Epitaxial liftoff microcavities for 1.55-μm quantum-well spatiallight modulators

Microcavities operating at 1.55 μm have been realized according to the epitaxial liftoff (ELO) technique. The process is described and characterized. No significant variation of the optical properties of the grafted devices has been found. The technique is then applied to a spatial light modulator made by inserting a 3-μm multiple-quantum-well device in a short asymmetric Fabry-Perot microcavity. An enhancement by a factor 1000 of the performances of the switching component is obtained. The input diffraction efficiency reaches 2% in a degenerated four wave mixing configuration with a pulse energy of 1 μJ/cm² and without any applied electric field     

An efficient ATM voice service with flexible jitter and delayguarantees

A transmission and multiplexing strategy appropriate for voice over asynchronous transfer mode (ATM), called delayed frame queueing (DFQ), is proposed. This frame-based strategy has features in common with the synchronous transfer mode and is thus well suited to service synchronous applications such as voice, while retaining the statistical multiplexing capabilities of ATM. In particular, the DFQ service discipline can provide explicit and nontrivial bounds for queue delay and jitter, for both bursty as well as continuous traffic streams. Furthermore, the DFQ discipline can combine a wide range of delay and jitter bounds while also managing the distribution of quality of service violations among the traffic streams when congestion occurs. Jitter control is performed at the network periphery and thus does not negatively influence multiplexing gain at intermediate nodes. This efficient strategy has major implications in terms of the preferred alternatives chosen by clients when implementing source clock recovery for voice. DFQ allows the entire range of implementation alternatives for voice over ATM to be appropriately serviced, such as ATM adaptation layer types 1 and 2 (AAL1/2), adaptive playout, and immediate playout     

Multichannel transmission of a multicore fiber coupled withvertical-cavity surface-emitting lasers

A two-channel simultaneous transmission is experimented using direct coupling between a vertical-cavity surface-emitting laser (VCSEL) array and a novel 2×2 core optical fiber. No crosstalk is observed. Coupling efficiency and mechanical tolerance are good enough to envisage system applications     

基于SOPC的雷达脉冲周期的测量方法

讨论了双游标法在周期测量中的应用,并在QuartusⅡ开发平台上,以VHDL语言为主要输入语言,设计了基于SOPC技术的雷达脉冲周期测量模块,实现雷达脉冲周期的测量,在使用同频率晶振的条件下,应用双游标法提高了测量的精度.经实践检验,具有实际应用价值.     

A 1-V low power gain boosted self-cascoding current mirror operational transconductance amplifier

A low-voltage, micro-power, low-noise, high-gain, high-output swing current mirror-based operational transconductance amplifier (OTA) is presented. The proposed OTA achieves high DC gain and output swing by the adoption of gain boosted current mirroring and self-cascoding techniques. From the simulation, the proposed OTA implemented on a 0.18 μm CMOS shows the DC gain up to 90 dB with a gain bandwidth of 700 KHz for a load capacitor of 1 pF and an output voltage swing of 600 mV. The OTA dissipates only 750 nW from 1.0 V supply.     

High pass filter with above IC integrated SrTiO3 high K MIM capacitors

This paper describes realization and characterization of SrTiO₃ (STO) high K MIM capacitors above BiCMOS integrated circuit (IC). These capacitances are connected to IC and are used as coupling capacitors in order to realize a high pass filter. Surface capacitance achieved is 10 nF/mm² with capacitance value of 1.2 nF. The process for STO MIM fabrication does not exceed 400 °C, which is compatible with interconnections. Typical K and dielectric losses values obtained are, respectively 110% and 2%. Yield obtained reaches 83% for capacitors. A functional high pass filter using these STO capacitors was realized in this study. It exhibits a cut-off frequency at 6.5 kHz and a constant gain at higher frequencies of −1.3 dB.     

Mumford-Shah model for one-to-one edge matching.

This paper presents a new algorithm based on the Mumford-Shah model for simultaneously detecting the edge features of two images and jointly estimating a consistent set of transformations to match them. Compared to the current asymmetric methods in the literature, this fully symmetric method allows one to determine one-to-one correspondences between the edge features of two images. The entire variational model is realized in a multiscale framework of the finite element approximation. The optimization process is guided by an estimation minimization-type algorithm and an adaptive generalized gradient flow to guarantee a fast and smooth relaxation. The algorithm is tested on T1 and T2 magnetic resonance image data to study the parameter setting. We also present promising results of four applications of the proposed algorithm: interobject monomodal registration, retinal image registration, matching digital photographs of neurosurgery with its volume data, and motion estimation for frame interpolation.     

Simple iterative receivers for MIMO LP-OFDM systems

In this paper,Lp-ofdm is combined with differentMimo schemes in order to improve performance in terms of diversity gain and to exploit capacity brought by theMimo channel. The original contribution is the development of a generic iterative receiver designed forLp mimo transmission able to work whatever the antenna configuration and the spatial coding scheme. By using a globalMmse criterion, interference terms coming from space-time coding and linear precoding are jointly treated leading to a very good trade-off between performance and complexity compared to trellis based detectors particularly for high order modulations, high number of antennas and/or large size of precoding matrices.     

An X-band high-efficiency MMIC power amplifier with 20-dBreturn losses

Describes the design principles and measured performance of an X-band high-efficiency monolithic-microwave-integrated-circuit (MMIC) power amplifier and discuss pertinent factors of the ion-implantation process. Also presented is a worst-case power prediction of the chip performance and a large-signal design using small-signal simulation. This balanced amplifier is fully monolithic with input and output return losses of better than 20 dB provided by Lange couplers. These return losses make it very convenient to cascade with other components. For high-efficiency operation, the drain voltage is 6 V. Across the 40% bandwidth from 8 to 12 GHz, the amplifier produces 1.6 to 2.1 W of output power at 33 to 40% power-added efficiency. For high-power operation, the drain voltage is 8.5 V. The amplifier can produce 2.4 to 2.8 W of output power at 26 to 29% power-added efficiency across the same 40% bandwidth