Crosstalk Characteristics Research Articles

Characterization of crosstalk of a TDM FBG sensor array using a laser source

The crosstalk characteristics of a time-division multiplexing fiber Bragg grating sensor array that uses a laser source are examined. The system performance is found to be limited by the extinction ratio of the input optical pulse modulation and can be improved significantly by properly modulating the laser wavelength.

Characteristics of crosstalk in the reproduced output of a newly developed multi-channel MR head

We prepared the multi-channel magnetoresistive head with a simple structural design and it has the advantages of high-density recording and ultra-high transfer rate. Characteristics of crosstalk in the reproduced output of our head have been estimated by a micromagnetic calculation using the Landau–Lifshitz–Gilbert (LLG) equation, while the specimen head was fabricated and evaluated. As a result, by applying a magnetic field of 40 Oe only between adjacent channels, the crosstalk was much decreased without reducing the reproduced output.

A comparison of the homodyne crosstalk characteristics of optical add-drop multiplexers

We compare the homodyne crosstalk characteristics of a number of different optical add-drop multiplexer (OADM) structures, in the context of wavelength-division multiplexed (WDM) ring or bus network links. Nine fixed-wavelength and rive reconfigurable OADM structures are examined. For the fixed-wavelength structures, we find considerable variation in the levels of incoherent crosstalk, and generally low coherent crosstalk levels. For the reconfigurable structures, incoherent crosstalk levels are quite similar, but the coherent crosstalk levels differ considerably. The range of homodyne crosstalk-induced power penalties is calculated for all structures, and the probability distribution is found for each reconfigurable OADM. The effects of the number of OADMs in the link and the number of wavelength channels in the network are also studied. We find that the best choice of OADM depends on the application.

Polarization-insensitive InGaAsP/InP vertical coupler filter with deep grating by five-step MOVPE growth

A novel fabrication technique to introduce a deep grating in a vertical coupler filter was studied in order to realize a polarization-insensitive semiconductor optical add and drop multiplexing device with low crosstalk characteristics. The process of fabricating the vertical coupler filter, consisting of InGaAsP quasi-square waveguides buried in InP and an InGaAsP/InP grating between the waveguides, is described. Devices with a grating having a depth of 200 nm were fabricated by a five-step metal organic vapor-phase epitaxy (MOVPE) process accompanied by reactive ion etching (RIE) and wet etching. The deep grating was formed by RIE, and was realized by optimizing surface treatment prior to MOVPE over-growth and growth conditions. The diffraction efficiency of the filter was successfully improved, and an extremely low crosstalk of −36 dB was achieved.

Cross-gain modulation and frequency conversion crosstalk effects in 1550-nm gain-clamped semiconductor optical amplifiers

We present data on the crosstalk characteristics of a gain-clamped semiconductor optical amplifier with input data on separate wavelength channels, spaced by /spl sim/1 nm. As predicted for a gain-clamped device, we observe very little crosstalk due to cross-gain modulation. Frequency conversion, most likely due to parametric amplification, occurs at relatively low thresholds (/spl sim/-7 dBm total input), but is limited entirely to the continuous-wave component of the optical input and does not appear to contribute to the RF crosstalk. Our data also reveal that input power levels have an observable impart on the signal-to-noise ratio at low injection levels.

Comparison of Cross-Talks between Phase Encoding and Amplitude Encoding in Phase Change Rewritable Optical Discs

The cross-talk characteristics in the case of phase encoding and amplitude encoding are studied for phase change rewritable optical media for different track pitches and different mark lengths on adjacent tracks. The results show that the cross-talk ratio in the case of phase encoding is larger and that the depth tolerance of the groove is smaller than those in the case of amplitude encoding. Although the use of phase encoding can result in an increase of the linear recording density, in the case of track density, the increase is far less than that reached using amplitude encoding.

Magneto-Optical Detection Using an Optical Phase Shifter in Higher Track Density Land/Groove Recording

We report the results of magneto-optical (MO) detection using an optical phase shifter in land/groove recording. We found that the MO detection method improves not only readout carrier level but also cross-talk characteristics against optical errors. Using this method with a 693-nm wavelength diode laser and a 0.55-NA objective lens, sufficient readout margins against optical errors were experimentally obtained at a 3.69-Gbit/in2 areal density, which yielded a 0.35-µm bit length and a 0.5-µm track pitch. Recording with a track density 1.4 times higher was achieved by introducing a 640-nm wavelength diode laser, a 0.7-NA objective lens, and a 0.258-µm bit length and yielded an areal density of 6.95 Gbit/in2.

Dynamically selective multiwavelength cross-connect based on fibre Bragg gratings and mechanical optical switches

A dynamically selective multiwavelength cross-connect for wavelength division multiplexed (WDM) networks based on fibre Bragg gratings (FBGs) and optical switches is reported. Dynamically single- or multi-channel cross-connect functionality can be realized according to control of the optical switches and the FBGs' arrangement. Bit-error-rate performance with negligible power penalty is achieved in a 2.5Gbs-1x3 WDM channels over 100km conventional single-mode fibre (SMF) network demonstration. The characteristics of low channel crosstalk, uniform channel loss, high scalability and cascadability, and low cost of this device could provide more reconfiguration flexibility and network survivability for WDM networks.

Transforming Growth Factor-β1 Inhibits Type I Inositol 1,4,5-Trisphosphate Receptor Expression and Enhances Its Phosphorylation in Mesangial Cells

A potentially important cross-talk characteristic of transforming growth factor-beta (TGF-beta) is to inhibit platelet-derived growth factor-induced intracellular calcium rise (Baffy, G., Sharma, K., Shi, W., Ziyadeh, F. N., and Williamson, J. R. (1995) Biochem. Biophys. Res. Commun. 210, 378-383) in murine mesangial cells. The present study examined the possible basis for this effect by evaluating the regulation of the type I inositol 1,4,5-trisphosphate receptor (IP3R) by TGF-beta. TGF-beta1 down-regulates IP3R protein expression by >90% with maximal and half-maximal effects after 8 and 2 h, respectively. TGF-beta1 also decreased IP3R mRNA expression by 59% after 1 h. Phosphorylation of the IP3R was also demonstrated as early as 15 min after TGF-beta1 exposure. Back phosphorylation assays of IP3R from TGF-beta1-treated mesangial cells with protein kinase A (PKA), indicated that TGF-beta1-induced phosphorylation of the IP3R occurs at similar sites as for PKA. In vitro kinase assays using the known IP3R peptide substrates for PKA, RPSGRRESLTSFGNP and ARRDSVLAAS, demonstrated that TGF-beta1 induces phosphorylation of both peptides (158 and 123% of control values, respectively). TGF-beta1-induced phosphorylation was prevented by the addition of the PKA inhibitor peptide in the in vitro kinase assay. It is proposed that TGF-beta-mediated effects on the IP3R may be an important characteristic of its ability to modulate the response of cells to factors that employ IP3R-mediated calcium release.

Angle-etched facet laser arrays (fan laser arrays)

We present a novel individually addressable diode laser array that uses angle-etched facets. By arranging the lasers in a fan-like structure, all lasers emit in different directions from a common effective aperture. Using this device design, we demonstrate lasers with beam directions that are fixed and distinct, stable, single mode, and capable of simultaneous and random access operation. We analyze both the effect of facet roughness on the performance of etched-facet diode lasers, as well as the thermal crosstalk characteristics of angle-etched facet lasers. Thermal crosstalk characteristics of angle-etched facet lasers are experimentally compared to parallel stripe lasers. The combination of the aperture and thermal crosstalk reduction allows us to reduce the effective thermal coupling between array elements by over one order of magnitude. We show a novel two-dimensional scanner built with a fan laser array: results demonstrate the feasibility of these novel arrays for multibeam applications.

Multiport wavelength routers using multimode interference

We propose a dynamic wavelength router using a multimode interference coupler and Bragg gratings implementing multiport wavelength switching in a single device together with a new wavelength dilation method using this device. We show a design of the new dynamic wavelength router and device performance using eigenmode decomposition. The flat passband and low crosstalk characteristics are attained.

5530356 Method and apparatus for generating magnetic fields for nuclear magnetic resonance imaging with cross-talk compensation

A generation of magnetic fields for a nuclear magnetic resonance imaging capable of preventing the occurrence of the cross-talk between coils for generating the magnetic fields easily. A coil system having a plurality of channels for generating magnetic fields is provided, and currents to drive the coil system is supplied from a power source. A controller generates the control signals indicating desired currents to be supplied from the power source to the coil system in an absence of cross-talks among the channels of the coil system, and then the cross-talks among the channels of the coil system are compensated by supplying the power source with cross-talk compensated control signals for controlling the currents to be supplied from the the power source to the coil system, where the cross-talk compensated control signals are obtained by adding the control signals with cross-talk compensation components derived according to predetermined cross-talk characteristics of the channels of the coil system.

16-channel optical add/drop multiplexer consistingof arrayed-waveguide gratings and double-gate switches

An optical add/drop multiplexer that enables full access to 16 individual wavelength channels has been fabricated on the planar lightwave circuit (PLC). The device consists of four arrayed-waveguide gratings which are connected through 16 double-gate thermo-optic switches. The crosstalk characteristics of the optical switches have been improved by adopting a double-gate configuration. The on-off crosstalks from main input or add port to main output or drop port are less than –28.4 dB and the on-chip insertion losses are 7.8–10.3 dB, respectively.

Experimental evaluation of basic circuit components using buried microstrip lines for constructing high-density microwave integrated circuits

The buried microstrip line (BMSL) is a promising transmission line structure for realizing low crosstalk characteristics. The measured crosstalk characteristics of model BMSL's have shown good agreement with the estimated ones based on the rectangular boundary division method and the finite-difference time-domain (FDTD) method, indicating that these calculation methods are appropriate for estimating the performance of BMSL's. These results also confirm our expectation that BMSL's have extremely low crosstalk characteristics such as -100 dB in real circuits at high microwave frequencies. The basic circuit components to construct high-density microwave circuits using BMSL's, couplers, stub matching circuits, and gap-coupled resonance filter circuits, were fabricated and experimentally evaluated.

Junction and interdiode capacitance of silicon pixel arrays

Several measurements of junction ( C j) and interdiode ( C ip) capacitance of silicon pixel detectors have been performed. These quantities play an important role in determining the noise and cross-talk characteristics of the detectors. Moreover, the importance of these measurements is related to the possibility of position interpolation by capacitive charge division and analogue readout in future pixel detectors for precision charged particle tracking in several apparatus connected to different front-end electronics. An attempt to model the interdiode capacitance on the geometry has been made. Good agreement has been found between this simple model and the experimental results. According to the model, by choosing sufficiently close diodes, the C ip C j ratio can be made large enough to make capacitive coupling effective.

Closely Spaced Independently Addressable Dual-Beam Visible Lasers with Strained GaInP Quantum Wells

Closely spaced (15 µ m center-to-center spacing) independently addressable dual-beam visible lasers were demonstrated using strained GaInP quantum well structures. Crosstalk characteristics were studied experimentally as well as theoretically. The estimated crosstalk of uncoated devices was around 3% with bias, and 10% without bias in CW-mode operation. The value of 3% was small enough for applications such as printers and optical disks.

High‐density pin‐board matrix switch and its crosstalk characteristics

AbstractThe purpose of this study is to realize the automated main distribution frame (MDF), which is indispensable in the new installation and transfer of the telephone set. the switching element, which is the key component in the matrix connection, as well as its crosstalk characteristics, are investigated. the following results are obtained: (1) systems based on various switching elements are compared, and it is shown that the pin‐board matrix is the best in the sense of the adaptability at the present stage. A detailed structure of the pin‐board matrix is proposed; (2) the effects of the shielding layer, the frequency and the defined route (insertion position of the pin) on the crosstalk characteristics of the single pinboard matrix switch is analyzed experimentally; and (3) a method is proposed and established for the probabilistic analysis of the pin‐board matrix switch with the threestage link connection.The proposed method of analysis is applied to the automated MDF. It is shown that the probability that the overall crosstalk does not satisfy the specification of the 320‐kbit/s time‐compression multiplexing transmission lines is very small (1.2 × 10‐5). In other words, it is shown that the automated MDF can accommodate the 320‐kbit/s time‐compression multiplexing transmission lines.

A boundary integral method for propagation problems in integrated optical structures

A boundary integral method is presented for the study of wave propagations in waveguiding structures that are considered difficult for the beam propagation method (BPM). We have demonstrated with 2-D simulations, that structures of large angle bends and arbitrary reflections can be easily modeled without excessive computational demand. This method provides a powerful tool for analyzing radiation loss, scattering, crosstalk and other characteristics in complex integrated photonic devices. >

Dual-channel and multifrequency radar system calibration

Uncertainty in absolute gain and crosstalk factors are the primary sources of error in dual-channel radar measurements. A full two-port calibration technique compensates for the errors introduced due to an imperfect antenna system and improves the isolation between orthogonal polarization channels as long as the observed cross section is above the equivalent system noise cross section. A novel technique for calibrating a dual-polarized network analyzer-based scatterometer system is discussed. Rigorous two-port S-parameter representation is used to describe absolute gain and crosstalk characteristics. Validity of the crosstalk correction is demonstrated by measuring the point target scattering matrix. Correction factors are obtained by measuring the S-parameters of trihedral and dihedral comer reflectors of known sizes. Results of absolute gain of the antenna system are verified using independent test target cross section measurements.

Backscatter-induced noise and crosstalk in a FDM multidimensional gyro system using two bias modulators in each gyro loop

Characteristics of backscatter-induced noise and crosstalk in a multidimensional FDM fibre-optic gyro system, using two bias modulators in each gyro loop, are investigated. The induced noise is in the order of a few degree per hour for a 1 mm coherence length source and typical gyro parameters. The crosstalk is larger than the noise and increases with the number of gyros to be multiplexed. Both the noise and crosstalk can be reduced by using proper modulation depths and frequencies. The noise can also be eliminated by using 50/50 loop couplers.