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Presents a study that proposed a type of silicon guided-wave electro-optic modulator. Use of the impact-ionization mechanism for carrier generation by the modulator; Electrical and wave propagation properties of the modulator; Attainment of numerical estimates of phase modulation due to refractive-index change.

Presents a study that analyzed a structure of planar waveguide directional coupler/switch composed of gallium arsenide (GaAs)/AlGaAs. Background on the electro-optic directional coupler (EDC)/modulator; Examination of the operational characteristics of the proposed EDC/modulator in the AlGaAs-GaAs ternary system; Assessment of bandwidth and power consumption.

Abstract: In this paper we present a design as well as the fabrication procedure of a new type of electro-optical modulator based on plasma dispersion effect. The device consists from a regular single mode silicon waveguide and periodically patterned electrodes made out an indium thin oxide (ITO) located along both sides of the optical core through which the photonic signal is propagating. By applying voltage on the electrodes a periodic change in the free electrons is occurred along the optical core. This change affects both the imaginary and real part of the refractive index resulting in the generation of periodic change in the refractive index that creates an effective Bragg reflector. Different fabrication strategies are reported. [Copyright &y& Elsevier]

Abstract: By simultaneously using an electro-optic (EO) modulator and a single-walled carbon nanotube saturable absorber (SWCNT-SA) in the cavity, a diode-pumped doubly Q-switched Nd:Lu0.33Y0.37Gd0.3VO4 (Nd:LuYGdVO4) laser is demonstrated. At the incident pump power 11.43W and f=2kHz, the minimum pulse width 17.6ns and the maximum pulse peak power 19,886W can be obtained. The experimental results show that this doubly Q-switched Nd:LuYGdVO4 laser can generate shorter pulse width and higher peak power compared to the singly Q-switched Nd:LuYGdVO4 laser with only EO or SWCNT-SA. [Copyright &y& Elsevier]

Abstract: We investigated the characteristics of electro-optic modulators composed of ZnTe and CdTe. Their modulation depths below 100kHz depend both on wavelength and input light power. The characteristics are explained by considering both the photoconduction effect and the Schottky effect. To keep the modulation depth constant below 100kHz, the wavelength of the light should be long enough to suppress the photoconduction effect. Using the ZnTe electro-optic modulator, we developed a sensitive voltage sensor that has constant sensitivity from DC to 30MHz. Clear electrocardiograms can be obtained with the sensor. [Copyright &y& Elsevier]

Abstract: In this paper, we present the fabrication and preliminary measurements of a novel electro optical nano modulator on silicon chip based on light scattering by a movable 50nm charged gold colloid particle. The idea is to modulate the 1.55μm light by electrically manipulating the highly conductive particle in a nano air gap created in a silicon waveguide to cause high scattering and absorption. With a length of 150nm of the air gap, the expected modulation rates can exceed few GHz while being implemented on a highly dense silicon chip. [Copyright &y& Elsevier]

Numerical simulations are performed for SiGeC/Si electrooptic modulators and photodetectors operating at near-IR wavelengths. The addition of carbon provides the ability to lattice match layers with high germanium composition to silicon, which is shown to allow structures with a substantial increase in the optical confinement factor. In addition, SiGeC/Si heterostructures provide strong confinement of large electron and hole concentrations. The large optical confinement factor and strong carrier confinement enable broadband electrooptic modulators with sub-100 μm lengths and switching times below 0.5 ns with 25 mA current as well as photodetectors with quantum efficiencies as high as 90% for 300 μm length. [ABSTRACT FROM AUTHOR]

Proposes a new approach to investigating electromagnetic field in a semi-coaxial cavity loaded with a crystal. Approach based on the mathematical modeling of steady-state electromagnetic fields in electro-optic modulators and on the application of Rvachev R-functions; Formulation of the problem; Numerical experiment; A priori determination of the assigned structure of the resonance field for laser-beam modulators.

Microwave and optical properties of lithium niobate electrooptic modulators are investigated in this paper. The effect of simultaneous matching of optical and microwave velocities and impedance matching, conductor loss, dielectric loss on the optical bandwidth of an ultra-high-speed lithium niobate modulator are presented here. The metal electrode design, buffer thickness, ridge depth, and the gap between electrodes at different operating frequencies on device performance are thoroughly investigated by using the finite element method. [ABSTRACT FROM AUTHOR]

The 3D finite-difference time-domain (FDTD) method and the 2D quasi-static formulation have been used to calculate the characteristic impedance and the microwave effective index of coplanar waveguide structures on lithium niobate (LiNbO3) single-crystal substrates with a yttria-stabilized zirconia (YSZ) or SiO2 buffer layer. The results shown can be a good source to predict the modulator characteristics. The effects of the thin buffer layer and anisotropy of the LiNbO3 crystal (x-cut and z-cut) are discussed. The comparison between the FDTD and quasi-static results shows good agreement. In this paper, the efficient modeling technique of the FDTD method for the coplanar waveguide (CPW) structures based on an anisotropic substrate with a thin buffer layer is developed. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 39: 234–237, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11178 [ABSTRACT FROM AUTHOR]

A novel modeling approach for Mach–Zehnder electro-optic modulators (MZ–EOMs) in microwave optical systems is presented. MZ–EOM traveling-wave electrodes are fully characterized by an electrode transfer function (ETF) which considers internal design parameters. This ETF is approximated by the modulator electrical response that, jointly with the half-wave voltage at dc and the optical insertion loss, are the three parameters on which the model is based. Frequency- and time-domain models are provided. An excellent agreement between theoretical and experimental results validates the proposed modeling approach, useful in simulating microwave optical systems. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 85–90, 2001. [ABSTRACT FROM AUTHOR]

Presents a novel electrooptic phase modulator featuring lens modulation. Application to the electrooptic chirping compression method for ultrashort optical pulse generation; Diagram showing the basic structure of electrooptic lens modulation; Suitability for negative and positive group delay dispersion.

Reports on the results of an investigation to minimize the local electronics in particle detectors using electro-optical intensity modulators. Characterization of the optical modulator system; Performance characteristics of a detector signal transfer scheme; Use of the charge output from a proportional chamber.

In the growth of KDP single crystals by the temperature decrease method, the dimensions of equipment for the growth of the crystal whose dimensions are desired for type I and type II phase matching of SHG are discussed, where the (001) plate and (101) plate are used as seed crystals, respectively. It is shown that the equipment has the smallest dimensions in the growth of the crystals for type II with the seeds of the (101) plate. Then the large crystals are grown with the seeds of the (101) plate and their optical characteristics are described. [ABSTRACT FROM AUTHOR]

Analysis on the modified phase reversal structure of electro-optic modulators. Bandwidth of integrated electro-optic modulators; Electrode structure; Mathematical analysis using Newton's iteration method; Frequency response of electro-optic modulator; Half-wave voltage and the bandwidth to the half-wave voltage (BVR) ratio; Optimization of the overlap integral for each section of a phase reversal modulator; Conclusions.

An intrinsic mechanism of optical intensity modulation occurring in electro-optic devices such as field sensors and modulators under applied fields is described. The optical modulation results from interactions between internally generated Fizeau interference patterns and electro-optic effects within the nonlinear crystal. Our results indicate that when phase matched with the conventional polarimetric signal, the intrinsic modulation mechanism can nearly double device sensitivity. [ABSTRACT FROM AUTHOR]

The authors report on a hybrid cross-linked electro-optic (EO) polymer/sol-gel Mach-Zehnder waveguide modulator with a half wave voltage (Vπ) of 0.65 V at 1550 nm. The low Vπ was achieved by a design that (1) combines both physical vertical tapers in the sol-gel core and photobleached index tapers in the EO polymer and (2) reduces the thickness of the device to 8 μm. These combined physical and index tapers result in improved optical mode confinement in the EO polymer with low adiabatic optical transition loss. The reduced thickness results in a larger field across the EO polymer for the same voltage, enabling a lower Vπ. [ABSTRACT FROM AUTHOR]

A wide-bandwidth Mach–Zehnder traveling-wave electro-optic modulator was realized using novel low-loss slow-wave coplanar strips on a GaAs/AlGaAs substrate. Microwave characteristics of the device were measured up to 40 GHz. The microwave loss at 40 GHz is 7 dB/cm, and a phase velocity of 8.15 cm/ns was obtained. The device demonstrates a half-wave voltage of 20.5 V and an extinction ratio of 9.5 dB. A flat large-signal modulation response up to 22 GHz was measured. © 1998 John Wiley & Sons, Inc. Microwave Opt Technol Lett 19: 184–186, 1998. [ABSTRACT FROM AUTHOR]

Studies a electro-optic polymer-based integrated optic Mach-Zehnder modulator. Maximum measured frequency response; Half-wave voltage; Modulation depth; Observation of modulation using direct detection.

An electro-optical ring modulator, used as a cavity output coupler, has permitted simultaneous active mode locking, Q switching, and cavity dumping of a continuous-pumped neodymium:yttrium aluminum garnet laser. We have obtained output pulses of 4 MW peak power and 35 ps duration at repetition rates up to 2.5 kHz. [ABSTRACT FROM AUTHOR]

We report a 1.3-μm GaAs traveling-wave electro-optic waveguide modulator with a 3-dB optical bandwidth in excess of 20 GHz. The bandwidth was determined by directly detecting the modulated optical signal with a high-speed InP/GaInAs photodiode. The modulator has a coplanar strip electrode configuration with a double heterojunction Al0.032Ga0.968As/GaAs/Al0.032Ga0.968As optical guide grown by low-pressure organometallic vapor phase epitaxy. [ABSTRACT FROM AUTHOR]

Demonstrates the fabrication and characterization of a high frequency traveling wave electro-optic phase modulator using cross-linked nonlinear optical polymer. Use of a threelayer structure with an integrated line circuit; Definition of the straight channel optical waveguides; Observation of optical modulation on a spectrum analyzer.

Presents improvements in strain-balanced indium gallium arsenide/gallium arsenide electro-optic effect device modulators. Absorption peak of the device; Use of the indium gallium arsenide/gallium arsenide multiple quantum well; Application of a 13-V reverse bias to obtain a single pass modulation contrast ratio.

Demonstrates a bistable self-electro-optic device (SEED) using Franz-Keldysh effects in an asymmetric Fabry-Perot optical modulator device. Observation on the contrast and reflectivity characteristics by the modulator; Provision of negative differential responsivity for SEED operation; Description of the photodetector used.

Investigates the electroabsorption in InGaAsP, bistable optical switches and electro-optical modulators. Comparison of absorption alteration values with the quantum-confined Stark effect; Observation of optical bistability; Determination of the absorption spectra.

Presents an all-polyimide system suitable for fabrication of electro-optic wave guide devices on silicon substrates. Source of cladding layers; Components of the electro-optic material; Fabrication of an all-polyimide Mach-Zehnder modulator.

A novel coplanar-strip (CPS) slow-wave structure for use in compound semiconductor electro-optic modulators is presented. The device uses interdigitated fins and pads to reduce the microwave phase (and group) velocity to match the speed of light in the optical waveguides, and thus to increase the bandwidth of such modulators well into the millimeter-wave range. These structures were fabricated on semiinsulating (SI) GaAs and show an electrical bandwidth in excess of 40 GHz. The effects on the microwave performance of the CPS slow-wave structures due to the presence of a thin layer of SiO2 (0.2 μm) between the SI GaAs and the metal structures, as well as the presence of the optical ridge waveguide (0.9 μm deep) were also investigated. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 15: 303–305, 1997. [ABSTRACT FROM AUTHOR]

A method for separating the propagation loss, the reflection loss, and the coupling loss in a pigtailed integrated electro-optic modulator is proposed. This method is based on the measurement of the reflected and transmitted powers at the input and output ports of the device at its on and off states, respectively. Experimental results are presented for a Mach-Zehnder modulator. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 14:305–307, 1997. [ABSTRACT FROM AUTHOR]

The N-over-N cascode push-pull modulator driver is demonstrated at 20 Gbit/s with IBM 130 nm technology. Electro-optical measurement of the modulator driver integrated with a Mach-Zehnder modulator (MZM) is also presented. This modulator driver achieves 50 Ω output impedance matching (for the MZM) with on-chip termination. The power consumption of the modulator driver is 312 mW and the output swing is 3.4 Vpp on the differential. [ABSTRACT FROM AUTHOR]

A widely tunable microwave photonic (MWP) notch filter with high linearity based on a dual-parallel Mach—Zehnder modulator (DPMZM) is proposed and experimentally demonstrated. The motivation of this work lies in the fact that the MWP notch filter previously reported has nonlinear distortions generally induced by the nonlinear property of electro-optic devices. In this scheme, even-order modulated sidebands at the DPMZM output are effectively suppressed by properly adjusting bias voltages of the DPMZM, which are the dominant factor to induce the nonlinear distortions into the MWP notch filter. The proposed scheme is theoretically analyzed and experimentally verified. [ABSTRACT FROM AUTHOR]

In a quantum key distribution system, it is crucial to keep the extinction ratio of the coherent pulses stable. This means that the direct current bias point of the electro—optic modulator (EOM) used for generating coherent pulses must be locked. In this paper, an autobias control system based on a lock-in-amplifier for the EOM is introduced. Its drift information extracting theory and control method are analyzed comprehensively. The long term drift of the extinction ratio of the coherent pulses is measured by a single photon detector, which indicates that the autobias control system is effective for stabilizing the bias point of the EOM. [ABSTRACT FROM AUTHOR]

Reports on the development of a silicon-based electro-optical modulator by Intel Corp. as of April 2004. Factor which affect the ability of silicon to modulate light; Features of the silicon-based electro-optical modulator which need to be improved; Potential significance of the device to the semiconductor industry.

We have demonstrated a polymeric electro-optic modulator based on a 1x2 Y-fed directional waveguide coupler. The symmetric geometry of the 1x2 Y-fed directional coupler provided the modulator unique characteristics of intrinsic 3 dB operating point and two complementary output ends. A low switching voltage of 3.6 V and a high extinction ratio of 26 dB were obtained with the modulator operating at a wavelength of 1.34 μm. The modulator was fabricated with a novel electro-optic polymer that was synthesized from polyurethane cross-linking with a chromophore. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]