Thermo-optically tunable arrayed-waveguide-grating made of polymer/Si

Inthe future,optical communication systems will usemore exceptional optical fiber with high bandwidth.Dense wavelength division multiplexing(DWDM)isconsidered as a promising solution to the demand fortransportingterabits ofinformation viafibers[1].Arrayed…     

Saw minimum peak sidelobe filter for 15-bitM-sequence phase code signals

This paper presents computation results of the minimum peak sidelobe filter (LP filter) for the 15-bitM-sequence phase coded signal with feedback connection [4,3,0] and initial condition 1001. The design of the filter resorts to the linear programming method. The peak sidelobe level is reduced to −21.47 dB by the LP filter of length 15, and is 7.49 dB lower than that by the matched filter. The LP filter can suppress the peak sidelobe even more by increasing its length. The minimum peak sidelobe filter for the 15-bitM-sequence phase coded signal (initial condition 1001) has been implemented with a surface acoustic wave (SAW) device. Experiments show that the peak sidelobe level of the manufactured filter is −19 dB and, thus, only differs from the theoretical value of −21.47 dB by 2.47 dB.     

MBE growth and characteristics of periodic index separate confinement heterostructure InGaAs quantum-well lasers

We have used solid-source molecular beam epitaxy (MBE) to grow InGaAs quantum-well lasers emitting at 980nm in a novel configuration of periodic index separate confinement heterostructure (PINSCH). Periodic multilayers (GaAs/AlGaAs) are utilized as optical confinement layers to reduce the transverse beam divergence as well as to increase the maximum output power. The multilayers are grown by temperature modulation MBE without any shutter operation. The heterointerfaces in the multilayers are linearly graded such that the energy barrier heights are greatly decreased. This has led to a drastic reduction in the series resistance which is essential in the performance of high output power. The 5μm × 750μm device has far-field angles of 10° by 20°, a threshold current of 45 mA, an external differential quantum efficiency of 1.15 mW/mA (90%), and an output power of 620 mW, all measured at room temperature under CW operation. A record high fiber coupling efficiency of 51% has been achieved and more than 130 mW of power is coupled into a 5μm-core single mode fiber.     

Flat-top silica-based arrayed waveguide grating with 40-channels

A wavelength multiplexer or demultiplexer plays ani mportant role in all wavelength division multiplexing( WDM) system.Silica-basedarrayed waveguide gratings(AWGs) offer attractive featuresinthis area due to theadvantage of large output channels and lowlo…     

Analysis of electro-optic switches with series-coupled multiple microring resonators

In terms of the coupled mode theory, microring resonance and electro-optic modulation princeple, a reasonable project is proposed for designing an electro-optic switch with the series-coupled multiple microring resonators. The simulation and optimization are performed at the resonant wavelength of 1550 nm. The results are as follows: the core size of the microring is 1.6 μm×1.6 μm, the confined layer between the core and the electrode is 1.6 μm, the thickness of the electrode is 0.15 μm, the radius of the m...     

Decoupled Power Allocation Through Pricing on a CDMA Reverse Link Shared by Energy-Constrained and Energy-Sufficient Data Terminals

We perform market-oriented management of the reverse link of a CDMA cell populated by data terminals, each with its own data rate, channel gain, willingness to pay (wtp), and link-layer configuration, and with energy supplies that are limited for some, and inexhaustible for others. For both types of energy budgets, appropriate performance indices are specified. Notably, our solution is “decoupled” in that a terminal can choose optimally, irrespective from choices made by the others, because it pays in proportion to its fraction of the total power at the receiver, which directly determines its signal-to-interference ratio (SIR), and hence its performance. By contrast, in other similarly-sounding schemes terminals’ optimal choices are interdependent, which leads to “games of strategy”, and their practical and theoretical complications. We study two situations: pricing for maximal (i) network revenue, and (ii) social benefit. The socially-optimal price is common to all terminals of a given energy class, and an energy-constrained terminal pays in proportion to the square of its power fraction. By contrast, the revenue-maximising network sets for each terminal an individual price that drives the terminal to the “revenue per Watt” maximiser. The network price is higher, and drives each terminal to consume less. Distinguishing features of our model are: (i) the simultaneous consideration of both limited and unlimited energy supplies, (ii) the performance metrics utilised (one for each type of energy supply), (iii) the generality of our physical model, which can lead to an optimal link-layer configuration, and (iv) our pricing of the received power fraction which yields a “decoupled” solution.     

Stability of thin films of microcrystalline silicon under light soaking

As an absorption layer in solar cells ,hydrogenatedmicrocrystalline silicon (μc-Si :H) has attracted consid-erable attention due to some of its unique properties .Currently,it is observed that the best cell performancehas been achievedfor silicon materia…     

Silica-based 71-channel arrayed waveguide grating

With the rapid increase of global information capaci-ty,all optical wavelength division multiplexing(WDM)networks are very attractive because they are capable ofprocessing broadband optical signals without convertingthem to electronic signals.Large channe…     

Thermoelectric Efficiency of a Quantum Dot in the Single-Electron Transistor Configuration

The thermoelectric efficiency of a single-dot (e.g., nanocrystal or molecule) device has been studied theoretically. The transport coefficients, the power factor, and the figure of merit (ZT) of the quantum dot in the single-electron transistor configuration have been calculated in the sequential tunneling regime when Coulomb blockade is important. Very high values of ZT have been found in the quantum regime, and they have been explained by quantum confinement. An approximate analytical formalism has been derived for ZT as a function of the separation between the energy levels of the dot, ΔE, and the thermal energy, k _B T. The electron–phonon coupling has been included in the calculations, and it is shown that it is important for realistic prediction of the thermoelectric efficiency of a quantum-dot device. It has been found that the thermoelectric efficiency decreases due to electron–phonon coupling. Distinct behavior has been obtained for weak and for strong electron–phonon coupling. Quantum confinement is the dominant mechanism determining the magnitude of ZT for weak electron–phonon coupling. For strong electron–phonon coupling, the energy conversion efficiency is determined by the phonon spectrum. In all cases, it has been found that the thermoelectric efficiency decreases rapidly with increasing temperature.     

Fabrication and Characterization of Small Unit-Cell Molecular Beam Epitaxy Grown HgCdTe-on-Si Mid-Wavelength Infrared Detectors

Small 15 μm unit-cell mid-wavelength infrared (MWIR) detectors have been fabricated and characterized at Raytheon Vision Systems (RVS) to enable the development of high resolution, large format, infrared imaging systems. The detectors are fabricated using molecular beam epitaxy (MBE) grown 4-in. HgCdTe-on-Si wafers with a p-on-n double layer heterojunction (DLHJ) device architecture. Advanced fabrication processes, such as inductively coupled plasma (ICP) etching, developed for large format MBE-on-Si wafers and 20 μm unit-cell two-color triple layer heterojunction (TLHJ) focal plane arrays (FPAs) have been successfully extended and applied to yield high performance 15 μm unit-cell single color detectors that compare favorably with state-of-the-art detectors with larger pitch. The measured 78 K MWIR cut-off wavelength for the fabricated detectors is near 5.5 μm, and the current–voltage characteristics of these devices exhibit strong reverse breakdown and RoA performance as a function of temperature with diffusion limited performance extending to temperatures down to 120 K.     

Output Feedback H ∞ Control for 2-D State-Delayed Systems

In this paper, we consider a class of two-dimensional (2-D) local state-space (LSS) Fornasini–Marchesini (FM) second models with delays in the states, and we study delay-independent and delay-dependent H _∞ control problems via output feedback. First, based on the definition of H _∞ disturbance attenuation γ for 2-D state-delayed systems, we propose a delay-dependent bounded real lemma. Specifically, a new Lyapunov functional candidate is introduced and free-weighting matrices are added to the difference Lyapunov functional for 2-D systems possessing two directions. Then delay-independent and delay-dependent output feedback H _∞ controllers are developed that ensure that the closed-loop system is asymptotically stable and has H _∞ performance γ in terms of linear matrix inequality (LMI) feasibility. Furthermore, the minimum H _∞ norm bound γ is obtained by solving linear objective optimization problems. Numerical examples demonstrate the effectiveness and advantages of the LMI approach to H _∞ control problems for 2-D state-delayed systems. This work was supported in part by the National Natural Science Foundation of China (60525303 and 60604004), NSF of Hebei Province (08M008) and the Key Scientific Research Project of the Education Ministry (204014).     

A novel high-isolation RF-SOI switch for 2.4 GHz multi-standard applications

Taking advantage of 1 KΩ·cm high-resistivity substrate and special device structure, a novel stack-by-two Single-pole-double-throw (SPDT) switch is fabricated in 0.18 μm partially depleted silicon-on-insulator technology for power handling capability and linearity improvement, targeting 2.4 GHz multi-standard transceiver application. The measured insertion loss is −1.1 dB at 2.4 GHz. With stacked switching device, the circuit exhibits a high measured input input-referred 1 dB power compression point (IP1 dB) of 21.5 dBm, which has more than 7 dB enhancement compared to previous work. The measured isolation is 43 dB. The switch has a overall occupied die area of 1200 × 560 μm².     

Delay-Range-Dependent L 2–L ∞ Filtering for Stochastic Systems with Time-Varying Interval Delay

This paper focuses on the problem of delay-range-dependent L ₂–L _∞ filter design for stochastic systems with time-varying delay. The time delay varies in an interval. A delay-range-dependent sufficient condition is formulated in terms of linear matrix inequalities (LMIs), which guarantees the existence of a linear filter. The proposed filter ensures that the filtering error system is stochastically asymptotically stable and that its L ₂–L _∞ performance satisfies a prescribed level. The corresponding filter design is cast into a convex optimization problem which can be efficiently handled by using standard numerical algorithms. Finally, a numerical example is given to illustrate the effectiveness of the proposed method. This work is partially supported by the Natural Science Foundation of China (60674055, 60774047), and the Taishan Scholar Programme of Shandong Province.     

P-μc-Si1-xGex ：H thin film by VHF-PECVD

In this paper, a series of boron doped microcrystalline hydrogenated silicon-germanium （p-μc-Si1-xGex：H） was deposited by very high frequency plasma-enhanced chemical vapor deposition （VHF-PECVD） from SiH4 and GeF4 mixtures. The effect of GeF4 concentration on films＇ composition, structure and electrical properties was studied. The results show that with the increase of GeF4 concentration, the Ge fraction x increases. The dark conductivity and crystalline volume fraction increase first, and then decrease. When the GC is 4%, p-μc-Si1-xGex：H material with high conductivity, low activation energy （σ= 1.68 S/cm, E8=0.047 eV）, high crystalline volume fraction （60%） and with an average transmission coefficient over the long wave region reaching 0.9 at the thickness of 72 nm was achieved. The experimental results were discussed in detail.     

One-Dimensional Modeling of Thermogenerator Elements with Linear Material Profiles

Graded and segmented thermoelectric elements have been studied for a long time with the aim of improving the performance of thermogenerators that are exposed to a large temperature difference. However, it has been shown that simply adjusting the maximum figure of merit ZT in each segment of a stacked or graded thermoelectric (TE) element is not a sufficient strategy to maximize thermoelectric device performance. Global optimization of a performance parameter is commonly based on a one-dimensional continua-theoretical model. Following the proposal by Müller and coworkers, the temperature profile T(x) can be calculated within a model-free setup directly from the one-dimensional (1D) thermal energy balance, e.g., based on continuous monotonic gradient functions for all material profiles, and independent and free variability of the material parameters S(x), σ(x), and κ(x) is assumed primarily, where S is the Seebeck coefficient, and σ and κ are the electrical and thermal conductivities, respectively. Thus the optimum current density can be determined from the maximum of the global performance parameter. This has been done up to now by means of numerical procedures using a 1D thermoelectric (TE) finite-element method (FEM) code or the algorithm of multisegmented elements. Herein, an analytical solution of the 1D thermal energy balance has been found for constant gradients, based on Bessel functions. For a constant electrical conductivity but linear profiles S(x) and κ(x), first results for the electrical power output of a thermogenerator are presented.     

Design and analysis on a Gires-Tournois resonator based interleaver

A flat-top interleaver,in which a mirror on one arm of the Michelson interferomefer is replaced by a G-T resonator,is proposed.In the interleaver,the parameters including the channel spacing of 50 GHz,ripple less than 0.05 dB,-0.5 dB passband of 43 GHz(86% of the spacing),-30 dB stopband of 42 GHz(84% of the spacing),and a channel isolation higher than 40 dB,are achieved.     

Crystallization of μc-Si on plastic substrate by using a pulsed double-frequency YAG laser

Thin film transistors （TFTs） of microcrystalline silicon （μc-Si） can provide higher mobility and stability than that of a-Si and better uniformity than that of poly-Si TFTs, and it would be more suitable to be applied to larger-area AMOLEDs. By using 2coYAG laser ann. ealing, crystalline μc-Si thin film on plastic substrate has been investigated and the proper laser energy needed for crystallization has been indicated. It has been found that the dehydrogenation process at 300-450℃ for a few of hours could be omitted by decreasing the H content in the crystallization precursor, which is suitable for laser crystallization on plastic substrates. The crystalline volume fraction （Xc） and the grain size of the resulted μc-Si could be adjusted by controlling the laser energy. By this method, the μc-Si on plastic substrate with Xc and grain size is respectively 85% （at the maximum） and 50 nm.     

Low Refractive Metamaterials for Gain Enhancement of Horn Antenna

A flat metamaterials (MTMs) structure with low refractive index is proposed as a cover in a high-gain horn antenna configuration. The MTMs is composed of two-layer metallic grids and slices of foam. For the characterization of the MTMs, the low refraction property is studied and the effective refractive index n ≈ 0.08 (12.0 GHz) is retrieved. The antenna gain and the radiation pattern are calculated. Because of the electromagnetic wave congregating effect of the MTMs, the gain of the horn with MTMs greatly increases (about 4 dB from 11.8 GHz–12.8 GHz) when compared with the conventional type. We conducted the experiments to verify the simulation results. The idea has a good potential application to the feed design of parabolas.     

A 4 mW 3–5 GHz current reuse g<Subscript>m</Subscript>-boosted short channel common-gate CMOS UWB LNA

A novel architecture is presented to optimize the noise performance and the power consumption of the transconductance ‘g_m’ boosted common-gate (CG) ultrawideband (UWB) low-noise amplifier (LNA), operating in the 3–5 GHz range, by employing current reuse technique. This proposed CG LNA utilizes a common source (CS) amplifier as the g_m-boosting stage and the bias current is shared between the g_m-boosting stage and the CG amplifying stage. The LNA circuit also utilizes the short channel conductance g_ds in conjunction with an LC T-network to further reduce the noise figure (NF). The proposed LNA architecture has been fabricated using the 130 nm IBM CMOS process. The LNA achieved input return loss (S₁₁) of −8 to −10 dB, and, output return loss (S₂₂) of −12 to −14 dB, respectively. The LNA exhibits almost flat forward voltage gain (S₂₁) of 13 dB, and reverse isolation (S₁₂) of −62 to −49 dB, with a NF ranging between 3.8 and 4.6 dB. The measurements indicate an input-referred third order intercept point (IIP3) of −6.1 dBm and an input-referred 1-dB compression point (ICP_1dB) of −15.4 dBm. The complete chip draws 4 mW of DC power from a 1.2 V supply.     

Box-like spectral response of a series-coupled microring resonant filter in a parallel channel

Inthelast decades ,microring resonator( MRR) wave-lengthfilters are developed rapidly because of their po-tential applications in wavelength division multiplexing( WDM) communicationsystems andtheir excellent fea-tures includingfunctionality,compactness a…