To support bursty traffic on the Internet (and especially WWW) efficiently, optical burst switching (OBS) is proposed as a way to streamline both protocols and hardware in building the future gener...

Optical burst switching (OBS) - a new paradigm for an optical Internet

We present a novel optical orthogonal frequency division multiplexing (O-OFDM) scheme, suitable for intensity-modulated direct-detection systems, where the modulation/demodulation processing takes advantage of the fast Hartley transform algorithm. Due to the properties of the discrete Hartley transform (DHT), the conventional transmission scheme can be streamlined. We demonstrate that asymmetrically clipping (AC) technique can also be applied to DHT-based OFDM; the signal can be transmitted without the need of a DC bias, resulting in a power-efficient system, not affected by clipping noise. Hermitian symmetry is not required for the input signal. Therefore, this technique supports the double of input symbols compared to both AC and DC-biased O-OFDM, based on standard Fourier processing. The analysis in an additive white Gaussian noise channel shows that the same performance can be achieved by replacing 4, 16, and 64 QAM (quadrature-amplitude modulation) AC optical-OFDM with a simpler system based on DHT, using binary phase-shift keying (BPSK), 4 and 8 PAM (pulse-amplitude modulation), respectively.

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Novel Power Efficient Optical OFDM Based on Hartley Transform for Intensity-Modulated Direct-Detection Systems

Orthogonal frequency division multiplexing (OFDM) is a modulation technique which is now used in most new and emerging broadband wired and wireless communication systems because it is an effective solution to intersymbol interference caused by a dispersive channel. Very recently a number of researchers have shown that OFDM is also a promising technology for optical communications. This paper gives a tutorial overview of OFDM highlighting the aspects that are likely to be important in optical applications. To achieve good performance in optical systems OFDM must be adapted in various ways. The constraints imposed by single mode optical fiber, multimode optical fiber and optical wireless are discussed and the new forms of optical OFDM which have been developed are outlined. The main drawbacks of OFDM are its high peak to average power ratio and its sensitivity to phase noise and frequency offset. The impairments that these cause are described and their implications for optical systems discussed.

OFDM for Optical Communications

We present a high-data rate optical wireless system. The implemented system exploits polarization (PM) and wavelength multiplexing, achieving the transmission of a total capacity of 1.6  Tbit/s over hybrid fiber free-space optics (FSO) system with no optical-electronic-optical conversion at the interfaces with air. Quadrature phase shift keying modulation in each channel and coherent detection were used. The system allows enough power budget to support the record transmission of 16 channels, operating each at 100  Gbit/s over 40 km of fiber and 80 m of FSO between two buildings. Performance of the fully transparent connection is presented in terms of bit-error rate.

Optical wireless transmission at 1.6-Tbit/s (16×100 Gbit/s) for next-generation convergent urban infrastructures

Spectrum slicing WDM for FSO communication systems under the heavy rain weather

Very high bit rates WDM transmission on a Transparent FSO System

The physical layer security of passive optical networks (PON) is investigated within a rigorous cryptoanalysis framework; we consider different threats and confidentiality attacks and propose different secure optical code division multiple access (OCDMA)-based architectures.

Physical layer security: All-optical cryptography in access networks

We report experiments on a fully transparent free space optic system operating at 2.5,10 and 40 Gbps. A on-field system operating on a 100 m link as been implemented and tested. Results demonstrate that this kind of system is able to exploit the high bandwidth provided by the fibers and that it can support WDM transmission; in particular it could be a competitive technology in the last mile/last hundred of meters scenario.

On field test of a Wavelength Division Multiplexing Free Space Optics transmission at very high bit rates

Free Space Optics (FSO) is a technology able to provide line of sight wireless high-bandwidth digital communication links between remote sites. Therefore it is a key solution for addressing the last hundred meters of broadband requirements. For enhancing the capacity of optical wireless links, DWDM transmission can be used. In this work, 10 Gb/s and 40 Gb/s bit rates have been used in a DWDM fully transparent system. The link has been demonstrated in both in- and outdoor experiments. System performance has been evaluated in terms of BER and Q-factor.

DWDM Transparent FSO System for In/Outdoor Applications at High Bit Rates

We present different optical secure point-to-point transmission schemes using a planar multiport encoder/decoder. We consider both bit- and block-cipher cryptography: in the first case, each bit (both mark and space) from each user is encoded in a two-key optical code-division multiplexing signal. Block-cipher cryptography encodes a stream of n bits into a single code and corresponds to optical M-ary transmission. We demonstrate that block-ciphers are more secure with respect to bit-ciphers schemes and also against known-plaintext and chosen-plaintext attacks.

V. Sacchieri

Papers

Very high bit rates WDM transmission on a Transparent FSO System

Physical layer security: All-optical cryptography in access networks

On field test of a Wavelength Division Multiplexing Free Space Optics transmission at very high bit rates

DWDM Transparent FSO System for In/Outdoor Applications at High Bit Rates

Secure OCDM Transmission Using a Planar Multiport Encoder/Decoder