Free space optical (FSO) communication has become more exciting during the last decade. It has un... more Free space optical (FSO) communication has become more exciting during the last decade. It has unregulated spectrum with a huge capacity compared to its radio frequency (RF) counterpart. Although FSO has many applications that cover indoor and outdoor environments, its widespread is humped by weather effects. Fog is classified as an extreme weather impairment that may cause link drop. Foggy channel modeling and characterization is necessary to analyze the system performance. In this paper, we first address the statistical behavior of the foggy channel based on a set of literature experimental data and develop a probability distribution function (PDF) model for fog attenuation. We then exploit our PDF model to derive closed form expressions and evaluate the system performance theoretically and numerically, in terms of average signal-to-noise ratio (SNR), and outage probability. The results show that for 10-3 outage probability and 22 dBm transmitted power, the FSO system can work over 80 m, 160 m, 310 m, and 460 m link length under dense, thick, moderate, and light fog respectively. Increasing the transmitted power will have high impact when the fog density is low. However, under very dense fog, it has almost no effect.
We demonstrate the viability of widely tunable far-L-band injection-locked quantum- dash laser as... more We demonstrate the viability of widely tunable far-L-band injection-locked quantum- dash laser as a source for NG-PONs by successful 128 Gb/s DP-QPSK transmission over ∼1621 nm subcarrier, and reaching a potential capacity of ∼4.0 Tb/s.
InAs/InP quantum-dash multi-wavelength laser is reported utilizing self-injection locking coheren... more InAs/InP quantum-dash multi-wavelength laser is reported utilizing self-injection locking coherency boosting technique. Subcarrier controllability between 1–16 Fabry-Perot modes (1600–1610nm) with ∼−3–9dBm mode power is achieved. Thereafter, a successful 64 Gbit/s DP-QPSK data transmission is demonstrated via a single self-injection locked mode over 20km single-mode-fiber.
Many solutions have been proposed for fiber-fault monitoring in passive optical networks (PONs) d... more Many solutions have been proposed for fiber-fault monitoring in passive optical networks (PONs) during the last years. Optical coding has attracted particular attention for detecting fiber faults in PONs. These coding modules have particular characteristics that make it suitable for monitoring PON such as inexpensive, passive, and mature devices in their coding settings. In this paper, we investigate and analyze the performance of a set of key optical coding schemes that we have previously introduced for monitoring optical networks. We will derive their key design parameters and evaluate their performance in terms of signal-to-noise ratio, probability of misdetection, and probability of false alarm. We also show how this special category of coding techniques scales up to monitor also various complex architectures of networks. In effect, we extend this to wavelength division multiplexing (WDM) and TDM over WDM-PON. Moreover, we further extend their application to metro ring networks and integrated metropolitan and access networks, referred as long-reach PONs.
In this paper, we consider and examine fog measurement data, coming from several locations in Eur... more In this paper, we consider and examine fog measurement data, coming from several locations in Europe and USA, and attempt to derive a unified model for fog attenuation in free space optics (FSO) communication links. We evaluate and compare the performance of our proposed model to that of many well-known alternative models. We found that our proposed model, achieves an average RMSE that outperforms them by more than 9 dB. Furthermore, we have studied the performance of the FSO system using different performance metrics such as signal-to-noise (SNR) ratio, bit error rate (BER), and channel capacity. Our results show that FSO is a short range technology. Therefore, FSO is expected to find its place in future networks that will have small cell size, i.e., <;1 km diameter. Moreover, our investigation shows that under dense fog, it is difficult to maintain a communications link because of the high signal attenuation, which requires switching the communications to RF backup. Our results show that increasing the transmitted power will improve the system performance under light fog. However, under heavy fog, the effect is minor. To enhance the system performance under low visibility range, multi-hop link is used which can enhance the power budget by using short segments links. Using 22 dBm transmitted power, we obtained BER=10-3 over 1 km link length with 600 m visibility range which corresponds to light fog. However, under lower visibility range equals 40 m that corresponds to dense fog, we obtained the same BER but over 200 m link length.
We demonstrate a single channel free space optical dual polarization - quadrature phase shift key... more We demonstrate a single channel free space optical dual polarization - quadrature phase shift keying (DP-QPSK) transmission using an injection-locked InAs/InP quantum dash (Qdash) laser by employing external modulation. A receiver sensitivity of −19 dBm at ∼1621 nm is observed over a 4 m indoor channel at 64 Gb/s transmission rate. This stems the potential of Qdash lasers as a source in optical wireless communication, which is being considered as an alternative optical access technology for future high speed communication networks.
Visible light communication (VLC) using indoor LED lighting generally assumes the existence of li... more Visible light communication (VLC) using indoor LED lighting generally assumes the existence of line of sight link in addition to multipath, delayed, lower power reflections. In this paper, we investigate the possibility to establish VLC links in shadowed areas, i.e., where the line of sight is blocked or unavailable. First, we study the system performance in terms of received power, SNR, BER, and rms delay spread. The results show acceptable, yet promising performance of $$\hbox {BER}=1.2\times 10^{-3}$$BER=1.2×10-3 in worst non-line of sight case. Second, we define three configuration scenarios for receiver’s PD orientation in which line of sight is absent. For each scenario, we evaluate the link performance. Our analysis shows that the system performance can be potentially improved when MIMO is considered for locations that have low performance with single photodetector.
Next generation 400Gbps and 1Tbps per wavelength optical transmission system will require the use... more Next generation 400Gbps and 1Tbps per wavelength optical transmission system will require the use of high spectral efficiency optical modulation schemes. Rather than wireless communication system, laser phase noise (PN) has a major impact on the performance of optical systems due to high speed of communication and high order modulations recently proposed/demonstrated in these communication systems. In this paper, we prototype a reference optical transmitter, that digitally emulates the effect of the laser phase noise. This experiment enables us to generate laser linewidths ranging from a kilohertz up to hundreds of megahertz. Moreover, this enables us to measure the performance of the generated high order MQAM modulated signals in case inexpensive low quality or alternatively expensive high quality laser is exploited. In our experimental performance investigation, we have addressed state-of-the-art symbol rates of 14, 16, and 25Gbaud and modulation orders ranging from QPSK up to 16QAM. In order to mitigate the phase noise effect a Kalman filter (KF) phase tracker is employed at the receiver side. Our simulation and experiment show that our transmitter makes successful emulation of the PN and our tracking algorithm makes appropriate tracking of 16QAM for a laser linewidth of 1MHz. However, when inexpensive lower quality 10 MHz laser is used, the recovery capacity of the algorithm becomes limited to QPSK.
Free space optical (FSO) communication has become more exciting during the last decade. It has un... more Free space optical (FSO) communication has become more exciting during the last decade. It has unregulated spectrum with a huge capacity compared to its radio frequency (RF) counterpart. Although FSO has many applications that cover indoor and outdoor environments, its widespread is humped by weather effects. Fog is classified as an extreme weather impairment that may cause link drop. Foggy channel modeling and characterization is necessary to analyze the system performance. In this paper, we first address the statistical behavior of the foggy channel based on a set of literature experimental data and develop a probability distribution function (PDF) model for fog attenuation. We then exploit our PDF model to derive closed form expressions and evaluate the system performance theoretically and numerically, in terms of average signal-to-noise ratio (SNR), and outage probability. The results show that for 10-3 outage probability and 22 dBm transmitted power, the FSO system can work over 80 m, 160 m, 310 m, and 460 m link length under dense, thick, moderate, and light fog respectively. Increasing the transmitted power will have high impact when the fog density is low. However, under very dense fog, it has almost no effect.
We demonstrate the viability of widely tunable far-L-band injection-locked quantum- dash laser as... more We demonstrate the viability of widely tunable far-L-band injection-locked quantum- dash laser as a source for NG-PONs by successful 128 Gb/s DP-QPSK transmission over ∼1621 nm subcarrier, and reaching a potential capacity of ∼4.0 Tb/s.
InAs/InP quantum-dash multi-wavelength laser is reported utilizing self-injection locking coheren... more InAs/InP quantum-dash multi-wavelength laser is reported utilizing self-injection locking coherency boosting technique. Subcarrier controllability between 1–16 Fabry-Perot modes (1600–1610nm) with ∼−3–9dBm mode power is achieved. Thereafter, a successful 64 Gbit/s DP-QPSK data transmission is demonstrated via a single self-injection locked mode over 20km single-mode-fiber.
Many solutions have been proposed for fiber-fault monitoring in passive optical networks (PONs) d... more Many solutions have been proposed for fiber-fault monitoring in passive optical networks (PONs) during the last years. Optical coding has attracted particular attention for detecting fiber faults in PONs. These coding modules have particular characteristics that make it suitable for monitoring PON such as inexpensive, passive, and mature devices in their coding settings. In this paper, we investigate and analyze the performance of a set of key optical coding schemes that we have previously introduced for monitoring optical networks. We will derive their key design parameters and evaluate their performance in terms of signal-to-noise ratio, probability of misdetection, and probability of false alarm. We also show how this special category of coding techniques scales up to monitor also various complex architectures of networks. In effect, we extend this to wavelength division multiplexing (WDM) and TDM over WDM-PON. Moreover, we further extend their application to metro ring networks and integrated metropolitan and access networks, referred as long-reach PONs.
In this paper, we consider and examine fog measurement data, coming from several locations in Eur... more In this paper, we consider and examine fog measurement data, coming from several locations in Europe and USA, and attempt to derive a unified model for fog attenuation in free space optics (FSO) communication links. We evaluate and compare the performance of our proposed model to that of many well-known alternative models. We found that our proposed model, achieves an average RMSE that outperforms them by more than 9 dB. Furthermore, we have studied the performance of the FSO system using different performance metrics such as signal-to-noise (SNR) ratio, bit error rate (BER), and channel capacity. Our results show that FSO is a short range technology. Therefore, FSO is expected to find its place in future networks that will have small cell size, i.e., <;1 km diameter. Moreover, our investigation shows that under dense fog, it is difficult to maintain a communications link because of the high signal attenuation, which requires switching the communications to RF backup. Our results show that increasing the transmitted power will improve the system performance under light fog. However, under heavy fog, the effect is minor. To enhance the system performance under low visibility range, multi-hop link is used which can enhance the power budget by using short segments links. Using 22 dBm transmitted power, we obtained BER=10-3 over 1 km link length with 600 m visibility range which corresponds to light fog. However, under lower visibility range equals 40 m that corresponds to dense fog, we obtained the same BER but over 200 m link length.
We demonstrate a single channel free space optical dual polarization - quadrature phase shift key... more We demonstrate a single channel free space optical dual polarization - quadrature phase shift keying (DP-QPSK) transmission using an injection-locked InAs/InP quantum dash (Qdash) laser by employing external modulation. A receiver sensitivity of −19 dBm at ∼1621 nm is observed over a 4 m indoor channel at 64 Gb/s transmission rate. This stems the potential of Qdash lasers as a source in optical wireless communication, which is being considered as an alternative optical access technology for future high speed communication networks.
Visible light communication (VLC) using indoor LED lighting generally assumes the existence of li... more Visible light communication (VLC) using indoor LED lighting generally assumes the existence of line of sight link in addition to multipath, delayed, lower power reflections. In this paper, we investigate the possibility to establish VLC links in shadowed areas, i.e., where the line of sight is blocked or unavailable. First, we study the system performance in terms of received power, SNR, BER, and rms delay spread. The results show acceptable, yet promising performance of $$\hbox {BER}=1.2\times 10^{-3}$$BER=1.2×10-3 in worst non-line of sight case. Second, we define three configuration scenarios for receiver’s PD orientation in which line of sight is absent. For each scenario, we evaluate the link performance. Our analysis shows that the system performance can be potentially improved when MIMO is considered for locations that have low performance with single photodetector.
Next generation 400Gbps and 1Tbps per wavelength optical transmission system will require the use... more Next generation 400Gbps and 1Tbps per wavelength optical transmission system will require the use of high spectral efficiency optical modulation schemes. Rather than wireless communication system, laser phase noise (PN) has a major impact on the performance of optical systems due to high speed of communication and high order modulations recently proposed/demonstrated in these communication systems. In this paper, we prototype a reference optical transmitter, that digitally emulates the effect of the laser phase noise. This experiment enables us to generate laser linewidths ranging from a kilohertz up to hundreds of megahertz. Moreover, this enables us to measure the performance of the generated high order MQAM modulated signals in case inexpensive low quality or alternatively expensive high quality laser is exploited. In our experimental performance investigation, we have addressed state-of-the-art symbol rates of 14, 16, and 25Gbaud and modulation orders ranging from QPSK up to 16QAM. In order to mitigate the phase noise effect a Kalman filter (KF) phase tracker is employed at the receiver side. Our simulation and experiment show that our transmitter makes successful emulation of the PN and our tracking algorithm makes appropriate tracking of 16QAM for a laser linewidth of 1MHz. However, when inexpensive lower quality 10 MHz laser is used, the recovery capacity of the algorithm becomes limited to QPSK.
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