Planar lightwave circuit based reconfigurable optical add-drop multiplexer architectures and reusable subsystem module

The main advantage of multi-band (MB) networks is to provide more capacity than C-band networks by using other unused bands like the L- and S-bands and, in this way, postpone the announced optical network capacity crunch. However, MB nodes have a more complex structure than C-band nodes, impacting their cost and enhancing their induced physical layer impairments (PLIs). The main goal of this paper is to analyze the impact of several MB node architectures (namely baseline, common-band and compact MB node architectures) on the total network capacity and total network cost-per-bit, using a routing, modulation format, and spectrum assignment (RMSA) network planning tool based on a Monte–Carlo simulation that also incorporates the impact of network PLIs. When the PLIs are neglected, the common-band architecture presents the lowest cost-per-bit compared to the remaining MB architectures, since only lower cost C-band components are used. However, with the PLIs impact, the common-band architecture leads to the lowest total network capacity and highest cost-per-bit due to additional noise coming from all-optical wavelength converters. In particular, the common-band total network capacity is less than half the baseline and compact total network capacities for a blocking probability of 1%, considering the best channel launch power. Also, the common-band cost-per-bit is almost twice the baseline and compact cost-per-bit due to the PLIs-induced degradation.

The switching and routing is essential for an advanced and reconfigurable optical network, and great efforts have been done for traditional single-mode system. We propose and demonstrate an on-chip switch compatible with mode-division multiplexing system. By controlling the induced phase difference, the functionalities of dynamically routing data channels can be achieved. The proposed switch is experimentally demonstrated with low insertion loss of ~1 dB and high extinction ratio of ~20 dB over the C-band for OFF-ON switchover. For further demonstration, the non-return-to-zero on-off keying signals at 10 Gb/s carried on the two spatial modes are successfully processed. Open and clear eye diagrams can be observed and the bit error rate measurements indicate a good data routing performance.

In this paper, we discuss TCP (transport control protocol data transfers over a reconfigurable optical network. We find the throughput to be diminished by false detection of congestion by TCP congestion control and avoidance mechanisms.

The MONET project ended in November 1999. Over the five year duration of this project, many significant advances were made in optical networking architectures, components, subsystems, systems, and network demonstrations. In this paper, we report on the major accomplishment of the last year of the MONET project, which was the completion and operation of a transparent, reconfigurable optical network in Washington, DC. This paper describes the network and summarizes experimental results achieved in the first months of operation.

We have designed and constructed a scalable and reconfigurable optical IP network system for use in residential premises. The network system consists of an optical fiber bus, bus interfaces attached to the bus, and a gateway. In the newly constructed network, 8 optical wavelengths in the course WDM standard were allocated to Gigabit optical transceivers and optical add/drop modules, respectively. The performance examination clarified that throughput of around 90 Mbps was obtained even when 8 personal computers belonging to the different 8 sub networks sent packets simultaneously. The scalability was also confirmed by experiment.

Optical performance monitoring might play a crucial role in enabling self-managed and reconfigurable high-performance optical networks. We will explore key motivating networking issues as well as potential monitoring techniques.

We propose and demonstrate a new stacked packaging structure using silica-based planar lightwave circuits (PLCs) with integrated micro-mirrors. This structure enables us to integrate active devices on PLCs with certain flexibility as regards optical coupling design and device selection. To achieve this, we developed an integrated micromirror with an accurate reflection angle and shielding structures to prevent crosstalk, and successfully demonstrated an 8-channel photodiode array module with excellent characteristics consisting of a high responsivity of > 0.85 A/W and a low crosstalk of < -65 dB.

We demonstrate a MEMS tunable silicon photonic ring resonator with a 20 µm radius and a 5 nm free spectral range (FSR) for wavelength selection in reconfigurable optical networks. The device shows a loaded Q of 12000, and 300 pm tuning range at a wavelength of 1544 nm.

Wavelength multiplexing and tuning capabilities are highly important for applications in optical interconnects and optical communications using wavelength division multiplexing (WDM). We review novel methods and experimental results to achieve these functions in vertical cavity surface-emitting lasers (VCSEL), we believe for the first time. By implementing spatially chirped layers in the laser cavities and obliquely aligning the array axes to the thickness chirp direction, we obtained 7 × 20 VCSEL array emitting 140 unique, non-redundant, controllable, uniformly separated single-mode wavelengths. A large total wavelength span of 43 nm is obtained without compromising the performance of the lasers. Moreover, our techniques are generic and can be readily extended to other wavelength regimes. In addition, we describe our work on wavelength-tunable VCSELs with a 1.8-nm (~540 GHz) continuous tuning and no mode hopping. The laser output power remains nearly constant throughout the tuning range. The wavelength tuning speed is ~400 ns. The multiple wavelength tunable laser arrays are promising for achieving ultrahigh bandwidth (hundreds Gbit/sec to Tbit/sec), high redundancy and reliability, reconfigurable optical networks.

Wavelength conversion in the transmission of a message masked by optical chaos is experimentally demonstrated. In our setup, chaos is generated by a distributed-feedback laser subject to delayed optical feedback, and hides a message by additive chaos masking. The optical wavelength is converted, along the transmission line, by four-wave mixing in a semiconductor optical amplifier. At the receiver, the message is extracted by master-slave synchronization. Our experiments demonstrate that secure communications based on chaos are compatible with channel switching as required in reconfigurable optical networks.

Optical on-chip interconnects enable significantly increased bandwidth and decreased latency in MPSoC. They are characterized by high static energy and low dynamic energy consumption. Achieving high energy-efficient communication thus requires a certain adaptability degree to the executed application and its communication traffic in order to reduce the static energy. In this paper, we introduce a mapping method for CHAMELEON, an optical interconnect allowing configuring dedicated communication channels according to an application and its corresponding communication traffic.

The authors discuss optical network devices and the performances that can be expected. The architectural features of a multiprocessor prototype machine's software tools, at system and user levels, are described. A survey of applications well suited for reconfigurable architectures using large networks built with optical components is also given. The presented optical network allows any link to be connected to any other link without contention. Such optical networks take advantage of the best features of two technologies by using optics for communications and electronics for computation. It is stated that massively parallel architectures using large networks can be reasonably envisaged with optical components. >

We developed an 86-Gbit/s DQPSK modulator by using four arrayed optical phase modulators with an LN waveguide and two 1times4 coupler PLCs by adopting the WFM technique. This modulator exhibited excellent DQPSK modulation performance

The explosive growth of data center (DC) traffic imposes unprecedented challenges on the current electrical switch-based data center networks (DCNs) with the bottleneck of limited bandwidth and high latency. Benefitting from transparency to the data rate and format, optical switching with theoretically infinite bandwidth could overcome the bandwidth bottleneck of electrical switching DCNs. However, DCNs normally deploy multitenant applications with a variety of DC traffic. It is hard to reconfigure the optical interconnections in real-time to provide adaptable bandwidth to the traffic with heterogeneous characteristics. Moreover, to improve the bandwidth utilization, statistical multiplexing is generally deployed in optical DCNs to forward the traffic flow in a time slot, which requires the network time to be precisely synchronized to all network nodes. For fast optical switches with a nanosecond switching configuration time, overall end node times must be synchronized at subnanosecond magnitude. In this paper, we propose and experimentally investigate a reconfigurable and picosecond-synchronized optical DCN (ReSAW) based on an arrayed waveguide grating router (AWGR) and the White Rabbit (WR) protocol. A scheduler based on a distributed field-programmable gate array is implemented in the proposed ReSAW to realize flexible wavelength configuration by controlling the fast laser array based on semiconductor optical amplifiers (SOAs) according to time slot and traffic priority. Moreover, the WR protocol is implemented in optical DCNs for what we believe is the first time to synchronize the time of the distributed top of racks (ToRs). The experimental demonstration validates that ReSAW achieves an average end-to-end latency of 317.44 ns and a precise synchronized time with an average 386 ps skew. When the load is 0.4, the packet loss after ReSAW reconfiguration is less than 1.83 × 10 − 6 , and the network latency is less than 1.73 µs. Based on the experimental parameters and results, the OMNeT++ simulation model is built to further verify the reconfigurability and scalability of the ReSAW network. Results show that the packet loss rate and latency performance increase 8.24% and 12.47%, respectively, at a load of 0.6 as the ReSAW network scales from 2560 to 40,960 servers compared to before the reconfiguration.

Numerous applications in science and technology nowadays utilize deep learning to tackle challenging computational tasks. With the increasing demand for deep learning, high-speed and energy-efficient accelerators are urgently needed. Although electronic accelerators are flexible, optical computers holds great promise due to their potential for massive parallelism and low power consumption. However, optical computing platforms demonstrated so far have mostly been limited to relatively small-scale computing tasks, despite the potential for scalability. Here, we propose and demonstrate a hardware-efficient design that allows deployment of a reconfigurable deep neural network (DNN) architecture without a direct isomorphism to standard DNN designs. Our proposed system is scalable and supports larger-scale computing. Our system realizes an optical neural network (ONN) using a digital micromirror device (DMD) for encoding data and trainable parameters, a complex medium for random complex weight mixing, and a camera for nonlinear activation and optical readout. A straight-through estimator enables backpropagation, even with a DMD as a binary encoding device. With this ONN as an elementary building block and automating the search for neural architectures, we can build complex and deep ONNs for a range of large-scale computing tasks, such as 3D medical image classification. The architecture-optimized deep ONNs are deployed by time-multiplexing data streams in one system. Our system enables large-scale training and inference in situ. Furthermore, we demonstrate that our system is capable of achieving task accuracies close to that of state-of-the-art benchmarks with more complex architectures implemented in silico.