Optical Routing Research Articles

Optical readout of singlet fission biexcitons in a heteroacene with photoluminescence detected magnetic resonance.

Molecular spin systems based on photoexcited triplet pairs formed via singlet fission (SF) are attractive as carriers of quantum information because of their potentially pure and controllable spin polarization, but developing systems that offer optical routes to readout as well as initialization is challenging. Herein, we characterize the electron spin magnetic resonance change in the photoluminescence intensity for a tailored organic molecular crystal while sweeping a microwave drive up to 10GHz in a broadband loop structure. We observe resonant transitions for both triplet and quintet spin sublevel populations showing their optical sensitivity and revealing the zero-field parameters for each. We map the evolution of these spectra in both microwave frequency and magnetic field, producing a pattern of optically detected magnetic resonance (ODMR) peaks. Fits to these data using a suitable model suggest significant spin polarization in this system with orientation selectivity. Unusual excitation intensity dependence is also observed, which inverts the signof the ODMR signal for the triplet features, but not for the quintet. These observations demonstrate optical detection of the spin sublevel population dictated by SF and intermolecular geometry, and highlight anisotropic and multi-scale dynamics of triplet pairs.

Versatile optical beam routers based on inversely designed supercell metagratings

Metagratings manipulating the wavefront with a subwavelength volume have been widely explored in recent years for their potential applications in optical beam routers, such as laser beam splitters and combiners. Current metagratings are hampered from practical beam rerouting due to inhibitive computational load of engineering design and expensive nanofabrication cost. In this work, we apply the emerging concept of supercell metagratings, which arranges random binary gratings of a unit cell in a one-dimensional periodicity, to simplify such design and fabrication processes. A high-performance inverse design framework for the supercell gratings is proposed. In such a framework, we use coupled wave algorithm as a fast-converging electromagnetic solver for the forward calculation and particle swarm optimization algorithm for the backward optimization. By manipulating the building blocks of a unit cell, specific diffraction orders of supercell gratings can be intentionally strengthened or eliminated. We finally realize high-efficiency, broadband and multi-functionality optical beam splitters and combiners both in visible and near-infrared regimes. We envision that the proposed method offers an avenue towards the mass production realization of flat optics.

Phase-change material assisted on-chip wavefront shaping for optical switching and beam splitting

On-chip wavefront shaping is indispensable for implementing optical routing and signal processing. By referring to the concept of metasurface used in free space, we can realize the on-chip wavefront shaping to manipulate the guided wave. In this paper, we combine the phase-change material Sb2S3 nanorods with 1D on-chip meta-lens to manipulate the optical routing direction. We use the 1550 nm TE0 mode to realize the functions of 1 × 2 and 1 × 3 optical switching, and then the 1 × 2 and 1 × 3 beam splitting. By combining the function of beam deflection and beam splitting, we can realize tunable beam steering and complex optical flow control.

A flexible optical router architecture with modified fuzzy queue based router (FQBR) algorithm for 5G and 6G communication

A flexible optical router architecture with modified fuzzy queue based router (FQBR) algorithm for 5G and 6G communication

Strict non-blocking four-port optical router for mesh photonic network-on-chip

We report a strict non-blocking four-port optical router that is used for a mesh photonic network-on-chip on a silicon-on-insulator platform. The router consists of eight silicon microring switches that are tuned by the thermo-optic effect. For each tested rousting state, the signal-to-noise ratio of the optical router is larger than 13.8 dB at the working wavelength. The routing functionality of the device is verified. We perform 40 Gbps nonreturn to zero code data transmission on its 12 optical links. Meanwhile, data transmission using wavelength division multiplexing on eight channels in the C band (from 1525 to 1565 nm) has been adopted to increase the communication capacity. The optical router’s average energy efficiency is 25.52 fJ/bit. The rising times (10% to 90%) of the eight optical switch elements are less than 10 µs and the falling times (90%–10%) are less than 20 µs.

Inverse‐Designed Integrated Nonlinear Optical Switches

AbstractDue to the slowdown of Moore's law, the integrated photonic devices have provided a route to promote the development of large‐scale optical communications with high performance. As one of the essential components of optical routers, an optical switch can fast transmit or block the optical signal. However, most of the integrated optical switches reported to date rely on thermo‐, magneto‐, or electro‐optical effects, which limit applications due to slow response times, large footprint, and complexity fabrication. Here, an integrated nonlinear optical switch designed by the inverse‐design method and fabricated on the SiN platform is introduced. The integrated optical switch is demonstrated with significant intensity‐dependent transmission at 1.5 µm waveband. The polarization‐depended capability is explored by using fundamental polarized lights (transverse electric and transverse magnetic, respectively), which exhibits opposite transmission change trends during the whole power range and opens potential applications such as photonic quantum information processing. In order to address the saturation of Kerr‐nonlinearity in SiN materials at high power, a MoS2/SiN hybrid integrated optical switch is fabricated by uniformly cladding few‐layer MoS2 on the surface of inverse‐designed region. That is demonstrated to enhance the nonlinear optical response of device efficiently and achieve more excellent switching capability at high power.

Optimized 6x6 Optical Router for Three Dimensional Optical Networks-on-Chip

The interconnection network is very influential in Multiprocessor system-on-chip (MPSoC) performance. Due to low power efficiency and high latency, conventional interconnects are replaced by electrical networks on-chip (ENoC). However, ENoCs cannot gratify the bandwidth, latency and loss requirements within the available power budget of optical integrated circuits. The reasons being restricted bandwidth, extended delay, and reasonably high power consumption. So, ENoC are being replaced by optical networks-on-chip (ONoC). ONoC has emerged as a promising substitute to provide greater bandwidth, low latency and low power ingestion in MPSoCs. Number of cores required on-chip is increasing which leads to demand of multilayer multi-core processors. Three dimensional (3D) ONoC has become essential for such multilayer multi-core processors. For 3D ONoC, in this paper we have proposed 6x6 non-blocking optical router using micro-ring resonator (MRR) with less number of waveguide crossings and waveguide bendings. Phoenix software is used to simulate proposed optical router. Insertion loss of proposed optical router is lowest among existing non-blocking optical routers of 3D ONoC.

Monolithically Integrated 8 × 8 Transmitter-Router Based on Tunable V-Cavity Laser Array and Cyclic Arrayed Waveguide Grating Router

A monolithic 8 × 8 transmitter-router chip fabricated on InGaAlAs-InP multi-quantum well wafer for distributed wavelength routing network in the O-band with a channel spacing of 400 GHz is experimentally demonstrated. A tunable V-cavity laser (VCL) array, a cyclic-arrayed waveguide grating router (AWGR) and a semiconductor amplifier (SOA) array are integrated using the quantum-well intermixing (QWI) technique for its fabrication simplicity and cost effectiveness. A 200 GHz-spaced compact-size VCL is demonstrated with a 27 nm tuning range and a side-mode suppression ratio (SMSR) around 40 dB using a single-electrode controlled tuning. The chip output power is 24.6 mW. Measurement results of the transmitter-router chip show that all 64 input-output combinations have cyclic response spectra. After passing through the SOA with 80 mA bias current, an output power of about 9.6 mW and optical signal-to-noise ratio (OSNR) up to 39 dB have been measured. The demonstrated transmitter-router chip is fabricated on the same quantum well structure without requiring multiple epitaxial growth and complex grating fabrication. The characteristics of multi-wavelength and multi-port transmissions enable the distributed optical routing networks with flexible bandwidth allocation, which can find wide application in datacenters and high-performance computers.

Dispersionless Coupling among Optical Waveguides by Artificial Gauge Field

Coupling among closely packed waveguides is a common optical phenomenon, and plays an important role in optical routing and integration. Unfortunately, this coupling property is usually sensitive to the working wavelength and structure features that hinder the broadband and robust functions. Here, we report a new strategy utilizing an artificial gauge field (AGF) to engineer the coupling dispersion and realize a dispersionless coupling among waveguides with periodically bending modulation. The AGF-induced dispersionless coupling is experimentally verified in a silicon waveguide platform, which already has well-established broadband and robust routing functions (directional coupling and splitting), suggesting potential applications in integrated photonics. As examples, we further demonstrate a three-level-cascaded AGF waveguide network to route broadband light to desired ports with an overwhelming advantage over the conventional ones in comparison. Our method provides a new route of coupling dispersion control by AGF and benefits applications that fundamentally rely on waveguide coupling.

Theoretical study of vortex beam generation based on geometric coordinate transformation

By performing a conformal optical mapping of an input beam from Cartesian to log-polar coordinates, we propose a method to generate vortex beam. By tilting the incident beam, a phase gradient is attached and evolves into a vortex phase due to the optical transformation. Thus, the topological charge of the generated vortex beam is continuously adjustable. With this method, vortex beams with integer and fractional orders are generated. The purity of the generated vortex beam is theoretically analyzed, as well as the possible effects of phase misalignment on the output vortex. The continuously tunable vortex beam achieved by this method is expected to be used in information processing and optical routing in optical communications.

Modeling and Performance Analysis of a Fault-Tolerant 3D Photonic Network-on-Chip Based on Hybrid Photonics-Plasmonics.

The performance of electro-optic modulators and optical routers and their routing algorithms are the key factors affecting the performance of networks on optical chips. This paper improves the mesh 3-dimensional photonic network-on-chip (3D-PNoC) topology. An SPP hybrid silicon-based electro-optic modulator and an improved fault-tolerant SPP router are used to improve the performance of the network on an optical chip. SPP switching and SPP MRR are combined to form a fault-tolerant SPP router. On this basis, an improved genetic optimization routing algorithm is implemented on the improved mesh 3D PNoC topology, which completes the data exchange of the IP core of the network on the optical chip. Compared with the case of traditional optoelectronic devices, the performance of on-chip optical networks can be improved effectively. The simulation results show that upon the application of the improved genetic optimization routing algorithm to the improved mesh 3D PNoC topology, the average end-to-end delay is reduced by 32.9%, the throughput rate is increased by 28.5%, and the system power consumption is reduced by 27.6%. On the other hand, the average insertion loss and noise of optical routers are increased by 2.94 dB and 2.95 dB, respectively.

Analysis of Engineering and Geological Conditions of International Submarine Optical Fiber Cable Routing in the East China Sea Section

The East China Sea section of the Chinese international submarine optical fiber cable generally starts from the Shanghai coast, crosses the East China Sea shelf and continental slope to the east, and intersects with the international optical fiber cable system in Okinawa Trough. In this paper, the regional tectonic, seismic, and other environmental conditions of the East China Sea section of the international submarine optical cable are briefly described based on the previous data. Additionally, the geological engineering conditions of the international optical cable routing in the East China Sea area will be analyzed based on the field investigation data such as multibeam, side-scan sonar, shallow stratigraphic profile, sediment sampling, and cone penetration test (CPT). It is found that the main geological factors in the East China Sea shelf area are submarine scouring, sandwave, shallow gas, and hard seabed; in the land slope area are steep slope, submarine valley, rock, landslide, and shallow gas (pockmark); and in the Okinawa Trough area are gully, sea mound/seamount, rock, shallow gas, fault, and hard strata outcrop. This paper briefly analyzes the impact of each geological disaster factor on the submarine cable project and proposes solutions for providing essential information and some scientific basis for designing, constructing, operating, and maintaining international submarine optical fiber cables in the East China Sea area.

Efficient non-blocking optical router for 3D optical network-on-chip

The number of cores in the multiprocessor system on the chip is growing exponentially because of the computational requirements of the applications. Efficient communication between processors on a chip intensely impacts the performance of the on-chip multiprocessor system in terms of power, speed, and space requirements. To tackle such complex integrated interconnect technology systems, three-dimensional (3D) Optical Network-on-Chip (ONoC) is a promising solution. As the optical router is a core of 3D ONoC, it needs the optimized router design in terms of the number of components used, insertion loss, power consumption, and other parameters. This paper proposes a novel design of a 6 × 6 intra-layer non-blocking optical router and an inter-layer (vertical) optical router using a micro-ring resonator (MRR). The performance analysis is carried out using the Phoenix simulator. The proposed 6 × 6 optical router has the lowest number of waveguide crossings and waveguide bendings than existing non-blocking optical routers of 3D ONoC. Furthermore proposed inter-layer optical router has reduced the number of waveguide crossings. The ONoC with X-Mesh topology using our design outperforms in terms of insertion loss and signal to noise ratio over benchmarks.

A compact formulation of all optical signal router by using plasmonic waveguides

A compact formulation of all optical signal router by using plasmonic waveguides

Fiber End-Facet Integrated Non-Volatile Optical Switch Based On Ge2Sb2Te5

The silicon photonic integrated network based on the thermo-optical or electro-optical effect generally has the disadvantages of volatile, large footprint, and significant energy loss. Here, we propose and demonstrate an all-optical controllable switch device with non-volatile, broadband adjustable, and bistable fast switching performance by integrating the phase-change material (Ge2Sb2Te5) on the optical fiber. By adjusting the energy of the laser pulse train exerting on the optical fiber, the phase state of the phase-change material can be switched, thereby realizing the ON and OFF function of the optical switch. As a result, a non-volatile optical switch with a wide bandwidth working range (up to 60 nm) and a significant transmission contrast (2 dB) is demonstrated. This device is expected to help realize fast and broadband optical routing in fiber optical communication networks as the optical switch. Furthermore, its logic operation function can impart optical fiber with new storage and computing functionalities except for transmission and sensing. It can be combined with an optical field-programmable gate array (OFPGA) and play a part in optical fiber photonic circuitry in the future.

Integrated refractive index sensor based on an AlN-PSiO2 hybrid plasmonic microdisk resonator.

In this paper, a microdisk resonator (MDR) based on an AlN-PSiO2 hybrid plasmonic waveguide (HPW) and its refractive index (RI) sensing characteristics are investigated. The plasmonic characteristics of the MDR based on the AlN-PSiO2 HPW (APHPW-MDR) in near-infrared wavelengths are studied by using the finite element method. Through the structure parameter optimizations, the propagation length (Lprop) of the APHPW-MDR is ∼165µm, which is ∼2.5 times as long as that of the MDR based on the AlN HPW (AHPW-MDR). The simulation results show that the quality factor (Q) and extinction rate (ER) of the APHPW-MDR are ∼621.3 and ∼30dB, respectively. The RI sensing sensitivity (S) of the RI sensor based on the APHPW-MDR is ∼276.6nm/RIU. The RI sensor based on the APHPW-MDR has wide application prospects in high-performance biochemical sensing, and it can also be used in integrated optical filters, modulators, switches, routers, and delay circuits.

A multicolor fluorescent sensor array based on curcumin and its analogs as a shrimp freshness indicator

The colorimetric sensing label is a simple, cost-effective, and user-friendly tool for monitoring ammonia vapor (NH3) concentrations in food packaging. Numerous natural dyes present excellent NH3-sensitivity, but their low solubility in water limits their food-related applications. Herein, a special cellulose-based ink system with an EtOH/water mixture as solvent was proposed to improve the dispersion of non-aqueous dyes (curcumin and its analogs (indexed as Bur and Bur-BF2)). Subsequently, three sensing labels containing different dyes were prepared by simple screen-printing after optimizing the inks' rheological properties. Benefiting from the different intramolecular charge-transfer (ICT) behaviors of dyes, each sensing label exhibited various characteristics in terms of the optical property, NH3-sensitivity, and fluorescent color-changing routes upon exposure to 0–50 ppm NH3. Importantly, all sensing labels showed excellent stability in environments with various relative humidity and temperature. Therefore, three sensing labels were used to construct a multicolor fluorescent sensor array, which aimed to visually monitor the freshness of shrimp for consumers.

Silicon-on-Insulator Optical Buffer Based on Magneto-Optical 1 × 3 Micro-Rings Array Coupled Sagnac Ring

Optical buffer is a key technology to control optical routing and solve channel competition, which directly determines the performance of information processing and storage. In this study, a switchable optical buffer using the nonreciprocal silicon-on-insulator (SOI) magneto-optical micro-ring (MOMR) array coupled with Sagnac ring was introduced, which can exceed the time-bandwidth limitation. The transmission equations and propagation characteristics of optical signal in 1 × 3 micro-rings and Sagnac ring coupled 1 × 3 micro-rings based on two kinds of phase-change materials were studied. The group time delay, effective buffer time and readout operation in the buffer were also investigated.

Reconfigurable add-drop filter based on an antisymmetric multimode photonic crystal nanobeam cavity in a silicon waveguide.

We have designed and demonstrated a reconfigurable channel add-drop filter (ADF) based on an antisymmetric multimode photonic crystal nanobeam cavity (AM-PCNC) in a silicon waveguide. The proposed AM-PCNC can realize channel add-drop filtering by selectively filtering and reflecting the fundamental mode (TE0) and 1st-order mode (TE1) in the multimode waveguide. A high-performance add-drop filter has been demonstrated with a high extinction ratio of 28.2 dB and an insertion loss of 0.18 dB. Meanwhile, the reconfigurable add-dropping has been realized by heating the nanobeam cavity to tune the filtering wavelength. A tuning efficiency of 0.464 nm/mW was measured. The rising and falling time are ∼6.5 µs and ∼0.6 µs, respectively, which are at microsecond time scale. The footprint of the involved nanobeam cavity is only 16.5 µm2. The device can potentially provide an integrated component for optical switch array, routers, and wavelength-division multiplexing in the optical networks.

Design, Simulation, and Optimization of Polarization-Independent Four-Port Optical Waveguide Circulator Based on a Ferrite Material

Optical circulators are used in optical devices such as multiplexers, demultiplexers, and optical routers. Usually, the magnetic material in the center of the circulator conducts light by interacting with the electromagnetic wave. In this research, a polarization-independent four-port optical waveguide circulator with the presence of a rhombus-shaped ferrimagnetic material has been designed, simulated, and optimized in the three-dimensional part of Comsol software. This designed circulator unlike the previous structures has four ports which use the transmission matrix method to conduct waves. By selecting the appropriate size and type of central ferrite, as well as the scale of input and output channels, the most optimal situation is obtained for power transmission with less than 1 dB loss when port 1 is input and port 2 is output.