Showing papers on "Optical switch published in 2020"

Sirius: A Flat Datacenter Network with Nanosecond Optical Switching

Abstract: The increasing gap between the growth of datacenter traffic and electrical switch capacity is expected to worsen due to the slowdown of Moore's law, motivating the need for a new switching technology for the post-Moore's law era that can meet the increasingly stringent requirements of hardware-driven cloud workloads. We propose Sirius, an optically-switched network for datacenters providing the abstraction of a single, high-radix switch that can connect thousands of nodes---racks or servers---in a datacenter while achieving nanosecond-granularity reconfiguration. At its core, Sirius uses a combination of tunable lasers and simple, passive gratings that route light based on its wavelength. Sirius' switching technology and topology is tightly codesigned with its routing and scheduling and with novel congestion-control and time-synchronization mechanisms to achieve a scalable yet flat network that can offer high bandwidth and very low end-to-end latency. Through a small-scale prototype using a custom tunable laser chip that can tune in less than 912 ps, we demonstrate 3.84 ns end-to-end reconfiguration atop 50 Gbps channels. Through large-scale simulations, we show that Sirius can approximate the performance of an ideal, electrically-switched non-blocking network with up to 74-77% lower power.

Electrical Tuning of Phase Change Antennas and Metasurfaces

Abstract: The success of semiconductor electronics is built on the creation of compact, low-power switching elements that offer routing, logic, and memory functions. The availability of nanoscale optical switches could have a similarly transformative impact on the development of dynamic and programmable metasurfaces, optical neural networks, and quantum information processing. Phase change materials are uniquely suited to enable their creation as they offer high-speed electrical switching between amorphous and crystalline states with notably different optical properties. Their high refractive index has also been harnessed to fashion them into compact optical antennas. Here, we take the next important step by realizing electrically-switchable phase change antennas and metasurfaces that offer strong, reversible, non-volatile, multi-phase switching and spectral tuning of light scattering in the visible and near-infrared spectral ranges. Their successful implementation relies on a careful joint thermal and optical optimization of the antenna elements that comprise an Ag strip that simultaneously serves as a plasmonic resonator and a miniature heating stage.

Niobium Carbide MXenes with Broad-Band Nonlinear Optical Response and Ultrafast Carrier Dynamics.

Abstract: Exploring the nonlinear photonics of emerging promising two-dimensional (2D) materials like MXenes will boost the development of broad-band optoelectronic and photonic applications. In this paper, the broad-band nonlinear optical response and the excited-carrier dynamics of an emerging MXene, Nb2C, are systematically investigated for the wavelength range of visible to the near-infrared band. The obtained nonlinear optical response shows a wavelength and excitation intensity dependence. The imaginary part of the third-order nonlinear optical susceptibility Imχ(3) and figure of merit were found to be -1.4 × 10-10 esu and 7.5 × 10-12 esu cm, respectively. The interesting nonlinear absorption response inversion properties (e.g., a shift from saturable absorption to two-photon absorption) of Nb2C nanosheets in the near-infrared promise possible important applications in nonlinear photonics, such as an optical switch. We also demonstrate that the wavelength-dependent relaxation times consist of two different relaxation components, that is, time constants in which one is hundreds of femtoseconds and the other is several picoseconds. Our results indicate promising potential in near-infrared nanophotonic applications of 2D Nb2C and offer a promising candidate for 2D-material-based nanophotonic devices and beyond.

Reversible optical tuning of GeSbTe phase-change metasurface spectral filters for mid-wave infrared imaging

Abstract: Tunable narrowband spectral filtering across arbitrary optical wavebands is highly desirable in a plethora of applications, from chemical sensing and hyperspectral imaging to infrared astronomy. Yet, the ability to reconfigure the optical properties, with full reversibility, of a solid-state large-area narrowband filter remains elusive. Existing solutions require either moving parts, have slow response times, or provide limited spectral coverage. Here, we demonstrate a 1-inch diameter continuously tunable, fully reversible, all-solid-state, narrowband phase-change metasurface filter based on a GeSbTe-225 (GST)-embedded plasmonic nanohole array. The passband of the presented device is ∼74nm with ∼70% transmittance and operates across the 3–5 µm thermal imaging waveband. Continuous, reconfigurable tuning is achieved by exploiting intermediate GST phases via optical switching with a single nanosecond laser pulse, and material stability is verified through multiple switching cycles. We further demonstrate multispectral thermal imaging in the mid-wave infrared using our active phase-change metasurfaces. Our results pave the way for highly functional, reduced power, compact hyperspectral imaging systems and customizable optical filters for real-world system integration.

High speed optical switching gain based EDFA model with 30 Gb/s NRZ modulation code in optical systems

Abstract: This study presents high speed optical switching gain based Erbium doped fiber amplifier model. By using the proposed model the optical fiber loss can be minimized. The system is stabilized with the power budget of 25.875 mW a long 75 km as a length of optical fiber in this study can be verified. The modulation rate of 10 Gb/s can be upgrade up to reach 30 Gb/s. The suitable power for the optical transmitter is −2.440 dBm and NRZ modulation code is verified. The receiver sensitivity can be upgraded with the minimum bit error rate and max Q factor are 1.806 e−009 and 5.899.

Nonlinear Chiral Meta-Mirrors: Enabling Technology for Ultrafast Switching of Light Polarization.

Abstract: Photonic nanostructures that realize ultrafast switching of light polarization are essential to advancements in the area of optical information processing. The unprecedented flexibility of metasurf...

Wavelength-selective 2 × 2 optical switch based on a Ge 2 Sb 2 Te 5 -assisted microring

Abstract: A novel wavelength-selective 2×2 optical switch based on a Ge2Sb2Te5 (GST)-assisted microring-resonator (MRR) is proposed. The present GST-assisted MRR consists of two access optical waveguides and an MRR coupled with a bent GST-loaded silicon photonic waveguide. The 2×2 optical switch is switched ON or OFF by modifying the GST state to be crystalline or amorphous. In particular, the microring waveguide and the bent GST-loaded waveguide are designed to satisfy the phase-matching condition when the GST is crystalline. As a result, the MRR becomes highly lossy and the resonance peak is depressed significantly. On the other hand, when it is off, there is little coupling due to the significant phase mismatching. Consequently, one has a low-loss transmission at the drop port for the resonance wavelength. In this paper, the simulation using the three-dimensional finite-difference method shows that the extinction ratio of the designed photonic switch is ∼20 dB at the resonance wavelength, while the excess losses at the through port and drop port are 0.9 dB and 2 dB. In particular, the resonance wavelength changes little between the ON and OFF states, which makes it suitable for multichannel wavelength-division-multiplexing systems.

Thermo Optical Switching and Sensing Applications of an Infrared Metamaterial

Abstract: Plasmonic induced transparency as an interesting physics behind many novel plasmonic devices is used to design a nano structure composed of graphene and Indium Antimonide (InSb). Due to temperature dependent of graphene and InSb permittivity, the structure is a good candidate for temperature sensor. The sensitivity of the proposed thermal sensor is optimized and the best value for sensitivity is obtained 160(nm/k). The switch application of the proposed structure is also analyzed and a switch with modulation depth of 98% and modulation efficiency of 82% is proposed which has very good values compare to other THz switch reported in literature.

Efficient Mode Transfer on a Compact Silicon Chip by Encircling Moving Exceptional Points

Abstract: Exceptional points (EPs) are branch point singularities of self-intersecting Riemann sheets, and they can be observed in a non-Hermitian system with complex eigenvalues. It has been revealed recently that dynamically encircling EPs by adiabatically changing the parameters of a system composed of lossy optical waveguides could lead to asymmetric (input-output) mode transfer. However, the length of the waveguides had to be considerable to ensure adiabatic evolution. Here we demonstrate that the parameters can change adiabatically along a smaller encircling loop by utilizing moving EPs, leading to significant shortening of the structures compared to fixed EPs. Meanwhile, the mode transmittance is remarkably improved and the transfer efficiency persists at ∼90%. Moving EPs are very promising for applications such as highly integrated broadband optical switches and convertors operating at telecommunication wavelengths.

Architecture and Devices for Silicon Photonic Switching in Wavelength, Polarization and Mode

Abstract: Switching can be performed with multiple physical dimensions of an optical signal. Previously optical switching was mainly focused in the wavelength domain. In this paper we discuss the general architecture of integrated silicon photonic switches by exploiting multi-dimensions in wavelength, polarization, and mode. To route a data channel from one input port to an arbitrary output port in a network node, three basic functions are required: de-multiplexing, switching, and multiplexing. The multiplexing and de-multiplexing processes can be realized in any one physical dimension. The capacity of a switch can be effectively scaled by using joint physical dimensions. As two examples, we first present a wavelength switch based on dual-nanobeam cavities with high quality factors, a low power consumption, and a compact footprint. We then propose a design of a mode-polarization-wavelength selective switch by leveraging three physical dimensions, and experimentally demonstrate the building blocks and key functionalities.

ROTOS: A Reconfigurable and Cost-Effective Architecture for High-Performance Optical Data Center Networks

Abstract: Fast and high capacity optical switching techniques have the potential to enable low latency and high throughput optical data center networks (DCNs) to afford the rapid increasing traffic boosted by multiple applications Flexibility of the DCN is of key importance to provide adaptive and dynamic bandwidth and capacity to handle the variable traffic patterns of heterogeneous applications Aiming at improving the network performance and the system flexibility of optical DCNs, we propose and investigate a novel optical DCN architecture named ROTOS based on reconfigurable optical top of rack (ToR) and fast optical switches In the proposed DCN architecture, the novel optical flexible ToRs employing multiple transceivers (TRXs) and a wavelength selective switch (WSS) are reconfigured by the software-defined networking (SDN) control plane The bandwidth can be dynamically allocated to the dedicated optical links on-demand according to the desired oversubscription (OV) and intra-/inter-cluster traffic matrix Numerical investigations of the novel architecture under realistic traffic model indicate that dynamically allocating the TRXs and elastically controlling the WSS, a packet loss below 1E-5 and a server-to-server latency lower than 3 μs can be guaranteed for different traffic patterns at load of 04 With respect to the DCN with static interconnections, the average packet loss of ROTOS decreases two orders of magnitude and the average server-to-server latency performance improves by 215% Scalability investigation to a large number of servers shows limited (11%) performance degradation as the network scale from 2560 to 40960 servers Additionally, the dynamic bandwidth allocation of the DCN is experimentally validated Network performance results show a packet loss of 005 and 585 μs end-to-end latency at the load of 08 Finally, investigations on the cost and power consumption confirm that the ROTOS DCN architecture has 284% lower cost and 350% better improvement for power efficiency with respect to the electrical switch based DCNs

Software-Defined WDM Optical Transport in Disaggregated Open Optical Networks

Abstract: Transparent optical networks operated by WDM coherent optical technologies for data transport are moving-on towards the implementation of the openness paradigm. In such a context, disaggregated network elements and subsystems can be abstracted to manage and control propagation of WDM optical data transport. It enables the application of the software-defined paradigm down to the physical layer, with optical transport fully summarized by a quality of transmission estimator.

Design of an Optical Switch and Sensor Based on a MIM Coupled Waveguide Using a DNA Composite

Abstract: A switchable surface plasmon polariton optical coupled waveguide made by exploiting a DNA composite is proposed in this paper. The switchable DNA element is used for controlling the electric field and transmission line shape. A multiband resonance is obtained for transmission to improve the optical sensing performance. Here, dumbbell-shaped cavity slots are utilized to control the effective length, with two resonances at 960 and 1260 nm for the low-conductivity mode, while there is one peak at 1590 nm for the high-conductivity mode. The DNA element is placed between two conductive silver lines, and thus acts as a switch. The structure can be controlled by switching between the DNA composite conductivity modes, and this ability can be considered for optical gates or switches at 960 and 1500 nm. The resulting switching factor is about 450 at 960 nm. The frequency shift and variation in full width at half maximum are evaluated as two functions for obtaining the sensitivity and figure of merit (FOM) of the refractive index. Therefore, this optical waveguide can be used both as an optical switch and as a refractive index (RI) sensor, with sensitivity of about 1260 nm/RIU and FOM of 120 RIU−1.

Highly efficient thermo-optic tunable micro-ring resonator based on an LNOI platform

Abstract: We demonstrate a high-efficiency thermo-optic (TO) tunable micro-ring resonator in thin-film lithium niobate. Thermal insulation trenches around the heated micro-ring resonator and the underlying silicon substrate significantly reduce the heating power consumption and improve the tuning efficiency. Compared to conventional TO devices without thermal insulation trenches, the proposed device achieves a full free spectral range wavelength shift with a 14.9 mW heating power, corresponding to a thermal tuning efficiency of 53.7 pm/mW, a more than 20-fold improvement of tuning efficiency. The approach enables energy-efficient high-performance TO devices such as optical switches, wavelength routers, and other reconfigurable photonic devices.

Low-Loss, Low-Crosstalk, and Large-Scale Optical Switch Based on Silicon Photonics

Abstract: We review the research progress of strictly nonblocking optical switches based on silicon photonics. We have developed a switch chip fabrication process based on a complementary metal-oxide-semiconductor pilot line and optical and electrical packaging technologies. We demonstrated all-paths transmission and switching of up to 32 input ports × 32 output ports with an average fiber-to-fiber insertion loss of 10.8 dB. Furthermore, we demonstrated an operating bandwidth wider than 100 nm for −30 dB crosstalk with double-Mach–Zehnder element switches in an 8 × 8 switch. For polarization-insensitive operation, we adopted a polarization diversity scheme and fabricated an 8 × 8 switch with fiber-based polarization-beam-splitters and two switch chips. The 8 × 8 switch exhibited a polarization-dependent loss of less than 0.5 dB. Moreover, an on-chip polarization diversity 8 × 8 switch integrated with polarization splitter rotators and two switch matrices on a single chip demonstrated a differential group delay less than 1 ps. Based on current technologies, we discuss the prospects for further port count expansion and remaining challenges for commercial deployment.

Performance of integrated optical switches based on 2D materials and beyond

Abstract: Applications of optical switches, such as signal routing and data-intensive computing, are critical in optical interconnects and optical computing. Integrated optical switches enabled by two-dimensional (2D) materials and beyond, such as graphene and black phosphorus, have demonstrated many advantages in terms of speed and energy consumption compared to their conventional silicon-based counterparts. Here we review the state-of-the-art of optical switches enabled by 2D materials and beyond and organize them into several tables. The performance tables and future projections show the frontiers of optical switches fabricated from 2D materials and beyond, providing researchers with an overview of this field and enabling them to identify existing challenges and predict promising research directions.

Tunable terahertz metamaterial for high-efficiency switch application

Abstract: We present two types of tunable terahertz (THz) metamaterials (TTM-1 and TTM-2) to explore their extraordinary optical properties. The proposed TTMs are composed of Au layers with 300 nm in thickness on Si substrates. The designs of TTMs exhibit superior properties in adjustability for high-efficiency THz switching characteristic. By changing the geometrical dimensions of TTMs, the corresponding electromagnetic responses could be tuned and switched between single-band and dual-band resonances. TTM-1 exhibits three switching windows with higher switching ratios by embedding different materials into the cavity underneath the complementary metamaterial. TTM-2 can be tuned to have two resonances and then merge into one resonance by increasing the height between the inner and outer rings. The transmission intensity of TTM-2 can be tuned from 0 to 0.7 at 0.57 THz by changing the sizes of inner and outer rings. TTM-2 exhibits tunable filter, single-/dual-band switch, tunable free spectrum range, and tunable bandwidth characteristics by varying the radius of the inner and outer rings. This study paves a way to the possibility of tunable high-efficiency switch, filter, polarizer, and other THz applications.

Dual-channel optical switch, refractive index sensor and slow light device based on a graphene metasurface

Abstract: In this paper, we propose a graphene-based metasurface that exhibits multifunctions including tunable filter and slow-light which result from surface plasmon polaritons (SPPs) of graphene and plasmon induced transparency (PIT), respectively. The proposed metasurface is composed by two pairs of graphene nano-rings and a graphene nanoribbon. Each group of graphene rings is separately placed on both sides of the graphene nanoribbon. Adjusting the working state of the nanoribbon can realize the functional conversion of the proposed multifunctional metasurface. After that, in the state of two narrow filters, we put forward the application concept of dual-channel optical switch. Using phase modulation of PIT and flexible Fermi level of graphene, we can achieve tunable slow light. In addition, the result shows that the graphene-based metasurface as a refractive index sensor can achieve a sensitivity of 13670 nm/RIU in terahertz range. These results enable the proposed device to be widely applied in tunable optical switches, slow light, and sensors.

High-responsivity graphene photodetectors integrated on silicon microring resonators

Abstract: Graphene integrated photonics provides several advantages over conventional Si photonics. Single layer graphene (SLG) enables fast, broadband, and energy-efficient electro-optic modulators, optical switches and photodetectors (GPDs), and is compatible with any optical waveguide. The last major barrier to SLG-based optical receivers lies in the low responsivity - electrical output per optical input - of GPDs compared to conventional PDs. Here we overcome this shortfall by integrating a photo-thermoelectric GPD with a Si microring resonator. Under critical coupling, we achieve $>$90% light absorption in a $\sim$6 $\mu$m SLG channel along the Si waveguide. Exploiting the cavity-enhanced light-matter interaction, causing carriers in SLG to reach $\sim$400 K for an input power of $\sim$0.6 mW, we get a voltage responsivity $\sim$90 V/W, demonstrating the feasibility of our approach. Our device is capable of detecting data rates up to 20 Gbit/s, with a receiver sensitivity enabling it to operate at a 10$^{-9}$ bit-error rate, on par with mature semiconductor technology. The natural generation of a voltage rather than a current, removes the need for transimpedance amplification, with a reduction of the energy-per-bit cost and foot-print, when compared to a traditional semiconductor-based receiver.

Ultracompact and low-power-consumption silicon thermo-optic switch for high-speed data

Abstract: Abstract Ultracompact and low-power-consumption optical switches are desired for high-performance telecommunication networks and data centers. Here, we demonstrate an on-chip power-efficient 2 × 2 thermo-optic switch unit by using a suspended photonic crystal nanobeam structure. A submilliwatt switching power of 0.15 mW is obtained with a tuning efficiency of 7.71 nm/mW in a compact footprint of 60 μm × 16 μm. The bandwidth of the switch is properly designed for a four-level pulse amplitude modulation signal with a 124 Gb/s raw data rate. To the best of our knowledge, the proposed switch is the most power-efficient resonator-based thermo-optic switch unit with the highest tuning efficiency and data ever reported.

Pump-Color Selective Control of Ultrafast All-Optical Switching Dynamics in Metaphotonic Devices.

Abstract: Incorporating active materials into metamaterials is expected to yield exciting advancements in the unprecedented versatility of dynamically controlling optical properties, which sheds new light on the future optoelectronics. The exploration of emerging semiconductors into terahertz (THz) meta-atoms potentially allows achieving ultrafast nanodevices driven by various applications, such as biomedical sensing/imaging, ultrawide-band communications and security scanners. However, ultrafast optical switching of THz radiation is currently limited to a single level of tuning speed, which is a main hurdle to achieve multifunctionalities. Here, a hybrid metadevice which can realize the pump-wavelength controlled ultrafast switching response by the functionalization of double photoactive layers is demonstrated experimentally. A whole cycle of electromagnetically induced transparency switching with a half-recovery state changes from 0.78 ns to 8.8 ps as pump wavelength varies from near infrared to near ultraviolet regions. The observed pump-color selective switching speed changing from nanosecond scale to picosecond scale is ascribed to the wavelength-dependent penetration length of Ge and the contrasting defect states between noncrystalline Ge and epitaxial Si layers. It is believed that the schemes regarding pump-color controllable ultrafast switching behavior introduced here can inspire more innovations across the field of ultrafast photonics and can boost the reconfigurable metamaterial applications.

Asymmetric optical camouflage: tuneable reflective colour accompanied by the optical Janus effect

Abstract: Going beyond an improved colour gamut, an asymmetric colour contrast, which depends on the viewing direction, and its ability to readily deliver information could create opportunities for a wide range of applications, such as next-generation optical switches, colour displays, and security features in anti-counterfeiting devices. Here, we propose a simple Fabry–Perot etalon architecture capable of generating viewing-direction-sensitive colour contrasts and encrypting pre-inscribed information upon immersion in particular solvents (optical camouflage). Based on the experimental verification of the theoretical modelling, we have discovered a completely new and exotic optical phenomenon involving a tuneable colour switch for viewing-direction-dependent information delivery, which we define as asymmetric optical camouflage. Applications including anti-counterfeiting measures may benefit from an optical device that encrypts information as viewpoint-dependent colours. Recent studies have shown that embedding metal nanoparticles within transparent materials can produce structural colours that appear differently when seen from the front or back. Yong-Sang Ryu from the Korea Institute of Science and Technology in Seoul and co-workers have now developed a simplified technique for tuning color output from these smart windows. The researchers created optical cavities by sandwiching a porous insulator between a reflecting layer and a film of gold nanoparticles. Dramatic color changes from both viewing directions were achieved by altering the cavity’s effective refractive index using surface modification and liquid infiltration. Engraved messages that were visible in air could be obscured on one side by submersing the windows into specific solvents.

Nonduplicate Polarization-Diversity 32 × 32 Silicon Photonics Switch Based on a SiN/Si Double-Layer Platform

Abstract: We fabricate and characterize a polarization-diversity 32 × 32 silicon photonics switch by newly introducing SiN overpass waveguides onto our nonduplicate polarization-diversity path-independent insertion-loss switch. The SiN overpass waveguides are used to simplify the optical paths with a uniform path length between the edge couplers and the switch matrix and significantly reduce the number of waveguide intersections. The switch chip is fabricated using a 300-mm silicon-on-insulator wafer pilot line. The fabricated switch comprises more than 7,600 components, making this the largest ever complementary-metal-oxide-semiconductor-based silicon photonics circuit. The switch chip is electrically and optically packaged and evaluated for a sampled port connection with 32 paths, with an average on-chip loss of ∼35 dB and an average polarization-dependent loss of 3.2 dB where 75% of the measured paths exhibit a loss of less than 3 dB. The differential group delay is measured to be 1.7 ps. The performance can be further improved by optimizing the device design.

Thermo-optical properties of binary one dimensional annular photonic crystal including temperature dependent constituents

Abstract: In this research article , we present theoretical and numerical investigations concerning the effects of temperature on the transmittance properties of one dimensional annular photonic crystals. The theoretical basis of our study adopts the modified transfer matrix method applied to optical fiber waveguides. The numerical results showed many features that could be of interest. In this regard , we investigate this design to enhance the values of sensitivity based on its geometry. Our design exhibits a remarkable response to temperature changes with a sensitivity of about 0.033 nm/°C which is considered significantly high . Also, it is found that the upper edge of the photonic band gap increases considerably with temperature changes, while the lower edge is almost unchanged . The effects of the core radius and number of periods on the transmittance of our annular photonic crystals design have been also investigated. It is found that an appropriate choice for the core would give flexibility of fabrication and stability of transmission output. In addition, this study reveals that the phase shift of the reflected cylindrical waves within the core is strongly dependent on temperature. We believe our structure is potentially promising in designing and fabrication of novel high-performance temperature sensors and integrated waveguide devices such as optical switches and filters.

Recent Advances of Spatial Self‐Phase Modulation in 2D Materials and Passive Photonic Device Applications

Abstract: Optical nonlinearity in 2D materials excited by spatial Gaussian laser beam is a novel and peculiar optical phenomenon, which exhibits many novel and interesting applications in optical nonlinear devices. Passive photonic devices, such as optical switches, optical logical gates, photonic diodes, and optical modulators, are the key compositions in the future all-optical signal-processing technologies. Passive photonic devices using 2D materials to achieve the device functionality have attracted widespread concern in the past decade. In this Review, an overview of the spatial self-phase modulation (SSPM) in 2D materials is summarized, including the operating mechanism, optical parameter measurement, and tuning for 2D materials, and applications in photonic devices. Moreover, some current challenges are also proposed to solve, and some possible applications of SSPM method are predicted for the future. Therefore, it is anticipated that this summary can contribute to the application of 2D material-based spatial effect in all-optical signal-processing technologies.

Ultrafast Optical Modulation of Harmonic Generation in Two-Dimensional Materials.

Abstract: The modulation of optical harmonic generation in two-dimensional (2D) materials is of paramount importance in nanophotonic and nano-optoelectronic devices for their applications in optical switching and communication. However, an effective route with ultrafast modulation speed, ultrahigh modulation depth, and broad operation wavelength range is awaiting a full exploration. Here, we report that an optical pump can dynamically modulate the third harmonic generation (THG) of a graphene monolayer with a relative modulation depth above 90% at a time scale of 2.5 ps for a broad frequency ranging from near-infrared to ultraviolet. Our observation, together with the real-time, time-dependent density functional theory (TDDFT) simulations, reveals that this modulation process stems from nonlinear dynamics of the photoexcited carriers in graphene. The superior performance of the nonlinear all-optical modulator based on 2D materials paves the way for its potential applications including nanolasers and optical communication circuits.

Photochromic Free MOF-Based Near-Infrared Optical Switch.

Abstract: We demonstrate herein an all-optical switch based on stimuli-responsive and photochromic-free metal-organic framework (HKUST-1). Ultrafast near-infrared laser pulses stimulate a reversible 0.4 eV blue shift of the absorption band with up to 200 s-1 rate due to dehydration and concomitant shrinking of the structure-forming [Cu2 C4 O8 ] cages of HKUST-1. Such light-induced switching enables the remote modulation of intensities of photoluminescence of single crystals of HKUST-1 as well visible radiation passing through the crystal by 2 order of magnitude. This opens up the possibility of utilyzing stimuli-responsive MOFs for all-optical data processing devices.

A Lateral MOS-Capacitor-Enabled ITO Mach–Zehnder Modulator for Beam Steering

Abstract: Here, we experimentally demonstrate an Indium Tin Oxide (ITO) Mach—Zehnder interferometer heterogeneously integrated in silicon photonics. The phase shifter section is realized in a novel lateral MOS configuration, which, due to favorable electrostatic overlap, leads to efficient modulation (VπL = 63 V.μm). This is achieved by (i) selecting a strong index changing material (ITO) and (ii) improving the field-overlap as verified by the electrostatic field lines. Furthermore, we show that this platform serves as a building block in an end-fire silicon photonics optical phased array (OPA) with a half-wavelength pitch within the waveguides with anticipated performance, including narrow main beam lobe ( 10 dB suppression of the side lobes, while electrostatically steering the emission profile up to ±80°, and if further engineered, can lead not only towards nanosecond-fast beam steering capabilities in LiDAR systems but also in holographic display, free-space optical communications, and optical switches.