Showing papers on "Optical switch published in 2004"

All-optical control of light on a silicon chip

Abstract: Photonic circuits, in which beams of light redirect the flow of other beams of light, are a long-standing goal for developing highly integrated optical communication components1,2,3. Furthermore, it is highly desirable to use silicon—the dominant material in the microelectronic industry—as the platform for such circuits. Photonic structures that bend, split, couple and filter light have recently been demonstrated in silicon4,5, but the flow of light in these structures is predetermined and cannot be readily modulated during operation. All-optical switches and modulators have been demonstrated with III–V compound semiconductors6,7, but achieving the same in silicon is challenging owing to its relatively weak nonlinear optical properties. Indeed, all-optical switching in silicon has only been achieved by using extremely high powers8,9,10,11,12,13,14,15 in large or non-planar structures, where the modulated light is propagating out-of-plane. Such high powers, large dimensions and non-planar geometries are inappropriate for effective on-chip integration. Here we present the experimental demonstration of fast all-optical switching on silicon using highly light-confining structures to enhance the sensitivity of light to small changes in refractive index. The transmission of the structure can be modulated by up to 94% in less than 500 ps using light pulses with energies as low as 25 pJ. These results confirm the recent theoretical prediction16 of efficient optical switching in silicon using resonant structures.

A fast low-power optical memory based on coupled micro-ring lasers.

Abstract: The increasing speed of fibre-optic-based telecommunications has focused attention on high-speed optical processing of digital information1. Complex optical processing requires a high-density, high-speed, low-power optical memory that can be integrated with planar semiconductor technology for buffering of decisions and telecommunication data2. Recently, ring lasers with extremely small size and low operating power have been made3,4,5,6,7, and we demonstrate here a memory element constructed by interconnecting these microscopic lasers. Our device occupies an area of 18 × 40 µm2 on an InP/InGaAsP photonic integrated circuit, and switches within 20 ps with 5.5 fJ optical switching energy. Simulations show that the element has the potential for much smaller dimensions and switching times. Large numbers of such memory elements can be densely integrated and interconnected on a photonic integrated circuit: fast digital optical information processing systems employing large-scale integration should now be viable.

Strong polarization in the optical transmission through elliptical nanohole arrays.

Abstract: Strong polarization dependence is observed in the optical transmission through nanohole arrays in metals. It is shown that the degree of polarization is determined by the ellipticity and orientation of the holes; the polarization axis lies perpendicular to the broad edge of the ellipse. Furthermore, the depolarization ratio shows a squared dependence on the aspect ratio of the holes, which is discussed in terms of coupling into and out of the surface plasmon modes. The observed results will be useful for tailoring the polarization behavior of metallic nanophotonic elements in many applications, including surface plasmon enhanced optical sensing and ultrafast optical switching.

Optical bistability on a silicon chip.

Abstract: We demonstrate, for the first time to our knowledge, optical bistability on a highly integrated silicon device, using a 5-microm-radius ring resonator. The strong light-confinement nature of the resonator induces nonlinear optical response with low pump power. We show that the optical bistability allows all-optical functionalities, such as switching and memory with microsecond time response and a modulation depth of 10 dB, driven by pump power as low as 45 microW. Silicon optical bistability relies on a fast thermal nonlinear optical effect presenting a 500-kHz modulation bandwidth.

Theory of optical signal amplification and processing by quantum-dot semiconductor optical amplifiers

Abstract: This work presents a theory of optical signal amplification and processing by quantum-dot semiconductor optical amplifiers (SOA's) based on the density matrix equations to treat electron-light interaction and the optical pulse propagation equations. The theory includes the linear optical response as well as the incoherent and coherent nonlinear response of the new devices with arbitrary spectral and spatial distribution of quantum dots in the active region under the multimode light. The incoherent nonlinear response was due to the incoherent spectral hole burning and the reduction in the carrier density by the stimulated emission. The coherent nonlinearity was due to the dynamic spectral hole burning caused by the population beating at the electronic states resonant to the multimode light and the carrier density pulsation caused by the carrier relaxation dynamics. Based on the theory, we numerically simulated the operation of quantum-dot SOA's, and succeeded in presenting their diverse promising features in a very systematical manner. We expect amplifiers with low power consumption, high saturation power, broad gain bandwidth, and pattern-effect-free operation under gain saturation, and also signal processing devices to realize high-speed (40 to 160 Gb/s) pattern-effect-free wavelength conversion by the cross-gain modulation with low frequency chirping and symmetric highly-efficient 1 to 2 THz wavelength conversion by the nondegenerate four-wave mixing. We point out that the nonlinear optical response due to the spectral hole burning plays a decisive role in the high-speed optical signal processing. Many of the theoretical predictions in this paper agree well with recent experimental demonstrations of device performance. This work will help not only design practical quantum-dot devices working in the photonic networks but also understand how carrier dynamics relates to the optical response of quantum dots with optical gain under current injection.

Linear and nonlinear optical properties of Ag-As-Se chalcogenide glasses for all-optical switching.

Abstract: We prepared Ag(x)(As0.4Se0.6)(100-x) chalcogenide glasses by a melt-quenching method and measured their linear and nonlinear optical properties to evaluate their potential applications to all-optical ultrafast switching devices. Their nonlinear refraction and absorption were measured by the Z-scan method at 1.05 microm. The addition of Ag to As2Se3 glass led to an increase in the nonlinear refractive index without introducing an increase in the nonlinear absorption coefficient. The glass with a Ag content of x = 20 at. % revealed high nonlinearity ranging from 2000 to 27,000 times that of fused silica, depending on the incident optical intensity.

All-optical switching on a silicon chip.

Abstract: We present an experimental demonstration of fast all-optical switching on a silicon photonic integrated device by employing a strong light-confinement structure to enhance sensitivity to small changes in the refractive index. By use of a control light pulse with energy as low as 40 pJ, the optical transmission of the structure is modulated by more than 97% with a time response of 450 ps.

Optical bistability in a three-level semiconductor quantum-well system

Abstract: Optical bistable behavior in a unidirectional ring cavity (or a Fabry–Perot cavity) containing a semiconductor quantum well, described as a three-level ladder-type system with similar transition energies, has been studied The system interacts with a strong driving field which is in two-photon resonance with the intersubband transition and thus simultaneously drives all three levels into phase-locked quantum coherence The threshold for switching to upper branch of the bistable curve is found to be reduced due to the presence of quantum interference Such system can be used for making efficient and fast all-optical switching devices

Methods and apparatus for sorting cells using an optical switch in a microfluidic channel network

Abstract: Apparatus and Methods are provided for a microfabricated fluorescence activated cell sorter based on an optical switch for rapid, active control of cell routing through a microfluidic channel network. This sorter enables low-stress, highly efficient sorting of populations of small numbers of cells (i.e., 1000-100,000 cells). The invention includes packaging of the microfluidic channel network in a self-contained plastic cartridge that enables microfluidic channel network to macro-scale instrument interconnect, in a sterile, disposable format.

Tunable optical switch using magnetic fluids

Abstract: With a tunable refractive index, magnetic fluid can be applied to the development of adjustable optical devices. In this work, a magnetic-fluid-based optical switch is designed and characterized. The optical switch is formed by sealing magnetic fluid between two glass prisms. When a light is incident to one side of one of the prisms, a reflected light from the magnetic fluid film comes out from the same prism, whereas a transmitted light through the film emits from the other prism. It was found that the intensity ratio of the reflected light to the transmitted light can be manipulated by varying the external magnetic field strength. This implies that the light intensity can be switched between two paths. The switching efficiency also depends on the incident angle of a light into the prism. We then theoretically derive the incident-angle dependent switching efficiency to clarify relevant physical mechanisms.

All-optical switching structure based on a photonic crystal directional coupler.

Abstract: A novel all-optical switching structure based on a photonic crystal directional coupler is proposed and analyzed. Efficient optical switching is achieved by modifying the refractive index of the coupling region between the coupled waveguides by means of an optical control signal that is confined in the central region. Small length (around 1.1 mm) and low optical power consumption (over 1.5 W) are the main features estimated for this switching structure.

Distributed and localized feedback in microresonator sequences for linear and nonlinear optics

Abstract: Sequences of optical microresonators can be used to construct densely integrated structures that display slow group velocity, ultrahigh or low dispersion of controllable sign, enhanced self-phase modulation, and nonlinear optical switching. We consider four archetypal geometries consisting of effectively one-dimensional sequences of coupled microresonators. Two of these cases exhibit distributed feedback such as is found in a traditional multilayered structure supporting photonic bandgaps. The other two exhibit localized feedback and resonant enhancement but are free from photonic bandgaps. All of these structures offer unique properties useful for controlling the propagation of light pulses on a chip.

All-optical wavelength conversion using a pulse reformatting optical filter

Abstract: We introduce a general concept for the design of all-optical wavelength converters with pulse reformatting functionality. The novel wavelength converters are based on a single semiconductor optical amplifier followed by an optical filter. A microelectromechanical system-based realization is shown and simultaneous 40 Gb/s wavelength conversion, switching and signal format conversion is demonstrated. The new pulse reformatting optical filter device outperforms current schemes with respect to input-power requirements, input-power dynamic range and signal quality.

Experimental demonstration of fiber-accessible metal nanoparticle plasmon waveguides for planar energy guiding and sensing

Abstract: Experimental evidence of mode-selective evanescent power coupling at telecommunication frequencies with efficiencies up to 75 % from a tapered optical fiber to a carefully designed metal nanoparticle plasmon waveguide is presented. The waveguide consists of a two-dimensional square lattice of lithographically defined Au nanoparticles on an optically thin silicon membrane. The dispersion and attenuation properties of the waveguide are analyzed using the fiber taper. The high efficiency of power transfer into these waveguides solves the coupling problem between conventional optics and plasmonic devices and could lead to the development of highly efficient plasmonic sensors and optical switches.

Ultrafast Optical Switches and Wavelength Division Multiplexing (WDM) Amplifiers Based on Bismuth Oxide Glasses

Abstract: Glasses with a high refractive index exhibit interesting properties. All optical switching and broadband amplification performances have been demonstrated using glasses based on bismuth oxide (Bi 2 O 3 ), Optical Kerr shutter (OKS) switching and degenerated four-wave mixing experiments for nonresonant-type Bi 2 O 3 -B 2 O 3 -SiO 2 glasses have been performed using femtosecond lasers. This glass exhibits an ultrafast response (<150 fs) in OKS operation. Moreover, terahertz-range (THz-range) optical switching has been successfully performed with this glass, using a 1.5-THz pulse train. Erbium-doped bismuth-based oxide glasses also have been prepared for wavelength division multiplexing (WDM) amplifiers. These glasses exhibit broadband emission and negligible concentration quenching, which indicates that the bismuth-based glass is suitable for broadband amplifiers and highly doped short-length fiber applications for metro use.

Optical phase modulators for MHz and GHz modulation in silicon-on-insulator (SOI)

Abstract: This paper reports the simulation of the direct current (dc), transient, and optical characteristics of low-loss single-mode optical phase modulators based on silicon-on-insulator (SOI) material. The devices operate by injecting free carriers to change the refractive index in the guiding region and have been modeled using the two-dimensional (2-D) device simulation package SILVACO and the optical simulator BeamPROP to determine their electrical and optical performance, respectively. These simulators have been employed to optimize the overlap between the injected free carriers in the intrinsic region and the propagating optical mode. Attention has been paid to both the steady state and transient properties of the device. In order to produce quantitative results, a particular p-i-n device geometry has been employed in the study, but the trends in the results are sufficiently general to be of help in the design of many modulator geometries. The specific example devices used are designed to support a single optical guided mode and are of approximately 1 mm in cross-sectional dimensions. The modeling results predict that the transient performance of the device is affected significantly by the contact width and the rib doping depth. Results presented encompass Gaussian and constant doping profiles in the n/sup +/ regions. The doping profile of the contacts has a tremendous effect on both the dc and transient performances. Phase modulators with drive currents as low as 0.5 mA and transient rise times of 0.3 ns and fall times of 0.12 ns are predicted. Following from these results, a realistic doping profile is proposed that surpasses the electrical results of the Gaussian and most of the constant doping profiles. The improvements in electrical device characteristics are at the expense of a slightly increased optical absorption loss. An alternative switching technique is also presented that could further improve the device speed.

Sub-/spl mu/s switching time in silicon-on-insulator Mach-Zehnder thermooptic switch

Abstract: We have demonstrated both rise and fall times below 1 /spl mu/s with 10%-90% modulation in a silicon-on-insulator thermooptical Mach-Zehnder switch. The switch is based on 9-/spl mu/m-thick and 10-/spl mu/m-wide single-mode rib waveguides. Very fast switching was achieved by using a differential control method. The switch was driven with a digital signal processor accompanied by simple electronic circuitry.

Optical signal processing based on self-induced polarization rotation in a semiconductor optical amplifier

Abstract: We demonstrate novel optical signal processing functions based on self-induced nonlinear polarization rotation in a semiconductor optical amplifier (SOA). Numerical and experimental results are presented, which demonstrate that a nonlinear polarization switch can be employed to achieve all-optical logic. We demonstrate an all-optical header processing system, an all-optical seed pulse generator for packet synchronization, and an all-optical arbiter that can be employed for optical buffering at a bit rate of 10 Gb/s. Experimental results indicate that optical signal processing functions based on self-polarization rotation have a higher extinction ratio and a lower power operation compared with similar functions based on self-phase modulation.

Electromagnetically actuated mirror arrays for use in 3-D optical switching applications

Abstract: This paper presents an electromagnetic MEMS mirror technology for use in 3-D optical switching applications. These mirrors may be actuated through large angles at low voltage and low current. Multiple coils on the backs of the mirrors interact with permanent magnetic fields to provide two-axis orthogonal actuation. A custom package brings the MEMS mirror array and magnets into close proximity. Actuation is linear versus drive current on both axes, and displays negligible charging and drift. These mirrors have achieved greater than 10/spl deg/ mechanical rotation per mA in each axis. The mirror rotation angle is hysteresis free to less than the 0.01/spl deg/ measurement accuracy.

Method and apparatus for controlling scanning of mosaic sensor array

Abstract: A scanning architecture that makes it possible to update only those ultrasonic transducer subelements of a mosaic transducer array that change from view to view. The configuration of the switch matrix is fully programmable. The switch matrix includes access switches that connect subelements to bus lines and matrix switches that connect subelements to subelements. Each subelement has a unit switch cell associated therewith, each unit switch cell comprising at least one access switch, at least one matrix switch, and addressing and control logic. Optionally, each unit switch cell also includes latches for storing the future switch states of the switches to be programmed. The switches themselves have memory for storing their current switch states.

High-frequency module and radio communication apparatus

Abstract: A high-frequency module comprises: a diplexer connected to an antenna terminal for branching a plurality of transmission/reception systems different in pass band from one another; switch circuits for switching the transmission/reception systems to transmission systems and reception systems; power amplifiers for amplifying transmission signals in the pass bands of the transmission systems; and matching circuits for matching the impedances of the power amplifiers to one another. The power amplifiers and the switch circuits are respectively formed by high-frequency semiconductor integrated circuit elements, and these high-frequency semiconductor integrated circuit elements are mounted on the surface of the multi-layer substrate. The high-frequency module is reduced both in size and loss and increased in isolation in its entirety.

Active vertical-coupler-based optical crosspoint switch matrix for optical packet-switching applications

Abstract: Packet-switching characteristics are optimized across an integrated 4 /spl times/ 4 optical crosspoint switch matrix consisting of active vertical-coupler-based switch cells. Optical gain difference between the shortest and the longest paths less than 3 dB is demonstrated. Bit error rate (BER) and power penalty measurements during packet routing have also been carried out over the entire 4 /spl times/ 4 matrix. At a 10-Gb/s packet data rate, a less than 1-dB power penalty is observed across the switch matrix, and the possibility for error-free packet routing is demonstrated with no BER floor observed.

Increasing the modulation bandwidth of semiconductor-optical-amplifier-based switches by using optical filtering

Abstract: A small-signal analysis of all-optical switches based on a single semiconductor optical amplifier followed by an optical filter is presented. Using the asymmetric Mach–Zehnder interferometer, which is the filter employed in the delayed-interference signal converter, as an example, we explain the principle of modulation bandwidth enhancement using optical filtering. We obtain analytical expressions for the optimum phase bias of the Mach–Zehnder interferometer filter and the resulting optical modulation bandwidth. By adopting a spectral approach, where the small-signal modulated field envelope is analyzed, we are able to generalize these results and calculate the bandwidth enhancement provided by an arbitrary filter.

Optical bridge for chip-to-board interconnection and methods of fabrication

Abstract: The present invention provides an optical bridge for interconnecting optical networking components and methods of making optical bridges that include a waveguide that are compatible with semiconductor processing steps. The optical bridge of the present invention has less optical losses and is less affected by misalignment that prior art interconnections. The waveguide is formed of a curable optical material that spans optically active areas of two components. In one embodiment of the present invention, one optical component is an optical circuit board and the connected optical component is an electro-optical integrated circuit package containing light emitting or light receiving elements. The method provides a curable optical liquid to the components, bringing the components together to form a continuous optical liquid between the components, and curing the optical liquid.

Polarization splitting grating couplers

Abstract: A polarization splitting grating coupler (PSGC) connects an optical signal from an optical element, such as a fiber, to an optoelectronic integrated circuit. The PSGC separates a received optical signal into two orthogonal polarizations and directs the two polarizations to separate waveguides on an integrated circuit. Each of the two separated polarizations can then be processed, as needed for a particular application, by the integrated circuit. A PSGC can also operate in the reverse direction, and couple two optical signals from an integrated circuit to two respective orthogonal polarizations of one optical output signal sent off chip to an optical fiber.

A microfluidic 2×2 optical switch

Abstract: A 2×2 microfluidic-based optical switch is proposed and demonstrated. The switch is made of an optically clear silicon elastomer, Polydimethylsiloxane (PDMS), using soft lithography. It has insertion loss smaller than 1 dB and extinction ratio on the order of 20 dB. The device is switching between transmission (bypass) and reflection (exchange) modes within less than 20 ms

Optical module and manufacturing method of the same, optical communication device, opto-electrical hybrid integrated circuit, circuit board, and electronic apparatus

Abstract: To provide an optical module capable of miniaturization, the optical module, to which an optical plug provided at one end of an optical transmission path is attached, so as to transmit and receive signal light via the optical transmission path for information communication, includes: a transparent substrate having light transmittance property with respect to a wavelength of used signal light; an optical socket, which is arranged on one surface side of the transparent substrate and to which the optical plug is attached; an optical element, which is arranged on the other surface side of the transparent substrate and emits the signal light to the one surface side of the transparent substrate according to a supplied electrical signal, or generates an electrical signal according to the intensity of the signal light supplied from the other surface of the transparent substrate; and a reflective portion, which is arranged on the other surface of the transparent substrate and changes a path of the signal light emitted from the optical element at substantially 90 degrees to guide it to the optical transmission path, or changes a path of the signal light emitted from the optical transmission path at substantially 90 degrees to guide it to the optical element.

Device based on coated nanoporous structure

Abstract: A nanostructured apparatus may include a mesoporous template having an array of regularly-spaced pores. One or more layers of material may conformally coat the walls to a substantially uniform thickness. Such an apparatus can be used in a variety of devices including optoelectronic devices, e.g., light emitting devices (such as LEDs, and lasers) and photovoltaic devices (such as solar cells) optical devices (luminescent, electro-optic, and magnetooptic waveguides, optical filters, optical switches, amplifies, laser diodes, multiplexers, optical couplers, and the like), sensors, chemical devices (such as catalysts) and mechanical devices (such as filters for filtering gases or liquids).

Ultrafast optoelectronic packet processing for asynchronous, optical-packet-switched networks [Invited]

Abstract: Feature Issue on Optical Interconnection Networks (OIN). We describe hybrid optical-electrical systems that perform header processing and buffering of ultrafast, asynchronous optical packets. Our systems are enabled by three key, novel devices: an all-optical serial-to-parallel converter, an optical clock-pulse generator, and a photonic parallel-to-serial-converter. These devices allow utilization of complementary metal-oxide semiconductor technology for compact, highly functional optical packet processing. A simplified node architecture for asynchronous, optical- packet-switched networks is made possible by these systems with all the necessary node functions integrated compactly. We also demonstrate an optical label swapper and a photonic random access memory for 40-Gbit/s, 16-bit, asynchronous optical packets.