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In this paper, a spectrally coded optical code division multiple access (OCDMA) system using a hybrid modulation scheme has been investigated. The idea is to propose an effective approach for simultaneous improvement of the system capacity and security. Data formats, NRZ (non-return to zero), DQPSK (differential quadrature phase shift keying), and PoISk (polarisation shift keying) are used to get the orthogonal modulated signal. It is observed that the proposed hybrid modulation provides efficient utilisation of bandwidth, increases the data capacity and enhances the data confidentiality over existing OCDMA systems. Further, the proposed system performance is compared with the current state-of-the-art OCDMA schemes. [ABSTRACT FROM AUTHOR]

Hybrid optical amplifiers (HOAs) are crucially important for broadband band amplification, and are widely deployed in high-capacity dense wavelength division multiplexed systems. We summarize the present state-of-the-art in this rapidly growing field. In addition, theoretical background and various inline configurations of optical amplifiers have been presented. Various issues such as gain flatness, gain bandwidth, transient effect, and crosstalk were presented in HOAs. Results show that the HOAs provide better gain flatness without using any expensive gain flattening techniques, and an acceptable range of gain, noise figure, bit error rate, and transience. [ABSTRACT FROM AUTHOR]

In this paper, security of the spectrally encoded-optical code division multiplexed access (OCDMA) system is enhanced by using 2-D (orthogonal) modulation technique. This is an effective approach for simultaneous improvement of the system capacity and security. Also, the results show that the hybrid modulation technique proved to be a better option to enhance the data confidentiality at higher data rates using minimum utilization of bandwidth in a multiuser environment. Further, the proposed system performance is compared with the current state-of-the-art OCDMA schemes. [ABSTRACT FROM AUTHOR]

We proposed a bandwidth efficient wavelength division multiplexed-passive optical network (WDM-PON) to simultaneously transmit 60 Gb/s unicast and 10 Gb/s multicast services with 10 Gb/s upstream. The differential phase shift keying (DPSK) multicast signal is superimposed onto multiplexed non-return to zero/polarization shift keying (NRZ/PolSK) orthogonal modulated data signals. Upstream amplitude shift keying (ASK) signals formed without use of any additional light source and superimposed onto received unicast NRZ/PolSK signal before being transmitted back to optical line terminal (OLT). We also investigated the proposed WDM-PON system for variable optical input power, transmission distance of single mode fiber in multicast enable and disable mode. The measured Quality factor for all unicast and multicast signal is in acceptable range (>6). The original contribution of this paper is to propose a bandwidth efficient WDM-PON system that could be projected even in high speed scenario at reduced channel spacing and expected to be more technical viable due to use of optical orthogonal modulation formats. [ABSTRACT FROM AUTHOR]