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Publications (142)
Dear All,
The Final White Paper on Optical Wireless Communication Technologies is now available on the NEWFOCUS Website.
Thank you,
Stan, Fary and Ali
There is an increasing need for quantum communication applications, including true random numbers and quantum key distribution. The Amplified Spontaneous Emission (ASE) is a quantum physics process, which can play a significant role in both cases. A physical model for detecting and acquiring the ASE noise is developed. The photon probability is cal...
Integrating Quantum Key Distribution service with classical high-speed optical data transmission using a dense wavelength division multiplexing technique in a fiber is a cost-effective solution to improve the network's security. In this multichannel system, several noise sources degrade the quality of the quantum channel. The dominant degradation e...
In this paper, a Reflective Semiconductor Optical Amplifier based, Radio-over-Fibre access network configuration has been proposed to feed future millimeter-wave radio systems. The system architecture combines several approaches to overcome the challenges of millimeter-wave signal transmission. Reflective semiconductor optical amplifier modulator r...
Vehicle-to-Vehicle (V2V) Communication is one of the most promising application opportunities of Visible Light Communication (VLC). This paper suggests a novel transmission technique for VLC-V2V applications, called 2x2 Differential Transmission (2x2 DT). This transmission method exhibits excellent common-mode optical noise rejection performance. T...
The bit generation algorithm of a quantum random number generator based on photon arrival time differences is improved in terms of the bit generation efficiency and bit generation rate. The method is analyzed mathematically, proving that, in theory, the improved generator still produces random numbers of high quality without the need of resorting t...
Polarization effects of channels such as turbulent free space and optical fibers can deteriorate the quality of polarization-sensitive communication schemes, for example, quantum key distribution. The exact nature of the channel is problematic to determine, and most theoretical results are based on approximations. We introduce a general model with...
In Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) communication links, Visible Light Communication (VLC) solutions have a unique deployment opportunity. This paper introduces an effective common-mode noise rejection technique for V2V-VLC. Transmission measurement results are presented, regarding the noise cancellation efficiency and i...
Future passive optical network (PON) designs with 5G have been expected to provide simultaneous multiple wireless signals to the end-users. This paper proposes and experimentally demonstrates the simultaneous transmission of baseband 4-pulse amplitude modulation (4-PAM), radio frequency (RF) filter bank multicarrier (FBMC), and universal filter ort...
The filter bank multicarrier (FBMC) modulation format is considered as a potential candidate for future wireless 5G due to its feature of high suppression for out-of-band emissions, which allows combining multiple sub-bands with very narrow band-gaps, and hence increases the overall wireless transmission capacity. In this paper, we experimentally d...
A quantum random number generation method based on measuring the time differences between photon detections is analyzed mathematically in terms of bit generation efficiency and bit generation rate. It was found that these two values cannot be maximized simultaneously by altering the incident photon rate of a light source with Poisson statistics, bu...
Vertical-cavity surface-emitting lasers (VCSELs) have multiple beneficial properties in quantum key distribution (QKD). However, polarization switching (PS), which happens between two orthogonally polarized eigenmodes, is characteristic of these lasers. PS is extremely problematic if it is unwanted in all polarization-sensitive applications. The or...
Communication applying visible light technology is a novel approach. Visible Light Communication (VLC) development is motivated by the increasing demand for wireless communication technologies. It has the potential to provide highspeed data communication with good security and improved energy efficiency. The rapid evolution of VLC was sustained by...
Expanding the functionality of LED indoor lighting with visible light communication (VLC) allows an additional communication channel beside wireless radio in buildings. This service may be based on various channel access methods and modulation types. Code division multiplexing (CDM) is a suitable method to such an application, but it is complicated...
Future 5G based passive optical networks (PON) are expected as capable of the simultaneous provision of wired and wireless services for multi-users. In this paper, for the first time, we propose and demonstrate the simultaneous delivery of wired 4-pulse amplitude modulation (4-PAM) and wireless multi-sub-bands filter bank multicarrier (FBMC) signal...
The filter bank multicarrier (FBMC) modulation format is considered as a potential candidate for future wireless 5G due to its feature of high suppression for out-of-band emissions, which allows combining multiple sub-bands with very narrow band-gaps, and hence increases the overall wireless transmission capacity. In this paper, we experimentally d...
The optical single sideband (OSSB) scheme is a common choice in radio over fiber system for compensating chromatic dispersion (CD) but it suffers from low signal to noise ratio (SNR). We present the novel technique for SNR improvement using unequal sideband intensity based modulation scheme, we name it optical vestigial sideband modulation scheme (...
This paper demonstrates a hybrid radio over multi-mode fibre and free space optics (RoMMF-FSO) system that can be used to extend the transmission range of the 4th generation long-term evolution (4G-LTE) signal in access networks. A single mode filtering technique (SMFT) is used to enhance 4G-LTE performance. The proposed scheme is evaluated in term...
In this paper, we propose a new technique for synchronization and channel estimation in M-QAM OFDM radio over fiber (RoF) system by using constant amplitude zero auto-correlation (CAZAC) sequence based training preamble. Delay and correlate method is used to identify the training sequence in the received signal vector and to correct the symbol timi...
This book focuses on optical wireless communications (OWC), an emerging technology with huge potential for the provision of pervasive and reliable next-generation communications networks. It shows how the development of novel and efficient wireless technologies can contribute to a range of transmission links essential for the heterogeneous networks...
Analogue optical links are widely used in radio-frequency, microwave and millimetre-wave signal range applications. One of parameters that affect the performance of an analogue optical link is the chromatic dispersion. Chromatic dispersion affects the signal transmission over the fibre-optic line and in some cases it can destroy the signal shape on...
The omnipresence of LEDs for illumination provides unique opportunities for indoor localization. Signals transmitted by the LEDs can be used to determine the position of a person or object within a room with high precision. The requirements of such applications are different from high speed VLC systems. One of the commonly employed methods for VLC-...
In this paper, we propose a hybrid radio over multi-mode/single-mode fibre and free space optics
(RoMMF/SMF-FSO) system to enhance the 4th generation-long term evolution (4G-LTE) signal performance when used in local area access networks. A single mode fibre pigtailed gradient index lens is used to minimise the modal effect of the optical link at d...
The quantum based communication techniques are one of the leading research topics of optical communication. Quantum based Free-Space Optical (FSO) communication systems are potential alternatives to high speed microwave communication. The high speed operation requires wide operation bandwidth for the elements applied in the FSO link including the t...
The paper proposes three different multiplexing methods that can be applied in a Visible Light Communication-based indoor-positioning system. Our solutions realize the positioning algorithms via simple means which do not influence the light sources' performance significantly. The measurement results show that the proposed procedures are suitable fo...
Next-generation access networks (NGANs) mainly include wavelength division multiplexing (WDM) based 60GHz Radio over Fibre systems (60G-RoF) and WDM Passive Optical Networks (WDM-PONs). Semiconductor optical amplifier may be the key device of colorless unit in these WDM based systems. The device can be effectively utilized as external modulator bec...
We propose unequal sideband intensity based modulation scheme called vestigial sideband scheme (VSB) for the radio over fiber system (RoF) using concatenated Mach-Zehnder modulator (MZM) and phase modulator (PM). This scheme can be generated with proper adjustment of the modulation indexes of the modulators. MZM-PM configuration can also be used fo...
In this paper, the method of generating optical single sideband (OSSB) scheme for radio over fiber (RoF) system using concatenated electro-optic amplitude modulator (AM) and phase modulator (PM) is presented. We provide the theoretical analysis of this configuration. With the proper control of parameters of the modulators, optical carrier to sideba...
This paper proposes an optimum hybrid radio over multi-mode fiber and free space optics (RoMMF–FSO) system to enhance the last mile bottleneck issues of wireless communication systems. Single mode fiber (SMF) and gradient index (GRIN) lenses are used as mode filtering techniques to optimize the system performance by mitigating the modal effects pro...
In-line and reflective semiconductor optical amplifiers (SOA and RSOA) can be effectively utilized as external optical intensity modulators. However the limited modulation bandwidth affects the application possibilities, because next generation access networks desire high transmission speed. Bandwidth enhancement can be achieved by means of optical...
In this paper we study the radio frequency (RF) signal properties generated by direct mixing two laser beams, which can be used in very high frequency (e.g. terahertz) communications. We show the supply source stability has a critical effect in this procedure. It can broaden the RF signal spectrum up to 1 GHz. Although the linewidth of the lasers i...
To increase capacity of radio over fiber (RoF) link, electrical subcarrier multiplexing technique can be used. This method introduces serious intermodulation distortion (IMD), which limits the transmission performance. In this paper, we propose a multiplexing technique in optical domain using polarization multiplexing (Pol-Mux) technique which is f...
In this paper two millimetre-wave (mm-wave) generation techniques involving optical heterodyne detection and the Mach-Zehnder Modulator (MZM) based optical comb technique are investigated. The heterodyne detection system is followed by a second order electrical feedback loop to reduce the phase noise. Simulations are carried out to study the effect...
In-line and reflective semiconductor optical amplifiers can be effectively utilized as external modulators because they can perform simultaneously amplification and modulation. The reflective device (RSOA- Reflective Semiconductor Optical Amplifier) is more practical in optical distribution network. The main limitation is the modulation bandwidth o...
The paper experimentally investigates indoor visible light communication (VLC) channels. The disturbances come from the light bulbs and other VLC systems. The paper demonstrates that the noisiest light bulbs are the fluorescent lamps which emit high frequency disturbances. Different light bulbs are examined to make an optimal carrier choice for the...
In this paper, the combination of radio over multimode fibre and radio over free space optical systems are experimentally investigated. A mode filtering technique is adopted in order to deal with the modal effects in such hybrid systems. Considering mode filtering effect, we have determined transfer function and performed link budget analysis. Meas...
In this paper, we propose a new scheme for the integration between the outdoor and indoor 4G long term evolution networks employing the radio-over free space optics technology for the rural environments applications to reduce the deployment cost. We experimentally characterise the system performance under the atmospheric fading effects including th...
In-line and reflective semiconductor optical amplifiers can be advantageously utilized as external modulators because they can perform simultaneously two functions (amp-lification and modulation). When the SOA is used in next generation access networks the modulation bandwidth is a crucial property, because it will limit the application. In the pap...
In-line and reflective semiconductor optical amplifiers can be advantageously utilized as external modulators because they can perform simultaneously two functions (amplification and modulation). When the SOA is used in next generation access networks the modulation bandwidth is a crucial property, because it will limit the application. In the pape...
Multimode fiber (MMF) links are currently attracting much interest as a medium for the transmission of radio signals over optical links called Radio over Fiber (RoF) link. However, the application is restricted, because the capacity of MMF transmission is limited by intermodal dispersion which is caused by the different propagation speeds of the fi...
In this paper a 2R all-optical regenerator will be presented, which based on the nonlinear self-phase modulation. The regenerator was simulated with the VPI TransmissionMaker and its optical filter module was examining, because the optical filter is the main element of these types of regenerators.
For interconnections between the stations of mobile networks optical links are frequently used. The mobile networks require new modulation methods to achieve higher transmission capacity. For that purpose the m-QAM modulation method is a proper approach. On the other hand, the signal transmission in the mobile network is strongly affected by multip...
VCSELs (Vertical-cavity surface-emitting lasers) offer a number of unique advantages: a threshold current that is low and stable with temperature so that electricity is converted to light with a very high efficiency; the ability to be modulated at very high frequencies; a circular output beam with low divergence, simplifying the optical system. Lif...
Ultrawide-band (UWB) is a promising short range communication technology due to its extremely low radiation power, very low operation signal-to-noise ratio (SNR), and wide bandwidth under unlicensed spectrum (3.1 – 10.6 GHz). To construct an optimal correlation receiver for UWB impulse radio, it is good to have all the incoming signal information i...
This paper investigates distribution and processing of Ultra Wide-Band (UWB) signals for radio over fibre network. An optically connected Impulse Radio UWB (IR-UWB) antenna system is proposed and experimentally demonstrated. To make this system cost effective uncooled, direct modulated VCSEL diodes and multimode optical fibres were applied. The cen...
The study presents theoretical and experimental investigations on radio over fibre links concerning the effect of fibre dispersion. An approach is presented to overcome the radio-frequency suppression effect in optical links based on the joint effect of semiconductor optical amplifier chirp, chromatic dispersion and non-linearities of optical fibre...
An optically controlled phased array antenna system employing dispersive optical waveguide enhanced wavelength-continuously tunable true time delay devices is proposed. The antenna array with control of azimuth and elevation by using optical wavelength tuning is suggested. By increasing the dispersion absolute value of waveguide the system size can...
A low cost radio over fiber (RoF) systems using vertical cavity surface emitting lasers (VCSEL) and multimode fiber (MMF) were studied. The system concept was designed and investigated by simulation. The electrical circuits were designed and fabricated. The simulation results were verified by measurement. The result of the simulations and measureme...
There is an increasing demand for broadband networks in today's rapidly developing communication systems. That requirement is achieved by the use of a combined optical-wireless communication system in which the wireless network serves small picocells and the picocells are interconnected by optical links. Using OFDM technique a robust system is achi...
Semiconductor optical amplifiers (SOAs) can be advantageously utilized as external modulators because they can simultaneously perform two functions: amplification and modulation. When the SOA is used in a subcarrier multiplexed system, the modulation linearity is a crucial property. In this paper, theoretical and experimental investigations are pre...
A new method is presented for establishing variable microwave time delay utilizing optical approaches. In many applications there is a need for a significant time delay which cannot be established by microwave methods. The optical fiber can offer a substantial time delay which can be utilized by converting the microwave signal into the optical doma...
Semiconductor optical amplifiers (SOAs) can be advantageously utilized as external modulators because they can perform simultaneously two functions: amplification and modulation. When the device is used in a subcarrier multiplexed system the modulation linearity is a crucial property. Theoretical and experimental investigations are presented with t...
A new method is presented for establishing variable microwave / millimetre wave true time delay utilizing photonic approaches. In many applications there is a need for a significant time delay which cannot be established by microwave methods. The optical fiber can offer a substantial time delay which can be utilized by converting the microwave sign...
The transmission properties of optical links carrying subcarrier channels are strongly affected by fiber dispersion, fiber nonlinearity and reflections. An approach is presented here to reduce the chromatic dispersion-induced distortions. This new method is based on the interplay of the fiber nonlinearity and the intensity dependent phase modulatio...
The semiconductor optical amplifiers (SOA) is very attractive device for optical communication systems for their capability to be multifunctional devices. SOAs have demonstrated their multifunctional facility by combining optical amplification with modulation, gating, photodetection, dispersion compensation, linearization, etc. The paper describes...
The application of microwave / millimeter-wave optical links for future mobile broadband services is limited by the dispersion of the fibre. We present an approach to reduce the chromatic dispersion-induced distortions in optical links carrying combined baseband and microwave signals. This new method is based on the interplay of intensity dependent...
Future broadband services will utilize millimeter-wave optical links. However, they can be distorted by fiber dispersion. We present an approach to reduce the chromatic dispersion-induced distortions in optical links carrying combined baseband and millimeter wave signals. This new method is based on the interplay of intensity dependent phase modula...
A collection of slides from the author's conference presentation is given. These discuss the effects of dispersion, fiber nonlinearities, harmonics behavior and a semiconductor optical amplifier compensator.
This paper demonstrates that in broadband networks in-line semiconductor optical amplifiers (SOAs) beside providing system gain can also be used as simultaneous transceivers. The SOA branching stages are studied and presented for bus config-uration. Using a steady-state model, we have made a small-signal approximation applying an equivalent circuit...
The paper demonstrates that in broad-band networks in-line semiconductor optical amplifiers that provides system gain can also be used as simultaneous transceiver. The SOA branching stages for bus configuration are studied and presented. We have made a small signal approximation using an equivalent circuit based the rate equations for laser amplifi...
A 400 km standard single mode fiber (SSMF) link with a single light-intensity modulator was upgraded for simultaneous transmission of STM-16 2.5 Gbps baseband data and digital-video-broadcast-terrestrial DVBT utilizing a 40 GHz subcarrier. An optical circulator and narrowband fiber Bragg gratings (FBG) were used to separate the signals in the optic...
Eliminating dispersion fast and early on is a critical concern when building next generation optical networks. Dispersion penalty has been investigated widely in 1550 nm fiber-optical links transmitting different kind of signals. However, only few papers were addressed to the harmonics generation effect. This paper presents theoretical and experime...
An approach is presented to reduce the chromatic dispersion-induced distortions in optical links carrying combined baseband and microwave signals. This new method is based on the interplay of intensity dependent phase modulation in semiconductor optical amplifiers (SOAs) and fiber nonlinearities. Theoretical and experimental results are demonstrate...
The wireless indoor communication system applying an optical transparent backbone provides an economic and flexible approach for local area networks in office buildings. The performance of the system is enhanced by assigning specific subcarriers for the individual picocells which enables the transmission of the wireless channels without altering th...
The semiconductor optical amplifier (SOA) is a proper component for simultaneous modulation and amplification what is a good approach for sub-carrier multiplexed optical signal transmission. However, cascading several SOAs a new problem arises, an increase in the distortion due to cross-modulation of the different channels. In the paper an optimum...
Sinusoidally modulated optical signal transmission is experimentally investigated over a 30 km standard single-mode fiber
using a range of optical input powers. Experiments and computer simulations showed that fiber-induced self-phase modulation
generates a chirp on the signal with an effect opposite to that induced by chromatic dispersion. Calcula...
The semiconductor optical amplifier (SOA) can be used as an efficient high-speed modulator in subcarrier multiplexed (SCM) systems. The modulation response, the noise performance and nonlinear behavior of SOAs are investigated and experimentally demonstrated.
Future wireless communications are being pushed to broadband communications with rates well above Gb/s. Millimeter wave access systems require innovation in optical and electronic hardware as part of the front end subsystems. This workshop addresses system architectures and performance of the front end opto-electronics that could meet information t...
All-optical wavelength conversion is one of the key functionalities in wavelength division multiplexed (WDM) systems, where channel routing is desired without any limitation. Semiconductor optical amplifiers offer several possible solutions for this functionality in the optical domain. Different possible solutions are compared, pointing out the adv...
The semiconductor optical amplifier (SOA) can be used as an efficient high-speed modulator. This paper presents optical subcarrier multiplexed label swapping/reinsertion utilizing this device associated to the wavelength converter block in packet-switched all-optical networks. For that purpose, the modulation response and nonlinear behavior of SOAs...
The semiconductor optical amplifier (SOA) can be used as an efficient high-speed modulator. The paper presents optical subcarrier multiplexed label swapping/reinsertion utilizing this device associated to the wavelength converter block in packet switched all optical networks. For that purpose the modulation response and nonlinear behavior of SOAs a...