Development of Surface Grating Distributed Feedback Quantum Cascade Laser for High Output Power and Low Threshold Current Density

We report on the room-temperature cascade laser （QCL） at λ -4.7μm. cw operation of a surface grating Both grating design and material distributed feedback （DFB） quantum optimization are used to decrease the threshold current density and to increase the output power. For a high-reflectivity-coated 13-μm-wide and 4- mm-long laser, high wall-plug efficiency of 6% is obtained at 20℃ from a single facet producing over I W of ew output power. The threshold current density of DFB QCL is as low as 1.13kA/cm^2 at 10℃ and 1.34kA/cm2 at 30℃ in cw mode. Stable single-mode emission with a side-mode suppression ratio of about 30 dB is observed in tile working temperature range of 20-50℃.

The scheme optimization on construction diversion with discharge control feature of upstream operational reservoir

There is a discharge control feature of construction diversion system with the upstream operational reservoir. The risk evaluation model of construction diversion is established by taking into consideration the risk factors of construction diversion system with discharge control feature as well as their composition. And the risk factors include the upstream operational reservoir discharge control, the interval flood and branch flood and the diversion system itself. And then based on analyzing of the conversion relation between risk index and investment index of diversion scheme, the risk control and conversion principals of diversion system are put forward, and the feasible diversion scheme model is built. At last, the risk and economic evaluation and scheme economic feasibility analysis method of diversion scheme are shown by an example of construction diversion scheme optimization with the discharge control condition of upstream hydropower station. The study is valuable for establishment and optimization of construction diversion scheme with upstream reservoir discharge control.