Parallel processing for multiplication modulo by means of phase modulation

A coherent laser phase shift range finder based on optical phase modulation and phase shift measurement can measure distance and velocity precisely at the same time. In this paper, methods to improve the sensitivity of the range finder is presented. Matched filter algorithm is used to calculate the range velocity in frequency domain. Experiment is conducted at different signal power. The relationship between RMSE of measured range, as well as measured velocity, and the signal power is shown in the result.

In this paper, we present a theory of an optical fiber acoustooptic phase modulator using piezoelectric zinc oxide (ZnO) coating. The effects of changing device parameters in the acoustooptic resonator are investigated for transducer design. These results are entirely different from those of the well-known; planar device structure since every part plays an important role in the resonator structure. Optical phase modulation in the frequency region up to 1 GHz is also demonstrated. Multiple sharp resonance peaks with a maximum phase shift of 0.7 radians are observed.

We studied the effect of varying gas concentration, buffer gas, length, and type of fibers on the performance of optical fiber photothermal phase modulators based on C2H2-filled hollow-core fibers. For the same control power level, the phase modulator with Ar as the buffer gas achieves the largest phase modulation. For a fixed length of hollow-core fiber, there exists an optimal C2H2 concentration that achieves the largest phase modulation. With a 23-cm-long anti-resonant hollow-core fiber filled with 12.5% C2H2 balanced with Ar, phase modulation of π-rad at 100 kHz is achieved with a control power of 200 mW. The modulation bandwidth of the phase modulator is 150 kHz. The modulation bandwidth is extended to ∼1.1 MHz with a photonic bandgap hollow-core fiber of the same length filled with the same gas mixture. The measured rise and fall time of the photonic bandgap hollow-core fiber phase modulator are 0.57 µs and 0.55 µs, respectively.

A novel calibration-free electrical spectrum analysis method for microwave characterization of electrooptic phase modulators is proposed and experimentally demonstrated based on frequency-shifted optical heterodyning. The method achieves the electrical domain measurement of the modulation efficiency of phase modulators without the need for correcting the responsivity fluctuation in the photodetection. Moreover, it extends double the measuring frequency range through setting a specific frequency relationship between the driving microwave signals. Modulation depth and half-wave voltage of phase modulators are experimentally extracted from the heterodyning spectrum of two phase-modulated signals with and without frequency shifting, and the measured results are compared to those obtained with the traditional optical spectrum analysis method to check the consistency. The proposed method provides calibration-free and accurate measurement for high-speed optical phase modulators with the high-resolution electrical spectrum analysis.

A photonic technique for microwave frequency measurement based on stimulated Brillouin scattering (SBS) with low measurement error and large measurement range is demonstrated. In the scheme, an optical phase modulator is employed and the intensity balance between the two sidebands of the phase-modulated signal is broken by use of SBS in a fibre. The frequency measurement is achieved by detecting the existence of a microwave signal after photoelectric detection of the phase modulated signal. The measurement error is experimentally shown to be 50 MHz in a narrow measuring range of ∼1 GHz and 100 MHz in a wide range of 20 GHz.

Recently, Si-photonics received a growing interest and started to move from laboratories to industrial product development, mainly for the applications inside data-centers. One of the weaknesses of Si is its relatively low plasma dispersion efficiency, making the size of phase modulator large. This efficiency can be improved by using the heterogeneous integration of material such as InP, InGaAsP, or SiGe to fabricate hybrid semiconductor–insulator–semiconductor (SIS) optical phase modulators. At the same time, the standard figure of merit for modulator benchmarking $V_{\pi }L_{\pi }$ does not consider the dynamic behavior of the SIS devices, nor is making the link with the system level specifications such as optical modulation amplitude (OMA), widely used in 100G to 400G parallel single mode or coarse wavelength division multiplexing applications. In this paper, we propose to simply link the modulator performance to the OMA, to derive a compact model for SIS devices and to compare hybrid device performances for various materials.

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Recently, optical phase modulation has been widely used in microwave photonics (MWP) systems, such as radio over fiber systems, photonic microwave filters, optical microwave and millimeter-wave signal generators, and optical subcarrier frequency up-converters. An optical phase-modulated signal can be converted to an intensity-modulated signal in a dispersive optical fiber. Due to the intrinsic nonlinearity of optical phase modulation, for linear applications such as microwave signal distribution and filtering, the modulation index should be kept small to minimize the unwanted modulation nonlinearity. However, for nonlinear applications such as microwave frequency multiplication and subcarrier frequency upconversion, the modulation index should be large to maximize the frequency multiplication and upconversion efficiency. In this paper, for the first time to our knowledge, we develop a thorough theoretical framework for the characterization of phase-modulation-based MWP systems, in which the phase modulation to intensity modulation conversion is realized using a dispersive fiber. Analytical models for the distributions of single-tone and two-tone microwave signals and for microwave frequency multiplication and subcarrier frequency upconversion are developed, which are verified by numerical simulations. The analytical models for single-tone and two-tone transmissions are further confirmed by experiments. The developed analytical models provide an accurate mathematical tool in designing phase-modulation-based MWP systems. </para>

We have designed and constructed a column parallel vision (CPV) system to realize an intelligent and general purpose image processing system with higher frame rate within 1 millisecond. The system consists of an original designed photo detector array (PDA) with high frame rate, a parallel processing unit with fully parallel processing elements (PEs), and a controller for PDA and PEs. The column parallel architecture enables the PDA 1 millisecond frame rate with 256 analog levels which is required for industrial image processing and measurements. The parallel processing unit has been fabricated by using FPGAs and has 128 X 128 PEs to perform the fully parallel image processing. The PEs have the S<SUP>3</SUP>PE architecture which has SIMD type parallel processing flow, and was constructed only 500 transistors suitable for integration in future. Since the PEs are operated by control signal from the controller, we can achieve desired image processing task to the system by changing the software. We have demonstrated that the system can be worked as a tracking system. The experimental results show the system was realized high speed feedback loop as 1000 frame/s including the tracking operation with noise reduction, matching (self-window algorithm) and moment calculation.

A proposed method of secondary phase modulation for open-loop fiber-optic gyroscopes is examined in general terms. To detect the rotation rate of a system through a beat-frequency channel, we employ linearly combined signals with different frequencies for the optical phase modulation. We find that the proper combinations of the modulation frequencies can optimize the sensitivity of gyroscopes. With this method we can employ a high-frequency band for optical phase modulations while keeping relative a lower-frequency band of the detection channel. The theoretically derived result is experimentally confirmed by using a lithium-niobate (LiNbO(3)) optical phase modulator. We also discuss the combination setup with an optical integrated-circuit device and digital signal processing.

In this study, the potential of employing SiNx (silicon nitride) waveguide platforms to enable the use of liquid-crystal-based phase shifters for on-chip optical modulators was thoroughly investigated using 3D-FDTD (3D finite-difference time-domain) simulations. The entire structure of liquid-crystal-based Mach–Zehnder interferometer (MZI) optical modulators, consisting of multi-mode interferometer splitters, different tapering sections, and liquid-crystal-based phase shifters, was systematically and holistically investigated with a view to developing a compact, wideband, and CMOS-compatible (complementary metal-oxide semiconductor) bias voltage optical modulator with competitive modulation efficiency, good fabrication tolerance, and single-mode operation using the same SiNx waveguide layer for the entire device. The trade-off between several important parameters is critically discussed in order to reach a conclusion on the possible optimized parameter sets. Contrary to previous demonstrations, this investigation focused on the potential of achieving such an optical device using the same SiNx waveguide layer for the entire device, including both the passive and active regions. Significantly, we show that it is necessary to carefully select the phase shifter length of the LC-based (liquid crystal) MZI optical modulator, as the phase shifter length required to obtain a π phase shift could be as low as a few tens of microns; therefore, a phase shifter length that is too long can contradictorily worsen the optical modulation.

Multifrequency Spin Wave Device for Parallel Data Processing using Micro Structured Yttrium Iron Garnet Thin Films

A fiber optic phase and polarization modulator is presented in which a thin transparent piezoelectric polyvinylidene fluoride film with indium tin oxide electrode metallization is placed directly in the path of the output of a single mode fiber. Experimental characterization is presented in terms of the linearity of response, phase shifting coefficient, and frequency response for two arrangements differing in the boundary clamping conditions. Many applications to fiber optic switches, intensity modulators and demultiplexers are indicated.

The effect of periodic phase modulation of light on a chaotic external-cavity semiconductor laser working in a regime of low-frequency fluctuations (LFFs) is studied numerically. It is observed that the phase modulation changes the time period between consecutive dropouts in the emitted laser intensity. A new variable ΦL is defined as the phase of the laser's LFFs, which increases in time with 2π after each power dropout event. The phase ΦPM of the periodic phase modulator is unfolded on the real axis and increases linearly at a rate given by the modulating frequency. It is shown that the phase difference between the laser and the modulator ΔΦ(t)=mΦL(t)−nΦPM(t), where m and n are integers, remains constant in time, leading to phase-synchronized states, for specific values of the modulating frequency and amplitude.

The multidimensional nonlinear Schrodinger equation governs the spatial and temporal evolution of an optical field inside a nonlinear dispersive medium. Although spatial (diffractive) and temporal (dispersive) effects can be studied independently in a linear medium, they become mutually coupled in a nonlinear medium. We present the results of numerical simulations showing this spatiotemporal coupling for ultrashort pulses propagating in dispersive Kerr media. We investigate how spatiotemporal coupling affects the behavior of the optical field in each of the four regimes defined by the type of group-velocity dispersion (normal or anomalous) and the type of nonlinearity (focusing or defocusing). We show that dispersion, through spatiotemporal coupling, can either enhance or suppress self-focusing and self-defocusing. Similarly, we demonstrate that diffraction can either enhance or suppress pulse compression or broadening. We also discuss how these effects can be controlled with optical phase modulation, such as that provided by a lens (spatial phase modulation) or frequency chirping (temporal phase modulation).

Cloud computing is a technology in which the Cloud Service Providers (CSP) provide many virtual servers to the users to store their information in the cloud. The faults occurring on the assignment and dismission of the virtual machines, the processing cost in the allocation of resources must also be considered. The parallel processing of the information on the virtual machines must be done effectively and in an efficient manner. A variety of systems were developed to facilitate Many Task Computing (MTC). These systems aim to hide the issues of parallelism and fault tolerant and they are used in many applications. In this paper, we introduced Nephele, a data processing framework to exploit dynamic resource provisioning offered by IaaS clouds. The performance evaluation of the virtual machines has been evaluated and the allocation and deallocation of job tasks to the specific virtual machines has also been considered. A performance comparison with the well known data processing framework hadoop has been done. Thus this paper tells about the effective and efficient manner of processing the data by parallel processing and allocating the correct resources for the desired task. It also helps to reduce the cost of resource utilization by exploiting the dynamic resource utilization.