In this paper we present the urgency for the optical transport networking evolution for 5G delivery and ultra-broadband services to users and communities of users, in the followings: (a) Cloud core, Metro-cloud core and edge cloud networking structure with optical SDN and SDN/NFV. (b) Photonic enabled technologies including principal devices and photonic processors. (c) Security aspects and transmission technology for secret keys in co-transmission of massive data transport.
Delivering maximum information capacity over MIMO antennae systems beam steering is critical so as to achieve the flexibility via beam steering, maximizing the number of users or community of users in Gb/s rate per user over distributed cloud-based optical-wireless access networks. This paper gives an overview of (i) demands of optical – wireless delivery with high flexibility, especially the beam steering of multi-Tbps information channels to information hungry community of users via virtualized beam steering MIMO antenna systems at the free-license mmW region; (ii) Proposing a novel photonic planar integrated waveguide systems composing several passive and active, passive and amplification photonic devices so as to generate mmW carrier and embedded baseband information channels to feed to antenna elements; (iii) Integration techniques to generate a radio over optical waveguide (RoOW) system-on-wafer (SoW) comprising MIMO planar antenna elements and associate photonic integrated circuits for both up- and down- links; (iv) Challenges encountered in the implementation of the SoW in both wireless and photonic domains; (v) Photonic modulation techniques to achieve maximum transmission capacity per wavelength per MIMO antenna system. (vi) A view on control-feedback systems for fast and accurate generation of phase pattern for MIMO beam steering via a bank of optical phase modulators to mmW carrier phases and their preservation in the converted mmW domain . (vi) The overall operational principles of the novel techniques and technologies based on the coherent mixing of two lightwave channels The entire SoW can be implemented on SOI Si-photonic technology or via hybrid integration. These technological developments and their pros- and cons- will be discussed to achieve 50Tera-bps over the extended 110 channel Cband single mode fiber with mmW centered at 58.6GHz and 7GHz free-license band.
Optical networking is evolving from classical service-provider base data-center centric (DCC) internetworking environment with massive capacity, hence demanding novel optical switching and interconnecting technologies. The traditional telecom networks are under a flattening transformation to meet challenges from DCC networks for massive capacity serving in order of multi-Pb/s. We present proposed distributed and concentric data center based networks and the essential optical interconnection technologies, from the photonic kernels to electronic and optoelectronic server clusters, in both passive and active structures. Optical switching devices and integrated matrices are proposed composing of tunable (bandwidth and center wavelength) optical filters and switches as well as resonant microring modulators (μRM)(switching and spectral demux/mux) for multi-wavelength flexible-bandwidth optical channels of aggregate capacity reaching Ebps. The design principles and some experimental results are also reported.
KEYWORDS: Analog electronics, Antennas, Digital signal processing, Radio over Fiber, Modulation, Optical networks, Integrated photonics, Internet, Broadband telecommunications, Channel projecting optics, Networks, Clouds, Extremely high frequency, Data centers, Selenium
Under the exponential increase demand by the emerging 5G wireless access networking and thus data-center based Internet, novel and economical transport of RF channels to and from wireless access systems. This paper presents the transport technologies of RF channels over the analog and digital domain so as to meet the demands of the transport capacity reaching multi-Tbps, in the followings: (i) The convergence of 5G broadband wireless and optical networks and
its demands on capacity delivery and network structures; (ii) Analog optical technologies for delivery of both the
information and RF carriers to and from multiple-input multiple-output (MIMO) antenna sites so as to control the beam steering of MIMO antenna in the mmW at either 28.6 GHz and 56.8 GHz RF carrier and delivery of channels of aggregate capacity reaching several Tbps; (ii) Transceiver employing advanced digital modulation formats and digital
signal processing (DSP) so as to provide 100G and beyond transmission rate to meet the ultra-high capacity demands
with flexible spectral grids, hence pay-on-demand services. The interplay between DSP-based and analog transport techniques is examined; (iii) Transport technologies for 5G cloud access networks and associate modulation and digital
processing techniques for capacity efficiency; and (iv) Finally the integrated optic technologies with novel lasers, comb generators and simultaneous dual function photonic devices for both demultiplexing/multiplexing and modulation are
proposed, hence a system on chip structure can be structured. Quantum dot lasers and matrixes of micro ring resonators
are integrated on the same Si-on-Silica substrate are proposed and described.
Tremendous efforts have been developed for multi-Tbps over ultra-long distance and metro and access optical networks. With the exponential increase demand on data transmission, storage and serving, especially the 5G wireless access scenarios, the optical Internet networking has evolved to data-center based optical networks pressuring on novel and economical access transmission systems. This paper reports (1) Experimental platforms and transmission techniques employing band-limited optical components operating at 10G for 100G based at 28G baud. Advanced modulation formats such as PAM-4, DMT, duo-binary etc are reported and their advantages and disadvantages are analyzed so as to achieve multi-Tbps optical transmission systems for access inter- and intra- data-centered-based networks; (2) Integrated multi-Tbps combining comb laser sources and micro-ring modulators meeting the required performance for access systems are reported. Ten-sub-carrier quantum dot com lasers are employed in association with wideband optical intensity modulators to demonstrate the feasibility of such sources and integrated micro-ring modulators acting as a combined function of demultiplexing/multiplexing and modulation, hence compactness and economy scale. Under the use of multi-level modulation and direct detection at 56 GBd an aggregate of higher than 2Tbps and even 3Tbps can be achieved by interleaved two comb lasers of 16 sub-carrier lines; (3) Finally the fundamental designs of ultra-compacts flexible filters and switching integrated components based on Si photonics for multi Tera-bps active interconnection are presented. Experimental results on multi-channels transmissions and performances of optical switching matrices and effects on that of data channels are proposed.
We present a modeling of the Raman amplification of various types of fibers employed for transmission and dispersion compensation in cascaded optical amplified transmission systems including (1) the physical properties and operational characteristics and (2) its implementation in the lightwave-modulated envelop propagation equation for transmission of 40 Gbits/s signals in mutliplexed wavelength optical systems. We demonstrate, by simulation using MATLAB Simulink, the integration of the Raman amplification gain and noise into the transmission system by (1) numerical techniques to solve these design parameters for a single channel bidirectionally pumped system operating in the C-band (1525 to 1565 nm) range at 1550 nm; (2) evaluations of the amplifier parameters such as the gain, the noise figure, and the dispersion factor of distributed and discrete Raman configurations. We design an optimum condition for hut-skipped undersea long-haul transmission using a hybrid combination of Raman and Er-doped fiber amplifers. The long-haul numerical solution is adapted from the average power to a Gaussian pulse operating at 40 Gbits/s and the propagation distributed along the fiber for integration into differential phase shift keying modulation format optical signals using models based on MATLAB Simulink.
Broadband optical modulators, especially the LiNbO3 interferometric types, are currently important in the generation of advanced modulation formats for operating bit rate in the 100 Gb/s range for 100-Gb/s optical Ethernet networks. In these devices the effectiveness of generation of the traveling electric field for electro-optic interaction is very critical. This work presents the modeling of the tilted wall of traveling wave electrodes and their impacts on the operating bandwidth over interferometric optical waveguide structures and modulators. The effects of the tilt of thick electroplated electrodes on the device bandwidth are significant. The electro-optic overlap integral can be evaluated with tilt electrodes. Key features for optimization of the electro-optic overlap integral are studied to realize modulators of low half-wave driving voltage and fabrication of optical modulators under limited etching facility. Experimental demonstration of the effects of tilted electrodes on the performance of a Mach-Zehnder interferometric modulator is given to confirm simulation results.
The impulse and step responses as well as the pulse responses of a quadratic phase medium, the single-mode optical fiber, are presented. Analytical expressions of the fiber impulse and step responses are obtained, indicating the change of the phase of the lightwave carrier. Both coherent and incoherent detection schemes under the amplitude shift keying and continuous phase frequency shift keying (CPFSK) incorporating the maximum likelihood sequence estimation are examined with respect to the uncertainty depending on the number of bits of the sequence. The detection uncertainty shows that the coherent detection offers a high degree of discrimination as compared to its incoherent counterpart, especially for the case of CPFSK. The frequency discrimination detection of the CP FSK is correlated with the bandwidth-bit period product, the product between filter bandwidth and the bit period. Resilience to dispersion of ±9520 ps/nm can be achieved due to this minute uncertainty of this detection scheme.
Optical filters employing acousto-optic polarized mode conversion techniques are implemented to demonstrate the filtering, selection, and switching of packets of wavelength multiplexed optical channels in LiNbO3 diffused optical waveguides. Geometrically tilted and chirped digital electrodes of the metallic interdigital transducer are used to excite acoustic surface waves for phase matching of the optical transverse electric (TE) and transverse magnetic (TM) guided modes, hence optical field coupling and transfer and filtering. By simultaneous launching of acoustics waves, the selection of wavelength channels can be made. A tuning range of >250 nm and that of the passband from <1 nm to >150 nm can be achieved with selectivity of optical channels of different wavelengths.
A geometrical and phasor representation technique is presented to illustrate the modulation of the lightwave carrier to generate quadrature amplitude modulated (QAM) signals. The modulation of the amplitude and phase of the lightwave carrier is implemented using only one dual-drive Mach-Zehnder interferometric modulator (MZIM) with the assistance of phasor techniques. Any multilevel modulation scheme can be generated, but we illustrate specifically, the multilevel amplitude and differential phase shift keying (MADPSK) signals. The driving voltage levels are estimated for driving the traveling wave electrodes of the modulator. Phasor diagrams are extensively used to demonstrate the effectiveness of modulation schemes. MATLAB Simulink models are formed to generate the multilevel modulation formats, transmission, and detection in optically amplified fiber communication systems. Transmission performance is obtained for the multilevel optical signals and proven to be equivalent or better than those of binary level with equivalent bit rate. Further, the resilience to nonlinear effects is much higher for MADPSK of 50% and 33% pulse width as compared to non-return-to-zero (NRZ) pulse shaping.
This paper demonstrates via simulation, the transmission of multiwavelength channels using vestigial single-side-band (VSB) modulation at 40 Gb/s bit rate over long-haul optically amplified fiber systems. Bit-error-rate (BER) of 10−12 or better can be achieved across all channels. The principal component, the optical filter, for eliminating one of the signal side bands is designed with asymmetric roll-off bands in order to relax the demands on the high order of the optical filtering system and hence increase ease of implementation in the photonic domain. Simulations of the transmission performance, BER versus receiver sensitivity and dispersion tolerance are demonstrated with wavelength channel spacing of 20–40 GHz. An optical filter, pass band of 28 GHz and a 20 dB cutoff band performs best for 40 Gb/s return-to-zero VSB due to optimum filtering and minimum noise contribution. Furthermore, the single side-band property of VSB format facilitates linear equalization by electronic processing. Two typical equalization schemes using linear and nonlinear equalizers are reported.
Transmission in a 40-Gbit/s alternating-phase (0 and ) duobinary modulation format with 67%, 50%, and 33% pulse width [modulation duobinary carrier suppression (CS) and carrier maximum pulse carving] is demonstrated. A minimum 136-ps/nm dispersion tolerance can be achieved at this transmission rate. At least 5- and 1.2-dB receiver sensitivity improvements are achieved for CS return-to-zero (RZ) 67% and 50% duobinary modulation, respectively, as compared with the experimental measurement under CS RZ differential phase-shift keying transmission over a 320-km three-span optically amplified dispersion-compensated standard single-mode fiber system. A MATLAB Simulink platform is described for simulation of the transmission performance.
We propose a series method to analyze detuned active mode-locked lasers. Using this method, we can analyze not only
noiseless lasers but also lasers modelled with amplified spontaneous emission (ASE) noise. Moreover, the method also
helps to study the transient evolution of the pulse inside the cavity, which cannot be done using classical analysis.
We propose two novel transmitter configurations for generation of linear and non-linear phase modulated optical minimum shift keying (MSK) signals based on approaches of continuous phase frequency shift keying (CPFSK) and I-Q component structure of offset/staggered DQPSK formats. The precoder for I-Q optical MSK structure is derived. The direct detection of optical ligtwave is utilized with implementation of the well-known differential non-coherent balanced receivers. Simulated spectral characteristics and dispersion tolerance to 40 Gb/s transmission are presented and compared to those of ASK and DPSK counterparts.
We report the BER performance characteristics of 16-ary Multi-level Amplitude-Differential Phase Shift Keying
(MADPSK) modulation formats. The modulation scheme is bandwidth efficient with an effective transmission symbol
rate equal to 1/4 of the bit rate. The BER performance of NRZ and RZ MADPSK formats are investigated for long haul
optically amplified transmission in the presence of optical noise, fiber residual chromatic dispersion and non-linearity.
Dual locking ranges in a harmonic mode-locked fiber laser with a birefringence cavity is reported in this paper.
Experimental results clearly show the existence of two separated locking ranges in the vicinity of the 834th harmonic of
the fundamental frequency. Theoretical explanation is given. Theoretical estimation of the locking range agrees well
with the experimental result. Simulation also reproduces the experimental results.
The generation and detection of linear, weakly non-linear and strongly non-linearly optical MSK long-haul transmission systems have been reported. The simulation test-beds based on Matlab Simulink platform have been successfully developed. The following significant results have been achieved: (i) BER of 10-38 is achieved for an OSNR of 22.2dB; (ii) At BER of 10-12, linear MSK is approximately 1 dB more tolerable to nonlinearity than weakly nonlinear MSK and 5.5dB more durable than strongly nonlinear MSK; (iii) (c).The sideband suppression ratio for linear MSK is approximately 22dB. New technique for calculation of performance evaluation implementing expected maximization (EM) theorem is utilized.
Transmission of 40 Gb/s alternating phases 0 and π duo-binary modulation format with 67%, 50% and 33% pulse
width (modulation duobinary carrier suppression-CS and carrier maximum pulse carving) is demonstrated. A minimum
136 ps/nm dispersion tolerance can be achieved at this transmission rate. At least 5 dB and 1.2 dB receiver sensitivity
improvement are achieved for CSRZ 67% and RZ 50% duobinary modulation respectively as compared with the
experimental measurement under CSRZ-DPSK transmission over 320 km 3-span optically amplified dispersion
compensated standard single mode fiber system.
Ultra-stable photonic fiber ring lasers are demonstrated at 10 and 40 Gpulses/s repetition rate operating under an optical-RF feedback mechanism with the in-ring hard pumped optical amplification. Ultra-stability is achieved when the circulating optical power is forced into saturation and hence acting as a distributed saturation absorber. Temporal diffraction with harmonic detuning are also analyzed and experimentally demonstrated. Further the pulse repetition rate of higher than 100GHz is achieved by incorporating an external temporal diffraction fiber length.
We report the transmission of 40Gb/s channels over DWDM optically amplified communications systems employing RZ, NRZ, CS-RZ amplitude and differential phase shift keying modulation over 320 km standard SMF and 328 km dispersion compensating modules. Impacts of optical filtering of 10 Gb/s DWDM transmission system on these 40G modulation formats are reported. The mutual impacts of 10 Gb/s and 40 Gb/s co-transmission are proven to be minimum.
We report a new mode-locking phenomenon in which ultra-high peak or "giant" pulse trains have certain pulse drops in an active mode-locked fiber ring laser. Generated pulse trains have properties similar to a return-to-zero format with a clear pedestal, with pulse trains circulating in the ring of peak power reaching 575 mW, which is about ten times higher than the actual peak output power. The temporal pulse trains and their optical spectra are described and discussed. It is believed that this is due to the interaction between copropagating pulses in the ring and the supermode competition.
A novel tunable multiwavelength erbium-doped fiber laser source based on a Sagnac loop filter is proposed and experimentally demonstrated. The filter, which is coupled together with the laser cavity, consists of a normal 3-dB fiber coupler, a polarization controller (PC1) and a segment of high-birefringence (Hi-Bi) fiber. The active gain medium, which is a polarization-maintaining erbium-doped fiber (PM-EDF) with an elliptical core, leads to possible multi-frequency lasing output at room temperature. In experiment, by changing the setting of the polarization controller (PC2), multiple frequency lasing lines with different wavelength spacing have been obtained. By applying some pressure to the PM-EDF, continuously tunable multiwavelength lasing output is achieved. Experimental results have shown several stable output lasing wavelengths with high extinction ratio at room temperature.
A novel spacing-tunable multiwavelength erbium-doped fiber laser source based on a Sagnac loop filter is proposed and experimentally demonstrated. The filter, which is coupled together with the laser cavity, consists of a normal 3-dB fiber coupler, a polarization controller (PC1), and a segment of high-birefringence (Hi-Bi) fiber. The active gain medium, which is a polarization-maintaining erbium-doped fiber (PM-EDF) with an elliptical core, leads to possible multifrequency lasing output at room temperature. In the experiment, by changing the setting of the polarization controller (PC2), multiple-frequency lasing lines with different wavelength spacing are obtained. Experimental results show several stable output lasing wavelengths with high extinction ratios at room temperature.
Free-space quantum key exchanges between ground stations and low earth orbiting satellites will be characterized by high link losses, typically of the order of 30 dB or higher. These losses, together with the need to transmit weak Poissonian laser pulses containing on average substantially less than 0.1 photons per transmitted bit to preserve security, will result in exceedingly low channel efficiencies, typically of the order of 10-5. In order to achieve even a relatively modest secure key bit rate of 100 kbps, it will therefore often be necessary to key the transmitter at rates in excess of 10 Gbps. In this paper we outline several different methods of achieving such fast polarization keying including the use of dual drive Mach-Zehnder intensity modulators on lithium niobate in a hybrid fibre-guided modulator structures. We then propose a total integrated polarization keying structure in LiNbO3. We describe the fabrication and testing of such ultra-broadband polarization keyers suitable for use in high loss, short-wave free-space quantum key distribution systems employing silicon photon counters. We also indicate how these devices may be incorporated into quantum key satellite courier payloads and ground station terminals.
We report advanced modulation formats in transmission systems operating for 40Gb/s DWDM for multi-Tb/s photonic transport networks including (1) efficient RZ, RZ-CS, RZ-CS VSB for optimizing dispersion tolerance in linear and nonlinear operating regimes (2) disperison management and compensation techniques (3) equalization of gain by lumped and distributed amplification. Simulated and some experimental results are given.
Given a set of lightpath connection requests in an all-optical wavelength division multiplexed (DWDM) network, lightpaths are designed and the wavelength channels are assigned so that the scheme minimizes on average the blocking of existing and provisional requests. This paper proposes a routing and wavelength assignment scheme for DWDM long-haul optical networks that includes routing, assignment and reservation of different wavelength channels operating under the G-MPLS environment. The modeling is implemented under the framework of an object-oriented modeling platform OMNeT++. Network performance tests are evaluated for a long-haul terrestrial fiber network composed of 12 gigaPoPs with an average degree of 3. Traffic blocking of lightpath requests are examined with the average link utilization in the network employing variable number of wavelength channels. Two principal algorithm for wavelength assignments, the first-fit and random types, are studied and proven that the random scheme offers significant better performance than that of its counterpart.
Quantum photonic informatics involves manipulation and processing of information at a photon energy level. The qu-bit with optical modes containing one photon energy is described and photonic gates representing its quantum states are given and expanded into quantum systems and networks for computing and information processing. Integrated photonic devices are proposed for implementation of the quantum gates and networks and case studies are examined for further expansion and implementation of quantum algorithms.
An accurate and yet simple simulation technique for optical modulators operating at multi-GHz region and optical modulators are critical for Tera-bps optical communications. This paper describes a simple, efficient and accurate analysis of the traveling wave electrodes for high speed optical modulation and the implementation of these electrodes in interferometric optical modulators. A finite difference approach is employed in modeling the traveling wave electrodes for efficient electro-optic interaction in interferometric optical modulators. Electrode configurations such as symmetric and asymmetric co-planar waveguide or strip structures and shielded electrode systems can be modeled. Simulated results demonstrate the efficiency of the presented method as compared with other methods such as the Green's function, conformal mapping, method if images, spectral domain analysis etc. Tilted and thick practical electro-plated electrodes are modeled and confirmed with implemented modulators operating up to 26 GHz in diffused LiNbO3 optical interferometric optical waveguide structures. The fabrication of optical waveguides and traveling wave electrodes are described for implementation of the electro-optic interferometric modulators.
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