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We fabricate and investigate two-dimensional photonic crystal H3 microcavities in an InGaAsP slab. The lasing action at room temperature is observed. The lasering threshold is 7mW under the pulsed pump of 0.75% duty cycle. The Q factor and the lasing mode characteristics are simulated by three-dimensional finite difference time domain method. The simulation result matches well with the experiment.

An edge emitting laser based on two-dimensional photonic crystal slabs is proposed. The device consists of a square lattice microcavity, which is composed of two structures with the same period but different radius of air-holes, and a waveguide. In the cavity, laser resonance in the inner structure benelits from not only the anomalous dispersion characteristic of the first band-edge at the M point in the first Brillouin-zone but also zero photon states in the outer structure. A line defect waveguide is introduced in the outer structure for extracting photons from the inner cavity. Three-dimensional finite-difference time-domain simulations apparently show the in-plane laser output from the waveguide. The microcavity has an effective mode volume of about 3.2(lambda/eta(slab))(3) for oscillation -mode and the quality factor of the device including line defect waveguide is estimated to be as high as 1300.

A numerical study of the defect modes in two-dimensional photonic crystals with deformed triangular lattice is presented by using the supercell method and the finite-difference time-domain method. We find the stretch or shrink of the lattice can bring the change not only on the frequencies of the defect modes but also on their magnetic field distributions. We obtain the separation of the doubly degenerate dipole modes with the change of the lattice and find that both the stretch and the shrink of the lattice can make the dipole modes separate large enough to realize the single-mode emission. These results may be advantageous to the manufacture of photonic crystal lasers and provide a new way to realize the single-mode operation in photonic crystal lasers.

Electroluminescence (EL) is observed from the Au/Si-rich SiO2 film/p-Si diodes, in which the Si-rich SiO2 films are scored deliberately by a diamond tip. The EL intensity of the scored diode annealed at 800 degreesC is about 6 times of that of the unscored counterpart. The EL spectrum of the unscored diode could be decomposed into two Gaussian luminescence bands with peaks at about 1.83 and 2.23eV, while for the EL spectrum of the scored diode, an additional Gaussian band at about 3.0eV appears, and the 1.83-eV peak increases significantly in intensity. The photoluminescence (PL) spectrum of an unscored Si-rich SiO2 film has only one band peaking at about 1.48eV, whereas the PL spectrum of the scored one has two bands at about 1.48 and 1.97eV. We consider that the high-density defect regions produced by the scoring provide new luminescence centres and become some types of nonradiative centres in the Si oxide layer, which thus result in changes of the EL and PL spectra.

After an Si oxide layer of 3 nm thickness had been grown by using magnetron sputtering on a p-type Si (100) substrate, an indium tin oxide (ITO) film was deposited onto the Si oxide layer by using electron beam deposition. Electroluminescence (EL) from such an ITO/Si oxide/p-type Si structure was measured under a forward bias of 5 V or more. Its EL power efficiency is about eight times as large as that of a semitransparent Au/Si oxide (3 nm)/p-Si structure. The experimental results indicate that the greater EL power efficiency is due not only to the higher optical transparency of the ITO film compared with Au film in a range of 300 to 900 nm, but also to some new luminescence centers introduced in the Si oxide layer during the ITO deposition process.

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.

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.

The slow light effect in a photonic crystal waveguide is investigated theoretically and experimentally. Theoretical calculation indicates that there is a slow light region for the even mode, from which the resonance and lasing in a microcavity would benefit. A photonic crystal waveguide microlaser is fabricated, which is related to the group velocity of c/120.6.

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.

We have studied the effects of γ-ray irradiation on electroluminescence (EL) from Au/extra thin Si-rich SiO2 film/p-Si Structures. After γ-ray irradiation, for the structure with a 600°C annealed Si-rich SiO2 film a new blue EL band with a peak at around 480 nm was observed, and for the structure with a 300°C annealed Si-rich SiO2 film the red EL band shifts from 670 to 660 nm and its intensity and full width at half maximum increase pronouncedly. The experimental results demonstrate that the defects induced by γ-ray irradiation are responsible for the blue EL band as well as for the variations of the red EL band.