We achieved the first wavelength division multiplexed (WDM) transmission in the 1.0µm band over a 6km PCF. As a light source, we generated a supercontinuum (SC) with a -10dB bandwidth of 2.8THz in a 1km-long, low loss PCF. Four 10Gb/s WDM signals obtained from part of the SC with arrayed waveguide gratings (AWG) were successfully transmitted with negligible power penalties. We show the possibility of realizing WDM transmissions at more than 1Tb/s in the 1.0µm band over a low loss PCF by using a supercontinuum source.
A 1.8V 12-bit 40MS/s pipelined ADC fabricated in a 0.18µm CMOS process is presented. The traditional closed-loop high performance residue amplifier in first stage is replaced by a simple open-loop amplifier to reduce power dissipation and increase circuit speed in the paper. To improve the stability and response speed of the amplifier, a novel circuit topology of open-loop amplifier is presented in this study. Also, a proposed (1+1)-bit/stage structure for pipelined ADC is used in the paper to convert residue voltage that exceeds the convert range. The occupied silicon area is 3.2× 3.7mm2 and the power consumption equals 210mW.
We present the new function of tunable hollow waveguides with a variable air core. We show a possibility of wide-angle beam steering from the hollow waveguide and efficient tilt-coupling in narrow air core hollow waveguides. Wide-angle beam steering was demonstrated by calculation and preliminary experiment. In addition, a possibility of an efficient optical coupling with a narrow air core was presented by the tilt-coupling scheme. Input and output coupling losses are 2.5dB and 1dB for 1µm air core, respectively. Wide tunability in sub-wavelength air cores enables us to realize new functions of tunable hollow waveguides and circuits.
It is introduced a new genetic algorithm to synthesize the negative-type second generation current conveyor (CCII-) by superimposing a voltage follower (VF) with a current follower (CF). First, the VF and CF are described by binary genes. Second, the gene CF is inverted, rigth-shifted and multiplied (AND operation) with the gene VF to verify that both genes can be superimposed to synthesize the CCII-. Finally, some synthesized CCII-s are presented which electrical characteristics are measured using HSPICE and standard CMOS technology of 0.35µm.
In this paper, to evaluate the applicability of electrostatically-actuated metal to metal direct-contact RF MEMS switches in practical RF fields, we performed three kinds of lifetime tests for the switches using three different conditions: cold-switching with no power, hot-switching with RF power, and hot-switching with DC current loads. The tested MEMS switch was demonstrating stable operation even after 109 cycles when cold-switching with no loads. We also experimentally showed that the tested switches could endure up to 106 cycles with 0.5W of RF power and 108 cycles with 30mA of DC current.
To alleviate the folded noise caused by coefficient mismatches between the two channels of two-channel time-interleaved (TI) ΣΔ modulators and simplify the circuit of the modulators, a novel two-channel TI second-order ΣΔ modulator is proposed. A new type of noise transfer function (NTF) which is a band-pass filter is adopted for the modulator to reduce the folded noise. The simulation results show that this two-channel TI second-order ΣΔ modulator is insensitive to channel mismatches. Moreover, the modulator only needs three operation amplifiers.
This paper investigates the influence of external field on the distribution of the critical current of Josephson junctions. The external field can cause trapped flux which may reduce the critical current. Experimental results show a formation of bunches in the distribution of the critical current when the external magnetic field rises a certain limit. From a theoretical point of view this formation can only be explained by attractive pinning points in the vicinity of the junction. The Josephson junctions were fabricated with the 1kA/cm2 Nb/Al2O3/Nb trilayer process of FLUXONICS Foundry.