1.3-μm InP-InGaAsP lasers fabricated on Si substrates by waferbonding

1.3-μm InP-InGaAsP lasers have been successfully fabricated on Si substrates by wafer bonding. InP-InGaAsP thin epitaxial films are prepared by selective etching of InP substrates and then bonded to Si wafers, after which the laser structures are fabricated on the bonded thin films. The bonding temperature has been optimized to be 400°C by considering bonding strength, quality of the bonded crystal, and compatibility with device processes. Room-temperature continuous-wave (RT CW) operation has been achieved for 6-μm-wide mesa lasers with a threshold current of 39 mA, which is identical to that of conventional lasers on InP substrates. Additionally, the lasers fabricated on Si have exhibited higher output powers than the lasers on InP, which is due to higher thermal conductivity of Si substrates. From these results, the wafer bonding is thought to be a promising technique to integrate optical devices on Si and implement optical interconnections between Si LSI chips     

Fabrication of alumina films with laminated structures by ac anodization

Anodization techniques by alternating current (ac) are introduced in this review. By using ac anodization, laminated alumina films are fabricated. Different types of alumina films consisting of 50–200 nm layers were obtained by varying both the ac power supply and the electrolyte. The total film thickness increased with an increase in the total charge transferred. The thickness of the individual layers increased with the ac voltage; however, the anodization time had little effect on the film thickness. The laminated alumina films resembled the nacre structure of shells, and the different morphologies exhibited by bivalves and spiral shells could be replicated by controlling the rate of increase of the applied potentials.     

Heavy metal precipitation by polycation-polyanion complex of PEI and its phosphonomethylated derivative

The removal of various heavy metal ions such as Cu2+, Co2+, Zn2+, Ni2+ and Pb2+ from aqueous solutions by precipitation with polyelectrolyte complex of PPEI and PEI was conducted. Heavy metal binding with PPEI was initially allowed to occur and then upon equilibration, PEI was added to initiate precipitation of the polyelectrolyte complex together with the heavy metal ion. The PPEI-PEI system was found effective for heavy metal scavenging purposes even in the presence of high concentrations of non-transition metal ions like Na+. Heavy metal concentration may be reduced beyond emission standards for industrial wastewaters. The PPEI-PEI polyelectrolyte complex was found to be more effective than traditional precipitation methods for the treatment of a representative electroless Ni plating waste solution.     

40 Gbit/s packet bit error ratio and loss real-time measurement for ultrahigh-speed packet switched network

A novel packet bit error rate (BER) and loss measurement method and system is proposed. A proposed 40 Gbit/s packet BER and loss measurement system is expressed in detail. A 40 Gbit/s BER and loss measurement with various conditions is demonstrated experimentally. In real time, only the payload part of a packet and burst stream with fluctuated guard time is evaluated. The BER and packet loss of a randomly received packet sequence due to routing and buffering can be also evaluated by the measurement system. A 10 Gbit/s packet BER and loss measurement with optical label switching, buffering, and preamble-free optical packet 3R are demonstrated experimentally.     

AlGaAs/GaAs lateral current injection multiquantum well (LCI-MQW)laser using impurity-induced disordering

A lateral current injection (LCI) multiquantum-well (MQW) laser having planar structure is proposed and its advantages compared with conventional vertical structure lasers. A LCI-MQW laser has been fabricated by using Si- and Zn-induced disordering of an MQW active layer. It is shown that a threshold current of 27 mA is achieved under pulsed current driven at room temperature and a very low stray capacitance of 0.27 pF is obtained at zero bias voltage     

用电子束曝光方法在优化设计的绝缘体上硅脊状波导上实现布拉格光栅的制作和评价

报道了一种用电子束曝光的方法在绝缘体上硅的脊状光波导上制做布拉格光栅的技术.考虑到实际的光子学集成的应用,讨论了这个带有布拉格光栅的脊状光波导的优化设计,给出了该布拉格光栅的测试和理论模拟结果.通过薄化绝缘体上硅的波导层的厚度和光栅的深腐蚀加工,获得了高达30cm-1的光栅耦合系数.     

4He Fluid in Extremely Narrow 1D Channels 1.5?nm in?Diameter

To examine whether one-dimensional (1D) helium quantum fluid is realized in narrower channels than those studied previously, we have measured heat capacities of ⁴He adsorbed in nanoporous material FSM with straight 1D channels 1.5 nm in diameter. From the heat of desorption for adsorbed ⁴He, the coverage n _f, up to which ⁴He film grows in the channels, is determined to be 15.4 ??mol/m² using the Frenkel-Halsey-Hill model. At coverages sufficiently below n _f, the temperature dependence of the ⁴He heat capacity has a shoulder, above which adsorbed ⁴He is delocalized from the substrate. On the other hand, the depression of the heat capacity indicating quantum effects has not been observed up to n _f, which suggests that ⁴He film in the channels remains amorphous-like normal fluid. Just above n _f, the quantum effect is observed in ⁴He adatoms on the grain surface of FSM powder, which indicates that 1.5 nm channels are slightly below the limit required to realize quantum effect in the inside ⁴He fluid.     

Advances in Digital Front-End and Software RF Processing： Part II

In the first editorial of this two-part special issue, we pointed out that one of the biggest trends in wireless broadband, radar, sonar, and broadcasting technology is software RF processing and digital front-end [1]. This     

Characterization on the Conformation of Glucoamylase from Rhizopus niveus and Rhizopus delemar

Using the pH-jump (neutral to above 11) for Tyr-OH ionization as a probe, two glucoamylases from Rhizopus niveus and Rhizopus delemar were found to be caused the change in conformation, which is in a kinetically single step. The pH titration at pHs below 12 was carried out on a multidimensional correlation spectrophotometer. Correlations among the spectrophotometric properties: fluorescence, absorption and circular dichroism are almost identical for the two enzymes. These results suggest that conformational characteristics of the niveus enzyme is almost the same as that of the delemar one.     

Short communication: estimation of plasma osmolality from plasma electrolytes, glucose, and urea in calves

Plasma osmolality estimated from plasma concentrations of Na+, Cl-, K+, glucose, and urea was compared with measured osmolality in preweaned Holstein calves. When calves (n = 5) were fed only milk replacer after fasting for 24 h, measured osmolality fluctuated almost in parallel with estimated osmolality during the 8-h period after feeding, although estimated values were about 90% of measured values. When calves (n = 5) were fed only calf starter after fasting for more than 16 h, measured osmolality did not parallel the estimated osmolality during the 8-h period after feeding. Some factors depressed measured osmolality in the first 2 h.