enabled its integration with an electroabsorption modulator to produce a 2.5 Gb/s eye diagram. The electroabsorption modulator was shown to have a 3 dB bandwidth of 5.5 GHz, which was limited by the contact capacitance. This paper demonstrates that such devices could be applied in a regrowth free, monolithic coherent wavelength division multiplexing transmitter.

Regrowth-Free Single Mode Laser Based on Dual Port Multimode Interference Reflector

This letter demonstrates an InP-based photonic integrated circuit that utilizes an etched facet and a dual port multimode interference reflector to create a lasing cavity. The laser was fabricated using UV lithography and did not require any epitaxial regrowth. A single deep etched slot produced single mode behavior due to the coupled cavity effect. By varying the bias of the two sub cavities, mode selectivity with a side mode suppression ratio of 30 dB is demonstrated.

All-fiber dual wavelength passive Q-switched fiber laser using a dispersion-decreasing taper fiber in a nonlinear loop mirror.

This paper describes a proposal and successful demonstration of a dual wavelength all-fiber passively Q-switched erbium-doped fiber ring laser. The Q-switch operation was realized by using a nonlinear loop mirror that incorporated an unbalanced dispersion-decreasing taper fiber to act as a saturable absorber without additional elements. This setup enabled a fiber ring laser to achieve a performance of 48.7 kHz repetition rate with pulse duration of around 3.2 μs and approximate pulse energy of 20 nJ.

Single facet semiconductor laser with deep etched V-notch reflectors integrated with an active multimode interference reflector

Abstract A single mode laser based on novel deep etched V-notch reflectors is presented in this paper. The reported device has a stable single mode operation and a side mode suppression ratio of 37 dB. The laser is widely tunable and it can be fine-tuned. Moreover, the laser cavity is monolithically integrated with an active multimode interference reflector, and has a total length of .