Due to the characteristics of spatially inhomogeneous polarization and unlimited spatial coordinates, a concept of hybrid multiplexing and encoding/decoding based on spatial coordinates and mode states of vector beams is proposed for potentially enhancing the channel capacity and spectrum efficiency. For the sake of verifying the potentiality, a new encoding/decoding method by the mode states (i.e., polarization and mode) and spatial coordinates of vector beams is also proposed in this paper. In addition, the hybrid multiplexed vector beams are also utilized as carriers (16 channels) for transmitting data by four spatial coordinates and four mode states. In order to verify the feasibility of the proposed concepts, the relevant experimental setups are elaborated and established in this paper. Meanwhile, a fast mode recognition method based on the lookup table (LUT), image processing, and digital signal processing are employed to decode data when the hybrid vector beams propagate in free space (FS). The experimental results demonstrate that the encoded sequences (i.e., 0, 66, and D9) by the mode states and spatial coordinates can be successfully received and demodulated to the original data without errors after propagating 115 cm when the hybrid multiplexed vector beams are used for encoding/decoding. The total transmission rate of 320 Gbit / s can be acquired by combining the 16 channels (four mode states and four spatial coordinates) when the hybrid multiplexed vector beams are used as carriers. Furthermore, bit error rate, constellation diagrams (different transmission distance, transmitting data rate), and crosstalk among different channels or coordinates are employed to evaluate the propagation performances when the hybrid multiplexed vector beams are used as carriers.
A series-cascaded fractal topological structure of microring arrays is proposed, by introducing fractal topological
structures to series-cascaded all-pass microring resonators. Its analytical model is established by the transfer matrix
method. Then the characteristics of this structure are investigated by the effects of coupling coefficients and loss.
Generally, there are dips with the resonator number in the transmission spectra. As the loss increases, the average
intensity decreases. However, the delay becomes interesting positive and negative delays. With the ring-bus coupling
coefficient decreases, the dips of the spectrum become degenerated. However, there are several delay peaks with some
positive delays and the other negative ones. These kinds of multiple positive and negative delays can be developed for
applications in all-optical delay lines.
KEYWORDS: Orthogonal frequency division multiplexing, Distortion, Radio over Fiber, Modulation, Modulators, Mathematical modeling, Signal to noise ratio, Nonlinear optics, Radio optics, Interference (communication)
This paper is concerned with the effect of the nonlinearity of an MZM (Mach-Zehnder modulator) on optical OFDM
signal distortion. The optical OFDM signal output from the MZM is expressed as a Taylor series including third-order
and fifth-order nonlinear distortion terms, by which we can easily establish a mathematical model of the optical OFDM
signals in different formats and rates. According to the model, we can get the EVM at the optimized point. Moreover, the
proposed theoretical model is proved in good agreement with experiment results of the RoF (Radio over Fiber) system.
The influence of higher-order harmonics produced in modulator on flat and stable optical comb generation based on recirculating
frequency shifter (RFS) for all-optical OFDM is analyzed and demonstrated in this paper. We also
theoretically analyze the condition for flatness of the optical frequency comb. The resulting theoretical analysis is
confirmed by a 16 comb lines and 12.5 GHz spacing RFS generation system. The results demonstrate that flat and stable
optical comb generation based on RFS can be a useful solution for multi-wavelength source in all-optical OFDM.
KEYWORDS: Orthogonal frequency division multiplexing, Extremely high frequency, Radio optics, Modulators, Radio over Fiber, Signal detection, Optical amplifiers, Signal attenuation, Fiber amplifiers, Photodiodes
This Letter proposes a low-cost Optical Frequency Multiplication (OFM) scheme based on dual drive Mach-Zehnder
Modulator (DD-MZM) to generate 40-GHz millimeter-Wave (mmW) signals and 32Gbps 64QAM-OFDM signal at the center frequency of 35GHz occupying 5.6GHz bandwidth applied to Radio-over-Fiber (RoF) system. The optimal driving power of Intensity Modulator (IM) is also discovered to achieve the smallest EVM (Error Vector Magnitude) for
the RoF system.
KEYWORDS: Orthogonal frequency division multiplexing, Radio optics, Modulators, Modulation, Radio over Fiber, Single mode fibers, Optical filters, Hybrid fiber radio, Extremely high frequency, Optical amplifiers
This paper introduces in detail a novel 40-GHz radio over fiber (RoF) system based on optical frequency multiplication
with up to 1.4Gbps 16QAM-OFDM wireless signal employing a Mach-Zehnder modulator with no optical filtering. And
also what is discovered as expected during the experiment --- the optimal driving power of the intensity modulator (IM)
to relieve high peak-to-average power ratio (PAPR) of OFDM signal on intensity modulator with an acceptable SNR.
KEYWORDS: Frequency combs, Modulators, Modulation, Optical filters, Signal to noise ratio, Optical amplifiers, Spectrum analysis, Frequency modulation, Signal attenuation, Bessel functions
The performance of the optical frequency comb generation based on the re-circulating frequency shifter has been
analyzed and demonstrated in this paper. We have theoretically analyzed the condition for flatness of the optical
frequency comb and the relative intensity noise influence. And the resulting performance analysis has been confirmed by
a successfully generated 16 comb lines, which are stable and flat with spacing 12.5 GHz.
KEYWORDS: Modulation, Orthogonal frequency division multiplexing, Modulators, Signal to noise ratio, Radio over Fiber, Extremely high frequency, Distortion, Signal processing, Antennas, Composites
This paper introduces a new bidirectional mmRoF system based on optical frequency multiplication (OFM) scheme
using dual drive Mach-Zehnder Modulator (DD-MZM) and OFDM modulation. The emphasis is put on the optimization
of optical modulation index to the MZ intensity modulator for OFDM signal with high PAR which imposes a limitation
on the system bit error rate (BER) performance due to the nonlinearity of the MZ modulator. The theoretic analysis on
carrier to composite triple beat ratio is performed. The extension to system BER for QAM format is presented and the
experimental proof is given in a 40 GHz mmRoF system.
Traditional free-space optical (FSO) communications use a single transmitting antenna (laser/VCSEL/LED) and a
receiving antenna (a photo-detector) for single channel communication between two nodes. In this paper we study two
transmitting antenna one receiving antenna M-FSO (mobile FSO) communication system. In the process of single
transmitting antenna moving, the optical beam broadens to make receive power smaller with the divergence angle larger
and the power is difficult to be detected when long-distance communication. When short-distance communication, the
divergence angle is so small that it makes a narrow beam which is hard to be aimed at receive aperture, even more
serious when the beam is out of target caused by vibration. We take advantage of space diversity technology to reduce
BER caused by atmospheric turbulence and mobile vibration. Through the multi-transmitter, the best choice of multi-divergence
angle reduces BER, thus the receiver accurately recovers information.
As a promising solution for the next generation broadband access network, Ethernet passive optical networks (EPONs) are being designed to deliver multiple services and applications, such as voice communications, video conferencing, real-time transactions and new evolving bandwidth-consuming applications. To support these applications with their various requirements, Quality-of-Service (QoS) management over EPON is required. In this study, we present a novel scheduling scheme, hierarchical weighted bandwidth guaranteed (HWBG) scheme, which could effectively support QoS. Simulation results validate that the proposed scheme can achieve high efficiency and improve packet delay performance.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.