Analysis of directional emission in square resonator lasers with an output waveguide

Square microcavity laser with an output waveguide is proposed and analyzed by the finite-difference time-domain (FDTD) technique. For a square resonator with refractive index of 3.2, side length of 4 microns, and output waveguide of 0.4-micron width, we have got the quality factors (Q factors) of 6.7×10~2 and 7.3×10~3 for the fundamental and first-order transverse magnetic (TM) mode near the wavelength of 1.5 microns, respectively. The simulated intensity distribution for the first-order TM mode shows that the coupling efficiency in the waveguide reaches 53%. The numerical simulation shows that the first-order transverse modes have fairly high Q factor and high coupling efficiency to the output waveguide. Therefore the square resonator with an output waveguide is a promising candidate to realize single-mode directional emission microcavity lasers.

Room temperature continuous wave operation of 1.33-micron InAs/GaAs quantum dot laser with high output power

Continuous wave operation of a semiconductor laser diode based on five stacks of InAs quantum dots (QDs) embedded within strained InGaAs quantum wells as an active region is demonstrated. At room temperature, 355-mW output power at ground state of 1.33-1.35 microns for a 20-micron ridge-waveguide laser without facet coating is achieved. By optimizing the molecular beam epitaxy (MBE) growth conditions, the QD density per layer is raised to 4*10^(10) cm^(-2). The laser keeps lasing at ground state until the temperature reaches 65 Celsius degree.

Monolithically Integrated Laser Diode and Electroabsorption Modulator with Dual-Waveguide Spot-Size Converter Output

A 1.60μm laser diode and electroabsorption modulator monolithically integrated with a novel dualwaveguide spot-size converter output for low-loss coupling to a cleaved single-mode optical fiber are demonstrated.The devices emit in a single transverse and quasi single longitudinal mode with an SMSR of 25.6dB. These devices exhibit a 3dB modulation bandwidth of 15. 0GHz, and modulator DC extinction ratios of 16.2dB. The output beam divergence angles of the spot-size converter in the horizontal and vertical directions are as small as 7. 3°× 18. 0°,respectively, resulting in a 3. 0dB coupling loss with a cleaved single-mode optical fiber.

An Efficient MMI SOI Splitter with Multimode Input/Output Waveguides

A 1×8 multimode interference power splitter with multimode input/output waveguides in SOI material is designed by the beam propagation method and fabricated by the inductive coupled plasma etching technology for use in fiber optics communication systems.The fabricated device exhibits low loss and good coupling uniformity.The excess loss is lower than 0.8dB,and the uniformity is 0.45dB at the wavelength of 1550nm.Moreover,the polarization dependent loss is lower than 0.7dB at 1550nm.The device size is only 2mm×10mm.

Passively Mode Locked Diode-End-Pumped Nd∶YAG Laser with In0.25 Ga0.75 As as Output Coupler

A novel InGaAs(LT-In0.25 Ga0.75 As) absorber grown by metal organic chemical vapor deposition at low temperature is presented.Using it as well as an output coupler,passive mode locking,which produces pulses as short as several hundred picoseconds for diode-end-pumped Nd∶YAG laser at 1.06μm,is realized.The pulse frequency is 150MHz.

1.5 mu m DFB integrated with vertical tapered spotsize converter fabricated by selective MOVPE

1.5 mu m DFB LD butt-joint integrated with vertical tapered spotsize converter was fabricated by LP-MOVPE. The vertical far field angle (FWHM) was decreased from 34degrees to 10degrees the threshold currents was as low as 19.8mA, the output power was 9.6mw at 100mA without HR coating and the SMSR was 35.8dB. The 1-dBm misalignment tolerance was 3.2 mu m, while the counterpart of the device without SSC was 2.2 mu m.

AlGaInP visible quantum well lasers for information technology

650 nm-range AlGaInP multi-quantum well (MQW) laser diodes grown by low pressure metal organic chemical vapor deposition (LP-MOCVD) have been studied and the results are presented in this paper. Threshold current density of broad area contact laser diodes can be as low as 350 A/cm(2). Laser diodes with buried-ridge strip waveguide structures were made, threshold currents and differential efficiencies are (22-40) mA and (0.2-0.7) mW/mA, respectively. Typical output power for the laser diodes is 5 mW, maximum output power of 15 mW has been obtained. Their operation temperature can be up to 90 degrees C under power of 5 mW. After operating under 90 degrees C and 5 mW for 72 hrs, the average increments for the threshold currents of the lasers at 25 degrees C and the operation currents at 5 mW (at 25 degrees C) are (2-3) mA and (3-5) mA, respectively. Reliability tests showed that no obvious degradation was observed after 1400 hours of CW operation under 50 degrees C and 2.5 mW.

Flat currents and solutions of the green-schwarz superstring on AdS(5)xS(5)

IEECAS SKLLQG

PbWO_4晶体的光输出与能量分辨研究；Study on Light Output and Energy Resolution of PbWO_4 Crystal

研究了多种包装材料和包装工艺对钨酸铅(PbWO4)晶体光输出和能量分辨的影响,测量结果与基于GEANT4的模拟结果符合很好,并由此确定了晶体的最佳包装方法。

80 MeV/u C-12离子诱变选育PHB高产菌株；A strain of high PHB output by mutagenesis of 80 MeV/u C-12 ions

用80MeV/u12C6+离子对一株积累聚β-羟基丁酸酯(PHB)的芽孢杆菌(BacillusP-9)进行诱变选育,最终获得PHB高产株菌G15,其PHB产量达2.93g/L,与出发菌株相比较,PHB积累量提高了1.5倍。研究结果表明,本试验辐照最佳剂量为15Gy。重离子辐照诱变育种效果显著,具有广阔的发展应用前景。

The temporal and spatial evaluation on China's agricultural policy output since 1978

Since reform and opening up, how much contribution has China's implementation of new agricultural policy made to agricultural output? This paper is trying to establish an agricultural policy output econometric model for doing a quantitative analysis of China's new agricultural policy. The results show that China's agricultural policies on agricultural output have an average contribution rate of about 7% since 1978, which is consistent with the OECD's basic forecast. There are obvious temporal and spatial differences. Generally speaking, we can divide the contribution of agricultural policy into three periods, which are the start-up phase from 1978 to 1991 (14 years), the stationary phase from 1992 to 2002 (11 years) and the rising phase from 2003 to 2008 (6 years). In space, the contribution of agricultural policy underwent a process from the all-low in the start-up phase, the gradual increase in the stationary phase to the all-high in the rising phase. Northern and western regions are more sensitive to policies. There are three major factors that can affect the contribution of regional agricultural policies, which are the process of national industrialization strategy, terrain and the level of local finance.