Volume 41, Issue 2 -

This article presents the architecture of optical microring resonator based on surface plasmon polaritons using different profile materials like silicon (Si), silver (Ag) and gold (Au). It is observed that 3.53e-005 w/m, 6.92e-005 w/m, 7.05e-005 w/m received optical powers are achieved in silicon (Si), silver (Ag) and gold (Au) profile materials, respectively, of optical microring resonator at 0.1 w/m minimum input transmission power for 1.55 μm input transmission wavelength. The result shows that the silicon profile is best for designing the optical microring resonator in terms of received optical power.

A serially coupled double-ring resonator using the low loss multilayer silicon wire waveguide is presented that has featured high out-of-band rejection and high finesse. The round trip loss and Q factor has also been calculated and found moderate. However, extremely low loss waveguide has shown reduced coupling between the ring and the waveguide.

This article proposed an all-digital code converter schematic. It converts input binary code into gray code output with an operating data rate of 50 Gbps. The design is based on exploiting nonlinear attributes with semiconductor optical amplifier, which is otherwise contemplated as cons if utilized as an amplifier. It is realized with a semiconductor optical amplifier placed symmetrically with both arms of Mach–Zehnder interferometer, and phase modulation occurs amid wings of the Mach–Zehnder structure. Accordingly, numerical simulations have been executed for the applied data inputs. Consequent gray code output patterns have been verified that resemble with theoretical digital logical outcome. Evaluations with design have illustrated impressive optical performance metric extinction factor beyond 10 dB for the imperative constituents and constraints, with semiconductor optical amplifier confine factor beyond 0.3, pump current of 0.4 A, active length of 0.05 mm, and with modulator chirp factor and on–off ratio beyond 0.5 and 10 dB, respectively. Accordingly, this investigation could be an assist for the impending optical computing complex networks for the contemporary digital globe, requiring code conversion as one of the imperative practices.

A novel architecture of N × N bidirectional-reconfigurable multiwavelength optical cross connect (B-RMOXC) based on tunable Fiber Bragg grating and optical circulator is proposed. B-RMOXC network is one of crucial network element for wavelength routing in dense wavelength division multiplexing system. This paper presents a high speed, power compensated bidirectional optical cross connect and verified the performance of bidirectionality with 0.8-nm channel spacing having bit rate of 10 Gbps at different transmission distances. Optical signal-to-noise ratio of 36.62 dB and 35.55 dB is achieved with acceptable Quality factor of 6.26 and 6.99 respectively for upstream and downstream at 60 km having input transmission power of −12 dBm. It is found that the data can be communicated bidirectionally to a distance of 60 km in the presence of fiber nonlinearities without optical amplifier.

Optical soliton compression in dispersion decreasing fibers with relaxing Kerr effect was investigated numerically. The results were compared with the instantaneous nonlinear response case. It was observed that, in general, the relaxing Kerr effect produces significantly worse results than the instantaneous nonlinear response. However, by the appropriate choice of fiber length, one can obtain a higher compression factor if the relaxation time is sufficiently short.

In this work, an optical switch based on electro-optic effect is reported. We used defect mode in two-dimensional photonic crystal made of Lithium Niobate. Under an applied voltage of 3 V, a refractive index change of −0.0702 is obtained which has led to a transmittance contrast about 60% for the ON state and a high extinction ratio of about 20 dB. Moreover, Slow light structure performance is investigated to optimize proposed optic switch. Due to elliptic shape of holes, the applied voltage is decreased to 0.5 V. Also, a refractive index change decrease around −0.0481, a transmittance contrast increase 65 %, and an extinction ratio increase by 5 dB have been observed. We used plan wave expansion and finite difference time domain methods to analyze the structures performances. It is seen that a defect mode shift about 40 nm and a switching length of 6.48 μm are obtained with drive voltage of 3 V for simple structure and only 0.5 V for slow light structure.

In this paper, a 16-QAM orthogonal frequency division multiplexing (OFDM) with companding technique is proposed and experimentally demonstrated in a high-speed visible laser light communication setup with low-cost 450 nm blue-light laser diode. Companding technique is used to reduce the high peak-to-average power ratio (PAPR) of the OFDM signal. The experimental results show a successfully achieved 2.5 Gb/s under 5 m free space transmission and a PAPR reduction of about 3.2 dB at a fixed complementary cumulative distribution function of 10 –3 when compared with the regular one without any technique.

Multi-tone-based wavelength division multiplexed passive optical networks are considered to provide cost-effective access network solution. We analysed and revealed the transmission performance, power budget concern and the cost investigation of the multi-tone-based WDM PON. A differential phase shift keying and re-modulated return to zero on/off keying signals for downlink and uplink, respectively, are transmitted via a single-mode fibre. The transmission performance of the proposed architecture is analysed using key parameters of bit error rate and optical signal to noise ratio using different data rates and channel spacing. The simulation results are in agreement with the theoretical analysis. The power budget is calculated for both upstream and downstream data signals showing excellent system margins for any unseen losses. The proposed setup is also analysed in terms of cost to prove it the cost-effective solution for the next-generation optical access networks.

In the evolvement of current passive optical networks (PONs), there is ever increasing bandwidth demand due to dynamic service requirements. This introduces challenge for the choice of multiplexing technique and physical layer bounds like fiber length, data rate, and number of users are critical over a suitable architecture. In this article, hybrid wave division multiplexing-time division multiplexing PON is analyzed using variable length of fiber with data rates up to 40 Gbps over a maximum of 128 end users. Comparative study using different frequency spacing’s has shown that it has negligible effect on the Q-factor performance parameter. Further in the work, variable data rates required for different services is successfully transmitted up to 30 km to 128 number of users for an acceptable level of bit error rate.

In this article, the impact of cross-phase modulation (XPM) and cross-polarization modulation (XpolM) on transmission of 112 Gb/s polarization multiplexed quadrature phase shift keying (POLMUX QPSK) signal in a wavelength division multiplexing (WDM) system has been investigated. This WDM system comprises of on-off keying (OOK) or differential phase shift keying (DPSK) channels. It is observed that the effects of XPM and XpolM are greatly reduced in a hybrid system of co-propagating OOK and DPSK channels. This is due to the dominance of phase modulation of DPSK signals rather than the intensity modulated OOK signals. The error vector magnitude (EVM) of the received optical signal is evaluated for the increase in number of neighbouring OOK and DPSK channels respectively within a bandwidth of 350 GHz. Also, the effect of increase in bit rate for two neighbouring OOK and DPSK channels has been observed individually on the 112 Gb/s POLMUX QPSK signal. It is concluded that DPSK signals display an improvement of −9.44 dB in EVM over OOK signals when there are eight neighbouring channels in the transmission system.

Abstracts Future 5 G networks can enhance their wireless capacity and speed by effectively using high-frequency millimetre waves. Radio over fibres (RoF) is the promising technology to deliver millimetre waves over optical fibres as it integrates radio domain with wireless domain. The current study employed cost-effective non-return to zero scheme to encode 10 Gbps – 60 GHz data and wavelength division multiplexing scheme to transmit four channels over 60 km optical fibre link.

Synchronized multi-pulse PPM “SMPPM” is a new proposed modulation scheme based on MPPM proposed for wireless optical systems. The proposed scheme resolves the symbol synchronization problem which may simplify the encoding and the decoding operations. It shows an important improvement in terms of data speed and bandwidth efficiency compared with conventional MPPM. On the other hand, SMPPM modulation shows a moderate power efficiency. In this article, we present the coding algorithm, expressions of spectral efficiency, normalized power requirements, and the data rate normalized to PPM, and we also present comparison of results with conventional MPPM.

In mode division multiplexing (MDM) free space optical (FSO) communication system, the atmospheric turbulences such as fog, rain, and haze cause adverse effects on system performance. This paper investigates the mitigation of atmospheric turbulences of FSO using MDM and decision feedback equalizer (DFE) with minimum mean square error (MMSE) algorithm. The implementation of the MMSE algorithm is used to optimize both the feedforward and the feedback filter coefficients of DFE. The proposed system comprises three parallel 2.5Gbit/s channels using Hermite–Gaussian modes. A data rate of 7.5Gbit/s over 40 m, 800 m, 1400 m, and 2km under medium fog, rain, haze, and clear weather, respectively, has been achieved. In addition, it is noticed that the link distance is reduced while increasing the attenuation. The simulation results revealed that a DFE improves the performance MDM FSO system while maintaining high throughput and desired low bit error rate.

Optical code division multiple access (OCDMA) is one of the promising technologies to be implemented using all-optical networks. The performance of OCDMA system is largely dependent on the particular codes used for encoding. A proper choice of code family as well as code dimension is of prime importance due to various transmitter and receiver design considerations. This paper mainly aims at evaluation of desirable characteristics of various spreading codes based on the prime sequences. An extensive effort has been done in this paper to evaluate the correlation characteristics of various types of one-dimensional (1-D), 2-D and 3-D prime codes for OCDMA communication system. The detailed mathematical modelling has also been explained. It is observed that an addition in coding dimension leads to significant improvement in the code characteristics.

In this paper, we have presented a global study of simple bonds, focusing on the main limitations introduced by different optical components as laser source, fiber, optical amplifier, and optical detector. The construction of a long-distance link requires the compensation of attenuation and chromatic dispersion phenomena. Thus, it is well known that the attenuations cause the drop of the signal intensity, whereas the pulse spreading, due to the dispersion, causes the increase of the Bit Error Rate (BER) and consequently the reduction of the signal to noise ratio (SNR). In this purpose, we have calculated the quality factor ( Q ) issues from the noisy signal’s simulations. We have found a Q of 7.02 to a BER of 0.8 e −12 . The founding results match well with fixes norms in telecommunication field.