Showing papers on "Optical Carrier transmission rates published in 2003"

Optical carrier supply module using flattened optical multicarrier generation based on sinusoidal amplitude and phase hybrid modulation

Abstract: This paper presents an optical carrier supply module (OCSM) that functions as a common multicarrier light source, a wavelength bank, for superdense wavelength-division multiplexing (SD-WDM) networks that utilize a large number of wavelengths with narrow channel spacing. A novel sideband generator based on a sinusoidal amplitude-phase hybrid modulation scheme is the key technique. The sideband generator generates nine flattened optical sidebands within 3 dB from one seed light source, and the input from wavelength-division multiplexing (WDM) seed carriers expands the number of generated sidebands. Scalability against the number of wavelengths is achieved by increasing the number of seed carriers used. The SD-WDM system employing OCSM reduces the number of laser diodes (LDs) and attendant wavelength monitoring/stabilization circuits. Multiple distributions to SD-WDM networks by splitting the OCSM output can promote this effect. We designed OCSM and experimentally investigated its performance pertaining to the electrical signal-to-noise ratio (SNR) of the OCSM output. The experimental results show the wavelength scalability to 1000 channels. We also developed an OCSM prototype that generated 12.5-GHz-spaced 256-channel WDM carriers. All the generated carriers exhibit the electrical SNR of more than 31.5 dB at 2.5 Gb/s and the power flatness of within 3 dB. The distribution over 100 SD-WDM networks is experimentally confirmed.

STOLAS: switching technologies for optically labeled signals

Abstract: GMPLS-based labeled optical burst switching (LOBS) networks are being considered as the next-generation optical Internet. GMPLS includes wavelength switching next to label and fiber (space) switching. We present a new concept of optically labeling bursts of packets suitable for LOBS networks supported by GMPLS. It is based on angle modulation, which enables control information to modulate the phase or frequency of the optical carrier, while payload data are transmitted via intensity modulation (IM). In particular, the optical label is orthogonally modulated, with respect to the payload, using either frequency shift keying or differential phase shift keying. We present a performance analysis of the modulation schemes by means of simulations where the influence of the payload IM extinction ratio and laser linewidth are investigated. In addition, the transmission performance of an IM/FSK combined modulated signal is experimentally validated at 10 Gb/s, demonstrating at the same time an FSK label swapping operation. Finally, a suitable optical label-controlled switch design is proposed that takes advantage of these novel labeling techniques, and efficiently combines widely tunable, fast switching lasers and SOA-MZI wavelength converters with an arrayed waveguide grating router.

A WDM-based optical access network for wide-area gigabit access services

Abstract: This article proposes and demonstrates a WDM-based access network that directly connects end users over a wide area to the center node and provides guaranteed full-duplex Gigabit Ethernet access services to each of over 100 users. The center node employs an optical carrier supply module that generates not only the optical carriers for the downstream signals but also those for the upstream signals. The latter are supplied to optical network units (ONUs) at users' homes/buildings via the network. Since the ONUs simply modulate the optical carriers supplied from the center node via the network, they are wavelength-independent.

Wideband versatile radio-frequency spectrum analyzer

Abstract: Operation of a wideband, versatile optical spectrum analyzer for radio-frequency (RF) signals is demonstrated. The device is based on spectral hole burning (SHB). The demonstration features 2.3-GHz instantaneous bandwidth, 500-kHz resolution, and a 32-dB dynamic range. A true RF signal, transferred to the optical carrier with the help of a Mach-Zehnder modulator, is analyzed with optical carrier suppression and zooming capabilities. This is to the authors' knowledge the largest instantaneous bandwidth ever demonstrated for a SHB-based processor in rare-earth-doped crystals.

A 0.18 /spl mu/m SiGe BiCMOS receiver and transmitter chipset for SONET OC-768 transmission systems

Abstract: A 43-Gb/s receiver (Rx) and transmitter (Tx) chip set for SONET OC-768 transmission systems is reported. Both ICs are implemented in a 0.18-/spl mu/m SiGe BiCMOS technology featuring 120-GHz f/sub T/ and 100 GHz f/sub max/. The Rx includes a limiting amplifier, a half-rate clock and data recovery unit, a 1:4 demultiplexer, a frequency acquisition aid, and a frequency lock detector. Input sensitivity for a bit-error rate less than 10/sup -9/ is 40 mV and jitter generation better than 230 fs rms. The IC dissipates 2.4 W from a -3.6-V supply voltage. The Tx integrates a half-rate clock multiplier unit with a 4:1 multiplexer. Measured clock jitter generation is better than 170 fs rms. The IC consumes 2.3 W from a -3.6-V supply voltage.

In-house networks using multimode polymer optical fiber for broadband wireless services

Abstract: A novel system concept is presented to transport microwave signals over an in-house multimode graded-index polymer optical fiber network, in order to feed the radio access points in high-capacity wireless LANs. By employing optical frequency multiplying, the network's intrinsically limited bandwidth is overcome. The feasibility of this concept to carry data at several hundreds of Mbit/s speed for various microwave signal formats at carrier frequencies in the tens of GHz range is shown. The concept enables cost-effective system implementation, and easy upgrading by offering data signal transparency. It can readily be integrated with other system technologies such as wired Gigabit Ethernet in a single multi-service in-house polymer optical fiber network.

Optical transmission system

Abstract: An optical transmission system comprises a light source to output an optical carrier having a predetermined wavelength, a photoelectric converter, an optical transmission line, an optical circulator to apply an output light from the light source to one end of the optical transmission line and to apply a light through the same end of the optical transmission line to the photoelectric converter, and an optical modulator disposed on the other end of the optical transmission line to return a portion of the light from the optical transmission line as a reference light to the optical transmission line without modulation and to modulate another portion of the light from the optical transmission line with a transmission signal to return it to the optical transmission line as a modulated light.

Method for optical carrier suppression and quadrature control

Abstract: A suppressed carrier optical communications signal is generated by driving (biasing) an optical modulator capable of complex modulation of an optical carrier signal to a bias point near a zero-crossing point of the modulator's E-field response. A complex input signal is then used to drive excursions of the E-field response to impress the input signal onto the optical carrier. The resulting lightwave emerging from the complex modulator exhibits an optical spectrum characterized by a pair of sidebands and a strongly suppressed carrier. Bias control of the complex modulator is implemented on the basis of the optical power detected at the output of the complex modulator. This enables the optical modulator to be treated as a “black box”, in that calculation of the bias signals does not relay on knowledge of the precise performance characteristics of the modulator.

A single light-source configuration for full-duplex 60-GHz-band radio-on-fiber system

Abstract: A simple full-duplex radio-on-fiber system using a single light source is described. A base station (BS) is simplified by giving it no local light or RF sources. The optical carrier for the uplink is sent along with the downlink optical signal to a remote BS. It is looped back to the central station after being modulated with an uplink RF signal. Fiber-optic full-duplex transmission of 60-GHz-band 155.52-Mb/s downlink and uplink signals over 25-km-long standard single-mode fibers is experimentally demonstrated and bit error rates of 10/sup -9/ for both links were achieved without any serious fiber dispersion due to the optical single-sideband format. The configuration of the proposed system is simpler because one light source is shared by the downlink and uplinks.

Performance-optimized microstrip coupled VCOs for 40-GHz and 43-GHz OC-768 optical transmission

Abstract: In this paper, we present 40- and 43-GHz voltage-controlled oscillators (VCOs) for use in SONET/SDH optical transmission systems operating at OC-768 rates. SONET system jitter requirements are explained, as are methods for achieving the requisite performance in manufacturable oscillators. We describe in detail a technique for using quadrature-coupled VCOs to achieve a fundamental improvement in jitter power performance. The 40-GHz oscillator has a tuning range of 5 GHz, a single-sideband phase-noise power spectral density of -99 dBc/Hz at 1-MHz offset from the carrier, and consumes 207 mW in the oscillator core. Total power consumption is 363 mW (including biasing and output buffers) from a 3-V supply. The oscillator occupies 0.189 mm/sup 2/ of die area and is implemented in a 120-GHz f/sub T/ SiGe BiCMOS process.

Design and performance of the bidirectional optical single-sideband modulator

Abstract: We present a detailed study of the design and performance of the bidirectional optical single-sideband modulator (BOSSM). This is a new scheme to achieve optical single-sideband modulation (OSSB) that uses a standard single-electrode Mach-Zehnder modulator (MZ-EOM) and passive fiber-optic components. The design is based on a novel technique to operate electrooptic modulators in which the radio frequency (RF) electrode is bidirectionally driven. The fundamentals of this bidirectional operation are analyzed thoroughly and it is found that it requires the use of a wide-bandwidth MZ-EOM with an electrode design that provides good velocity match between the optical and microwave modes. Deriving the expressions for the optical field and power at the output of the BOSSM, the OSSB operation is shown to be independent of the MZ-EOM bias. Therefore, the optical modulation depth at the output of the device can be enhanced using minimum transmission biasing to provide suppression of the optical carrier. Moreover, it is found that the second-order distortion is unaffected by the MZ-EOM bias; hence the technique can be applied to multi-octave bandwidth systems. Finally, the performance of the BOSSM is evaluated using a prototype based on a commercial 10 Gb/s MZ-EOM. The experimental characterization of the electrooptical parameters of this device reveals that the RF electrode design is not optimized for bidirectional operation. Therefore, the performance of the prototype is limited by the particular MZ-EOM deployed. However, sideband suppression over 10 dB is measured for most frequencies up to millimeter-waves, with peaks in the 20 dB to 30 dB range for narrow bands. This performance has enabled the demonstration of a 22-km fiber link transmitting a 29-GHz subcarrier conveying binary phase-shift keying modulated data at 622 Mb/s. The BOSSM reduces the dispersion-induced power penalty in the link to less than 1.5 dB. Furthermore, the bit error rate of the link is increased by five orders of magnitude using the carrier suppression technique.

40-43-Gb/s OC-768 16:1 MUX/CMU chipset with SFI-5 compliance

Abstract: In this paper, we present two copackaged ICs that provide complete OC-768 16:1 multiplexer (MUX) and clock multiplying unit (CMU) functionality. The 17-input 2.5-2.68-Gb/s parallel interface is Serdes Framer Interface Level 5 (SFI-5) compliant while the 40-43-Gb/s output satisfies OC-768 jitter generation specifications with 7 dB of margin. The system architecture and two-chip partitioning are discussed, followed by descriptions of the design challenges including SFI-5 compliance, 40-Gb/s MUX timing, and 20-GHz clock generation. A novel technique for stabilizing timing margins in the final high-speed multiplexer stage using in-phase and quadrature clocks is also presented. This chipset accommodates 11 bits of static skew and 21 bits of dynamic wander at the SFI-5 interface, while generating 125 fs rms of random jitter and 3.1 ps peak-to-peak of deterministic jitter at its 40-43-Gb/s outputs. The measured bit-error ratio is less than 10/sup -15/ for 2/sup 31/-1 PRBS data and is measurement time limited. The two chips occupy 15.6 mm/sup 2/ and 8.25 mm/sup 2/ of die area. Both are implemented in a 120-GHz f/sub T/ SiGe BiCMOS process.

Method and apparatus for the transmission fault detection in an access network

Abstract: An optical network unit (ONU) interconnected by passive optical network (PON) equipment to an optical line terminal (OLT) is identified using secondary modulation of the optical carrier to impress an identifier of the ONU onto the carrier. This resolves a recurring ONU failure mode detection problem caused by failure of a laser driver that causes the ONU to be stuck in an on state.

Optical E-field modulation using a Mach-Zehnder interferometer

Abstract: A method for modulating the E-field of an optical carrier signal utilizes a Mach-Zehnder modulator having a pair of independently controllable branches. A pair of independent branch drive signals V L (t) and V R (t) are derived. Each branch of the MZ modulator is driven with a respective one of the independent branch drive signals. By this means, a low cost conventional MZ modulator (interferometer) can be used to perform complex modulation of the E-field of the optical carrier. In some embodiments, this functionality is used to facilitate precompensation of optical impairments of an optical communications system.

A hybrid CATV/256-QAM/OC-48 DWDM system over an 80 km LEAF transport

Abstract: A hybrid dense-wavelength-division-multiplexing (DWDM) system for CATV, 256-QAM and OC-48 trunking is proposed and demonstrated. It used two wavelengths for AM-VSB CATV, one wavelength for 256-QAM digital passband signals and four wavelengths for OC-48 (2.5 Gb/s) digital baseband signals transport. Good performances of carrier-to-noise ratio (CNR) /spl ges/ 50 dB, composite second order (CSO) /spl ges/ 67 dB and composite triple beat (CTB) /spl ges/ 65 dB were obtained for AM-VSB CATV; and low bit error rate (BER < 10/sup -9/) had been achieved for 256-QAM and OC-48 digital signals over an 80 km large effective area fiber (LEAF) transport.

Field trial of end-to-end OC-768 transmission using 9 WDM channels over 1000 km of installed fiber

Abstract: We report the first end-to-end OC-768 transmission over 1000 km of installed fiber, using an all-Raman DWDM system with OC-768 intra-office client interfaces. Error-free transmission with more than 8 dB of OSNR margin was achieved.

High speed modulation of optical subcarriers

Abstract: A method for transmitting digital data includes splitting a coherent optical carrier having a subcarrier into mutually coherent optical carriers, producing corresponding sequences of phase shifts in each of the mutually coherent optical carriers, and then, interfering the mutually coherent optical carriers. The interfering produces an output optical carrier whose subcarrier has modulated inphase and quadrature components with a corresponding sequence of pairs of values. The pairs of values of the modulated inphase and quadrature phase components produced by the interfering correspond to a sequence of coordinate pairs for the signal points the 4-PSK 2D, 16-QAM 2D, or 16-PSK 2D constellation.

Method and apparatus for optical division of a broadband signal into a plurality of sub-band channels

Abstract: A data signal is modulated onto an optical carrier, sub-band channels are then removed therefrom by microresonators, and each data sub-band channel is then combined in a detector with a corresponding local oscillator optical signal removed by a microresonator from a frequency comb modulated onto another optical carrier.

Method and apparatus for controlling modulator phase alignment in a transmitter of an optical communications system

Abstract: A method of controlling phase alignment in a modulator of a transmitter in an optical communications system uses a narrowband optical filter to monitor changes in power spectral density of a modulated output at and around the optical carrier frequency. In one embodiment, a method controls alignment of a carrier-suppressed-return-to-zero (CSRZ) pulse train in accordance with changes in the power spectral density of the CSRZ modulated optical signal at and around the optical carrier frequency and generates phase adjustment control signals by executing a phase-control loop to maintain the power spectral density of the CSRZ modulated output at the optical carrier frequency at a desired level.

Data transmission method in gigabit ethernet passive optical network

Abstract: Disclosed is a upstream data transmission method in a gigabit Ethernet-passive optical network (GE-PON) system. In the GE-PON system including an optical line termination having a scheduler and optical network units connected to the optical line termination, the optical line termination receives bandwidth allocation request signals from the optical network units at a start of a first cycle, allocates transmission bandwidths to the respective optical network units in accordance with the bandwidth allocation request signals, and transmits the allocated transmission bandwidths to the respective optical network units before a second cycle that follows the first cycle.

Electronic equalization for enabling communications at OC-192 rates using OC-48 components

Abstract: We propose using electronic equalization technology to allow components typically used in 2.5Gb/s systems to be used at 10Gb/s. We simulate the performance of links exploiting this concept and study the effect of receiver bandwidth on equalized systems in general. Links utilizing transmitters designed for 2.5Gb/s rates are experimentally demonstrated. Experiments also show that photo-receivers with 2.5 GHz bandwidths add minimal penalty when post-detection electronic equalization is employed.

Microwave photonic direct-sequence transmitter and heterodyne correlation receiver

Abstract: This paper proposes and demonstrates a new architecture for the transmission, heterodyne reception, and correlation of direct-sequence (DS) signals encoded onto an optical carrier. The approach is practical for pseudo-noise in-modulated laser radar and free-space optical-code-division multiple-access communications. Although the local oscillator is free running, we show that the received signal is free from laser phase noise. Furthermore, by applying DS coding to both the transmitted signal and the local oscillator, the delay required for correlation can be realized via a combination of electrical and optical means.

High performance 10-12.5 Gbit/s modulator driver in InP SHBT technology

Abstract: A high performance modulator driver circuit is presented using 4" InP SHBT technology. The IC was developed for driving EAM modulators in OC-192 (10 Gbit/s) and with forward error correction (FEC: 10.7 Gbit/s or 12.5 Gbit/s) optical fibre systems. The monolithic integrated circuit features output amplitude control, output crossing point control and output DC offset control. Measured results show the circuit operates at 10 to 12.5 Gbit/s with a swing of 3.1 V/sub p-p/ at each output and 20/18 ps rise/fall times. The power dissipation is 1.4 W with a standard power supply of -5.2 V.

Optical duobinary single sideband modulator

Abstract: An apparatus for modulating information bearing symbols onto an optical carrier includes a polybinary coder that operates on a binary information signal to produce an envelope compatible polybinary signal; and an optical single sideband modulator that modulates an optical carrier with the envelope compatible polybinary signal to produce a single sideband optical signal. This provides an improvement over both polybinary signaling and optical single sideband. This action combines the chromatic dispersion advantages of SSB modulation with the DC level and bandwidth reduction of duo-binary coding.

Frequency comb for an optical WDM network

Abstract: In order to reduce the effects of non-linear phenomena in WDM optical transmission networks, the optical carrier frequencies of the multiplex signals belong to a comb of frequencies that are spectrally spaced apart in irregular manner while nevertheless belonging to a chart of optical frequencies that are spectrally spaced apart in regular manner at a pitch df. These frequencies are selected in such a manner as to enable them to be dropped from the multiplexed signals by N respective periodic optical filtering operations having the same free spectrum interval (Df) equal to M.df, where M is an integer greater than or equal to N, the filtering operations enabling N consecutive frequencies to be dropped from the chart. In addition, the spacing between any pair of frequencies of the comb is different from any integer multiple greater than or equal to 1 of the free spectrum interval (Df).

Harmonic generation of photonic microwave frequencies utilizing the properties of a phase modulator

Abstract: We present new techniques to generate a harmonic microwave frequency modulated on an optical carrier. All these techniques utilizes the properties of a phase modulator, and we achieve 40 GHz modulation using only 10 GHz electronics.

Design and Evaluation of Vertical Cavity Surface Emitting Lasers for Microwave Applications

Abstract: With the rapid developments of wireless communication networks such as cellular systems for mobile communication and wireless local area networks, as well as developments in radars and defence systems, there is an increasing demand for efficient and cost-effective transmission and distribution of RF and microwave signals. In this respect, fiber optics provide advantages such as low loss, mechanical flexibility, low weight, and natural immunity to electromagnetic interference, enabling densely spaced and electrically isolated transmission paths. Semiconductor lasers are used as light sources in such links where modulation of the RF signal onto the optical carrier is most easily achieved by directly modulating the laser. With increasing demand for cost-effective solutions, it is also of interest to find low cost components. For short range transmission of digital signals in local area networks and interconnects, the vertical cavity surface emitting laser (VCSELs) has established itself as a low cost, high performance alternative to edge-emitting lasers. As the requirements on the light source used in analog systems differ in some respects from the requirements on a light source in digital systems, especially in terms of noise and linearity, it is the purpose of the work presented in this thesis to investigate whether VCSELs also fulfill basic performance requirements for analog fiber optic links in the low-GHz range. Different GaAs based VCSEL designs are investigated with respect to their high frequency modulation characteristics in order pin-point limitations and to find the optimum design. Fiber optic RF links using VCSELs and multimode fibers are also assembled and evaluated to demonstrate that potentially low cost and high performance links can be constructed. It is found that optimised single mode VCSELs provide the highest performance and that the performance of links using VCSELs and high bandwidth multimode fibers satisfies the requirements in a number of applications, including radars, mobile communication systems, and wireless local area networks. The performance is also comparable to that of more sophisticated single mode fiber links using edge emitting lasers. However, the cost of a link using a VCSEL and a multimode fiber should be lower due to lower component costs and larger misalignment tolerances.

Dispersion effects of fiber Bragg gratings on true-time-delay beamforming networks

Abstract: Fiber Bragg gratings (FBGs) are key components in wideband true-time-delay beamforming networks. Different time delays are obtained when an RF modulated optical signal is reflected by an array of FBGs located at different physical locations of an optical delay line. In this paper, we report the study of dispersion effects of uniform FBGs on FBG-based true-time-delay beamforming networks. The RF signal is modulated on an optical carrier using double-side-band (DSB) modulation and single-side-band (SSB) modulation. The results indicate that the time delay performance is affected greatly by the dispersion induced by the FBGs. The results also show that the dispersion effect is reduced by four times if an SSB modulation scheme is employed.

Stolas: switching technologies for

Abstract: GMPLS-based labeled optical burst switching (LOBS) networks are being considered as the next-generation optical Internet. GMPLS includes wavelength switching next to label and fiber (space) switching. In this article, we present a new concept of optically labeling bursts of packets suitable for LOBS networks supported by the GMPLS protocol. It is based on angle modulation, which enables control information to modulate the phase or frequency of the optical carrier, while payload data are transmitted via intensity modulation (IM). In particular, the optical label is orthogonally modulated, with respect to the payload using either frequency shift keying or differential phase shift keying. We present a performance analysis of the aforementioned modulation schemes by means of simulations where the influence of the payload IM extinction ratio and laser linewidth are investigated. In addition, the transmission performance of an IM/FSK combined modulated signal is experimentally validated at 10 Gb/s, demonstrating at the same time FSK label swapping operation. Finally, a suitable optical label-controlled switch design is proposed that takes advantage of these novel labeling techniques, and efficiently combines widely tunable, fast switching lasers and SOA-MZI wavelength converters with an arrayed waveguide grating router.

Multiple wavelength optical transmitter

Abstract: PROBLEM TO BE SOLVED: To reduce costs while equalizing a level difference between channels in a multiple-wavelength optical transmitter using an LN modulator. SOLUTION: The transmitter is provided with a multiple-wavelength light source generating multiple-wavelength light having a plurality of wavelength components, a polarization-holding optical fiber amplifier which amplifies the optical power of the multiple-wavelength light while holding the polarization of the multiple-wavelength light, an optimal demultiplexer which demultiplexes the amplified multiple-wavelength light into a plurality of optical carrier waves having different wavelength while holding polarization, the LN modulator which respectively modulates the demultiplexed optical carrier waves of the respective wavelengths and outputs modulated light, an optical multiplexer for wavelength- multiplexing the modulated light of the respective wavelength, a polarization independent optical fiber amplifier for amplifying the optical power of the wavelength-multiplexed modulated light without depending on the polarization of the wavelength-multiplexed modulated light, and a polarization independent gain equalizer for equalizing the optical level of the wavelength-multiplexed modulated light outputted from the optical multiplexer or an amplified wavelength-multiplexed modulated light without depending on polarization. COPYRIGHT: (C)2003,JPO