Showing papers on "Optical communication published in 2006"
TL;DR: Net on/off gain over a wavelength range of 28 nm is demonstrated through the optical process of phase-matched four-wave mixing in suitably designed SOI channel waveguides, allowing for the implementation of dense wavelength division multiplexing in an all-silicon photonic integrated circuit.
Abstract: The development of silicon-compatible optical components that simultaneously amplify and process a broad range of wavelength channels is critical for future data communication technology based on photonic chips. Until now, such devices have only been able to amplify a single wavelength channel. Now, using nanoscale silicon waveguides designed for the purpose, Foster et al. have achieved broadband amplification. The key is the exploitation of a nonlinear optical effect known as four-wave mixing. This process can also be used for other all-optical functions previously only possible in extended lengths of optical fibre. Phase-matched four-wave mixing can take place with high efficiency in a suitably designed silicon waveguide — this advance could allow for the implementation of dense wavelength channels for optical processing in an all-silicon photonic chip. Developing an optical amplifier on silicon is essential for the success of silicon-on-insulator (SOI) photonic integrated circuits. Recently, optical gain with a 1-nm bandwidth was demonstrated using the Raman effect1,2,3,4,5,6,7,8,9, which led to the demonstration of a Raman oscillator10,11, lossless optical modulation12 and optically tunable slow light13. A key strength of optical communications is the parallelism of information transfer and processing onto multiple wavelength channels. However, the relatively narrow Raman gain bandwidth only allows for amplification or generation of a single wavelength channel. If broad gain bandwidths were to be demonstrated on silicon, then an array of wavelength channels could be generated and processed, representing a critical advance for densely integrated photonic circuits. Here we demonstrate net on/off gain over a wavelength range of 28 nm through the optical process of phase-matched four-wave mixing in suitably designed SOI channel waveguides. We also demonstrate wavelength conversion in the range 1,511–1,591 nm with peak conversion efficiencies of +5.2 dB, which represents more than 20 times improvement on previous four-wave-mixing efficiencies in SOI waveguides14,15,16,17. These advances allow for the implementation of dense wavelength division multiplexing in an all-silicon photonic integrated circuit. Additionally, all-optical delays18, all-optical switches19, optical signal regenerators20 and optical sources for quantum information technology21, all demonstrated using four-wave mixing in silica fibres, can now be transferred to the SOI platform.
923 citations
05 Jun 2006
TL;DR: This paper discusses the generation and detection of multigigabit/s intensity- and phase-modulated formats, and highlights their resilience to key impairments found in optical networking, such as optical amplifier noise, multipath interference, chromatic dispersion, polarization-mode dispersion.
Abstract: Fiber-optic communication systems form the high-capacity transport infrastructure that enables global broadband data services and advanced Internet applications. The desire for higher per-fiber transport capacities and, at the same time, the drive for lower costs per end-to-end transmitted information bit has led to optically routed networks with high spectral efficiencies. Among other enabling technologies, advanced optical modulation formats have become key to the design of modern wavelength division multiplexed (WDM) fiber systems. In this paper, we review optical modulation formats in the broader context of optically routed WDM networks. We discuss the generation and detection of multigigabit/s intensity- and phase-modulated formats, and highlight their resilience to key impairments found in optical networking, such as optical amplifier noise, multipath interference, chromatic dispersion, polarization-mode dispersion, WDM crosstalk, concatenated optical filtering, and fiber nonlinearity
772 citations
TL;DR: In this article, a coherent optical orthogonal frequency division multiplexing (OFDM) was proposed to combat dispersion in optical media, and it was shown that optical-signal-to-noise ratio penalty at 10 Gbit/s is maintained below 2 dB for 3000 km transmission of standard-singlemode fiber without dispersion compensation.
Abstract: Coherent optical orthogonal frequency division multiplexing is proposed to combat dispersion in optical media. It is shown that optical-signal-to-noise ratio penalty at 10 Gbit/s is maintained below 2 dB for 3000 km transmission of standard-singlemode fibre without dispersion compensation.
629 citations
TL;DR: The generation and detection of multigigabit/second intensity- and phase-modulated formats are reviewed to highlight their resilience to key impairments found in optical networking, such as optical amplifier noise, chromatic dispersion, polarization-mode dispersion.
Abstract: Advanced optical modulation formats have become a key ingredient to the design of modern wavelength-division-multiplexed (WDM) optically routed networks. In this paper, we review the generation and detection of multigigabit/second intensity- and phase-modulated formats and highlight their resilience to key impairments found in optical networking, such as optical amplifier noise, chromatic dispersion, polarization-mode dispersion, WDM crosstalk, concatenated optical filtering, and fiber nonlinearity
490 citations
TL;DR: A thorough study of an all-optical chaotic communication system, including experimental realization real-world testing and performance characterization through bit-error-rate analysis, showed that chaotic communication systems does not act as a considerably deteriorating factor in the final performance.
Abstract: A thorough study of an all-optical chaotic communication system, including experimental realization real-world testing
and performance characterization through bit-error-rate analysis, is presented. Pseudorandom data that are effectively
encrypted in the chaotic emitter and sent for transmission are recovered at the receiver with bit-error-rate (BER) values
as low as 10-7 for 1 Gb/s data rate. Different data code lengths and bit-rates at the Gb/s region have been tested. Optical
transmission using 100km fiber spools in an in-situ experiment and 120km in an installed optical network showed that
chaotic communication systems does not act as a considerably deteriorating factor in the final performance.
399 citations
TL;DR: In this article, the authors review the current state of the art of MEMS devices and subsystems for lightwave communication applications, which can either be broadband (wavelength independent) or wavelength selective.
Abstract: The intensive investment in optical microelectromechanical systems (MEMS) in the last decade has led to many successful components that satisfy the requirements of lightwave communication networks. In this paper, we review the current state of the art of MEMS devices and subsystems for lightwave communication applications. Depending on the design, these components can either be broadband (wavelength independent) or wavelength selective. Broadband devices include optical switches, crossconnects, optical attenuators, and data modulators, while wavelength-selective components encompass wavelength add/drop multiplexers, wavelength-selective switches and crossconnects, spectral equalizers, dispersion compensators, spectrometers, and tunable lasers. Integration of MEMS and planar lightwave circuits, microresonators, and photonic crystals could lead to further reduction in size and cost
341 citations
TL;DR: Optical Orthogonal frequency division multiplexing (OOFDM) is shown to outperform RZ-OOK transmission in high-speed optical communications systems in terms of transmission distance and spectral efficiency.
Abstract: Optical Orthogonal frequency division multiplexing (OOFDM) is shown to outperform RZ-OOK transmission in high-speed optical communications systems in terms of transmission distance and spectral efficiency. The OOFDM in combination with the subcarrier multiplexing offers a significant improvement in spectral efficiency of at least 2.9 bits/s/Hz.
326 citations
TL;DR: In this article, the use of optical frequency combs generated from semiconductors for ultrawideband signal processing and communication applications is discussed, which can be used for communication applications relying on direct detection, dense wavelength division multiplexing (WDM), coherent-detection WDM, optical time-division multiple access, and optical code division multiple access.
Abstract: Modelocked semiconductor lasers are used to generate a set of phase-locked optical frequencies on a periodic grid. The periodic and phase coherent nature of the optical frequency combs makes it possible for the realization of high-performance optical and RF arbitrary-waveform synthesis. In addition, the resulting optical frequency components can be used for communication applications relying on direct detection, dense wavelength division multiplexing (WDM), coherent-detection WDM, optical time-division multiplexing, and optical code division multiple access. This paper highlights the recent results in the use of optical frequency combs generated from semiconductors for ultrawideband signal processing and communication applications.
289 citations
TL;DR: In this article, the role of optical and electronic technologies in future high-capacity routers is examined, and the authors conclude that optical buffers are likely to remain integral components in the signal transmission path of future high capacity routers.
Abstract: This paper examines the role of optical and electronic technologies in future high-capacity routers. In particular, optical and electronic technologies for use in the key router functions of buffering and switching are compared. The comparison is based on aggressive but plausible estimates of buffer and switch performance projected out to around 2020. The analysis of buffer technologies uses a new model of power dissipation in optical-delay-line buffers using optical fiber and planar waveguides, including slow-light waveguides. Using this model together with models of storage capacity in ideal and nonideal slow-light delay lines, the power dissipation and scaling characteristics of optical and electronic buffers are compared. The author concludes that planar integrated optical buffers occupy larger chip area than electronic buffers, dissipate more power than electronic buffers, and are limited in capacity to, at most, a few IP packets. Optical fiber-based buffers have lower power dissipation but are bulky. The author also concludes that electronic buffering will remain the technology of choice in future high-capacity routers. The power dissipation of high-capacity optical and electronic cross connects for a number of cross connect architectures is compared. The author shows that optical and electronic cross connects dissipate similar power and require a similar chip area. Optical technologies show a potential for inclusion in high-capacity routers, especially as the basis for arrayed-waveguide-grating-based cross connects and as components in E/O/E interconnects. A major challenge in large cross connects, both optical and electronic, will be to efficiently manage the very large number of interconnects between chips and boards. The general conclusion is that electronic technologies are likely to remain as integral components in the signal transmission path of future high-capacity routers. There does not appear to be a compelling case for replacing electronic routers with optically transparent optical packet switches
203 citations
TL;DR: This work demonstrates 1550 nm photon-counting optical communications with a NbN-nanowire superconducting single-photon detector with error-free performance and the highest reported data rate for a photon- Counting receiver.
Abstract: We demonstrate 1550 nm photon-counting optical communications with a NbN-nanowire superconducting single-photon detector. Source data are encoded with a rate-1/2 forward-error correcting code and transmitted by use of 32-ary pulse-position modulation at 5 and 10 GHz slot rates. Error-free performance is obtained with ~0.5 detected photon per source bit at a source data rate of 781 Mbits/s. To the best of our knowledge, this is the highest reported data rate for a photon-counting receiver.
TL;DR: In this paper, the authors investigated the optimum carrier-to-sideband ratio (CSR) for maximizing the transmission performance of an optically modulated millimeter-wave signal in a fiber-wireless system via experiment, theory, and simulation.
Abstract: In this paper, we investigate the optimum carrier-to-sideband ratio (CSR) for maximizing the transmission performance of an optically modulated millimeter-wave signal in a fiber-wireless system via experiment, theory, and simulation. We present a simple analytical model to assess the performance enhancement resulting from optical CSR variations. The model is capable of analyzing systems incorporating binary phase-shift keyed and quaternary phase-shift keyed modulation formats. We quantify the optical CSR of a point-to-point fiber-radio link and establish that the performance of the fiber-wireless links can be significantly improved when the optical signal is transmitted at the optimum CSR of 0 dB. The analysis further shows that the optimum optical CSR is independent of transmission bit rates.
TL;DR: Closed-form solutions for the bit-error rate of a freespace, heterodyne optical communication system is derived when the optical beam is subjected to K-distributed optical turbulence.
Abstract: Closed-form solutions for the bit-error rate of a freespace, heterodyne optical communication system is derived when the optical beam is subjected to K-distributed optical turbulence. It is assumed that the scintillation index is confined to the range (2,3) or that the number of scatterers in the propagation path is a random variable.
05 Jun 2006
TL;DR: In this article, a multichannel optical coherence tomography system for turbid materials utilizing multiple channels of information comprising spatial, angle, spectral and polarization domains is presented. But the system is not suitable for imaging a vessel, biliary, GU and/or Gl tract of a patient.
Abstract: A system for optical coherence tomographic imaging of turbid materials utilizing multiple channels of information comprising spatial, angle, spectral and polarization domains. The multichannel optical coherence tomographic methods can be incorporated into an endoscopic probe for imaging a patient. The endoscope comprises an optical fiber array and can comprise a plurality of optical fibers adapted to be disposed in the patient. The optical fiber array transmits the light from the light source Into the patient, and transmits the light reflected by the patient out of the patient. The plurality of optical fibers in the array are in optical communication with the light source. The multichannel optical coherence tomography system comprises a detector for receiving the light from the array and analyzing the light. The methods and apparatus may be applied for imaging a vessel, biliary, GU and/or Gl tract of a patient.
TL;DR: This paper introduces the pixelated wireless optical channel, which transmits data at high rates using a series of coded time-varying images to exploit the inherent spatial degrees of freedom and to realize significant gains in spectral efficiency over single-element systems.
Abstract: This paper introduces the pixelated wireless optical channel, which transmits data at high rates using a series of coded time-varying images. This multiple-input/multiple-output point-to-point wireless optical channel uses arrays of optical intensity transmitters and detectors to exploit the inherent spatial degrees of freedom and to realize significant gains in spectral efficiency over single-element systems. Spatial discrete multitone modulation is introduced as a means to combat low-pass spatial distortion and to alleviate spatial alignment problems of previous systems. The capacity of pixelated wireless optical channels is estimated by way of a water-pouring spectrum. A proof-of-concept experimental prototype is constructed using a 512times512 pixel liquid crystal display panel and 154times154 pixels of a charge-coupled device camera. A channel model is developed and the capacity estimated to be 22.4 kb/frame. An unoptimized multilevel code and multistage decoder is applied over the spatial frequency bins and shown to yield spectral efficiencies of approximately 1.7 kb/s/Hz over a range of 2 m
01 Nov 2006
TL;DR: It is shown that ACO- OFDM with 4-QAVI subcarrier modulation has the same bandwidth efficiency but requires 2 dB less energy per bit than on-off keying, andACO-OFDM with larger constellation sizes gives higher bandwidth efficiencies and lower optical power than other modulation schemes.
Abstract: Orthogonal frequency division multiplexing (OFDM) is used in many wired and wireless broadband communication systems because of its resilience in the presence of signal dispersion or multipath distortion. OFDM has not been used in practical optical communication systems because the bipolar waveform cannot be used in intensity-modulated direct detection (IM/DD) systems. A new unipolar form of OFDM, asymmetrically clipped optical OFDM (ACO-OFDM), has recently been developed. For the case of an AWGN channel, we compare ACO- OFDM and other modulation schemes. It is shown that ACO- OFDM with 4-QAVI subcarrier modulation has the same bandwidth efficiency but requires 2 dB less energy per bit than on-off keying. ACO-OFDM with larger constellation sizes gives higher bandwidth efficiencies and lower optical power than other modulation schemes. Unlike existing methods, the performance of ACO-OFDM is limited by the bandwidth of the transmitter and receiver not the dispersion of the channel.
TL;DR: In this paper, the authors present a survey of optical instrumentation based on the concept of space-time duality, including a time-lens timing-jitter compensator for ultralonghaul dense-wavelength-division-multiplexed dispersion-managed soliton transmission.
Abstract: The last two decades have seen a wealth of optical instrumentation based upon the concepts of space-time duality. A historical overview of how this beautiful framework has been exploited to develop instruments for optical signal processing is presented. The power of this framework is then demonstrated by reviewing four devices in detail based upon space-time dualities that have been experimentally demonstrated: 1) a time-lens timing-jitter compensator for ultralong-haul dense-wavelength-division-multiplexed dispersion-managed soliton transmission, 2) a multiwavelength pulse generator using time-lens compression, 3) a programmable ultrafast optical delay line by use of a time-prism pair, and 4) an enhanced ultrafast optical delay line by use of soliton propagation between a time-prism pair.
TL;DR: In this paper, the authors provide a review of recent progress of slow and fast light using semiconductor devices and discuss results obtained with semiconductor quantum-well/quantum-dot absorber and optical amplifiers.
Abstract: The ability to manipulate the speed of light has recently become one of the most exciting emergent topics in optics. There are several experimental demonstrations showing the capability to slow down light more than six orders of magnitude in a variety of media, ranging from atomic vapor, solid state crystal, to semiconductors. These results have led to intensive research into new materials, devices, and system studies that examine their impact to new applications. It is believed that we are on the verge of a dramatic change in the way we envision and construct communication, processing and control systems. One direct application of slow and fast light devices is in the area of communications. One grand challenge remaining in information technology today is to store and buffer optical signals directly in optical format. As such, optical signals must be converted to electronic signals to route, switch, or be processed. This resulted in significant latencies and traffic congestions in current networks. In addition, keeping the data in optical domain during the routing process can greatly reduce the power, complexity and size of the routers. To this end, a controllable optical delay line can effectively function as an optical buffer, and the storage is proportional to the variability of the group velocity. In addition to optical buffers, slow and fast light devices can be used as tunable true-time delay elements in microwave photonics, which are important for remotely controlling phased array antenna. Other novel applications include nonlinear optics, optical signal processing, and quantum information processing. There are various approaches that can be used to vary the optical group velocity. Ultraslow or fast group velocity may result from a large material dispersion, waveguide dispersion, or both. In this paper, the authors provide a review of recent progress of slow and fast light using semiconductor devices. Specifically, they will discuss results obtained using semiconductor quantum-well/quantum-dot absorber and optical amplifiers. Slow and fast light are controllable electrically by changing the bias current or voltage as well as optically by changing the pump laser intensity and wavelength. Delay-bandwidth tradeoff and other figures of merits are analyzed
TL;DR: In this paper, numerical simulations of the transmission performance of AMOOFDM signals are undertaken in directly modulated DFB laser (DML)-based single-mode-fiber (SMF) links without optical amplification and dispersion compensation.
Abstract: Based on a recently proposed novel optical-signal-modulation technique of adaptively modulated optical orthogonal frequency-division multiplexing (AMOOFDM), numerical simulations of the transmission performance of AMOOFDM signals are undertaken in directly modulated DFB laser (DML)-based single-mode-fiber (SMF) links without optical amplification and dispersion compensation. It is shown that a 30-Gb/s transmission over a 40-km SMF with a loss margin of greater than 4.5 dB is feasible in the aforementioned simple configuration using intensity modulation and direct detection (IMDD). In addition, the DFB-laser frequency chirp and the transmission-link loss are identified to be the key factors limiting the maximum achievable transmission performance of the technique. The first factor is dominant for transmission distances of 80 km. It is also observed that fibers of different types demonstrate similar transmission performances, on which fiber nonlinear effects are negligible.
TL;DR: A novel algorithm to overcome the issues related to the practical availability of finite-range birefringent components and to solve the requirement for endless stabilization is presented.
Abstract: The control of the state of polarization (SOP) of light remains one of the open issues in optical communications. In particular, the achievement of a stabilization of the SOP can find many applications in advanced optical communication systems: from the mitigation of polarization-mode dispersion to the development of novel multilevel modulation formats. In this paper, theoretical and experimental aspects of polarization stabilization are dealt with, and a novel algorithm to overcome the issues related to the practical availability of finite-range birefringent components and to solve the requirement for endless stabilization is also presented. A complete analysis of the control algorithm, based on the Jones matrix formalism, is also presented. The practical implementation of the polarization stabilizer is discussed, and experimental demonstrations based on liquid crystal and magnetooptical retarders are shown
TL;DR: In this article, the authors investigated the impact of backreflection lights on upstream transmission in WDM single-fiber loopback access networks, where a WDM light source is located at the central office (CO) and each optical network unit (ONU) includes an optical modulator with optical amplifiers.
Abstract: This paper investigates the impact of backreflection lights on upstream transmission in wavelength division multiplexing (WDM) single-fiber loopback access networks, where a WDM light source is located at the central office (CO) and each optical network unit (ONU) includes an optical modulator with optical amplifiers. This study considers backreflection lights from two sources, the continuous wave (CW) light at the CO (Reflection-I) and the modulated signal at the ONU (Reflection-II). It is confirmed, for the first time, that the impact of Reflection-II increases strongly with ONU gain. To estimate the impact of these backreflection lights, a simple intensity noise estimation scheme is presented. This scheme clarifies that the acceptable transmission line losses is 10 dB for 1.25 Gb/s under the optical return loss (ORL) of -32 dB.
TL;DR: A ring-resonator-based integrated photonic chip with ultrafine frequency resolution, providing programmable, stable, and accurate optical-phase control is demonstrated in this article, where the authors report their use as programmable spectral-phase encoders (SPEs) and decoders for wavelength-division-multiplexing (WDM)-compatible optical code-division multiple access (OCDMA).
Abstract: A novel ring-resonator-based integrated photonic chip with ultrafine frequency resolution, providing programmable, stable, and accurate optical-phase control is demonstrated. The ability to manipulate the optical phase of the individual frequency components of a signal is a powerful tool for optical communications, signal processing, and RF photonics applications. As a demonstration of the power of these components, we report their use as programmable spectral-phase encoders (SPEs) and decoders for wavelength-division-multiplexing (WDM)-compatible optical code-division multiple access (OCDMA). Most important for the application here, the high resolution of these ring-resonator circuits makes possible the independent control of the optical phase of the individual tightly spaced frequency lines of a mode-locked laser (MLL). This unique approach allows us to limit the coded signal's spectral bandwidth, thereby allowing for high spectral efficiency (compared to other OCDMA systems) and compatibility with existing WDM systems with a rapidly reconfigurable set of codes. A four-user OCDMA system using polarization multiplexing is shown to operate at data rates of 2.5 Gb/s within a 40-GHz transparent optical window with a bit error rate (BER) better than 10/sup -9/ and a spectral efficiency of 25%.
TL;DR: In this paper, a laboratory-simulated free-space optical link under various turbulence levels is implemented to propose and experimentally demonstrate the use of saturated optical amplifiers as a simple and efficient approach for suppression of scintillation due to atmospheric turbulence.
Abstract: A laboratory-simulated free-space optical link under various turbulence levels is implemented to propose and experimentally demonstrate the use of saturated optical amplifiers as a simple and efficient approach for suppression of scintillation due to atmospheric turbulence. The use of erbium-doped fiber amplifier (EDFA) or semiconductor optical amplifier (SOA) requires the received signal be coupled into a fiber. The system performance of receiver structures employing a saturated EDFA and a SOA (in saturation and conversion modes) are measured and compared to that of fiberless direct detection (DD). It is shown that in higher turbulence levels, where no data transmission can be achieved by DD, remarkable eye opening results when using saturated amplifiers
TL;DR: The fade level of fiber-coupled signals at desired fade probability is investigated and it is shown that the average bit error ratio significantly degrades with the random angular jitter normalized by the mode field radius larger than about 0.3 when the Airy disk size is optimally selected.
Abstract: Free-space laser communication systems use optical-fiber-based technology such as optical amplifiers, receivers, and high-speed modulators. In these systems using single-mode fibers, the fiber coupling efficiency is one of the most significant issues to be solved. Optimum relationships between a focused optical beam and mode field size of the optical fiber in the presence of random angular jitter are discussed in relation to fiber-coupled optical systems. Maximum fiber coupling efficiency is analytically derived with the optimum Airy disk radius normalized by the mode field radius as a function of random angular jitter. The fade level of fiber-coupled signals at desired fade probability is investigated. It is shown that the average bit error ratio significantly degrades with the random angular jitter normalized by the mode field radius larger than about 0.3 when the Airy disk size is optimally selected.
TL;DR: This paper intends to summarize some of the most interesting proposed modulation formats for high bit rate (especially 40 Gb/s) WDM transmissions.
Abstract: With the progress of optical communication systems, and especially the constraints brought by wavelength division multiplexing (WDM) transmissions and increased bit rates, new ways to convert the binary data signal on the optical carrier have been proposed. It appears clearly now that several of the methods proposed by research laboratories will be applied into commercial products soon due to the large improvements generated. This paper intends to summarize some of the most interesting proposed modulation formats for high bit rate (especially 40 Gb/s) WDM transmissions
TL;DR: Room-temperature slow light that is electrically and optically controllable by using a quantum-dot (QD) semiconductor optical amplifier (SOA) at zero and low bias below the transparency current is demonstrated.
Abstract: We demonstrate room-temperature slow light that is electrically and optically controllable by using a quantum-dot (QD) semiconductor optical amplifier (SOA) at zero and low bias below the transparency current. The absorption spectrum of the QD SOA exhibits a spectral dip with a corresponding group-index dispersion and group delay owing to coherent population oscillation caused by the interaction of pump and probe laser light near resonance of the first heavy-hole-conduction-state transition. At an optical pump power of approximately 0.3 mW inside the single-mode waveguide without current injection, a group-index change of 3.0 with a bandwidth of 2 GHz was measured. This group-index change can be controlled by injection of electrical current and by changing the optical pump power.
TL;DR: In this paper, a low-cost option for transporting global system for mobile communication, Universal Mobile Telecommunication System and wideband local area network (WLAN) signals using multimode fiber (MMF) with 850-nm vertical-cavity surface-emitting lasers (VCSELs) is investigated through range predictions from a link budget analysis.
Abstract: A low-cost option for transporting global system for mobile communication, Universal Mobile Telecommunication System and wideband local area network (WLAN) signals using multimode fiber (MMF) with 850-nm vertical-cavity surface-emitting lasers (VCSELs) is investigated through range predictions from a link budget analysis. These predictions are experimentally verified for WLAN signal transmission in an office environment, using a commercial access point and a 300-m (OM1/OM2) MMF link with low-cost 850-nm VCSEL transmitters. The analysis indicates that good performance and signal coverage is possible with optimum design of indoor fiber-fed wireless systems, even when using such inexpensive components
Patent•
15 Sep 2006TL;DR: Simplified laser drivers for closed path digital optical cables and digital optical cable including the simplified laser drivers as discussed by the authors can include a bias source and modulation source, and the bias source can have a single constant current bias point for all laser diodes.
Abstract: Simplified laser drivers for closed path digital optical cables and digital optical cables including the simplified laser drivers. The laser driver can include less transistors than conventional laser drivers for optical communication cables. The laser can include a bias source and modulation source. The bias source can have a single constant current bias point for all laser diodes. The modulation current source can have a single temperature coefficient for all laser diodes. The laser driver can exclude, for example, any one of or combination of temperature compensation of the modulation or bias current sources, external programming of the modulation or bias current sources, power control based on output of the laser diode, and/or control based on feedback received from a monitor device or other sensor within the cables.
TL;DR: The effects of a micrometer-scale silicon ring resonator with a FWHM of 0.078 nm (9.6 GHz) on a nonreturn to zero amplitude-modulated optical signal with a modulation rate of 10 Gbps are experimentally investigated.
Abstract: The effects of a micrometer-scale silicon ring resonator with a FWHM of 0.078nm (9.6GHz) on a nonreturn to zero amplitude-modulated optical signal with a modulation rate of 10Gbps are experimentally investigated. By transmitting the optical signal through the device, significant spectral distortion and sideband attenuation is introduced, as characterized by amplitude Bode plots, and a power penalty of 0.8dB is observed. Carrier wavelengths within the transmission resonance, but detuned from the center wavelength, are investigated as well. Numerical simulations further support the experimental results.
TL;DR: In this reported work, the outage probability of a multi-hop FSO communication system with amplify-and-forward relays, assuming strong turbulence fading channels, is analytically derived.
Abstract: Free space optical (FSO) communication is highly sensitive to atmospheric turbulence. The use of relays where the distance between the transmitter and the receiver is scaling down via multi-hop routing can improve the performance of an FSO link. In this reported work, the outage probability of a multi-hop FSO communication system with amplify-and-forward relays, assuming strong turbulence fading channels, is analytically derived. The turbulence-induced fading is modelled as a multiplicative random process which follows the K or the negative exponential distribution.