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The potential of 1.3-μm AlGaInAs quantum-well (MQW) laser diodes for uncooled operation in high-speed optical communication systems is experimentally evaluated by characterizing the temperature dependence of key parameters such as the threshold current, transparency current density, optical gain and carrier lifetime. Detailed measurements performed in the 20°C-100°C temperature range indicate a localized T0 value of 68 K at 98°C for a device with a 208 μm ridge width and 700μm cavity length. The transparency current density is measured for temperatures from 20°C to 60°C and found to increase at a rate of 7.7 A.cm-2 · °C-1. Optical gain characterizations show that the peak model gain at threshold is independent of temperature, whereas the differential gain decreases linearly with temperature, whereas the differential gain decreases linearly with temperature at a rate of 3 × 10-4 A-1 · °C-1. The differential carrier lifetime is determined from electrical impedance measurements and found to decrease with temperature. From the measured carrier lifetime we derive the monomolecular (A), radiative (B), and nonradiative Auger (C) recombination coefficients and determine their temperature dependence in the 20°C-80°C range. Our study shows that A is temperature independent, B decreases with temperature. The experimental observations are discussed and compared with theoretical predictions and measurements performed on other material systems. [ABSTRACT FROM AUTHOR]

Laser cooling and trapping of radioactive atoms represent the new frontier in atomic physics and a new powerful tool in nuclear physics. We are setting up at the INFN-Legnaro National Laboratories a laser cooling facility that has as a first goal the realization of a 210Fr magneto-optical trap. The general outline of the experiment and the improvements of the final trap efficiency are discussed. Some preliminary results are presented. [ABSTRACT FROM AUTHOR]

Ultrashort pulse, high-power mode locking is demonstrated in InGaAs quantum dot lasers using a flared waveguide laser incorporating a narrow waveguide sections acting as both a mode filter and saturable absorber. 24 GHz mode locking with 780 fs pulses and 500 mW peak powers are demonstrated at an emissions wavelength of 1.3 μm. [ABSTRACT FROM AUTHOR]

35 GHz passive mode-locking of 1.3 μm (InGa)As/GaAs quantum dot lasers is reported. Hybrid mode-locking was achieved at frequencies up to 20 GHz. The minimum pulse width of the Fourier-limited pulses was 7 ps with a peak power of 6 mW. Low uncorrelated timing jitter below 1 ps was found in cross correlation experiments. High-frequency operation of the lasers was eased by a ridge waveguide design that includes etching through the active layer. [ABSTRACT FROM AUTHOR]

The key parameters in the fabrication of deep-etch high-order λ/4 Bragg gratings for short-wavelength nitride-based lasers are investigated. Calculations indicate that, for an air-gap thickness of 1.73 µm and single-spot Gaussian beam profile, the reduction in grating reflectivity due to light diffraction in the air gaps is only 17% with respect to a first-order structure with 0.1 µm air gaps. Scanning electron microscopy and microphotoluminescence characterizations confirm the validity of the numerical predictions and show that the 28%-38% reflectivity obtained from prototype focused-ion-beam-etched air/nitride gratings is mainly limited by imperfections and material disorder due to etching. Improving the etching technique would, therefore, allow standard lithographic fabrication of reduced-threshold GaN lasers. © 2001 American Institute of Physics. [DOI: 10.1063/1.1424061]. [ABSTRACT FROM AUTHOR]

18 GHz passive modelocking with Fourier-transform-limited optical pulses in InGaAs/GaAs quantum dot lasers emitting at ∼1.3 mm has been achieved for the first time. An upper limit of 600 fs is estimated for the root-mean-square timing jitter (2.5–50 MHz). [ABSTRACT FROM AUTHOR]

Hybrid modelocking of monolithic quantum dot lasers is reported for the first time. A marked performance improvement over passive modelocking is demonstrated. Both hybrid and passive modelocking at ∼10 GHz are achieved for the first time in quantum dot lasers. [ABSTRACT FROM AUTHOR]