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At present days, metropolitan and access communication networks are markedly developing utilizing a variety of technologies. Their bearer communication infrastructures will be mostly exploiting the optical transmission medium where wavelength division multiplexing techniques will play a key role. Wavelength-Division Multiplexed Passive Optical Networks (WDM-PON) attract considerable attention for the next generation optical metropolitan and access networked systems. Simultaneously, the utilization of common optical network resources in wavelength domains will be more important. The main purpose of this paper is presented by the evaluation of resource efficiencies for the non-symmetric dynamic wavelength allocation method applied in the WDM-PON network design with a conventional topology. This contribution introduces a novel non-symmetric Dynamic Wavelength Allocation (DWA) method for a selected network design with the utilization only passive optical splitters in remote nodes. This novel wavelength allocation method is oriented on minimizing a number of working wavelengths that will be used for compliance of customers' requests for data transmitting in the common point-to-multipoint WDM–PON network design. For evaluation of wavelength scheduling, a simulation model related to the conventional WDM-PON network design is realized in the MATLAB programming environment is presented with results. Finally, different traffic loading scenarios are determined and, subsequently, resource efficiencies of the presented non-symmetric DWA method are evaluated from a viewpoint of application in future WDM-PON network designs. [ABSTRACT FROM AUTHOR]

In this paper, we propose and experimentally demonstrate a tunable erbium-doped fiber laser (EDFL) with Sagnac interference loop with 45° angle shift spliced polarization maintaining fibers (PMFs). In the Sagnac loop, two PMFs with similar lengths. The Sagnac loop outputs a relatively complex interference spectrum since two beams transmitted in clockwise and counterclockwise encounter at the 3 dB coupler, interfere, and form two interference combs when the light transmitted in the Sagnac loop. The laser will excite and be stable when two interference lines in these two interference combs overlap together. Then by adjusting the polarization controller, the wide wavelength tuning is realized. Experimental results show that stable single wavelength laser can be realized in the wavelength range of 1585 nm–1604 nm under the pump power 157.1 mW. The side-mode suppression ratio is not less than 53.9 dB. The peak power fluctuation is less than 0.29 dB within 30 min monitor time and the side-mode suppression ratio is great than 57.49 dB when the pump power is to 222.7 mW. [ABSTRACT FROM AUTHOR]

We investigate the wavelength dependence of stress-induced time of flight variations in graded-index multimode fibers (GI-MMFs) for wavelength λ = 1.26 μm ∼1.58 μm, theoretically and experimentally. Calculations were made based on simple equations using the refractive index of silica fibers. We measured the wavelength dependence of stress-induced time of flight variations by a newly proposed measurement method. We confirmed the similar wavelength dependence of GI-MMFs to that for standard single mode fibers (SSMF). However, the value of them is different. We compare the experimental and theoretical results for two types of fibers. The comparison indicates that the difference of stress-induced time of flight variations between two types of fibers is mainly due to the group velocity difference. We conclude that there is no significant difference of the photo-elastic constant between the measured SSMFs and GI-MMFs. Although many properties of GI-MMFs depended on the mode power distribution in general, we conclude the dependence of stress-induced time of flight variations on mode power distribution is small for the measured fibers. [ABSTRACT FROM AUTHOR]

We present a method for transmitting 25-Gb/s optical nonreturn-to-zero signals at a wavelength of 1550nm over a 40-km single-mode fiber without any dispersion compensation methods. We propose optimized self-phase modulation by varying parameters of the fiber launching power and the extinction ratio of optical non-return to zero signals to overcome severe signal distortions by the chromatic dispersion effect. Using the optimization of the self-phase modulation effect, we were able to transmit 25-Gb/s optical nonreturn-to-zero signals over a 40-km single-mode fiber, which can be applicable to passive optical networks with a single wavelength channel and a high split ratio. We demonstrated that the self-phase modulation effect can be controlled by the extinction ratio and the fiber launching power. [ABSTRACT FROM AUTHOR]