Volume 33, Issue 2

This paper investigates theoretically the amplification performance of a synchronized quantum cascade laser for an input subcarrier-multiplexed phase modulated lightwave. The output optical phase-modulation amplitude corresponding to a given microwave subcarrier has been calculated. The third order intermodulation distortion of the desired optical phase modulation by a microwave subcarrier has been calculated and its dependence on the input phase modulation (PM) index has been studied analytically.

The performance of a all-optical header extraction scheme using semiconductor optical amplifier and Mach–Zehnder-Interferometer (SOA-MZI) with bidirectional data injection was studied at the packet rate of 80Gb/s for ultrafast all-optical packet switching networks. Numerical analysis and simulation results showed that the contrast ratio of optical header extraction could exceed 18 dB when input signal energy was as low as 0.1 pJ. In addition, the parameters of SOA-MZI and the input signal features were discussed to optimize the performance of proposed scheme.

In this article, an efficient compact two dimensional finite-difference frequency-domain (2-D FDFD) method has been used to model photonic Crystal fiber (PCF). Different values of dispersion coefficient can be obtained by changing fiber parameters using FDFD method. Since for each one of these parameters there exists a different value for dispersion coefficient, selection of optimal point will be a time consuming process. Here, first of all, we calculate parameter K , which is the key factor to design dispersion compensated fibers, so the design process will be faster and easier. The optimal value for K parameter is around 301.8 nm for transmission line fibers. So, it is enough to sketch both dispersion curve and K parameter versus PCF parameters, in a single coordinate system. Proper parameters will be obtained by analyzing the curves.

In passively mode locked fiber laser, case of 8FL (Eight Fiber Laser), the management of length, linear and non linear parameters of the cavity plays a paramount role in the generation of stable ultra short pulses with high peak powers. In this work, we propose an 8FL consisted of MOF (Microstructured Optical Fiber). According to the various properties of the MOF, we studied the variation of the pulses peak power and width. We demonstrated that there are optimal parameters of the MOF for which the peak power is maximal and the width is minimal.

In all-optical WDM networks, feasibility of a lightpath are determined by physical layer impairment accumulation. Physical layer impairment-aware routing and wavelength assignment (PLIA-RWA) algorithms select a feasible route keeping signal to noise ratio value at the receiver above the threshold limit. This paper reviews the impairments present in optical fiber emphasizing those that result in performance degradation of WDM system. Different types of channel allocation schemes to reduce the number of four wave mixing components generated and performance of the WDM optical network under these channel allocation schemes have also been reviewed. The performance of WDM network due to collective effect of FWM-SRS and FWM-XPM has been discussed. Limitations of amplifier and its optimal location have also been discussed. The article further examines and surveys the role of wavelength converters/regenerators in regard to efficient network design. The paper also presents a survey of different PLIA-RWA algorithms and identifies several open problems for future research.

A new framework for traffic scheduling in bufferless slotted all-optical packet switched (OPS) networks is proposed, where combination of contention resolution and reduction schemes is used to reduce packet loss rate. Three merits are proposed for scheduling of optical packets in core nodes as number of hops an optical packet has travelled, type of user packets carried in an optical packet, and number of deflections an optical packet has experienced. Physical layer impairments are also taken into account in packet scheduling by evaluating signal polarization mode dispersion (PMD) and routing optical packets through shortest-hop-path routes. An optical packet is dropped (i) when the optical packet finds an unacceptable PMD along the path toward its destination, (ii) when there is no available resource to switch the optical packet in an OPS switch (either by wavelength conversion or by deflection routing); and (iii) when the optical packet experiences a threshold on the number of deflections along its path. Three packet aggregation schemes to support Quality of Service (QoS) are also evaluated as Timer-based/Threshold-based bandwidth Access, Compound-TTA, and Distribution-based bandwidth Access. Performance evaluations show the effectiveness of the proposed framework in improving delay and traffic loss.

In this paper, we demonstrated the transmission performance through simulation for Integrated Dense Wavelength Division Multiplexing and Optical-OFDM system with OADM including the fiber nonlinearity effect. The effects on transmitted channels, fiber link length, operating optical signal wavelength, optical transmitted signal power, optical signal bandwidth, transmission bit rate, optical received power and bit error rate at the receiving side are observed.

The objective of this paper is to develop and analyze new bandwidth efficient modulation scheme that offers higher spectral efficiency than traditional PPM, and improvement in data rate. While in conventional optical PPM, only one level of optical pulse is used, this technique “Tow levels PPM” (2LPPM) combines multilevel (Two levels) photon communication `PAM' with pulse position modulation (PPM), thus information is represented by different combinations of the positions and the levels of the pulses. This paper analyses the proposed modulation scheme in terms of data rate, band-utilization efficiency and power requirements.