Coherent Exciton-Biexciton Dynamics in GaN
Physical Review B: Condensed Matter and Materials Physics 65 (2002) 193102 4pp
Photon-number squeezing in a free-running quantum-well laser operating at 980 nm
Journal of Optics B: Quantum and Semiclassical Optics 4:2 (2002) 129-133
Abstract:
We present intensity noise investigations of a free-running InGaAs quantum-well laser diode operating at 980 nm at room temperature. The laser had a threshold current of 17 mA. Photon-number squeezing was achieved for drive currents of 48 mA when the laser was operating on two dominant longitudinal modes. The degree of squeezing obtained was 9%, which was in reasonable agreement with the current-to-current efficiency of 11%. No squeezing was observed at 35 K.Growth mechanism and additive effect of high-T-c superconducting crystals
J CRYST GROWTH 237 (2002) 772-777
Abstract:
Two spiral growth patterns in different scales are observed on the base plane of high-T-c crystals. The nanometer spiral exhibits the top-most atomic layer with weak bonding along c-axis and the step height of one or half-C cell parameter. A Cluster model is proposed to understand the growth mechanism and to conduct the additive application. A special additive has been found to improve not only the crystal growth, but also the superconductivity. The amount of the additive needs to be controlled in order to achieve the best effect. As a result. several sin.-le crystals in various families with size up to centimetre have been obtained by flux method. YBa2Cu3O7-delta crystal exhibits high transition temperature (T-c) of 93.7 K with sharp width of 0.1 K. (La,Sr)(2)CuO4 Crystal shows T-c = 38.5 K with 1.5 K width, which is the best record so far for the flux grown crystals. T(c)similar to34K is obtained in the first time for the flux as-grown La2CuO4+delta crystal without further oxidation. (C) 2002 Elsevier Science B.V. All rights reserved.Hot phonons and non-thermal carrier states in GaN
Physica B: Condensed Matter 314:1-4 (2002) 30-34
Abstract:
Non-thermal carrier states at early times are studied using femtosecond pump-probe spectroscopy in GaN. After the residual chirp on the continuum probe is removed, the normalized difference spectra (NDS) for different probe energies are synchronized, recovering the full time resolution of our laser pulse (120 fs). Our Monte-Carlo simulation agree well with the unchirped NDS spectrum, which shows the development of the carrier distribution at early times, where phonon satellites are seen, together with a strong non-thermal electron distribution in the region of the LO-phonon energy arising from the remarkably strong electron-LO phonon interaction. Employing a new technique which involves the integration of the normalized NDS multiplied by the corresponding energy, a measure of the mean energy of the carriers in non-thermal states is obtained. By comparing the time-dependent energy loss with the theoretical energy loss rate, we estimate the effective temperature of the phonon modes as well as the population of phonons. Our Monte-Carlo model agrees well with this data, and confirms the dominance of hot phonon effects at early times. © 2002 Elsevier Science B.V. All rights reserved.Saturation of gain in In0.02 Ga0.98 N/In0.16 Ga0.84 N MQW plasmas
Physica B: Condensed Matter 314:1-4 (2002) 47-51