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Experimental Setup (LD: laser diode, VOA: variable optical attenuator, PC: polarization controller, IM: impedance matching, ISO: isolator, BPF: band-pass filter, PD: photodiode, TIA: trans-impedance amplifier).
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We report experimental results showing direct current modulation of a commercial semiconductor optical amplifier (SOA) for electrical to optical conversion of a 64-QAM OFDM analog signal at 54 Mbit/s on 2.5 and 5 GHz carriers. This is believed to be the highest frequency yet experimentally reported for RF signal transmission using a directly modula...
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... this paper we will focus on the uplink; studying the performance of the SOA as a modulator for analog signals such as OFDM signals on 2.5 and 5 GHz carriers in order to investigate the feasibility of the proposed base station and to understand the constraints imposed on the modulation function by the SOA. Fig. 2 shows the experimental setup of the analog OFDM signal conversion. The output of a laser diode at 1562 nm, where the SOA amplification gain is maximum, is injected into the SOA (Optospeed 1550MRI) through a variable attenuator and a polarization controller (our SOA is a polarization sensitive amplifier). The SOA bias current is ...
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Citations
... This challenge let the researchers to look for other technologies to realize the high-speed applications. Different technologies were proposed to achieve this goal such as semiconductor optical amplifiers (SOA) [7,8], periodically poled lithium niobate (PPLN) waveguides [9][10][11], and ring resonators [12,13], electrical to optical conversion (E/O) [14], and photonic crystal [15] are some representation forms. ...
In this paper, different topologies were discussed and their effect on the design of photonic crystal applications was evaluated. They can be classified into four categories (i.e., ring resonator, self-collimation, waveguide, and cavity-based structures). The figure of merits of each topology and its impact on design modules were explained and compared for two different applications (i.e., half-adder and decoder). Finite difference time domain (FDTD) and plane wave expansion methods are the two numerical approaches that were used to analyze the proposed designs. The truth table for each application was introduced. Comparison tables were organized to discriminate the valued characteristics for each structure. Based on the extracted tables, the appropriate topology can be chosen for the required design application according to the needed characteristic.
... It is noteworthy that although the limit for acceptable EP, EP = 1 × 10 −9 , which is the standard requirement in digital communication systems [39], is several orders of magnitude tighter than that employed in other filtering schemes proposed to enable faster RSOA direct modulation by NRZ data [17][18][19], still the BFL managed to successfully confront this ultimate challenge. Since the RSOA nominal modulation bandwidth can be broadened by taking into account, and intervening on, factors such as the dimension [41], optical confinement [42], packaging [43], impedance matching [44] and transport effects [45] of the active device, it can be realized that there is further margin for increasing the RSOA direct modulation speed by means of the BFL. In this direction, the BFL potential was also verified in the time domain and the results are compiled and presented in Figure 12. ...
The feasibility of employing a birefringent fiber loop to enhance the performance of a directly modulated reflective semiconductor optical amplifier is experimentally demonstrated for the first time. The birefringent fiber loop acts as an optical filter of opposite slope than that of the reflective semiconductor optical amplifier electro-optical response and counteracts the finite reflective semiconductor optical amplifier modulation bandwidth of only 0.89 GHz. By proper adjustment of its detuning, the birefringent fiber loop tailors the spectral components that physically manifest due to the reflective semiconductor optical amplifier dynamic perturbation subject to direct modulation in the saturated gain regime, and suppresses the pattern-dependent distortions in the time domain. In this manner, the birefringent fiber loop manages to significantly improve the quality characteristics of the encoded signal at higher data rates than those enabled by the reflective semiconductor optical amplifier limited modulation capability. Owing to the birefringent fiber loop, the reflective semiconductor optical amplifier modulation range is extended to 4 Gb/s at the raw bit error rate of 1.0×10−9, and to 11 Gb/s at the forward error correction limit of 3.8×10−3. These results, which are unique against the evaluation criterion adopted in the first case, and the modulation speed achieved with post-filtering schemes in the second, highlight the beneficial role that the birefringent fiber loop can play in supporting reflective semiconductor optical amplifier operation for intensity amplification and modulation purposes.
... The implementation of emerging lightwave applications, such as radio over fiber (Vacondio et al. 2006), slow and fast light (Meehan and Connelly 2015), colorless passive optical networks (Lee et al. 2010), data erasing/rewriting (Takesue and Sugie 2003), signal transmission using advanced optical modulation formats (Wei et al. 2009), subcarrier multiplexed optical communication systems (Udvary and Berceli 2010), optical mixing of microwave signals (Capmany et al. 2002) and fiber-optical cable television (Peng et al. 2013), critically relies on the ability to imprint information in electrical form onto an optical signal. A possible way of achieving this data encoding is by directly modulating the current that drives a semiconductor optical amplifier (SOA) (Hansen et al. 1989;Gillner 1992). ...
We demonstrate through numerical simulations that a passive single-bus microring resonator (MRR) employed as notch filter enables to directly modulate an ordinary semiconductor optical amplifier (SOA) at 10 Gb/s. This data rate constitutes a fourfold increase in the speed that it is possible to modulate the SOA due to its finite differential carrier lifetime. The theoretical analysis unveils how the MRR radius and detuning must be selected so that the MRR-based filtering scheme efficiently overcomes the pattern-dependent impairments incurred by the SOA narrow electrical bandwidth. Moreover, the small-signal analysis conducted to correlate the perturbations in power of the modulated optical signal inserted in the MRR with those at the MRR output confirms the enhancement in the electrical bandwidth of the SOA–MRR combination. Provided that the MRR response is tailored as suggested, which is technologically feasible, the MRR action permits the encoded signal to exhibit at extended data rate a pulse and eye diagram profile of acceptable quality, tolerable amplitude difference indices, an error probability below the forward error correction limit, and a sufficient system net gain for medium-haul transmission in standard single-mode fiber with dispersion compensation. These performance improvements can be beneficial for the direct modulation of standard SOAs. Together with SOAs inherent amplification capability, they can open new perspectives in using these active elements as external modulators in various target applications.
... A 64-quadrature-amplitude-modulation (64-QAM) format is applied via electrical injection to an RSOA. A similar experiment has been reported on SOAs [13] but, for the first time, to the best of our knowledge, the signal is applied to an RSOA and the device responds as expected. Optimized RSOAs allow the integration of the wireless and optical technologies and demonstrate the feasibility of a distributed broadband wireless system (DBWS) which uses a DAS architecture in combination with a high-throughput radio interface. ...
Next-generation wireless communications systems need to have high throughputs to satisfy user demand, to be low-cost, and to have an efficient management as principal features. Using a high-performance, low-cost reflective semiconductor optical amplifier (RSOA) as a colorless remote modulator at the antenna unit, the wavelength-division multiplexing (WDM) technique can be used for supporting distributed antenna systems (DASs). Each antenna unit is connected to the central unit using optical fiber and all links are used to transmit radio signals. Due to a large optical bandwidth, RSOAs are potential candidates for cost effective WDM systems. In this paper, simulations are carried out to determine optimized RSOA devices for wireless technology. New RSOA structures are fabricated and evaluated. The optimized RSOA is electrically driven by a standard Wi-Fi input signal (IEEE 802.11 g) with a 64-quadrature amplitude modulation (QAM) format. A large modulation bandwidth and a high electrooptic gain are demonstrated, which are confirmed by good performance when using orthogonal frequency-division multiplexing techniques. Characteristics such as high linearity and large electrooptic modulation bandwidth of our RSOA are sufficient to ensure an error vector magnitude (EVM) lower than 5% with a dynamic range exceeding 35 dB in a back-to-back configuration (at 0 dBm). Uplink transmission over a 20 km of single-mode fiber is also demonstrated with EVM lower than 5% and a dynamic range exceeding 25 dB (at 5 dBm).
... As can be seen onFigure 3, maximum CNR is reached when the SOA operates at saturation, that is, for maximum optical input power. This result agrees with the results found by (Vacondio, et al. 2006), who proposed the use of SOA's as external modulators. Additionally, operation at saturation minimizes cross-talk interference. ...
We propose a novel multi-antenna to one receiver GPS-over-fiber architecture with real-time relative hardware delay monitoring. The purpose of this architecture is to perform receiver single difference observation processing without having to deal with a relative receiver clock error parameter and thus to achieve millimetric vertical precision for short baselines. Indeed, past simulations have already shown that a 2 to 3 factor improvement in vertical precision is expected if relative receiver clock error is eliminated in single difference processing and if the relative receiver hardware delay is monitored at millimeter-level precision. In this paper, the proposed GPS-over-fiber setup is first presented and explained. Then, the results of the experiments to test the GPS-over-fiber performance and the relative delay monitoring system are presented. Finally, the calibration procedure and GPS observation processing methodology are described. Results show that with proper oscillators' synchronization in the RF front-end, signal-to-noise degradation by the opto-electrical circuit can be kept below 2 dB with no significant effect on positioning accuracy. At the same time, the proposed relative delay monitoring system can track the relative delay variations at millimeter-level. The complete system is still under development.
We propose to use an optical bandpass filter (OBPF) placed after a birefringent fiber loop (BFL) to improve the performance of a semiconductor optical amplifier (SOA), which is directly modulated at an extended data rate than that enabled by its limited modulation bandwidth. The OBPF complements the BFL action by being detuned toward the opposite sideband than the BFL. The obtained experimental results demonstrate and confirm that compared with the BFL only, the filter-assisted BFL scheme can further reduce the chirp and pulse peak amplitude variations, reshape the eye diagram, and make more symmetric and narrow the spectrum of the encoded data signal after the SOA. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2247–2251, 2015
Fibre-to-the premises (FTTP) is considered as the main solution in order to satisfy the demand for higher capacity networks. For next-generation access networks, upgradeability and high capacity could be obtained using Wavelength-Division Multiplexing in PON (WDM-PON). However, cost and compatibility with existing TDM-PON networks is still an important issue. If wavelengths are to be dynamically allocated, one to each RAU, colorless devices are needed in order to minimize the deployment cost. Reflective Semiconductor Optical Amplifier (RSOA) devices can be used as a low-cost solution due to their wide optical bandwidth. In this study, RSOAs are optimized for WDM PON and R-o-F access technology. The design, fabrication and system evaluation are presented. This study oscillates between a theoretical approach, a modeling of the physical mechanisms as well as experimental measurements. 2-section RSOAs are also investigated. Finally, the envisaged architectures of access and RoF networks based on optimized RSOA are evaluated.
We have proposed and experimentally demonstrated three different optical front-ends to implement in wavelength-division-multiplexing (WDM) radio-over-fiber (ROF) networks to minimize the cost of the ROF system. When the number of WDM channels is small, such as smaller than four channels, the simplest front-end to generate WDM optical millimeter (mm)-wave signals is to use only broadband direct-modulation laser (DML) for each WDM channel. In this case, the expensive external modulator can be removed. However, when the number of WDM channels is large, such as larger than four, the frond-end to generate WDM optical mm-wave signals can be realized by using an external modulator to upconvert simultaneously all channels after the WDM channel signals are multiplexed. In this way, the cost of the expensive external modulator will be shared by all channels. For seamless integration of WDM signals that come from the existing backbone with ROF system, a broadband external modulator can be used to upconvert WDM signals.
