Multifunctional disk device for optical switch and temperature sensor

A multifunctional surface plasmon polariton disk device coupled by two metal-insulator-metal（MIM） waveguides is proposed and investigated numerically with finite-difference time-domain simulation. It can be used as optical switch and temperature sensor by filling disk with liquid crystal and ethanol, respectively. The simulation results demonstrate that the transmission characteristics of an optical switch can be manipulated by adjusting the radius of disk and the slit width between disk and MIM waveguides. The transmittance and modulation depth of optical switch at 1550 nm are up to 64.82% and 17.70 d B, respectively. As a temperature sensor, its figure of merit can reach 30.46. In this paper, an optical switch with better efficiency and a temperature sensor with better sensitivity can be achieved.

Sub-nanosecond optical switch based on silicon racetrack resonator

We experimentally demonstrate a small-size and high-speed silicon optical switch based on the free carrier plasma dispersion in silicon. Using an embedded racetrack resonator with a quality factor of 7400, the optical switch shows an extinction ratio exceeding 13 dB with a footprint of only 2.2 × 10-3 mm^2. Moreover, a novel pre-emphasis technique is introduced to improve the optical response performance and the rise and the fall times are reduced down to 0.24 ns and 0.42 ns respectively, which are 25% and 44% lower than those without the pre-emphasis.

Observation of V-type electromagnetically induced transparency and optical switch in cold Cs atoms by using nanofiber optical lattice

Optical nanofiber(ONF)is a special tool to achieve the interaction between light and matter with ultralow power.In this paper,we demonstrate V-type electromagnetically induced transparency(EIT)in cold atoms trapped by an ONFbased two-color optical lattice.At an optical depth of 7.35,90%transmission can be achieved by only 7.7 pW coupling power.The EIT peak and linewidth are investigated as a function of the coupling optical power.By modulating the pWlevel control beam of the ONF-EIT system in sequence,we further achieve efficient and high contrast control of the probe transmission,as well as its potential application in the field of quantum communication and quantum information science by using one-dimensional atomic chains.

Fabrication of high-quality colloidal photonic crystals with sharp band edges for ultrafast all-optical switching

Application of the pressure controlled isothermal heating vertical deposition method to the fabrication of colloidal photonic crystals is systematically investigated in this paper. The fabricated samples are characterized by scanning electron microscope and transmission spectrum. High-quality samples with large transmissions in the pass bands and the sharp band edges are obtained and the optimum growth condition is determined. For the best sample, the transmission in the pass bands approaches 0.9 while that in the band gap reaches 0.1. More importantly, the maximum differential transmission as high as 0.1/nm is achieved. In addition, it is found that the number of stacking layers does not increase linearly with concentration of PS spheres in a solution, and a gradual saturation occurs when the concentration of PS spheres exceeds 1.5 wt.%. The uniformity of the fabricated samples is examined by transmission measurements on areas with different sizes. Finally, the tolerance of the fabricated samples to baking was studied.

Optical switching based on the manipulation of microparticles in a colloidal liquid using strong scattering force

This paper demonstrates the realization of an optical switch by optically manipulating a large number of polystyrene spheres contained in a capillary. The strong scattering force exerted on polystyrene spheres with a large diameter of 4.3 μm is employed to realize the switching operation. A transparent window is opened for the signal light when the polystyrene spheres originally located at the beam centre are driven out of the beam region by the strong scattering force induced by the control light. The switching dynamics under different incident powers is investigated and compared with that observed in the optical switch based on the formation of optical matter. It is found that a large extinction ratio of - 30 dB and fast switching-on and switching-off times can be achieved in this type of switch.

Electrically controlled optical switch in the hybrid opto-electromechanical system

To promote the future quantum information technologies, we demonstrate an electrically driven optical switch based on quantum interference in a hybrid opto-electromechanical system, which consists of an opto-mechanical cavity and an external electric circuit. The key element of our scheme is a moveable mirror of cavity as a charged mechanical oscillator capacitively coupled to a fixed charged plate in a variable capacitor. By adjusting the voltage of the capacitor, the displacement of the moveable mirror is modulated, then the cavity field can be electrically turned on or off due to the detuning of the cavity. Based on the cavity induced transparency, the transparency window can be electrically switched on or off by turning on or off the cavity field. Therefore, the susceptibility of the medium in the cavity can be electrically controlled, i.e., the scheme of the electrically controlled absorption switching can be demonstrated. This electrically driven optical switch will excite a development trend and implementation prospect towards the integration and miniaturization of quantum module device in a chip.

Ferroelectric Liquid Crystal Optical Switches

The dynamic response of molecular orientation, and the temperature and pulse shape dependences of the switching behavior in ferroelectric liquid crystal are described. The switching speed and the surface energy of ferroelectric liquid crystal are given.

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

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.

A 7-bit photonic true-time-delay system based on an 8×8 MOEMS optical switch

We demonstrate a 7-bit photonic true-time-delay （TTD） system which uses an 8 × 8 micro-optical-electro- mechanical system （MOEMS） optical switch for phased array antennas （PAAs） beamforming applications. The switch controls the optical signal to pass by the fiber delay lines （FDLs） of different lengths. Different time delays between adjacent channels are obtained due to the chromatic dispersion of FDLs. Therefore, the system cannot be disturbed by the environment. The measured time delay responses are nearly linear with the wavelength spacing between optical carriers as well as the lengths of FDLs, which agrees well with the theoretical analysis.

Integrated optical switch matrices for packet data networks

Integrated circuit technologies are enabling intelligent,chip-based,optical packet switch matrices.Rapid real-time reconfigurability at the photonic layer using integrated circuit technologies is expected to enable cost-effective,energy-efficient,and transparent data communications.InP integrated photonic circuits offer high-performance amplifiers,switches,modulators,detectors,and de/multiplexers in the same wafer-scale processes.The complexity of these circuits has been transformed as the process technologies have matured,enabling component counts to increase to many hundreds per chip.Active–passive monolithic integration has enabled switching matrices with up to 480 components,connecting 16 inputs to 16 outputs.Integrated switching matrices route data streams of hundreds of gigabits per second.Multi-path and packet time-scale switching have been demonstrated in the laboratory to route between multiple fibre connections.Wavelength-granularity routing and monitoring is realised inside the chip.In this paper,we review the current status in InP integrated photonics for optical switch matrices,paying particular attention to the additional on-chip functions that become feasible with active component integration.We highlight the opportunities for introducing intelligence at the physical layer and explore the requirements and opportunities for cost-effective,scalable switching.

Orbital-angular-momentum-based reconfigurable optical switching and routing

Orbital angular momentum(OAM) has gained interest due to its potential to increase capacity in optical communication systems as well as an additional domain for reconfigurable networks. This is due to the following:(i) coaxially propagated OAM beams with different charges are mutually orthogonal,(ii) OAM beams can be efficiently multiplexed and demultiplexed, and(iii) OAM charges can be efficiently manipulated. Therefore, multiple data-carrying OAM beams could have the potential capability for reconfigurable optical switching and routing. In this paper, we discuss work involving reconfigurable OAM-based optical add/drop multiplexing, space switching,polarization switching, channel hopping, and multicasting.

4×4 nonblocking optical switch fabric based on cascaded multimode interferometers

We experimentally demonstrate a 4 × 4 nonblocking silicon thermo-optic(TO) switch fabric consisting of three stages of tunable generalized Mach–Zehnder interferometers. All 24 routing states for nonblocking switching are characterized. The device's footprint is 4.6 mm × 1.0 mm. Measurements show that the worst cross talk of all switching states is-7.2 dB. The on-chip insertion loss is in the range of 3.7–13.1 dB. The average TO switching power consumption is 104.8 mW.

Numerical investigations of an optical switch based on a silicon stripe waveguide embedded with vanadium dioxide layers

A novel scheme for the design of an ultra-compact and high-performance optical switch is proposed and investigated numerically. Based on a standard silicon(Si) photonic stripe waveguide, a section of hyperbolic metamaterials(HMM) consisting of 20-pair alternating vanadium dioxide (VO_2)∕Si thin layers is inserted to realize the switching of fundamental TE mode propagation. Finite-element-method simulation results show that, with the help of an HMM with a size of 400 nm × 220 nm × 200 nm(width × height × length), the ON/OFF switching for fundamental TE mode propagation in an Si waveguide can be characterized by modulation depth(MD) of5.6 d B and insertion loss(IL) of 1.25 dB. It also allows for a relatively wide operating bandwidth of 215 nm maintaining MD > 5 dB and IL < 1.25 dB. Furthermore, we discuss that the tungsten-doped VO_2 layers could be useful for reducing metal-insulator-transition temperature and thus improving switching performance. In general, our findings may provide some useful ideas for optical switch design and application in an on-chip all-optical communication system with a demanding integration level.

Thermal effect analysis of silicon microring optical switch for on-chip interconnect

The silicon microring resonator plays an important role in large-scale,high-integrability modern switching matrixes and optical networks,as silicon photonics enables ring resonators of an unprecedented compact size.But as the nature of resonators is their sensitivity to temperature,their performances are vulnerable to being affected by thermal effect.In this paper,we analyze the dominant thermal effects to the application of silicon microring optical switch.On the one hand we theoretically analyze and experimentally measure the thermal crosstalk among adjacent microring optical switches with different distances,and give possible solutions to minimize the affect of thermal crosstalk.On the other hand we analyze and measure the thermooptic dynamic response of microring switch;the experiment shows for the thermal-tuning that the rising edge is around 2/is,and the falling edge is around 35 μs.We give the explanation of the asymmetric rise-time and fall-time.

Analysis of S-SEED’s characteristics in optical switch

This article introduces the basic structure of a symmetric self-electrooptic effect device （S-SEED）, and applies the Kirchoff＇ s current law and a purely equivalent capacitive model, to analyze S-SEED＇s switch characteristics. Linear approximation and N-segment approximation are utilized to obtain S-SEED＇s voltage-time （V-T） and characteristics. Theoretical analysis is verified by simulations, and the results demonstrate that the precision of S-SEED＇s switch time can satisfy the requirement in applications with linear approximation. Moreover, the simulations compare S-SEED＇s switch characteristics with different input powers and input contrast ratios, which reveal that increasing input contrast ratio is an effective way to improve S-SEED＇s switch characteristics.

Suspended twin-core f iber for optical switching

A kind of novel fiber, comprising two fiber cores which are suspended in air inside the outer cladding via a central thin membrane ,is proposed for optical switching application. When a hydrostatic pressure applied on the optical fiber, the pressure-induced refractive index change of the two fiber cores will contribute to the periodical change of the intensity of guided light in the fiber core. The mode coupling of two cores under different hydrostatic pressure and influences of each structure parameter of the proposed fiber on the switching nressure have been numerically invo.stigated.

MEMS Torsion-Mirror Actuators for Optical Switching or Attenuating Applications

Novel MEMS torsion-mirror actuators with monolithically integrated fiber self-holding structures are fabricated, and investigated experimentally and theoretically. Their electromechanical and optical characteristics are acceptable for optical switching or attenuating applications.

Optimization of Waveguide Structure for Tunable Optical Switch in Si/SiGe System

A new electro-optical device using Si/SiGe-system with two parallel ridge waveguides is proposed for optical switching and the optimization of the structure for a single mode operation is investigated.

Optimizing Fiber Topologies for WDM Optical Networks Based on Multi-Granularity Optical Switching Technology

For the quality of service （QoS） and fairness considerations, the hop counts of various lightpaths in a wavelength division multiplexing （WDM） optical network should be short and compact. The development of multi-granularity optical switching technology has made it possible to construct various fiber topologies over a fixed physical topology. This paper describes a fiber topology design （FTD） problem, which minimizes the maximum number of required fibers in the physical links for a maximum lightpath hop count in the fiber topology. After the formular description for the FTD problem, a method was given to obtain the lower bound on the maximum number of required fibers. For large or moderate scale networks, three heuristic algorithms are given to efficiently solve the FTD problem. This study gives a new way to optimize the resource configuration performance in WDM optical networks at the topology level and proves its effectiveness via both analyses and numerical experiments.