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A proposed new design of optical cross add drop multiplexer (OXADM) is presented. It reduces the number of required circulators and total insertion losses compared with other circulator and FBG based designs. This enhances the isolation and crosstalk levels. In the new design, the homodyne crosstalk is eliminated in the drop signal. Also, the homodyne crosstalk in the output signal is reduced by more than 30 dB. Keywords: magnetically tunable fiber Bragg grating, asymmetric optic al cross add drop multiplexer, optical crosstalk.

A new device, optical cross add drop multiplexer (OXADM), is proposed and analyzed. It uses the combination concept of optical add drop multiplexer (OADM) and optical cross connect (OXC). It enables a wavelength switch while implementing add and drop functions simultaneously. So, it expands the applications in fiber to the home (FTTH) and optical core networks. A very high isolation crosstalk level (~ 60 dB) is achieved. Also, a bidirectional OXADM and N×N OXADM are proposed. Finally, a multistage OXADM is presented making some sort of wavelength buffering. To make these devices operate more efficient, tunable fiber Bragg gratings (TFBGs) switches are used to control the operation mechanism.

In this paper, the dispersion compensation in transmission is modeled and investigated using apodized fiber Bragg grating (AFBG). The two-beam interferometer is used in AFBG manufacture. The effect of different interferometer parameters is studied for large bandwidth transmission at a zero eye closure penalty with linearly chirped gratings. The parameters under investigation for only one arm of the interferometer are d (arm length), the angle θ (beam angle) and λ (the writing wavelength). Eight different apodization profiles are studied including their effects on the performance of the compensator.

This work aims to study the improvement that has been achieved when replacing the traditional single-element (SE) receivers by imaging (IMG) receivers in line of sight (LOS) links, which can reduce the received ambient light noise, multipath distortion and co-channel interference. Also in non-directed non-LOS, the replacement of diffuse (DIF) transmitters by multi-beam (quasi-diffuse) (QDIF) transmitters has been studied; such replacement leads to reduction in the path loss. This study first based on making validation to a previous approximate and exact analysis to LOS and non-LOS links, and then a parametric study to some parameters has been made to check their effect on the link performance. We quantify the performance of the LOS and NLOS links using two main parameters; the reduction in the required transmitter power and high improvement in the signal to noise ratio (SNR).

Error rate performance of pulse position modulation (PPM) schemes for indoor wireless optical communication (WOC) applications is investigated. These schemes include traditional PPM and multiple PPM (MPPM). Study is unique in presenting and evaluating symbol error behaviour under wide range of design parameters such symbol length (L), number of chips per symbol (n), number of chips forms optical pulse (w). Effect of signal to noise ratio levels and operating bitrates on symbol error performance is also discussed. A comparison between studying modulation schemes is done. Relation with IrDA and IEEE 802.11 indoor WOC standardization is also investigated. Results indicate that PPM achieve great symbol error performance at reasonable signal to noise ratio and high bitrates with large symbol length.

This paper demonstrates a tunable optical buffer with widely variable time delays using an array of fiber Bragg gratings (FBGs) filter and tunable wavelength converters (WCs). The flexibility of the proposed system gives an exact required delay and, consequently, better output port utilization. This system is designed to be compatible with 10 to 40 Gbps RZ communication systems.

A triangular lattice GaAs photonic crystal structure was proposed in a previous work [1] for optical storage in a dynamic modulation process. This work presents a defect optimization of this tunable coupled resonator array. Preserving translational invariance and adiabaticity, this structure exhibits an optical analogue to electromagnetic induced transparency. This triangular lattice structure shows an advantage over the previously proposed square one [2, 3] in compressing higher bandwidth pulses. The main problem of this structure is the introduction of higher group-velocity dispersion. In the present work, the structure is redesigned so as to change the operating range of frequency for the propagating pulse. In this way, the group-velocity dispersion is eliminated to values close to that of the square lattice structure. The final design, therefore, combines both higher compressible bandwidth and lower group-velocity dispersion in addition to a fabrication advantage.