2,988 research outputs found
BER performance analysis of 100 and 200 Gbit/s all-optical OTDM node using symmetric Mach-Zehnder switches
New insight to the feasibility of all-optical ultra speed switching up to 200 Gb/s. The technique will reduce the dependency and bottleneck on the electronic-to-optical-to-electronic conversion. Current conversion speed is up to 40 Gb/s in laboratories. The novel clock extraction technique proposed shows the potential of an all-optical switch. The research results are directly relevant to the access technology where optical fibre and RF is competing to be the solution. The growing demands of bandwidth will exceed RF capability while the optical fibre will be the optimum solution. A PhD project (Le-Minh) funded by the University Studentship, completed in 2007
All-optical flip flop based on a symmetric Mach-Zehnder switch with a feed-back loop and multiple forward set/reset signals
The paper proposed an improved performance for optical flip-flop using symmetric Mach-Zehnder interformeter with a feedback and multiple forward configurations. At the optimum operating condition for the optical flip-flop, high contrast ratio of 22 dB can be achieved. The findings in the paper will have an impact on the design of future optical flip-flop and other optical logic gates such as exclusive OR and NAND gates. A PhD research (Le-Minh) funded by the University Studentship, completed in 200
Simulation of an all-optical 1 x 2 SMZ switch with a high contrast ratio
Abstract — An all-optical 1×2 high contrast ratio (CR) switch based on the symmetric Mach-Zehnder (SMZ) interferometers is presented. Simulation results show a remarkable improvement of the inter-output CR (~25 dB) between the two outputs compared with an existing SMZ switch. It is shown that the proposed switch offers high values of inter-output CR (> 32dB) over a wide range of input powers using appropriate power of the control pulses. I
1 x M packet-switched router based on the PPM header address for all-optical WDM networks
This paper presents an all-optical 1xM router architecture for simultaneous multiple-wavelength packet routing, without the need for wavelength conversion. The packet header address is based on the pulse position modulation (PPM) format, which allows the use of only a single-bitwise optical AND gate for fast packet header address correlation. The proposed scheme offers both multicast and broadcast capabilities. We’ve demonstrated a high speed packet routing at 160 Gb/s in simulation, with a low channel crosstalk (CXT) of ~ -27 dB with a channel spacing of > 0.4 THz and a demultiplexer bandwidth of 500 GHz. The output transfer function of the PPM header processing (PPM-HP) module is also investigated in this paper
Improving the Knowledge Gradient Algorithm
The knowledge gradient (KG) algorithm is a popular policy for the best arm
identification (BAI) problem. It is built on the simple idea of always choosing
the measurement that yields the greatest expected one-step improvement in the
estimate of the best mean of the arms. In this research, we show that this
policy has limitations, causing the algorithm not asymptotically optimal. We
next provide a remedy for it, by following the manner of one-step look ahead of
KG, but instead choosing the measurement that yields the greatest one-step
improvement in the probability of selecting the best arm. The new policy is
called improved knowledge gradient (iKG). iKG can be shown to be asymptotically
optimal. In addition, we show that compared to KG, it is easier to extend iKG
to variant problems of BAI, with the -good arm identification and
feasible arm identification as two examples. The superior performances of iKG
on these problems are further demonstrated using numerical examples.Comment: 32 pages, 42 figure
MnasNet: Platform-Aware Neural Architecture Search for Mobile
Designing convolutional neural networks (CNN) for mobile devices is
challenging because mobile models need to be small and fast, yet still
accurate. Although significant efforts have been dedicated to design and
improve mobile CNNs on all dimensions, it is very difficult to manually balance
these trade-offs when there are so many architectural possibilities to
consider. In this paper, we propose an automated mobile neural architecture
search (MNAS) approach, which explicitly incorporate model latency into the
main objective so that the search can identify a model that achieves a good
trade-off between accuracy and latency. Unlike previous work, where latency is
considered via another, often inaccurate proxy (e.g., FLOPS), our approach
directly measures real-world inference latency by executing the model on mobile
phones. To further strike the right balance between flexibility and search
space size, we propose a novel factorized hierarchical search space that
encourages layer diversity throughout the network. Experimental results show
that our approach consistently outperforms state-of-the-art mobile CNN models
across multiple vision tasks. On the ImageNet classification task, our MnasNet
achieves 75.2% top-1 accuracy with 78ms latency on a Pixel phone, which is 1.8x
faster than MobileNetV2 [29] with 0.5% higher accuracy and 2.3x faster than
NASNet [36] with 1.2% higher accuracy. Our MnasNet also achieves better mAP
quality than MobileNets for COCO object detection. Code is at
https://github.com/tensorflow/tpu/tree/master/models/official/mnasnetComment: Published in CVPR 201
- …