Showing papers on "Modulation published in 2012"
01 Dec 2012
TL;DR: It is shown via computer simulations that the proposed OFDM with index modulation achieves significantly better error performance than classical OFDM due to the information bits carried by the indices of OFDM subcarriers under both ideal and realistic channel conditions.
Abstract: In this paper, a novel orthogonal frequency division multiplexing (OFDM) scheme, which is called OFDM with index modulation (OFDM-IM), is proposed for frequency-selective fading channels. In this scheme, inspiring from the recently introduced spatial modulation concept for multiple-input multiple-output (MIMO) channels, the information is conveyed not only by M-ary signal constellations as in classical OFDM, but also by the indices of the subcarriers, which are activated according to the incoming bit stream. Different transceiver structures are proposed and a theoretical error performance analysis is provided for the new scheme. It is shown via computer simulations that the proposed scheme achieves significantly better error performance than classical OFDM due to the information bits carried in the spatial domain by the indices of OFDM subcarriers.
574 citations
Patent•
04 Sep 2012
TL;DR: In this article, a surgical generator and related method for mitigating overcurrent conditions is provided, which includes a power supply, a radio frequency output stage, an overcurrent detection circuit in operative communication with an interrupt circuit, and a processor.
Abstract: A surgical generator and related method for mitigating overcurrent conditions are provided. The surgical generator includes a power supply, a radio frequency output stage, an overcurrent detection circuit in operative communication with an interrupt circuit, and a processor. The power supply generates a power signal and supplies the power signal to the radio frequency output stage. The radio frequency output stage generates a radio frequency signal from the power signal. The overcurrent detection circuit detects an overcurrent of the power signal and/or an overcurrent of the radio frequency signal. The interrupt circuit provides an interrupt signal in response to a detected overcurrent. The processor receives the interrupt signal and supplies a pulse-width modulation signal to the power supply and incrementally decreases the duty cycle of the pulse-width modulation signal in response to the interrupt signal. The radio frequency output stage may be disabled in response to the detected overcurrent.
495 citations
TL;DR: A generalised spatial modulation scheme with multiple active transmit antennas, named as multiple active-spatial modulation (MA-SM), is proposed in this paper and a near-optimal detection scheme with low complexity for MA-SM is proposed and analyzed.
Abstract: A generalised spatial modulation (SM) scheme with multiple active transmit antennas, named as multiple active-spatial modulation (MA-SM), is proposed in this paper. By allowing multiple transmitting antennas in the SM system to transmit different symbols at the same time instant, MA-SM takes advantages of the low complexity of SM and high multiplexing gain of Vertical-Bell Lab Layered Space-Time (V-BLAST) system. In the MA-SM system, the transmitted symbols are mapped into a high dimensional constellation space including the spatial dimension. The general principle for designing the efficient MA-SM for arbitrary number of transmit antennas and modulation scheme is presented. Moreover, a near-optimal detection scheme with low complexity for MA-SM is also proposed and analyzed. A closed form bound for the bit error probability (BEP) of the proposed detection scheme is also derived in this paper. Numerical results with the comparison among the existing multiple-input multiple-output (MIMO) systems such as space time block code (STBC) and V-BLAST demonstrate the efficiency of MA-SM.
457 citations
TL;DR: In this paper, the authors demonstrate an on-chip, ultra-compact, electro-optic modulator with a record-high 1 dB per micrometer extinction ratio over a wide bandwidth range of 1 μm in ambient conditions.
Abstract: Electro-optic modulators have been identifi ed as the key drivers for optical communication and signal processing. With an ongoing miniaturization of photonic circuitries, an outstanding aim is to demonstrate an on-chip, ultra-compact, electro-optic modulator without sacrifi cing bandwidth and modulation strength. While silicon-based electro-optic modulators have been demonstrated, they require large device footprints of the order of millimeters as a result of weak non-linear electro-optical properties. The modulation strength can be increased by deploying a high-Q resonator, however with the trade-off of signifi cantly sacrifi cing bandwidth. Furthermore, design challenges and temperature tuning limit the deployment of such resonance-based modulators. Recently, novel materials like graphene have been investigated for electro-optic modulation applications with a 0.1 dB per micrometer modulation strength, while showing an improvement over pure silicon devices, this design still requires device lengths of tens of micrometers due to the ineffi cient overlap between the thin graphene layer, and the optical mode of the silicon waveguide. Here we experimentally demonstrate an ultra-compact, silicon-based, electro-optic modulator with a record-high 1 dB per micrometer extinction ratio over a wide bandwidth range of 1 μm in ambient conditions. The device is based on a plasmonic metal-oxide-semiconductor (MOS) waveguide, which effi ciently concentrates the optical modes ’ electric fi eld into a nanometer thin region comprised of an absorption coeffi cient-tuneable indium-tin-oxide (ITO) layer. The modulation mechanism originates from electrically changing the free carrier concentration of the ITO layer which dramatically increases the loss of this MOS mode. The seamless integration of such a strong optical beam modulation into an existing silicon-on-insulator platform bears signifi cant potential towards broadband, compact and effi cient communication links and circuits.
422 citations
TL;DR: In this paper, the authors presented the first optical modulation at 50 Gb/s with a 3.1dB extinction ratio obtained from carrier depletion based phase shifter incorporated in a Mach-Zehnder interferometer.
Abstract: Optical modulators formed in silicon are the keystone to many low cost optical applications. Increasing the data rate of the modulator benefits the efficiency of channel usage and decreases power consumption per bit of data. Silicon-based modulators which operate via carrier depletion have to the present been demonstrated at data rates up to 40 Gb/s; however, here we present for the first time optical modulation at 50 Gb/s with a 3.1-dB extinction ratio obtained from carrier depletion based phase shifter incorporated in a Mach-Zehnder interferometer. A corresponding optical insertion loss of approximately 7.4 dB is measured.
413 citations
TL;DR: In this article, a modulation method for the modular multilevel converter is proposed based on a fixed pulse pattern where harmonic elimination methods can be applied to achieve stable operation at the fundamental switching frequency without measuring the capacitor voltages or using any other form of feedback control.
Abstract: This paper presents a new modulation method for the modular multilevel converter. The proposed method is based on a fixed pulse pattern where harmonic elimination methods can be applied. In the proposed modulation method, the pulse pattern is chosen in such a way that the stored energy in each submodule remains stable. It is shown that this can be done at the fundamental switching frequency without measuring the capacitor voltages or using any other form of feedback control. Such a modulation scheme has not been presented before. The theoretical results are verified by both simulations and experimental results. The simulation results show successful operation at the fundamental switching frequency with a larger number of submodules. When a smaller number of submodules are used, harmonic elimination methods may be applied. This is verified experimentally on a converter with eight submodules per phase leg. The experimental results verify that stable operation can be maintained at the fundamental switching frequency while successfully eliminating the fifth harmonic in the ac-side voltage.
287 citations
TL;DR: It is shown that the attenuation and modulation depth in optically driven silicon modulators can be significantly enhanced by deposition of graphene on silicon (GOS), and a wide-band tunability of the terahertz transmission is observed.
Abstract: New applications in the realms of terahertz (THz) technology require versatile adaptive optics and powerful modulation techniques. Semiconductors have proven to provide fast all-optical terahertz wave modulation over a wide frequency band. We show that the attenuation and modulation depth in optically driven silicon modulators can be significantly enhanced by deposition of graphene on silicon (GOS). We observed a wide-band tunability of the THz transmission in a frequency range from 0.2 to 2 THz and a maximum modulation depth of 99%. The maximum difference between the transmission through silicon and GOS is Δt = 0.18 at a low photodoping power of 40 mW. At higher modulation power, the enhancement decreased due to charge carrier saturation. We developed a semianalytical band structure model of the graphene–silicon interface to describe the observed attenuation and modulation depth in GOS.
234 citations
06 May 2012
TL;DR: U-OFDM uses different time sample states and an innovative rearrangement of the Orthogonal Frequency Division Multiplexing (OFDM) frame to create unipolar OFDM signals required for Optical Wireless Communication (OWC) with Light Emitting Diodes (LEDs).
Abstract: A novel modulation technique coined U-OFDM is proposed. U-OFDM uses different time sample states and an innovative rearrangement of the Orthogonal Frequency Division Multiplexing (OFDM) frame which allow for the creation of unipolar OFDM signals required for Optical Wireless Communication (OWC) with Light Emitting Diodes (LEDs). In comparison to similar techniques like DC-biased Optical OFDM (DCO-OFDM) and Asymmetrically Clipped Optical OFDM (ACO-OFDM), U-OFDM is both optically and electrically more power efficient in an Additive White Gaussian Noise (AWGN) channel, which is prevalent in an optical wireless system.
228 citations
TL;DR: In this article, the rotor position of an interior permanent magnet synchronous machine (IPMSM) is estimated using signal injection sensorless control at standstill and/or in very low speed rotating condition.
Abstract: The rotor position of an interior permanent-magnet synchronous machine (IPMSM) can be estimated without a position sensor by signal injection sensorless control at standstill and/or in very low speed rotating condition. In the signal injection sensorless control, however, the fundamental control performance is limited by the frequency of the injected signal, and no negligible acoustic noise is generated. If the frequency of the injected voltage signal would increase to pulsewidth modulation (PWM) switching frequency and if the switching frequency is near or above audible range, the dynamics of the sensorless control can be improved, and the acoustic noise can be remarkably reduced or totally eliminated. This paper describes how to extract the rotor position information of IPMSM using the voltage signal injection whose frequency is the same as the PWM switching frequency. Compared to the conventional heterodyning process, the proposed method is simple to implement and appropriate for PWM switching frequency signal injection. The high-frequency voltage signal can be injected in the stationary reference frame or in the estimated rotor reference frame. In this paper, the 5- and 16-kHz signal injections are proposed, implemented, and compared. The experimental results confirm the effectiveness of the proposed method.
208 citations
TL;DR: In this paper, the integration of aluminum nitride (AlN) films on silicon substrates to bring active functionalities to chip-scale photonics is reported, and the authors demonstrate electro-optic modulation up to 4.5 Gb/s with very low energy consumption (down to 10 fJ/bit).
Abstract: Photonic miniaturization requires seamless integration of linear and nonlinear optical components to achieve passive and active functions simultaneously. Among the available material systems, silicon photonics holds immense promise for optical signal processing and on-chip optical networks. However, silicon is limited to wavelengths above 1.1 μm and does not provide the desired lowest order optical nonlinearity for active signal processing. Here we report the integration of aluminum nitride (AlN) films on silicon substrates to bring active functionalities to chip-scale photonics. Using CMOS-compatible sputtered thin films we fabricate AlN-on-insulator waveguides that exhibit low propagation loss (0.6 dB/cm). Exploiting AlN’s inherent Pockels effect we demonstrate electro-optic modulation up to 4.5 Gb/s with very low energy consumption (down to 10 fJ/bit). The ultrawide transparency window of AlN devices also enables high speed modulation at visible wavelengths. Our low cost, wideband, carrier-free photoni...
197 citations
TL;DR: The analogy to optical orthogonal frequency division multiplexing is discussed and it is shown that using appropriate algorithms, Nyquist pulse shaped modulation formats can be encoded on a single wavelength at speeds beyond 100 Gbit/s in real-time.
Abstract: Nyquist sinc-pulse shaping provides spectral efficiencies close to the theoretical limit. In this paper we discuss the analogy to optical orthogonal frequency division multiplexing and compare both techniques with respect to spectral efficiency and peak to average power ratio. We then show that using appropriate algorithms, Nyquist pulse shaped modulation formats can be encoded on a single wavelength at speeds beyond 100 Gbit/s in real-time. Finally we discuss the proper reception of Nyquist pulses.
TL;DR: This analysis demonstrates that the channel capacity is largely affected by the life expectancy of molecules, and indicates that the extended modulation scheme can achieve nearly one bit per slot at the expense of extra molecules under optimal conditions.
Abstract: In this paper, we analyze the capacity of a molecular communication channel in a one dimensional environment where information is represented with molecules that are released by a transmitter nanomachine, propagate via Brownian motion, degrade over time, and stochastically reach the receiver nanomachine. The channel is modeled as a time slotted binary channel, and two modulation schemes are proposed: a naive modulation scheme and an extended modulation scheme with a redundant number of molecules. Our analysis demonstrates that the channel capacity is largely affected by the life expectancy of molecules. Our analysis also indicates that the extended modulation scheme can achieve nearly one bit per slot at the expense of extra molecules under optimal conditions.
01 Dec 2012
TL;DR: In this article, the authors present the most important topologies of multilevel inverters, including diode-clamped inverter (neutral-point clamped), capacitor-capped, and cascaded multi-level with separate dc sources.
Abstract: Multilevel inverters have been attracting in favor of academia as well as industry in the recent decade for high-power and medium-voltage energy control. In addition, they can synthesize switched waveforms with lower levels of harmonic distortion than an equivalently rated two-level converter. The multilevel concept is used to decrease the harmonic distortion in the output waveform without decreasing the inverter power output. This paper presents the most important topologies like diode-clamped inverter (neutral- point clamped), capacitor-clamped (flying capacitor), and cascaded multilevel with separate dc sources. This paper also presents the most relevant modulation methods developed for this family of converters: multilevel sinusoidal pulse width modulation, multilevel selective harmonic elimination, and space-vector modulation. Authors strongly believe that this survey article will be very much useful to the researchers for finding out the relevant references in the field of topologies and modulation strategies of multilevel inverter.
TL;DR: Fast nonlinear optical switching between two laser pulses with as few as 140 photons of pulse energy is demonstrated by utilizing strong coupling between a single quantum dot (QD) and a photonic crystal cavity.
Abstract: We demonstrate fast nonlinear optical switching between two laser pulses with as few as 140 photons of pulse energy by utilizing strong coupling between a single quantum dot (QD) and a photonic crystal cavity. The cavity-QD coupling is modified by a detuned pump pulse, resulting in a modulation of the scattered and transmitted amplitude of a time synchronized probe pulse that is resonant with the QD. The temporal switching response is measured to be as fast as 120 ps, demonstrating the ability to perform optical switching on picosecond timescales.
TL;DR: A decomposition of guided modes propagating in optical fibers is implemented and it is shown that the observed field can be reconstructed with very high fidelity.
Abstract: A procedure for the real-time analysis of laser modes using a phase-only spatial light modulator is outlined. The procedure involves encoding into digital holograms by complex amplitude modulation a set of orthonormal basis functions into which the initial field is decomposed. This approach allows any function to be encoded and refreshed in real time (60 Hz). We implement a decomposition of guided modes propagating in optical fibers and show that we can successfully reconstruct the observed field with very high fidelity.
TL;DR: The optical performances of the all-optical switching based on Yb3+-doped fiber Bragg grating (FBG) are investigated under the case of self- phase modulation (SPM) and cross-phase modulation (XPM) and the optical bistability of FBG under different parameters is investigated.
Abstract: The optical performances of the all-optical switching based on Yb3+-doped fiber Bragg grating (FBG) are investigated under the case of self-phase modulation (SPM) and cross-phase modulation (XPM). For the SPM case, the optical bistability of FBG under different parameters is investigated. It shows that the width of the hysteresis loop and threshold switching power are strongly dependent on the fiber grating length, fiber grating detuning, and coupling constant. For the XPM case, the expressions of the threshold switching power in the different detuning range are given. The influence of parameters about different detuning and coupling constant to the threshold switching power and extinction ratio are also studied. In comparison with the SPM case, the switching power of FBG under XPM case can be reduced to less than 20 mW by optimizing the parameters of FBG.
Patent•
04 Apr 2012
TL;DR: In this paper, a multi-dimensional encryption anti-counterfeiting printing technology based on binary signals was proposed, which can resist illegal copying behaviors based on a camera, a scanner, an electronic document and the like more effectively.
Abstract: The invention discloses a multi-dimensional encryption anti-counterfeiting printing technology based on binary signals. According to the anti-counterfeiting printing technology, two-dimensional encryption anti-counterfeiting information can be generated into binary modulation signals by encryption and channel coding, and the anti-counterfeiting information is orderly changed in an amplitude modulation screening form and embedded into a whole page in a modulation mode of a circulating table look-up method, so that the anti-counterfeiting information can be identified from a random fragment during presswork identification. The technology has strong fragment resistance, can resist illegal copying behaviors based on a camera, a scanner, an electronic document and the like more effectively, and can be widely applied in the anti-counterfeiting field of presswork.
TL;DR: This paper develops the first optimal receiver design for diffusion-based molecular communication scenarios with and without inter-symbol interference, based on a linear and time invariant signal propagation model and an additive noise model based on Brownian motion molecular statistics.
TL;DR: Evaluating the performance of three direct-detection orthogonal frequency-division multiplexing schemes in combating multipath distortion in indoor optical wireless links, comparing them to unipolar M-ary pulse-amplitude modulation (M-PAM) with minimum mean-square error decision-feedback equalization (MMSE-DFE).
Abstract: We evaluate the performance of three direct-detection orthogonal frequency-division multiplexing (OFDM) schemes in combating multipath distortion in indoor optical wireless links, comparing them to unipolar M-ary pulse-amplitude modulation (M-PAM) with minimum mean-square error decision-feedback equalization (MMSE-DFE). The three OFDM techniques are DC-clipped OFDM and asymmetrically clipped optical OFDM (ACO-OFDM) and PAM-modulated discrete multitone (PAM-DMT). We describe an iterative procedure to achieve optimal power allocation for DC-OFDM. For each modulation method, we quantify the received electrical SNR required at a given bit rate on a given channel, considering an ensemble of 170 indoor wireless channels. When using the same symbol rate for all modulation methods, M-PAM with MMSE-DFE has better performance than any OFDM format over a range of spectral efficiencies, with the advantage of (M-PAM) increasing at high spectral efficiency. ACO-OFDM and PAM-DMT have practically identical performance at any spectral efficiency. They are the best OFDM formats at low spectral efficiency, whereas DC-OFDM is best at high spectral efficiency. When ACO-OFDM or PAM-DMT are allowed to use twice the symbol rate of M-PAM, these OFDM formats have better performance than M-PAM. When channel state information is unavailable at the transmitter, however, M-PAM significantly outperforms all OFDM formats. When using the same symbol rate for all modulation methods, M-PAM requires approximately three times more computational complexity per processor than all OFDM formats and 63% faster analog-to-digital converters, assuming oversampling ratios of 1.23 and 2 for ACO-OFDM and M-PAM, respectively. When OFDM uses twice the symbol rate of M-PAM, OFDM requires 23% faster analog-to-digital converters than M-PAM but OFDM requires approximately 40% less computational complexity than M-PAM per processor.
TL;DR: The total demonstrated net capacity, taking into account 20% of FEC-overhead and 7.5% additional overhead (Ethernet and training sequences), is 57.6 Tb/s, corresponding to a spectral efficiency of 12 bits/s/Hz.
Abstract: Transmission of a 73.7 Tb/s (96x3x256-Gb/s) DP-16QAM mode-division-multiplexed signal over 119km of few-mode fiber transmission line incorporating an inline multi mode EDFA and a phase plate based mode (de-)multiplexer is demonstrated. Data-aided 6x6 MIMO digital signal processing was used to demodulate the signal. The total demonstrated net capacity, taking into account 20% of FEC-overhead and 7.5% additional overhead (Ethernet and training sequences), is 57.6 Tb/s, corresponding to a spectral efficiency of 12 bits/s/Hz.
TL;DR: An electro-optic modulator that integrates single-layer graphene in a sub-wavelength thick, reflective modulator structure is reported on, offering solutions to a variety of high-speed amplitude modulation tasks that require optical amplitude modulation without phase distortions, a flat frequency response, or ultra-thin geometries.
Abstract: Graphene’s featureless optical absorption, ultrahigh carrier mobility, and variable optical absorption by an applied gate voltage enable a new breed of optical modulators with broad optical and electrical bandwidths. Here we report on an electro-optic modulator that integrates single-layer graphene in a sub-wavelength thick, reflective modulator structure. These modulators provide a large degree of design freedom, which allows tailoring of their optical properties to specific needs. Current devices feature an active aperture ~100 µm, and provide uniform modulation with flat frequency response from 1 Hz to >100 MHz. These novel, low insertion-loss graphene-based modulators offer solutions to a variety of high-speed amplitude modulation tasks that require optical amplitude modulation without phase distortions, a flat frequency response, or ultra-thin geometries, such as for controlling monolithic, high-repetition rate mode-locked lasers or active interferometers.
Journal Article•
TL;DR: The project is aimed at designing an intelligent communication system where the receiver is able to detect the modulation scheme of the signal it receives using Automatic Modulation Recognition (AMR) algorithms, without having minimum or no prior knowledge of the transmitted signal.
Abstract: The project is aimed at designing an intelligent communication system where the receiver is able to detect the modulation scheme of the signal it receives using Automatic Modulation Recognition (AMR) algorithms, without having minimum or no prior knowledge of the transmitted signal. Six digital modulation schemes namely QPSK, BPSK, 2ASK, 4ASK, 2FSK, 4FSK and 16QAM were used. Algorithms based on deriving key statistical features from the communication signal, were formed. Features were also extracted using Azzouz and Nandi‟s techniques. Neural Networks were applied to the extracted features to distinguish between signals having different modulation schemes. The simulations were performed for different SNR values as well as different number of neurons in a one and two hidden layers.
TL;DR: In this article, a method for achieving high-efficiency linear transmitters by codesign of the RF power amplifier (PA), dynamic supply, and signal processing is presented, which achieves 52.5% composite power-added efficiency with high linearity for a W-CDMA signal with a 23MHz supply modulator bandwidth.
Abstract: This paper presents a method for achieving high-efficiency linear transmitters by codesign of the RF power amplifier (PA), dynamic supply, and signal processing. For varying amplitude signals, the average efficiency of the PA is improved by adding a supply modulator with requirements derived from nonstandard PA modeling. The efficient PA and supply modulator both introduce signal distortion. A targeted linearization procedure is demonstrated with reduced complexity compared to standard digital predistortion. Experimental results on a 2.14-GHz 81% efficient 40-W peak power GaN PA illustrate the codesign method by achieving 52.5% composite power-added efficiency with high linearity for a W-CDMA signal with a 23-MHz supply modulator bandwidth.
31 Dec 2012
TL;DR: This paper will explain how self-interference can be reduced by a basic and a double-sided serial interference cancellation technique and show that these interference cancellation techniques improve the GFDM bit error rate to match the theoretical performance of the well studied orthogonal frequency division multiplexing (OFDM).
Abstract: Generalized frequency division multiplexing (GFDM) is a new digital multicarrier concept. The GFDM modulation technique is extremely attractive for applications in a fragmented spectrum, as it provides the flexibility to choose a pulse shape and thus allows reduction of the out-of-band leakage of opportunistic cognitive radio signals into incumbent frequency space. However, this degree of freedom is obtained at the cost of loss of subcarrier orthogonality, which leads to self-inter-carrier-interference. This paper will explain how self-interference can be reduced by a basic and a double-sided serial interference cancellation technique and show that these interference cancellation techniques improve the GFDM bit error rate to match the theoretical performance of the well studied orthogonal frequency division multiplexing (OFDM).
TL;DR: Simulation results show that, under the same spectral efficiency, the proposed schemes provide considerable system performance improvement compared with the conventional SM systems, particularly in correlated channel conditions.
Abstract: In this paper, link-adaptation schemes, where the transmit parameters are dynamically adapted to the changing channel conditions, are developed for spatial modulation (SM) transmission systems. The proposed schemes are based on the adaptive modulation (AM) and transmit-mode switching (TMS) techniques, to further exploit the spatial freedom of the multiple-input-multiple-output channel. More specifically, an optimal hybrid-SM (OH-SM) scheme that jointly uses both AM and TMS techniques is first developed to efficiently utilize the channel resources. In OH-SM, the transmit mode is jointly adapted with modulation orders according to the channel condition. Moreover, a suboptimal hybrid SM scheme, termed as a concatenated SM (C-SM) scheme, is also proposed. The C-SM scheme exploits the multistage adaptation strategy to balance the tradeoff between computational complexity and performance. The performance of the proposed schemes is evaluated by using the nearest neighbor approximations, to derive the parameter selection criterions. Simulation results show that, under the same spectral efficiency, the proposed schemes provide considerable system performance improvement compared with the conventional SM systems, particularly in correlated channel conditions.
TL;DR: In this paper, a 1.1-Gb/s visible light communication (VLC) system employing carrierless amplitude and phase modulation (CAP) and a commercially available phosphorescent white light emitting diode (LED) was demonstrated.
Abstract: We demonstrate 1.1-Gb/s visible light communication (VLC) employing carrier-less amplitude and phase modulation (CAP) and a commercially available phosphorescent white light emitting diode (LED). Optical blue filtering, precompensation, and decision feedback equalization are used to compensate the frequency response of the phosphor-based white LED. Various modulation orders of CAP signals are investigated to maximize the capacity of the VLC system. The record data rate of 1.1 Gb/s with the bit error rate performance below the FEC limit of 10-3 is successfully achieved >; 23-cm air-transmission via a 220-MBaud 32-CAP signal.
TL;DR: In this paper, the authors compare 4-pulse amplitude modulation and on-off keying modulation formats at high speed for short-range optical communication systems, using a vertical-cavity surface-emitting laser operating at a wavelength of 850 nm.
Abstract: In this work, we compare 4-pulse amplitude modulation and on-off keying modulation formats at high speed for short-range optical communication systems. The transmission system comprised a directly modulated vertical-cavity surface-emitting laser operating at a wavelength of 850 nm, an OM3+ multimode fiber link, and a photodetector detecting the intensity at the receiver end. The modulation formats were compared both at the same bit-rate and at the same symbol rate. The maximum bit-rate used was 25 Gbps. Propagation distances up to 600 m were investigated at 12.5 Gbps. All measurements were done in real time and without any equalization.
TL;DR: A highly efficient approach for the modulation of photonic signals at the nanoscale is developed, combining an ultrasubwavelength plasmonic guiding scheme with a robust electroabsorption effect in degenerate semiconductors.
Abstract: We develop a highly efficient approach for the modulation of photonic signals at the nanoscale, combining an ultrasubwavelength plasmonic guiding scheme with a robust electroabsorption effect in degenerate semiconductors. We numerically demonstrate an active electro-optical field-effect nanoplasmonic modulator with a revolutionary size of just 25 × 30 × 100 nm(3), providing signal extinction ratios as high as 2 at switching voltages of only 1 V. The design is compatible with complementary metal-oxide-semiconductor (CMOS) technology and allows low-loss insertion in standard plasmonic and Si-photonic circuitry.
TL;DR: A distributed III-V-on-Si electroabsorption modulator based on an asymmetric segmented electrode has been developed on the hybrid silicon platform for the 1.3 μm transmission window and large signal measurements show clearly open eye diagrams at 50 Gb/s.
Abstract: A distributed III-V-on-Si electroabsorption modulator based on an asymmetric segmented electrode has been developed on the hybrid silicon platform for the 1.3 μm transmission window. The measured modulation response shows a 2 dB drop at 67 GHz and an extrapolated 3 dB bandwidth of 74 GHz. Large signal measurements show clearly open eye diagrams at 50 Gb/s. An extinction ratio of 9.6 dB for back to back transmission and an extinction ratio of 9.4 dB after 16 km transmission were obtained with a drive voltage of 2.2 V.
TL;DR: The effects of two major interference sources, Intersymbol Interference and Co-channel Interference are evaluated in the CvD system using different modulation techniques to evaluate channel capacity performances.