D.M. Forin

Bio: D.M. Forin is an academic researcher from University of Rome Tor Vergata. The author has contributed to research in topics: Passive optical network & Optical amplifier. The author has an hindex of 9, co-authored 49 publications receiving 263 citations. Previous affiliations of D.M. Forin include Instituto Politécnico Nacional & Fondazione Ugo Bordoni.

Free Space Optical Technologies

Abstract: Free Space Optics (FSO), also known as Optical Wireless or Lasercom (i.e. Laser Communications), is a re-emerging technology using modulated optical beams to establish short, medium or long reach wireless data transmission. Most of the attention on FSO communication systems it was initially boost by military purposes and first development of this technology was dedicated to the solution of issues related to defense applications. Today’s market interest to FSO refers to both civil and military scenarios covering different situations and different environments, from undersea to space. In particular, due to the high carrier frequency of 300 THz and the consequently high bandwidth, the most prominent advantage of Free Space Optical (FSO) communication links may be their potential for very high data rates of several Gbps (up to 40 Gbps in the future (J. Wells, 2009)). Other advantages like license-free operation, easy installation, commercial availability, and insensitivity to electromagnetic interference, jamming, or wiretapping make FSO interesting for applications like last mile access, airborne and satellite communication (L. Stotts et alt, 2009), temporary mobile links and permanent connections between buildings. Mainly, the adoption of FSO is needed when a physical connection is not a practicable solution and where is requested to handle an high bandwidth. As a matter of fact, FSO is the only technology, in the wireless scenario, able to grant bandwidth of several Gigabits per second. The interest in this technology is also due to the low initial CAPEX (Capital Expenditure) requirement, to the intrinsic high-level data protection & security, to the good flexibility and great scalability innate in this solution. For these reasons FSO possible applications cover today, as mentioned, a wide range. Thus this technology generates interest in several markets: the first/last mile in dense urban areas, network access for isolated premises, highspeed LAN-to-LAN (Local Area Networks) and even chip-to-chip connections, transitional and temporary network connection, undersea and space communication. Furthermore FSO can be used as an alternative or upgrade add-on to existing wireless technologies when the climatic conditions permit its full usage. 13

All-Optical Conversion From RZ to NRZ Using Gain-Clamped SOA

Abstract: An all-optical converter from return-to-zero (RZ) pulses to the nonreturn-to-zero (NRZ) format is presented. The converter operates in two stages: the laser generated in a gain-clamped semiconductor optical amplifier (SOA) is modulated with the data signal; afterwards this signal is wavelength-converted by cross-gain modulation in a common SOA. The setup is noninverting and can feature wavelength conversion. Experimental error-free conversion from 5- and 40-ps RZ pulses to NRZ format is presented at 10 Gb/s using a 211-1 bit sequence

All-optical fiber 2+1 auxiliary carrier transponder-regenerator

Abstract: The authors report simulations and experimental results about a new kind of all-optical reamplification and reshaping (2R) regenerator. The novelty is based on the principle that the ordinary four-wave-mixing process, inside a particular dispersion-shifted fiber, is able to induce input signal replicas on a third copropagating auxiliary carrier even if its state of polarization is orthogonal to that of the pump. Test results on a deployed cable showing improved 2R function and wavelength conversion capability are reported.

Improved remote node configuration for passive ring-tree architectures

Abstract: In this paper, a set of optically fed passive remote node configurations for a ring-tree extended reach PON which allow increased efficiency and resilience are presented.

Experimental Investigation of Quality of Service in an IP All-Optical Network Adopting Wavelength Conversion

Abstract: We experimentally show how the virtual private large-area network service (VPLS) technique, a layer 2 service, can improve optical network performance in terms of quality of service (QoS), and how a VPLS network behaves when it adopts all-optical wavelength conversion (AOWC), a new optical process that will be introduced in future optical networks. The advantages of VPLS are based on the capability to generate logical reliable paths in each wavelength channel, permitting suitable partitioning of the bandwidth according to the user requirements. In particular, we show the advantages of VPLS in access networks based on passive optical networks, and we test QoS properties of VPLS paths when an AOWC process occurs both in the core and in the access networks. The experimental investigation is carried out in a wide-area, all-optical gigabit Ethernet testbed with an access section based on an Ethernet passive optical network. As far as the core segment is concerned, we chose a high-efficiency AOWC process based on four-wave mixing in dispersion-shifted fiber; conversely in the access segment we chose a cheaper AOWC process based on cross gain modulation in a semiconductor optical amplifier. The reported results show that gigabit Ethernet transmission, with the relative layer 2 techniques, is also well suitable for wide-area WDM architectures, and in particular it is able to guarantee end-to-end QoS for huge bandwidth services such as high-definition TV and also in the case of congestion, restoration, and wavelength conversion processes.

Density-matrix theory of semiconductor lasers with relaxation broadening model - Gain and gain-suppression in semiconductor lasers

Abstract: The density-matrix theory of semiconductor lasers with relaxation broadening model is finally established by introducing theoretical dipole moment into previously developed treatments. The dipole moment is given theoretically by the k . p method and is calculated for various semiconductor materials. As a result, gain and gain-suppression for a variety of crystals covering wide wavelength region are calculated. It is found that the linear gain is larger for longer wavelength lasers and that the gain-suppression is much larger for longer wavelength lasers, which results in that single-mode operation is more stable in long-wavelength lasers than in shorter-wavelength lasers, in good agreement with the experiments.

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

Abstract: 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.

WDM FSO network with turbulence-accentuated interchannel crosstalk

Abstract: A wavelength division multiplexing (WDM) access network using high-speed free-space optical (FSO) communication for the distribution link is proposed. Combining FSO communication with optical fiber can reduce the system cost and provide high-bandwidth access in regions where optical fiber installation is problematic. The WDM channels suffer from interchannel crosstalk, while the FSO communication performance in a clear atmosphere is limited by atmospherically induced scintillation. These impairments, plus the amplified spontaneous emission noise from optical amplification, combine in a potentially problematic way, particularly in the upstream direction, which is investigated here. This turbulence-accentuated crosstalk effect is considered for the cases of 1) signal turbulent but crosstalk not and 2) crosstalk turbulent but signal not. Error floors are obtained in each case. The FSO link length that can be supported in the general case of the hybrid network is investigated.

Optical switch and optical waveform monitoring device utilizing optical switch

Abstract: The polarization direction of an optical signal is changed by a polarization controller so as to be orthogonal to a main axis of a polarizer. A control pulse generator generates control pulses from control beam with a wavelength which is different from the wavelength of the optical signal. The optical signal and the control pulse are input to a nonlinear optical fiber. In the nonlinear optical fiber, the optical signal, during a time period in which the optical signal and the control pulse coincide, is amplified with optical parametric amplification around a polarization direction of the control pulse. The optical signal, during the time period in which the optical signal and the control pulse coincide, passes through the polarizer.