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The insulated-gate bipolar transistor (IGBT) has a parasitic thyristor. Latch-up can occur when the current density exceeds a particular current density. Conventional methods employed to increase the latching current density will lead to some other performance degradations. To overcome these problems and further increase the latching current density of IGBT, a novel IGBT with a floating N-doped buried layer in P-base is proposed. By implanting a floating N-doped buried layer in the P-base, the hole current flowing underneath the N+ emitter can be reduced significantly. Thus, the current density that is needed to trigger the latch-up of the parasitic thyristor increases. Numerical simulation results show that the proposed IGBT can increase the latching current density by more than 100% without compromising the output and switching characteristics when compared with the conventional IGBT.

The optical processes of a single-atom model in the phonon field have been studied. To deal with the quantum electrodynamics phenomena in condensed matter microcavities, the influence of electron-phonon interactions has to be taken into account. As a clear picture, the effect of the lattice's oscillation on the optical transition in condensed matter microcavities is reduced to a model of a single atom in a phonon field. We deduce that in the case with a phonon participating, the Bloch equation is still satisfied. In the process of spontaneous emission for an electron interacting with a phonon, we derive the Rabi oscillation for the simple atom in the phonon field.

Green lasers can be used in many fields such as colour display, optical storage, laser medicine. The main requirements for the green lasers in the applications are compact, stable, high beam quality. It is one of the most efficient way to obtain green lasers by frequency doubling of Nd:YVO4(or Nd:YAG) lasers pumped by LD, which have been researched widely.

In KNSBN several crystallographic sites can be partially empty , which allow crystal composition to be tailored. The magnitude of longitudinal (r51) and transverse (r33) electro-optic coefficient depend greatly on the ratios of Ba/Na and K/Na. So either r33 or r51 can be made large, absorption and response wave range can be controlled in the desired spectral range by changing the dopant and its concentration . Accoding to these the crystal with partially- filled composition Cu -doped (K0.5Na0.5)0.2 (Sr0.1Ba0.39)0.9 Nb2O6 is grown.

Two different kinds of dynamic stable resonator—the resonator insensitive to axial shift of the mirrors of the resonator, and the resonator insensitive to thermo-perturbation of the thermo-lens in the resonator—and their general criteria are distinguished in detail. At the same time both coincident conditions are also discussed.