Generation and Transmission of Optical Ultra-wideband Signals for Optical Fiber and Wireless Communication Links

The demand for high bandwidth in wireless communication in the past years has been growing rapidly as the personal smart devices are becoming more and more an inseparable part of modern life. Accordingly, the current wireless personal area network (WPAN) has to migrate to a higher radio frequency in order to satisfy the demand for high data rates. Ultrawideband (UWB) systems are considered to be one of the most promising technologies for short range broadband wireless communication, due to their numerous attractive features such as low power spectral density, wide bandwidth, enhanced ability for penetrating obstacles , immunity to multi-path fading, coexistence with other wireless systems and capability of providing Gbps data transmission. In the year 2002, the U.S. Federal Communications Commission approved the unlicensed use of the UWB spectrum from 3.1 GHz to 10.6 GHz, with a power spectral density lower than -41.3 dBm/MHz. Due to the low power spectral density, the wireless coverage of UWB technology is limited to a few meters, while the broadband access technology demands a larger coverage in range of kilometers. In order to satisfy this demand and also integrate the local UWB environment into the fixed wired network, UWB-over-fiber (UWBoF) is proposed as a promising solution. The concept of UWBoF is to transmit the UWB signals over optical channels in order to extend the coverage area and benefit from the features offered by the optical fiber such as, low loss and immunity to electromagnetic interference. Moreover, generating and encoding the UWB signals directly into the optical domain is highly desirable, in order to avoid the use of wideband electronics and the need for extra optical-electrical conversion. Furthermore, optical generation of UWB signals has many other advantages such as light weight, small size and large tunability. This dissertation proposes a novel concept on the optical generation of UWB pulses. In particular, the ultimate goal is to introduce a technique which satisfies the demands of the future fiber optic based WPAN industry such as: simplicity in transmitters and receivers, low cost, the most effective utilization of the imposed FCC mask, ability to deliver high data rates (range of Gbps), offering a huge coverage area (range of 10s of kilometers), compatibility with the time-division-multiplexing passive-optical-networks (TDM-PONs) and compatibility with the wavelength-division-multiplexing passive-optical-networks (WDM-PONs). Accordingly, a simple and cost effective approach based on the direct modulation of a semiconductor laser and optical filtering is investigated and experimentally demonstrated. The novel pulse shaping techniques are reported and their compliance to the FCC mask in terms of bandwidth, spectral power efficiency and wireless coverage is studied. The impact of the fiber transmission on the generated UWB signals based on the proposed technique is investigated and a coverage area of up to 60 km is experimentally verified. The compatibility of the transmitter with the TDM-PON is demonstrated through the generation and error-free transmission of a 1.25-Gbps UWB signal and a 10-Gbps-non-return-to-zero (NRZ) signal with the use of only one single light source and in different time slots of a TDM architecture. Additionally, the performance evaluation of a bidirectional, symmetric and WDM-compatible transmission of 1.25 Gbps UWB over 60 km fiber is performed and error-free transmission is obtained. Finally, transmission of a 2.5 Gbps UWB signal is made possible by employing a new modulation technique in the transmitter. The outstanding achievements of this thesis underline the great potential of UWBoF for the future of smart, cost effective, energy efficient and broadband WPAN applications

Simultaneous wavelength and orbital angular momentum demultiplexing using tunable MEMS-based Fabry-Perot filter

In this paper, we experimentally demonstrate simultaneous wavelength and orbital angular momentum (OAM) multiplexing/demultiplexing of 10 Gbit/s data streams using a new on-chip micro-component – tunable MEMS-based Fabry-Perot filter integrated with a spiral phase plate. In the experiment, two wavelengths, each of them carrying two channels with zero and nonzero OAMs, form four independent information channels. In case of spacing between wavelength channels of 0.8 nm and intensity modulation, power penalties relative to the transmission of one channel do not exceed 1.45, 0.79 and 0.46 dB at the harddecision forward-error correction (HD-FEC) bit-error-rate (BER) limit 3.8 × 10¯³ when multiplexing a Gaussian beam and OAM beams of azimuthal orders 1, 2 and 3 respectively. In case of phase modulation, power penalties do not exceed 1.77, 0.54 and 0.79 dB respectively. At the 0.4 nm wavelength grid, maximum power penalties at the HD-FEC BER threshold relative to the 0.8 nm wavelength spacing read 0.83, 0.84 and 1.15 dB when multiplexing a Gaussian beam and OAM beams of 1st, 2nd and 3rd orders respectively. The novelty and impact of the proposed filter design is in providing practical, integrable, cheap, and reliable transformation of OAM states simultaneously with the selection of a particular wavelength in wavelength division multiplexing (WDM). The proposed on-chip device can be useful in future high-capacity optical communications with spatial- and wavelengthdivision multiplexing, especially for short-range communication links and optical interconnects

Generation and Transmission of Optical Ultra-wideband Signals for Optical Fiber and Wireless Communication Links

The demand for high bandwidth in wireless communication in the past years has been growing rapidly as the personal smart devices are becoming more and more an inseparable part of modern life. Accordingly, the current wireless personal area network (WPAN) has to migrate to a higher radio frequency in order to satisfy the demand for high data rates. Ultrawideband (UWB) systems are considered to be one of the most promising technologies for short range broadband wireless communication, due to their numerous attractive features such as low power spectral density, wide bandwidth, enhanced ability for penetrating obstacles , immunity to multi-path fading, coexistence with other wireless systems and capability of providing Gbps data transmission. In the year 2002, the U.S. Federal Communications Commission approved the unlicensed use of the UWB spectrum from 3.1 GHz to 10.6 GHz, with a power spectral density lower than -41.3 dBm/MHz. Due to the low power spectral density, the wireless coverage of UWB technology is limited to a few meters, while the broadband access technology demands a larger coverage in range of kilometers. In order to satisfy this demand and also integrate the local UWB environment into the fixed wired network, UWB-over-fiber (UWBoF) is proposed as a promising solution. The concept of UWBoF is to transmit the UWB signals over optical channels in order to extend the coverage area and benefit from the features offered by the optical fiber such as, low loss and immunity to electromagnetic interference. Moreover, generating and encoding the UWB signals directly into the optical domain is highly desirable, in order to avoid the use of wideband electronics and the need for extra optical-electrical conversion. Furthermore, optical generation of UWB signals has many other advantages such as light weight, small size and large tunability. This dissertation proposes a novel concept on the optical generation of UWB pulses. In particular, the ultimate goal is to introduce a technique which satisfies the demands of the future fiber optic based WPAN industry such as: simplicity in transmitters and receivers, low cost, the most effective utilization of the imposed FCC mask, ability to deliver high data rates (range of Gbps), offering a huge coverage area (range of 10s of kilometers), compatibility with the time-division-multiplexing passive-optical-networks (TDM-PONs) and compatibility with the wavelength-division-multiplexing passive-optical-networks (WDM-PONs). Accordingly, a simple and cost effective approach based on the direct modulation of a semiconductor laser and optical filtering is investigated and experimentally demonstrated. The novel pulse shaping techniques are reported and their compliance to the FCC mask in terms of bandwidth, spectral power efficiency and wireless coverage is studied. The impact of the fiber transmission on the generated UWB signals based on the proposed technique is investigated and a coverage area of up to 60 km is experimentally verified. The compatibility of the transmitter with the TDM-PON is demonstrated through the generation and error-free transmission of a 1.25-Gbps UWB signal and a 10-Gbps-non-return-to-zero (NRZ) signal with the use of only one single light source and in different time slots of a TDM architecture. Additionally, the performance evaluation of a bidirectional, symmetric and WDM-compatible transmission of 1.25 Gbps UWB over 60 km fiber is performed and error-free transmission is obtained. Finally, transmission of a 2.5 Gbps UWB signal is made possible by employing a new modulation technique in the transmitter. The outstanding achievements of this thesis underline the great potential of UWBoF for the future of smart, cost effective, energy efficient and broadband WPAN applications

Amplitude Noise Suppression and Orthogonal Multiplexing Using Injection-Locked Single-Mode VCSEL

We experimentally demonstrate BER reduction and orthogonal modulation using an injection locked single-mode VCSEL. It allows us suppressing an amplitude noise of optical signal and/or double the capacity of an information channel.Peer reviewe

Injection-Locked Single-Mode VCSEL for Orthogonal Multiplexing and Amplitude Noise Suppression

It has been shown earlier, that the injection locked semiconductor lasers enable effective amplitude noise suppression [1] and makes possible an extra level of signal multiplexing-orthogonal modulation [2], where DPSK and ASK NRZ channels propagate at the same wavelength [3]. In our work we use an injection-locked 1550 nm VCSEL as a slave laser providing separation of amplitude and phase modulations, carrying independent information flows. To validate the possibility of phase modulation extraction by an injection-locked VCSEL, an experimental setup shown in Fig. 1 has been built.Peer reviewe

TDM-PON compatible generation of 10 Gbps NRZ and 1.25 Gbps UWB signals by a single light source

A novel and cost-efficient technique is presented to generate non-return-to-zero (NRZ) and ultra-wideband (UWB) signals in different time slots of time division multiplexing-passive optical network (TDM-PON) by using a single chirped controlled semiconductor laser associated with an optical bandpass filter. In this technique, the chirp of the laser is controlled by different bias burst amplitudes (BBA) for different time slots. Through the proper selection of the burst amplitudes, 10 Gbps NRZ and 1.25 Gbps UWB signals are generated in different time slots. Principle of operation is discussed, the complete chirp behavior of the laser is experimentally investigated, data transmission of the generated signals is demonstrated and bit-error-rate (BER) level of 10−9 is achieved