Zheng Wanhua

High Polarization Single Mode Photonic Crystal Microlaser

Generally, dipole mode is a doubly degenerate mode. Theoretical calculations have indicated that the single dipole mode of two-dimensional photonic crystal single point defect cavity shows high polarization property. We present a structure with elongated lattice, which only supports a single y-dipole mode. With this structure we can eliminate the degeneracy, control the lasing action of the cavity and demonstrate the high polarization property of the single dipole mode. In our experiment, the polarization extinction ratio of the y-dipole mode is as high as 51 1.

Photoluminescence Studies on Very High-Density Two-Dimensonal Electron Gases in Pseudomorphic Modulation-Doped Quantum Wells

We present photoluminescence studies on highly dense two-dimensional electron gases in selectively Si δ-doped GaAs/In0.18Ga0.82As/Al0.25Ga0.75As quantum wells (Ns = 4.24 × 1012 cm-2). Five well-resolved photoluminescence lines centered at 1.4194, 1.4506, 1.4609, 1.4695 and 1.4808 eV were observed, which are attributed to the subband exciton emission. The subband separations clearly exhibit the feature of a typical quantum well with triangle and square potential. These very intensive and sharp luminescence peaks with linewidths of 2.2 to 3.5 meV indicate the high quality of the structures. Their dependence on the excitation intensity and temperatures are also discussed.

Tunable high-power BaB2O4 optical parametric oscillator pumped at 355nm

We report the operation of a β-BaB2O4 (BBO) optical parametric oscillator (OPO) broadly tunable in the visible and the near infrared. Quantum efficiency of 22.7% for the signal and 34.1% for the idler corresponding to the total energy conversion efficiency of 25.9% has been achieved. The maximum average output power and the maximum output energy reached 220mW and 22mJ/pulse, respectively. By changing the matching angle of the OPO, the output wavelength was continuously scanned throughout 425-2144nm.

Picosecond narrow-band superluminescent optical parametric self-amplification in β-BaB2O4 crystal pumped at 354.7nm

A tunable picosecond narrow band β-BaB2O4 (BBO) superluminescent optical parametric self-amplification (OPSA) pumped by the third harmonic of an actively-passively mode-locked Nd:YAG laser has been demonstrated. The output wavelength of the OPSA was tunable from 406.6nm to 2777nm. The maximum energy conversion efficiency was 11%. The maximum peak power of the visible output was as high as 13MW.