Communication traffic grows relentlessly in today’s networks, and with ever more machines connected to the network, this trend is set to continue for the foreseeable future. It is widely accepted that increasingly faster communications are required at the point of the end users, and consequently optical transmission plays a progressively greater role even in short- and medium-reach networks. Silicon photonic technologies are becoming increasingly attractive for such networks, due to their potential for low cost, energetically efficient, high-speed optical components. A representative example is the silicon-based optical modulator, which has been actively studied. Researchers have demonstrated silicon modulators in different types of structures, such as ring resonators or slow light based devices. These approaches have shown remarkably good performance in terms of modulation efficiency, however their operation could be severely affected by temperature drifts or fabrication errors. Mach-Zehnder modulators (MZM), on the other hand, show good performance and resilience to different environmental conditions. In this paper we present a CMOS-compatible compact silicon MZM. We study the application of the modulator to short-reach interconnects by realizing data modulation using some relevant advanced modulation formats, such as 4-level Pulse Amplitude Modulation (PAM-4) and Discrete Multi-Tone (DMT) modulation and compare the performance of the different systems in transmission.
We propose and experimentally demonstrate the generation of various modulation formats using a directly modulated
chirp-managed laser (CML), including phase-shaped binary transmission (PSBT), inverse-return-to-zero duobinary
(IRZ-duobinary), Manchester-duobinary, return-to-zero differential phase shift keying (RZ-DPSK) and return-to-zero
differential quadrature phase-shift-keying (RZ-DQPSK). The CML-based modulation formats improved dispersion
tolerance and their corresponding transmitters have the features of compactness, low power consumption and costeffectiveness,
which are desired in metro/access networks. System applications of such formats are also studied.
KEYWORDS: Transmitters, Signal generators, Tolerancing, Modulators, Signal detection, Single mode fibers, Clocks, Eye, High speed electronics, Telecommunications
We propose and demonstrate a simple chirp-free optical Manchester signal transmitter that consists of a single-drive
Mach-Zehnder modulator and a passive electronic power combiner. A 5-Gb/s optical Manchester signal is generated and
its dispersion tolerance enhancement is investigated. The bandwidth of the modulator and driving circuit is reduced by
half.
A new adaptive erbium-doped fiber amplifier (EDFA) is proposed. In the amplifier, an array of 1×2 optical switches is
controlled to select the optimum length of erbium-doped fiber for different input power, and meanwhile pump power is
regulated, so good adaptivity for different applications can be obtained. Simulation experiments have demonstrated that
this amplifier can get high performance. It can be applied as preamplifier and line amplifier as well as power amplifier.
We propose a novel multicast-enable wavelength-division-multiplexed (WDM) passive-optical-network (PON)
architecture that uses two sidebands of Optical Carrier Suppressed (OCS)-DPSK signal to carry the unicast and multicast
data. The multicast wavelength control is realized through a Wavelength Selective Switch (WSS). At the optical line
terminal (OLT), for each WDM channel, a single drive Mach-Zehnder modulator (MZM) is used to generate a subcarrier
double-sideband (DSB) DPSK signal. Then, the lower-sideband signals are separated by an interleaver and subsequently
modulated to deliver the multicast data, while the remaining upper-sideband DPSK signals carry the downstream unicast
data. In the optical network units (ONUs), part of the downstream unicast signal power is re-modulated for upstream
transmission, which enables color-free ONUs. This proposed scheme is experimentally demonstrated with a 1.25Gb/s
downstream unicast and multicast data.
We propose a novel scheme to realize unicast and multicast in WDM-PON. Unicast data and multicast data are
modulated in Amplitude Shift Keying (ASK) format and Differential Phase Shift Keying (DPSK) format respectively.
Reflective Semiconductor Optical Amplifier (RSOA) is used to selectively erase the DPSK signal by controlling the
optical switch, and multicast is realized.
All-optical format conversion from inverse-return-to-zero (inverse-RZ) to non-return-to-zero (NRZ) is realized by using a half-bit-delay Mach-Zehnder delay interferometer. Experimental results demonstrate that the converted NRZ signal has better receiver sensitivity than the back-to-back inverse-RZ signal.
In an asynchronous optical packet switching network, contention occurs at a node whenever two or more packets
are trying to leave the node from the same output port on the same wavelength. As a means of contention
resolution, fiber delay lines (FDLs) are commonly implemented in optical buffers. This paper presents an
analytic model to study single-wavelength FDL buffer systems with finite waiting places. Considering the delay
quantization in FDLs the deference between waiting time and delay time is discussed detailedly and then the
packet lengths are modified. Analytic results of the queuing performance can be figured out for the finite FDL
buffer system. Accuracy of the proposed model is finally validated through numerical simulation.
This paper introduces a kind of Adaptive Optical Label Packet Switching (AOLPS) technology. Based on Optical Packet
Switching (OPS), AOLPS uses optical label to achieve self-routing, and the size of optical packet is self-adaptive. At the
edge nodes, IP packets are fist classified into different
first-in-fist-out memories (FIFOs) according to their priority
levels and destinations, and then being encapsulated into optical packets. The traffic at each FIFO is real-time monitored,
and the controller in edge node employs an optimal strategy to generate suitable sized packets for transmission. Large
sized packets will be adopted when traffic is heavy, and small sized packets will be used when traffic is light. This self-adaptive
switching granularity can greatly improve the network performance.
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