Showing papers on "Optical Carrier transmission rates published in 2010"

All-optical phase and amplitude regenerator for next-generation telecommunications systems

Abstract: Fibre-optic communications systems have traditionally carried data using binary (on-off) encoding of the light amplitude. However, next-generation systems will use both the amplitude and phase of the optical carrier to achieve higher spectral efficiencies and thus higher overall data capacities(1,2). Although this approach requires highly complex transmitters and receivers, the increased capacity and many further practical benefits that accrue from a full knowledge of the amplitude and phase of the optical field(3) more than outweigh this additional hardware complexity and can greatly simplify optical network design. However, use of the complex optical field gives rise to a new dominant limitation to system performance-nonlinear phase noise(4,5). Developing a device to remove this noise is therefore of great technical importance. Here, we report the development of the first practical ('black-box') all-optical regenerator capable of removing both phase and amplitude noise from binary phase-encoded optical communications signals.

Highly Linear Radio-Over-Fiber System Incorporating a Single-Drive Dual-Parallel Mach–Zehnder Modulator

Abstract: We propose a highly linear radio-over-fiber system with low intermodulation distortion (IMD) using a single-drive dual-parallel Mach-Zehnder modulator (SD-DPMZM). The optical carrier is modulated in one of the two parallel modulators, while remaining unmodulated in the other one. There exists optimal working points for SD-DPMZM that makes its two kinds of origins of third-order IMD (IMD3) have opposite phase and equal intensity, and cancel each other; hence the output IMD3 is suppressed dramatically. Experimental results show that the proposed scheme can achieve a spurious-free dynamic range of up to 122.9 dB · Hz2/3, which is in agreement with the theoretical analysis. It is about 20 dB more than a conventional MZM. The error vector magnitude of the proposed scheme, for a 16-QAM 10-MSym/s signal centered at 4 GHz, is 1.94%.

BiDirectional optical communication with AquaOptical II

Abstract: This paper describes AquaOptical II, a bidirectional, high data-rate, long-range, underwater optical communication system. The system uses the software radio principle. Each AquaOptical II modem can be programmed to transmit user defined waveforms and record the received waveforms for detailed analysis. This allows for the use of many different modulation schemes. We describe the hardware and software architecture we developed for these goals. We demonstrate bidirectional communication between two AquaOptical II modems in a pool experiment. During the experiment AquaOptical II achieved a signal to noise ration of 5.1 over a transmission distance of 50 m at pulse widths of 1 µsec, 500 ns, and 250 ns. When using discrete pulse interval modulation (DPIM) this corresponds to a bit-rate of 0.57 Mbit/s, 1.14 Mbit/s, and 2.28 Mbit/s.

120 Gbit/s Over 500-km Using Single-Band Polarization-Multiplexed Self-Coherent Optical OFDM

Abstract: In this paper, we experimentally demonstrate a single-band self-coherent polarization-multiplexed optical orthogonal frequency-division multiplex system with a raw data rate of 120 Gbit/s. The transmitter uses a novel RF structure that eliminates the need for RF mixers and optical filters. The receiver uses a novel architecture where the optical carrier is filtered and amplified for self-coherent detection. The receiver is polarization diverse and allows for the usual frequency guard band between the carrier and the sideband to be reduced in width, thus increasing spectral efficiency. Using two commercial 20 GS/s arbitrary-waveform generators to generate a single information-carrying band per polarization, we achieve a raw data rate of 120 Gbit/s over 500 km of standard single-mode fiber.

CMOS-Compatible Si-Ring-Assisted Mach–Zehnder Interferometer With Internal Bandwidth Equalization

Abstract: We demonstrate, to the best of our knowledge, the first electrooptic ring-assisted Mach-Zehnder interferometric (RAMZI) modulator in a CMOS-compatible technology The RAMZI modulator is manufactured on a CMOS-compatible platform and entirely fabricated in a commercial CMOS foundry We demonstrate a small-signal 3-dB bandwidth >15 GHz in a silicon-based carrier-depletion modulator with a 2-V·cm V?L product, which is approximately two times smaller than previously reported We achieved a 10-Gb/s eye diagram with a 2-dB extinction ratio using a 4-Vp-p drive in a modulator with a 680-?m optic/RF interaction region In addition, we demonstrate internal bandwidth equalization within the tunable CMOS-compatible RAMZI modulator, and discuss the optical carrier and modulation sideband response, and relaxation characteristics that lead to this behavior within resonant modulators

Dynamic Microwave Photonic Filter Using Separate Carrier Tuning Based on Stimulated Brillouin Scattering in Fibers

Abstract: Dynamic reconfiguration of a microwave photonic filter by tuning its basic delay based on stimulated Brillouin scattering-induced slow light and optical phase shift of the optical carrier is experimentally implemented. The measurements confirm that the free spectral range of the filter changes when a Brillouin pump is applied. These results demonstrate the potential of the separate carrier technique in microwave photonics applications.

Significant improvements in optical power budgets of real-time optical OFDM PON systems

Abstract: Based on a comprehensive theoretical optical orthogonal frequency division multiplexing (OOFDM) system model rigorously verified by comparing numerical results with end-to-end real-time experimental measurements at 11.25Gb/s, detailed explorations are undertaken, for the first time, of the impacts of various physical factors on the OOFDM system performance over directly modulated DFB laser (DML)-based, intensity modulation and direct detection (IMDD), single-mode fibre (SMF) systems without in-line optical amplification and chromatic dispersion compensation. It is shown that the low extinction ratio (ER) of the DML modulated OOFDM signal is the predominant factor limiting the maximum achievable optical power budget, and the subcarrier intermixing effect associated with square-law photon detection in the receiver reduces the optical power budget by at least 1dB. Results also indicate that, immediately after the DML in the transmitter, the insertion of a 0.02nm bandwidth optical Gaussian bandpass filter with a 0.01nm wavelength offset with respect to the optical carrier wavelength can enhance the OOFDM signal ER by approximately 1.24dB, thus resulting in a 7dB optical power budget improvement at a total channel BER of 1 × 10(-3).

Orthogonally polarized optical single sideband modulation for microwave photonics processing using stimulated Brillouin scattering

Abstract: We present a novel technique to generate orthogonally polarized optical single sideband modulated signals. The modulation scheme is based on all optical stimulated Brillouin scattering processing of the optical carrier of an optical single sideband modulated signal, by means of the polarization state dragging induced by this non-linear effect. This modulation technique can be used in several microwave photonics applications, such as antenna beamforming or microwave photonics filters. In order to perform a proof-of-concept experiment, the orthogonal modulator is deployed for the implementation of an RF phase-shifter.

Optical Millimeter-Wave Generation and Transmission Without Carrier Suppression for Single- and Multi-Band Wireless Over Fiber Applications

Abstract: A new optical millimeter-wave generation scheme to double the beating frequency without suppressing the carrier by taking advantages of the out-of-phase property between sidebands of a phase-modulated optical carrier is proposed for the first time. Theoretical analysis shows that the generated 60 GHz optical millimeter-wave (mm-wave) can tolerant ±0.016 nm wavelength drifting with filter bandwidth ranging from 70 to 100 GHz to sustain first to second harmonic suppression ratio of 18 dB. The doubled frequency is continuously tunable from 60 to 90 GHz within 100 GHz filter bandwidth with RF power variation of less than 2 dB. In addition, simultaneously generating and transmitting multi-band signal: millimeter-wave band, microwave band, and baseband leveraging the same concept is also proposed. Error-free transmission of 2.5 Gb/s wireless baseband signals carried by the generated 60 GHz mm-wave is successfully demonstrated in both single- and multi-band network environments over a combined optical fiber and wireless distance with a proper equivalent isotropically radiated power of about 20 dBm for in-building access. Moreover, dispersion effect on the generated frequency-doubled optical mm-wave is analyzed by experimentally comparing the link performance of both single mode fiber (SMF-28) and dispersion-shifted fiber cases. It is concluded that for single-band service delivery, the proposed scheme is immune to the interference from the dispersion-induced, redundant 1st harmonics; however, to deliver multi-band services, launching lightwave at zero-dispersion wavelength over SMF-28 is highly recommended to mitigate inter-band interference.

Adaptive polarization tracking and equalization in coherent optical receivers

Abstract: A method for operating an optical receiver includes at each of a sequence of sampling times, producing a first 2D complex digital signal vector whose first component is indicative of a phase and amplitude of one polarization component of a modulated optical carrier and whose second component is indicative of a phase and amplitude of another polarization component of the carrier. For each one of the sampling times, the method includes constructing a second 2D complex digital signal vector that is a rotation of the first 2D complex digital vector for the one of sampling times. The rotation compensates a polarization rotation produced by transmission of the modulated optical carrier between an optical transmitter and the optical receiver.

Multi-service Ethernet-over-SONET silicon platform

Abstract: An integrated circuit device for use in connecting synchronous optical networks to packet networks and synchronous time division multiplexed subscriber lines and a method of operation of same is disclosed. An embodiment of the invention may include SONET/SDH compatible optical carrier framing, cross connect, and packet mapping functionality. In addition, it may support Ethernet packet network connections and DS1/E1 and DS3/E3 time division multiplexed subscriber circuits, and may include a telecom bus compatible interface for the connection of additional communications devices. An embedded microprocessor core and embedded memory may permit the present invention to support enhanced remote diagnostic, trouble reporting, traffic management, and software update capabilities.

A photonic analog-to-digital converter based on an unbalanced Mach-Zehnder quantizer

Abstract: A Mach-Zehnder modulator (MZM) based analog to digital converter (ADC) is described. The signal to be digitized is applied to a single electrode of a high speed unbalanced modulator that acts as a quantizer. The rest of the system consists of commercially available wavelength division multiplexing (WDM) components. Analysis indicates that 6 bit operation at 40 Giga Samples per second (GS/s) is possible with moderate optical carrier power.

Impact of LED nonlinearities on optical wireless OFDM systems

Abstract: Nonlinearities can drastically degrade the performance of optical communication systems based on intensity modulation (IM) of the optical carrier using the time domain orthogonal frequency division multiplexing (OFDM) electrical signal variations. The light emitting diode (LED) transfer function distorts the signal amplitude and forces the lower signal peaks to be clipped at the LED turn-on voltage (TOV). Additionally, the upper signal peaks are purposely clipped before modulating the LED to avoid chip overheating. The induced distortion can be controlled by optimizing the bias point and/or backing-off the signal power. In this paper, a model that incorporates amplitude distortion and that provides a parameterized upper clipping to control nonlinearity induced distortion is proposed. Through Monte Carlo simulations, the model can be used to determine the optimum bias point and to optimize the signal power to obtain best performance. In this context, an analytical approach to evaluate symbol error probability is proposed. A comparison with Monte Carlo simulation results is carried out to verify the accuracy of this approach.

A UWB Over Fiber System Compatible With WDM-PON Architecture

Abstract: We present a novel ultra-wideband (UWB) over fiber system that is compatible with wavelength-division-multiplexing passive optical network architecture based on a Fabry-Perot laser diode (FP-LD). Through external injection, the FP-LD operates as an active optical filter. By locating the optical carrier of a phase-modulated injection optical signal at one slope of the filter response, phase-modulation to intensity-modulation conversion is achieved, leading to the generation of a UWB signal having a power spectrum meeting the FCC-specified spectral mask. The proposed system is experimentally evaluated, with eye diagrams and bit-error rates measured. An error-free operation is achieved after 20-km single-mode fiber transmission for both cases where the FP-LD is placed in the center office and the remote site. The power penalty for the transmission is less than 3.2 dB.

System, apparatus and method for communicating data via polarization multiplexing

Abstract: Systems, apparatus and method for modulating digital data onto an optical carrier to produce a modulated optical carrier in which symbol-modulated optical signals of orthogonal polarizations are temporally interleaved and adapted to be processed by electronic time-division demultiplexing to recover the digital data modulated onto the orthogonal polarizations of the optical signals.

Instantaneous Microwave Frequency Measurement Using Programmable Differential Group Delay (DGD) Modules

Abstract: We propose and experimentally demonstrate a photonic approach for the measurement of microwave frequencies with adjustable measurement range and resolution. After an unknown microwave signal is modulated onto an optical carrier by a Mach-Zehnder modulator (MZM), the optical output of the MZM is sent to two programmable differential group delay (DGD) modules to introduce different microwave power fading effects, respectively. When the microwave powers of the two channels are measured with two photodetectors separately, a fixed relationship between the microwave power ratio and the microwave frequency is established. The frequency measurement range and resolution can be tuned by electrically varying the DGD values. Frequency measurement with good accuracy for the microwave signals is experimentally realized. When the input power of a continuous-wave microwave signal is within the range of 15 to 3 dBm, the measured errors remain within 0.04 GHz for a measurement range of 4.5-6.5 GHz.

A high stability semiconductor laser system for a $^{88}$Sr-based optical lattice clock

Abstract: We describe a frequency stabilized diode laser at 698 nm used for high resolution spectroscopy of the 1S0-3P0 strontium clock transition. For the laser stabilization we use state-of-the-art symmetrically suspended optical cavities optimized for very low thermal noise at room temperature. Two-stage frequency stabilization to high finesse optical cavities results in measured laser frequency noise about a factor of three above the cavity thermal noise between 2 Hz and 11 Hz. With this system, we demonstrate high resolution remote spectroscopy on the 88Sr clock transition by transferring the laser output over a phase-noise-compensated 200 m-long fiber link between two separated laboratories. Our dedicated fiber link ensures a transfer of the optical carrier with frequency stability of 7 \cdot 10^{-18} after 100 s integration time, which could enable the observation of the strontium clock transition with an atomic Q of 10^{14}. Furthermore, with an eye towards the development of transportable optical clocks, we investigate how the complete laser system (laser+optics+cavity) can be influenced by environmental disturbances in terms of both short- and long-term frequency stability.

Optical Carrier Regeneration for Carrier Wavelength Reuse in a Multicarrier Distributed WDM Network

Abstract: We experimentally demonstrate optical carrier regeneration for carrier wavelength reuse in a multicarrier distributed wavelength-division-multiplexing network. The regenerated signal with a wavelength well matched with the reused data signal and has high signal quality.

Optical time-domain mixer

Abstract: We simulate an optical time-domain mixer that can be used to make a photonic analog-to-digital converter (ADC) or a digital demodulator for high-speed optical communications signals. In the basic mixer, a high frequency RF signal modulates a repetitively chirped optical carrier; this RF/optical waveform then is dispersed in one transverse dimension, and imaged onto a 2-dimensional transparency or spatial light modulator whose pixels are modulated with randomly chosen transmission or reflection coefficients (the optical mixing matrix). Following transmission through or reflection from the mixing matrix, the optical waveform from each row of the matrix is recombined and directed to a photodiode and electronics that integrate over the repetition period of the chirped source. Finally, each of these signals is digitized by an independent ADC sampling at a rate equal to the pulse repetition rate of the chirp source. A digital replica of the input RF signal can be recovered by digital signal processing from the digital output of the ADCs and the values of the transmission or reflection coefficients of the mixing matrix. The effective sampling rate is given by the number of pixels per row of the mixing matrix times the repetition rate of the chirp source while the effective resolution is controlled by the resolution of the electronic ADCs and the distortions introduced by the optical mixing process.

Ultra-Wideband Low-Noise Amplifier andSix-Port Transceiver for High Speed DataTransmission

Abstract: Today’s data rates in wired networks can reach 100 Gbit/s using optical fiber while data rates in wireless networks are much lower - tens of Mbit/s for 3G mobile communication and 480 Mbit/s for ul ...

System feasibility of using stimulated Brillouin scattering in self coherent detection schemes

Abstract: We demonstrate the first self-coherent detection of 10 Gbit/s BPSK signals based on narrow-band amplification of the optical carrier by means of Stimulated Brillouin effect in a common fiber. We found that this technique is very effective only if it is combined with proper line coding and high-pass electrical filtering at the receiver. In this case we obtain OSNR-performance close to the ideal coherent receiver.

Passive optical network system and optical line terminal based on optical code division multiple access multiplexing

Abstract: The invention provides a passive optical network system and an optical line terminal based on optical code division multiple access multiplexing. The system comprises an optical line terminal, an optical distribution network and at least one optical network unit, wherein the optical line terminal is used for modulating downlink data to an optical carrier, encoding the modulated downlink data, outputting the encoded downlink data after the processing of intensive wavelength division multiplexing, receiving uplink data, carrying out decrypting intensive wavelength division multiplexing and decoding the received uplink data; the optical distribution network is used for carrying out decrypting intensive wavelength division multiplexing, outputting the downlink data output by the optical line terminal, receiving the uplink data, carrying out intensive wavelength division multiplexing on the received uplink data and outputting the data to the optical line terminal; and the optical network unit is used for receiving the downlink data output by the optical distribution network, decoding the received downlink data, encoding the uplink data and transmitting the encoded uplink data to the optical distribution network, wherein the encodes adopted on each wavelength channel by different users are different. The access user capacity of an OCDMA (Optical Code Division Multiple Access)-PON (Passive Optical Network) can be enlarged by utilizing the technical scheme.

Optical performance monitoring for coherent optical systems

Abstract: Most commercial optical communication systems use intensity modulation/direct detection (IM/DD) schemes in which the intensity of semiconductor lasers is modulated to carry the information and the optical signal is detected directly by a photodiode. In contrast to the IM/DD scheme, a coherent optical communication system detects the transmitted signal using homodyne or heterodyne detection schemes. It not only transmits information by modulating the intensity of the optical carrier but also the phase or the polarization. With the invention of erbium-doped fiber amplifiers (EDFAs), direct detection systems could achieve receiver sensitivity within a few decibels of coherent receivers, which made the shot-noise-limited receiver sensitivity of the coherent receiver less attractive. In addition, the technical difficulties of coherent detection make it less practical. Coherent detection requires sophisticated manipulation and processing of phase and polarization. Since the state of polarization (SOP) of the incoming optical signal is scrambled in the fiber, a dynamic polarization controller is needed to match the SOP of the signal and LO. The dynamic polarization controller is usually a bulky and expensive device. The difficulty in stable locking of the carrier phase drift also prevents practical application of the coherent detection. Coherent detection has resurged to attract great interest in recent years, which is highlighted by remarkable theoretical and experimental demonstrations from various groups around the world.

Method and system for bi-directional communication over a single optical fiber

Abstract: Gigabit Ethernet connectivity is realized using off-the-shelf GIGABIT INTERFACE CONVERTER transceivers, wave division multiplexer/demultiplexers, and a single optical fiber. Simultaneous and bi-directional optical communication over a single optical fiber connecting two or more nodes is achieved by using at least one GIGABIT INTERFACE CONVERTER transceiver having at least one optical signal output and an optical signal input that are of different wavelengths from each other.

Method for sending and receiving clock signal as well as optical transmitter, optical receiver and system thereof

Abstract: The invention relates to a method for sending and receiving a clock signal as well as an optical transmitter, an optical receiver and a system thereof. The sending method comprises superposing the following steps: a clock signal to be sent to an optical carrier by optical amplitude modulation to form a pilot tone modulated light carrier; superposing a service signal to be sent to the pilot tone modulated optical carrier by light amplitude modulation to form an optical modulation service signal; and sending the optical modulation service signal through a fiber link. The receiving method comprises the following steps: receiving an optical modulation service signal from a fiber link; outputting a mixed electrical signal including a service signal and a clock signal after photoelectric conversion and optical amplitude modulating are carried out to the received optical service-modulated signal; filtering the mixed electrical signal for separation to obtain the clock signal. The invention realizes receiving or unvarnished transmission of the clock signal without taking up other extra bandwidth or access resources of the optical transmission system, and greatly reduces network construction cost and maintenance cost, and is easy to realize.

Passive millimeter wave imaging using a distributed aperture and optical upconversion

Abstract: We report on our initial results of passive, real-time imaging in the Q-band using a distributed aperture and optical upconversion The basis of operation is collection of incident mmW radiation by the distributed aperture, as embodied by an array of horn antennas, which is then amplified and upconverted to optical frequencies using commercially available electro-optic modulators The non-linear mixing of the modulators creates sidebands containing the mmW signal with both amplitude and phase preserved These signals are relaunched in the optical domain with a homothetic mapping of the antenna array The optical carrier is stripped via dielectric stack filters and imagery is synthesized from the sidebands using the Fourier transform properties of a simple lens This imagery is collected using a standard nearinfrared camera with post-processing to enhance the signal of interest and reduce noise Details of operation and presentation of sample imagery is presented herein

Microwave Frequency Measurement Using Fiber Bragg Grating as V-shape Filter

Abstract: Broadband, low loss and cost-effective transmission capability of optical fiber links has led to a widespread applications in almost every field. Instantaneous microwave frequency measurement is one of the fields facilitated by optical communication. In this paper, a new optical technique for microwave frequency measurement, which was based on an optical V-shape fiber Bragg grating (FBG) filter and RF power monitoring, is proposed theoretically and experimentally. The microwave signal was modulated onto an optical carrier using a Mach-Zehnder modulator (MZM) which was biased at quadrature point, and divided into two identical parts afterwards by an optical coupler. One part of the light was reflected by an FBG, and the other served as a reference signal. Both the reflected and reference signals are compared to get a monotone frequency dependent power ratio function (PRF). Through a table looking up process from the PRF, the frequency of an unknown microwave signal can be obtained.

Real-time homodyne reception of 40-Gb/s BPSK signal by digital optical phase-locked loop

Abstract: We demonstrate real-time homodyne demodulation of a 40-Gb/s BPSK signal by using novel digital optical phase-locked loop with a Costas-loop structure. The optical carrier is locally recovered in the receiver side with a slow-speed digital signal processor employing bandwidth-enhanced samplers.

Optimisation of carrier-to-sideband ratio by triple-arm Mach-Zehnder modulators in radio-over-fibre links

Abstract: A novel Mach-Zehnder modulation technique based on a 1-3 multimode interference coupler and three optical phase-modulator waveguides for the generation of optical single sideband (SSB) signals in the radio-over-fibre millimeter-wave system is proposed. Two of the three modulator arms are biased by the direct current (DC) voltage and modulated by the radio frequency (RF) signal in the same way as conventional SSB modulation method to produce optical RF signals, but the third one which can be named as -dc arm- is only biased by DC to change the path of the optical carrier passing through it. The interference at the output of the triple-arm modulator happens at the optical carrier frequency, which makes the power of the optical carrier in the SSB signal controllable. Optimised modulation depth between the sideband component and the carrier of the generated SSB signal could be obtained by adjusting the bias voltage applied to the -dc arm-. It is proposed and analysed that the novel technique could improve the sensitivity of the optical receiver significantly compared with the conventional SSB modulation scheme.