810 W continuous-wave and single-transverse-mode fibre laser using 20 /spl mu/m core Yb-doped double-clad fibre

It is shown that continuous-wave kW-power fibre lasers can be built using double-clad fibres with relatively small cores. 810 W in a single-transverse-mode output (M/sup 2/=1.27) is demonstrated experimentally with 20 /spl mu/m core low-NA (NA=0.06) Yb-doped double-clad fibre. A laser numerical model matches experimental results and predicts scalability of achievable powers into a multi-kW range.     

1.47 /spl mu/m Tm/sup 3+/:ZBLAN fibre laser pumped at 1.064 /spl mu/m

A large core area (1257 /spl mu/m/sup 2/) Tm/sup 3+/-doped ZBLAN fibre laser operated at 1.47 /spl mu/m is demonstrated. The pump source is a Nd:YAG laser operated at 1.064 /spl mu/m. A laser output power of 1.56 W continuous wave was obtained for 5.2 W of launched pump power. The slope efficiency with respect to the launched pump power was measured to be 33%.     

FDTD simulation of 30 /spl mu/m diameter polymer micro-ring

Numerical results on polymer surrounded by an air micro-ring coupled to waveguides are presented. The FDTD method predicts a filter width of 1.4 nm and an extraction efficiency of almost 80% for a gap of 0.15 /spl mu/m.     

1.65 /spl mu/m-band optical amplification with Er/sup 3+/-doped fluorozirconate fibre using 0.8 /spl mu/m upconversion pumping

In order to expand the available bandwidth for wavelength division multiplexing transmission systems, a 1.65 /spl mu/m-band optical fibre amplifier with Er/sup 3+/-doped fluorozirconate fibre using 0.8 /spl mu/m upconversion pumping has been demonstrated. The positive gain, 3.8 dB, is the first ever achieved by means of (/sup 2/H/sub 11/2/, /sup 4/S/sub 3/2/) /spl rarr/ /sup 4/I/sub 9/2/ stimulated emission transition.     

A 34 /spl mu/m/SUP 2/ DRAM cell fabricated with a 1 /spl mu/m single-level polycide FET technology

Dynamic RAM test arrays have been fabricated using a single-level polycide FET technology and a cell layout in which the top electrode of a given cell storage capacitor is provided by the adjacent word line. This layout achieves the same density as the conventional double-polysilicon cell, and comparable performance is obtained using a low-resistance polycide word line. Hi-C implants in the storage region provide increased capacitance, better isolation, and reduced transient noise. Design and operation considerations for the cell and arrays are described and measured results are compared to the design values. A cell area of 34 /spl mu/m/SUP 2/ is achieved using a scaled-down n-channel FET technology with a 22.5 nm gate oxide and 1 /spl mu/m minimum mask feature size.     

RF noise in 0.18-/spl mu/m and 0.13-/spl mu/m MOSFETs

Studied the gate finger number and gate length dependence on minimum noise figure (NF/sub min/) in deep submicrometer MOSFETs. A lowest NF/sub min/ of 0.93 dB is measured in 0.18-/spl mu/m MOSFET at 5.8 GHz as increasing finger number to 50 fingers, but increases abnormally when above 50. The scaling gate length to 0.13 /spl mu/m shows larger NFmin than the 0.18-/spl mu/m case at the same finger number. From the analysis of a well-calibrated device model, the abnormal finger number dependence is due to the combined effect of reducing gate resistance and increasing substrate loss as increasing finger number. The scaling to 0.13-/spl mu/m MOSFET gives higher NF/sub min/ due to the higher gate resistance and a modified T-gate structure proposed to optimize the NF/sub min/ for further scaling down of the MOSFET.     

E-band fibre Raman amplifier and implications of 1.4 /spl mu/m water absorption

An E-band Raman amplifier in nonzero dispersion fibre is demonstrated. 1.4 /spl mu/m water absorption does not hinder the amplifier itself but its characterisation due to water vapour in the external measurement instruments. The E-band could be used to extend the optical telecommunications bandwidth using nonzero dispersion fibre-based systems.     

1.3-/spl mu/m Vertical-cavity surface-emitting lasers with double-bonded GaAs-AlAs Bragg mirrors

We demonstrate, for the first time, double-bonded AlGaInAs strain-compensated quantum-well 1.3-/spl mu/m vertical-cavity surface-emitting lasers (VCSELs). GaAs-AlAs Bragg mirrors were wafer-bonded on both sides of a cavity containing the AlGaInAs strain-compensated multiple-quantum-well active layers sandwiched by two InP layers. The lasers have operated under pulsed conditions at room temperature. A record low pulsed threshold current density of 4.2 kA/cm/sup 2/ and a highest maximum light output power greater than 4.6 mW have been achieved. The maximum threshold current characteristic temperature T/sub 0/ of 132 K is the best for any long wavelength VCSELs. The laser operated in a single-longitudinal mode, with a side-mode suppression ratio of more than 40 dB, which is the best results for 1.3-/spl mu/m VCSELs.     

Low threshold current 1.3-/spl mu/m GaInNAs VCSELs grown by MOVPE

The structure of the conventional contact 1.3-/spl mu/m GaInNAs-GaAs vertical-cavity surface-emitting lasers (VCSELs) was optimized and low threshold current 1.3-/spl mu/m GaInNAs VCSELs grown by metal-organic vapor-phase epitaxy were reported. The idea is to optimize the active region, the doping profiles, and the pairs of p-distributed Bragg reflectors, and the detuning between the emission wavelength and the photoluminescence gain peak wavelength. The continuous-wave 1.0-mA threshold current was achieved for the single-mode VCSEL. For the multiple-mode VCSELs, the below 2-mA threshold currents at 5/spl deg/C-85/spl deg/C , the 1.13-mA threshold current at 55/spl deg/C, and 1.52-mA threshold current at 85/spl deg/C are the best results for 1.3-/spl mu/m GaInNAs VCSELs.     

Optical amplification at 0.54 /spl mu/m by Er/sup 3+/-doped fluoride fibre

Demonstrated is a 16.5 dB all-fibre optical amplifier at 546 nm using Er³⁺-doped fluoride fibre for a signal power of -30 dBm by forward upconversion pumping of a 974 nm laser diode. Results show Er ³⁺-doped fluoride fibre is a promising candidate for 0.54 mum optical amplifiers     

Optical amplification at 0.54 /spl mu/m by Tb/sup 3+/-doped fluoride fibre

0.54 mum band amplification using Tb³⁺-doped fluoride fibre is demonstrated. Spectroscopic properties of Tb³⁺-doped fluoride glass are clarified. A gain of 5.3 dB has been obtained in a 1 wt.% Tb³⁺-doped fluoride fibre for a signal power of -30 dBm by forward pumping at a wavelength of 0.488 mum with power of 100 mW     

500 /spl mu/m diameter CMOS compatible avalanche photodiodes with 500 MHz bandwidth

Novel silicon-on-insulator, large area (500 /spl mu/m diameter), CMOS avalanche photodiodes for use with plastic optical fibre are presented. Patterns have been formed on the devices to reduce junction capacitance. Measurements on the patterned devices, at 650 nm and 26 V reverse bias, revealed bandwidths of >500 MHz.     

K-band low-noise amplifiers using 0.18 /spl mu/m CMOS technology

Two K-Band low-noise amplifiers (LNAs) are designed and implemented in a standard 0.18 /spl mu/m CMOS technology. The 24 GHz LNA has demonstrated a 12.86 dB gain and a 5.6 dB noise figure (NF) at 23.5 GHz. The 26 GHz LNA achieves an 8.9 dB gain at the peak gain frequency of 25.7 GHz and a 6.93 dB NF at 25 GHz. The input referred third-order intercept point (IIP3) is >+2 dBm for both LNAs with a current consumption of 30 mA from a 1.8 V power supply. To our knowledge, the LNAs show the highest operation frequencies ever reported for LNAs in a standard CMOS process.     

Electrical breakdown in atmospheric air between closely spaced (0.2 /spl mu/m-40 /spl mu/m) electrical contacts

The increasing importance of electrical contacts in air with micrometer spacing prompted recent experiments on the electrical breakdown behavior of these gaps. The electrical field between the contacts used in one of the experiments was analyzed using finite element analysis to model the electric field. The experimental data on the electrical breakdown voltage could be divided into three regions as a function of the gap spacing. First, at close gap spacing (/spl les/4 /spl mu/m) both the breakdown voltages as well as the electrical fields at the cathode were similar to values measured during the breakdown of vacuum gaps of less than 200 /spl mu/m. Second, at larger gaps (>6 /spl mu/m) the breakdown voltages followed Paschen's curve for the Townsend electron avalanche process in air. Finally, in between these two regions the breakdown values were below the expected values for purely vacuum breakdown or purely Townsend breakdown. The breakdown phenomena have been discussed in terms of field emission of electrons from the cathode and their effect on initiating the observed breakdown regimes.     

Bragg section effects on linewidth and lineshape in 1.55-/spl mu/m DBR tunable laser diodes

We report linewidth and lineshape measurements on 1.55-/spl mu/m distributed Bragg reflector tunable laser diodes using the heterodyne method. We measure Lorentzian linewidths ranging from 3.5 to 25 MHz without any passive section injection. Biasing the Bragg section enhances the residual linewidth up to 6.2 MHz, changes the linewidth-power product, and brings an additional Gaussian lineshape. The feedback sensitivity of the overall setup is also demonstrated.     

Low-threshold proton-implanted 1.3-/spl mu/m vertical-cavity top-surface-emitting lasers with dielectric and wafer-bonded GaAs-AlAs Bragg mirrors

We demonstrate a new structure for long-wavelength (1.3-/spl mu/m) vertical-cavity top-surface-emitting lasers using proton implantation for current confinement. Wafer bonded GaAs-AlAs Bragg mirrors and dielectric mirrors are used for bottom and top mirrors, respectively. The gain medium of the lasers consists of nine strain-compensated AlGaInAs quantum wells. A record low room temperature pulsed threshold current density of 1.13 kA/cm/sup 2/ has been achieved for 15-/spl mu/m diameter devices with a threshold current of 2 mA. The side-mode-suppression-ratio is greater than 35 dB.     

Singly Ho/sup 3+/-doped fluoride fibre laser operating at 2.92 /spl mu/m

A singly Ho/sup 3+/-doped fluoride fibre laser that uses energy transfer upconversion to maintain the population inversion has produced 340 mW at 2.92 /spl mu/m. The /spl sim/1100 nm output from a diode-cladding-pumped Yb/sup 3+/-doped silica fibre laser was used as the pump source and a maximum slope efficiency of 5% was obtained.     

Fiber-Optical Transmission Between 0.8 and 1.4 /spl mu/m

The present state of the art and expected development in discrete components for Fiber-optic transmission systems are reviewed. Predicted performance of fiber systems in the 0.85, 1.06, and 1.27 /spl mu/m regions is presented, and the advantages of longer wavelength operation quantified. Itisconcluded that operation near 1.27 /spl mu/m is particularly attractive for a) moderate data rate systems employing LED's and multimode fibers whose chromatic dispersion and attenuation are greatly reduced compared with 0.85 and 1.06 /spl mu/m, and b) high data rate systems employing lasers and monomode fibers. In systems employing lasers and graded index multimode fibers, the advantage of 1.27/spl mu/m versus 1.06 /spl mu/m operation is not as pronounced, although transmission distances at both of these longer wavelengths are significantly increased from those at 0.85 /spl mu/m.