Photonic Switching Research Articles

All-optical photon switching, router and amplifier using a passive-active optomechanical system

We propose a feasible and flexible scheme to realize all-optical photon switching, router and amplifier by using a passive-active optomechanical system consisting of a passive cavity, an active cavity and a common movable membrane oscillator. Due to the cooperation between the gain effect of the active cavity and the interference effect between the probe fields, some novel phenomena arise, such as the frequency-independent perfect reflection first proposed in this paper, controllable photon routing, tunable fast and slow lights and so on. Based on the results, a photon switching of absorption-amplification and fast-slow-light transitions, and a photon router with controllable direction and intensity can be realized by adjusting relevant parameters such as the strengths of control fields and the relative phase between probe fields. Such a scheme may provide a promising platform for controllable photon transport and photonic device fabrication.

Tunneling Modulation of Transistor Lasers: Theory and Experiment

The coherent photons generated at the base quantum wells in the transistor laser (TL) interact with the collector field and “assist” electron tunneling from the valence band of the base to the conduction band states of the collector. The cavity coherent photon intensity effect on photon-assisted tunneling in the TL has resulted in the realization of a novel photon-field enhanced optical absorption. This intra-cavity photon-assisted tunneling (ICPAT) in the TL or the light-emitting transistor is the unique property of voltage (field) modulation and the basis for ultrahigh speed direct tunneling photon modulation and switching. In addition, a new tunneling current modulation gain in a “new form” of transistor is discovered based on the collector tunneling holes feedback to the base and dielectric relaxation base transport. The TL, owing to its unique three-terminal configuration and the complementary nature of its optical and electrical collector output signals, enables fast base recombination, collector tunneling, and OEO feedback, which has resulted in the realization of compact electro-optical applications, such as non-linear signal-mixing, frequency multiplication, OE tunneling transistor, and electrical and optical bistability.

Spin-photon interface and spin-controlled photon switching in a nanobeam waveguide.

The spin of an electron is a promising memory state and qubit. Connecting spin states that are spatially far apart will enable quantum nodes and quantum networks based on the electron spin. Towards this goal, an integrated spin-photon interface would be a major leap forward as it combines the memory capability of a single spin with the efficient transfer of information by photons. Here, we demonstrate such an efficient and optically programmable interface between the spin of an electron in a quantum dot and photons in a nanophotonic waveguide. The spin can be deterministically prepared in the ground state with a fidelity of up to 96%. Subsequently, the system is used to implement a single-spin photonic switch, in which the spin state of the electron directs the flow of photons through the waveguide. The spin-photon interface may enable on-chip photon-photon gates, single-photon transistors and the efficient generation of a photonic cluster state.

Scheduling with Machine-Learning-Based Flow Detection for Packet-Switched Optical Data Center Networks

A scalable, low-latency, high-speed, and energy-efficient data center network is a key element in the deployment of future large-scale data centers, and photonic switching has recently been recognized as a promising solution to fulfill these goals. In this study, we present a packet-switched optical network (PSON) architecture with centralized control for intra-data-center connectivity. For efficient PSON operation, intelligent yet low-complexity bandwidth-scheduling algorithms are critical. To align with realistic traffic flows in a data center, we consider “mice flow,” which occurs frequently but carries a small number of bytes, and “elephant flow,” which occurs occasionally but has a huge number of bytes. To classify traffic flows with different characteristics, we investigate various machine-learning (classification) techniques, such as C4.5 and Naïve Bayes Discretization, and compare their performance in terms of accuracy and classification speed. We also develop a priority-aware scheduling algorithm for packet switching, which is optimized for PSON, and is adaptive to flow classification under a dynamic traffic scenario. Numerical simulations show that our proposed scheduling algorithm assisted by flow-classification techniques can outperform a benchmark algorithm in terms of average delay and packet-loss ratio.

Performance of highly connected photonic switching lossless metro-access optical networks

The present work analyzes the performance of photonic switching networks, optical packet switching (OPS) and optical burst switching (OBS), in mesh topology of different sizes and configurations. The “lossless” photonic switching node is based on a semiconductor optical amplifier, demonstrated and validated with experimental results on optical power gain, noise figure, and spectral range. The network performance was evaluated through computer simulations based on parameters such as average number of hops, optical packet loss fraction, and optical transport delay (Am). The combination of these elements leads to a consistent account of performance, in terms of network traffic and packet delivery for OPS and OBS metropolitan networks. Results show that a combination of highly connected mesh topologies having an ingress e-buffer present high efficiency and throughput, with very low packet loss and low latency, ensuring fast data delivery to the final receiver.

Impact of Topology on the Scalability of Mach–Zehnder-Based Multistage Silicon Photonic Switch Networks

We analyze the scalability of electro-optic Mach–Zehnder-based silicon photonic switch networks. We describe a simulation framework based on the transfer matrix method that enable to model any type of multistage networks. We simulate three common network topologies – Benes, path-independent loss, and double-layer – and analyze their scalability by performing optical link numerical simulations for 50 Gbps non-return-to-zero signals. Our study shows that for a radix-16, the double-layer network performs better with a link power penalty smaller than 1 dB thanks to its dilated arrangement. For equivalent radix, the Benes and path-independent loss networks have link power penalties larger than 4 dB. Our simulations also show stringent requirements for the waveguide crossing crosstalk, whose value should be smaller than −35 dB to close any realistic link budget.

Unipolar photonic memristive-like nonlinear switching in split-ring resonator based metamaterials

Photonic memristor, which performs the function as memristor working on electromagnetic fields, can accelerate the development of all-optical network. A unipolar photonic memristive-like switching behavior in split-ring resonator based metamaterials was reported. Transmission-power (T-P) loops are observed in the metamaterials. And the T-P loops change with the detect frequency which indicates the tunability and designability of the photonic memristor. These behaviors are attributed to the increasing dielectric constant of MgTiO3 ceramic caused by the interaction of sample and electromagnet field. The mechanism supplies a general foundation for photonic memristors which can be used from radio frequency to optical wavelength.

Scalable Path-Setup Scheme for All-Optical Dynamic Circuit Switched NoCs in Cache Coherent CMPs

Nanophotonics is a promising solution for on-chip interconnection due to its intrinsic low-latency and low-power features, which can be useful for performance and energy in future Chip Multi-Processors (CMPs). This article proposes a novel arbitrated all-optical path-setup scheme for tiled CMPs adopting circuit-switched optical networks. It aims at significantly reducing path-setup latency and overall energy consumption. The proposed arbitrated scheme is able to configure multiple photonic switches simultaneously, instead of sequentially as it is done in state-of-the-art proposals. The proposed fast optical path-setup solution reduces the overhead in each transmission and, most importantly, allows optical circuit-switched networks to effectively serve cache coherence traffic, which is mainly composed of relatively small messages. Specifically, we propose a single-arbiter scheme where the whole topology is managed by a central module (single-arbiter) that takes care of the path-setup procedures. Then, to tackle scalability, we propose a logically clustered architecture (multi-arbiter) in which an arbiter is allocated in each logical core-cluster and an ad hoc distributed reservation protocol coordinates arbiters to manage inter-cluster path reservations. We show that our proposed single-arbiter architecture outperforms a state-of-the-art optical network with sequential path-setup (optical baseline) in the case of 8- and 16-core tiled CMP setups. However, due to serialization issues, the single-arbiter solution is not able to compete with a reference electronic baseline for bigger 32- and 64-core setups even if still performing much better than the optical baseline. Conversely, our multi-arbiter hierarchical solution allows us to improve performance up to almost 20% and 40% for 32- and 64-core setups, respectively, demonstrating a wide applicability of the proposed technique. Energy-wise, the analyzed solutions enable significant savings compared to both the optical baseline with sequential path setup, and to the electronic counterpart. Specifically, results show more than 25% average improvement for the single-arbiter in the 8- and 16-core cases, and more than 40% and 15% savings for the multi-arbiter in the 32- and 64-core cases, respectively.

Bistability in a mesoscopic Josephson junction array resonator

We present an experimental investigation of stochastic switching of a bistable Josephson junctions array resonator with a resonance frequency in the GHz range. As the device is in the regime where the anharmonicity is on the order of the linewidth, the bistability appears for a pump strength of only a few photons. We measure the dynamics of the bistability by continuously observing the jumps between the two metastable states, which occur with a rate ranging from a few Hz down to a few mHz. The switching rate strongly depends on the pump strength, readout strength and the temperature, following Kramer's law. The interplay between nonlinearity and coupling, in this little explored regime, could provide a new resource for nondemolition measurements, single photon switches or even elements for autonomous quantum error correction.

Tutorial: Integrated-photonic switching structures

Recent developments in waveguided 2 × 2 and N × M photonic switches are reviewed, including both broadband and narrowband resonant devices for the Si, InP, and AlN platforms. Practical actuation of switches by electro-optical and thermo-optical techniques is discussed. Present datacom-and-computing applications are reviewed, and potential applications are proposed for chip-scale photonic and optoelectronic integrated switching networks. Potential is found in the reconfigurable, programmable “mesh” switches that enable a promising group of applications in new areas beyond those in data centers and cloud servers. Many important matrix switches use gated semiconductor optical amplifiers. The family of broadband, directional-coupler 2 × 2 switches featuring two or three side-coupled waveguides deserves future experimentation, including devices that employ phase-change materials. The newer 2 × 2 resonant switches include standing-wave resonators, different from the micro-ring traveling-wave resonators. The resonant devices comprise nanobeam interferometers, complex-Bragg interferometers, and asymmetric contra-directional couplers. Although the fast, resonant devices offer ultralow switching energy, ∼1 fJ/bit, they have limitations. They require several trade-offs when deployed, but they do have practical application.

Burst Mode Optical Receiver With 10 ns Lock Time Based on Concurrent DC Offset and Timing Recovery Technique

This paper describes a low-power, low-latency, 7–10 Gb/s burst-mode DC-coupled receiver for photonic switch networks. The receiver includes a transimpedance amplifier (TIA) followed by a three-stage differential amplifier. For burst-mode operation, DC and timing recovery loops work concurrently in the proposed architecture to achieve 5.8 ns lock time. The DC recovery loop employs a successive approximation algorithm to recover signal-dependent offset that takes only six cycles of C8 (1/8th of data rate) clock. The timing recovery uses a quarter-rate injection scheme that is immune to duty cycle distortion. The recovered clock jitter is 10 ps p-p for 10 Gb/s operation. The receiver consumes only 33 mW while operating at 10 Gb/s, and less than 2 mW (leakage power and bias circuit) during idle time. The completely inductor-less receiver occupies a 465 pm × 265 pm area in 0.13 pm technology.

Silicon Photonic Switch Subsystem With 900 Monolithically Integrated Calibration Photodiodes and 64-Fiber Package

A packaged and fully operational 32 × 32 silicon photonic switch chip having 448 switch cells and 1856 crossings is demonstrated. The switch chip includes 900 monolithically integrated photodiodes used for calibrating the thermo-optic Mach–Zehnder switch cells. The calibration procedure employs an external laser source and follows a reachability-tree sequence to calibrate all switch cells. The accuracy of the calibration is demonstrated by the measurement of switch cell extinction ratios, for both states of each switch cell. The mean extinction ratio for both states is 35 dB. Arbitrary light path switching is demonstrated. Measurement of the channel-to-channel crosstalk was performed for a large number of aggressor and victim light path combinations. The matrix crosstalk is dominated by contributions from waveguide crossings. The die was wire-bonded to a custom ceramic package, to which a 68-fiber ribbon was permanently attached, which coupled the input and output optical signals to edge couplers on the chip through a waveguide pitch- and mode-concentrating silica chip. The fiber-to-fiber loss of on-chip loopback waveguides was less than 6.5 dB from 1530 to 1565 nm. The entirety of switch cells and monitors was driven by controller boards and A/D chips using a controller field-programmable gate array (FPGA). The calibration procedure was completed in less than 10 min using only the on-chip monitors, without off-chip detectors. The chip was recalibrated after six months storage, and the measured change in drive current was within the calibration uncertainty, indicating that the chip and driver are stable over time.

Silicon Photonics towards Disaggregation of Resources in Data Centers

In this paper, we demonstrate two subsystems based on Silicon Photonics, towards meeting the network requirements imposed by disaggregation of resources in Data Centers. The first one utilizes a 4 × 4 Silicon photonics switching matrix, employing Mach Zehnder Interferometers (MZIs) with Electro-Optical phase shifters, directly controlled by a high speed Field Programmable Gate Array (FPGA) board for the successful implementation of a Bloom-Filter (BF)-label forwarding scheme. The FPGA is responsible for extracting the BF-label from the incoming optical packets, carrying out the BF-based forwarding function, determining the appropriate switching state and generating the corresponding control signals towards conveying incoming packets to the desired output port of the matrix. The BF-label based packet forwarding scheme allows rapid reconfiguration of the optical switch, while at the same time reduces the memory requirements of the node’s lookup table. Successful operation for 10 Gb/s data packets is reported for a 1 × 4 routing layout. The second subsystem utilizes three integrated spiral waveguides, with record-high 2.6 ns/mm2, delay versus footprint efficiency, along with two Semiconductor Optical Amplifier Mach-Zehnder Interferometer (SOA-MZI) wavelength converters, to construct a variable optical buffer and a Time Slot Interchange module. Error-free on-chip variable delay buffering from 6.5 ns up to 17.2 ns and successful timeslot interchanging for 10 Gb/s optical packets are presented.

Photonic Scattering on a Trimer with PT-Symmetry

We analyze photonic scattering on a trimer with PT symmetry, where the photon propagates in an array of cavities. In the system, a passive and an active cavity couple to another cavity without loss and gain simultaneously, which is in the middle of the cavity array. Such three cavities can be regarded as the scattering target coupling to the unlimited number of cavities from two directions respectively. Our approach is to use the Schrodinger equation to calculate the reflection coefficient and transmission coefficient, and then let photonic transmission spreads from gain or loss cavity. It shows that the scattering of the photon is closely associated with the PT symmetric characteristic of the dynamics of the system. The atom’s modulation on the photonic transmission is also investigated. We found that the scattering center can behave as a photonic switch, which could be used potentially to control the photonic transmission.

Characteristics of silicon-based Sagnac optical switches using magneto-optical micro-ring array

ABSTRACTThe miniaturization and integration of optical switches are necessary for photonic switching networks and the utilization of magneto optical effects is a promising candidate. We propose a Sagnac optical switch chip based on the principle of nonreciprocal phase shift (NPS) of the magneto-optical (MO) micro-ring (MOMR) array, composed of SiO2/Si/Ce:YIG/SGGG. The MO switching function is realized by controlling the drive current in the snake-like metal microstrip circuit layered on the MOMRs. The transmission characteristics of the Sagnac MO switch chip dependent on magnetization intensity, waveguide coupling coefficient and waveguide loss are simulated. By optimizing the coupling coefficients, we design an MO switch using two serial MOMRs with a circumference of 38.37 μm, and the 3dB bandwidth and the extinction ratio are respectively up to 1.6 nm and 50dB for the waveguide loss coefficient of . And the switching magnetization can be further reduced by increasing the number of parallel MOMRs. The frequency response of the MO Sagnac switch is analyzed as well.

Switching response of dual-output Mach–Zehnder modulator in channel-interleaved photonic analog-to-digital converter

This Letter theoretically and experimentally studies the response of photonic switching in a channel-interleaved photonic analog-to-digital converter (PADC) with high sampling rate and wide input frequency range. A figure of merit (FoM) is introduced to evaluate the switching response of the PADC when a dual-output Mach–Zehnder modulator (MZM) serves as the photonic switch to parallelize the sampled pulse train into two channels. After the optimization of the FoM and utilization of the channel-mismatch compensation algorithm, the system bandwidth of PADC is expanded and the signal-to-distortion ratio is enhanced.

Optimize the Power Consumption and SNR of the 3D Photonic High-Radix Switch Architecture Based on Extra Channels and Redundant Rings

The demand from exascale computing has made the design of high-radix switch chips an attractive and challenging research field in EHPC (exascale high-performance computing). The static power, due to the thermal sensitivity and process variation of the microresonator rings, and the cross talk noise of the optical network become the main bottlenecks of the network’s scalability. This paper proposes the analyze model of the trimming power, process variation power, and signal-to-noise ratio (SNR) for the Graphein-based high-radix optical switch networks and uses the extra channels and the redundant rings to decrease the trimming power and the process variation power. The paper also explores the SNR under different configurations. The simulation result shows that when using 8 extra channels in the 64×64 crossbar optical network, the trimming power reduces almost 80% and the process variation power decreases 65% by adding 16 redundant rings in the 64×64 crossbar optical network. All of these schemes have little influence on the SNR. Meanwhile, the greater channel spacing has great advantages to decrease the static power and increase the SNR of the optical network.

Broadband nonvolatile photonic switching based on optical phase change materials: beyond the classical figure-of-merit.

In this Letter, we propose a broadband, nonvolatile on-chip switch design in the telecommunication C-band with record low loss and crosstalk. The unprecedented device performance builds on: 1)a new optical phase change material (O-PCM) Ge2Sb2Se4Te1 (GSST), which exhibits significantly reduced optical attenuation compared to traditional O-PCMs, and 2)a nonperturbative design that enables low-loss device operation beyond the classical figure-of-merit (FOM) limit. We further demonstrate that the 1-by-2 and 2-by-2 switches can serve as basic building blocks to construct nonblocking and nonvolatile on-chip switching fabric supporting arbitrary numbers of input and output ports.

Non-reciprocal photonics based on time modulation

Reciprocity is a fundamental principle in optics, requiring that the response of a transmission channel is symmetric when source and observation points are interchanged. It is of major significance because it poses fundamental constraints on the way we process optical signals. Non-reciprocal devices, which break this symmetry, have become fundamental in photonic systems. Today they require magnetic materials that are bulky, costly and cannot be integrated. This is in stark contrast with most photonic devices, including sources, modulators, switches, waveguides, interconnects and antennas, which may be realized at the nanoscale. Here, we review recent progress and opportunities offered by temporal modulation to break reciprocity, revealing its potential for compact, low-energy, integrated non-reciprocal devices, and discuss the future of this exciting research field. The progress on non-reciprocal photonic devices enabled by temporal modulation is reviewed.

On-chip wavelength locking for photonic switches.

We present an on-chip wavelength reference with a partial drop ring resonator and germanium photodetector. This approach can be used in ring-resonator-based wavelength-selective switches where absolute wavelength alignment is required. We use the temperature dependence of heater resistance as a temperature sensor. Additionally, we discuss locking speed, statistical variation of heater resistances, and tuning speed of the switches.