Low threshold room temperature pulsed and -57°C CW operationsof 1.3 μm GaInAsP/InP circular planar buried heterostructuresurface-emitting lasers

Room temperature pulsed lasing operation of a 1.3-μm GaInAsP/InP vertical-cavity surface-emitting laser has been achieved by using an effective carrier confinement of circular planar buried heterostructure (CPBH) and high reflectivity SiO₂/Si dielectric multilayer mirrors. The threshold current for a device having a nearly 12-μm-diameter active region was 34 mA at 24°C under pulsed operation. The optimized window cap structure reduces the series resistance to 6~15 Ω. Continuous wave lasing was also obtained up to -57°C, and the threshold below -61°C was still lower than 22 mA     

Index profiling of distributed-index lenses by a total reflection method

A simple index profiling method using total reflection is proposed. By a preliminary experiment, its accuracy was confirmed to be about 0.1% and its spatial resolution about 2?m. The index profile of a planar microlens was measured and compared with theoretical calculations.     

The impact of environmental factors on benthos communities and freshwater gastropod diversity in urban sinkhole ponds in roadside and forest contexts

Sinkhole ponds originated as a result of human activity leading to ground subsidence and create important habitats for the diversity of benthos fauna in urban areas. The objectives of this study were to determine whether the context (roadside/forest) is important in relation to the composition and diversity of macroinvertebrates, and to evaluate the influence of environmental factors (e.g. water quality) on snail communities. The study showed that the context of ponds had an impact on the properties of the water. Ponds located along roads were characterised by higher conductivity and a higher concentration of calcium and phosphates. The fauna was composed of 47 taxa, including 26 taxa found in both pond contexts. The density of macroinvertebrates was higher in forest ponds. CCA analysis showed that conductivity and concentration of nitrates were most strongly associated with the distribution of gastropods. Alien snail species more often inhabited the roadside ponds.     

Loss reduction of an ARROW waveguide in shorter wavelength and itsstack configuration

The reduction of the propagation loss of an antiresonant reflecting optical waveguide (ARROW) to 0.3 dB/cm in a short-wavelength band by using transparent TiO₂/SiO₂ interference cladding is discussed. An analysis method for ARROW is developed to analyze its propagation characteristics. Two uncoupled parallel ARROWs were stacked with 2-μm spacing, to obtain three-dimensional optical interconnection     

Intensity noise and polarization stability of GaAlAs-GaAs surfaceemitting lasers

The intensity noise characteristics of GaAlAs-GaAs vertical cavity surface emitting (SE) lasers have been investigated. A low-intensity noise of -145 dB/Hz was obtained with an output power of 2.2 mW. The spontaneous emission factor is estimated to be 2×10^-5, both from the bias dependence of the intensity noise and from the relative mode intensity below threshold. This is in good agreement with theoretical expectation. The possibility of low-noise operation of a microcavity SE laser with an extremely low output power of less than ~100 μW is shown. The polarization stability of the surface emitting laser is demonstrated by measuring the intensity fluctuations of an individual polarization state     

An integrated poly‐Si TFT current data driver with a data‐line pre‐charge function

Abstract— We have developed an integrated poly‐Si TFT current data driver with a data‐line pre‐charge function for active‐matrix organic light‐emitting diode (AMOLED) displays. The current data driver is capable of outputting highly accurate (±0.8%) current determined by 6‐bit digital input data. A novel current‐programming approach employing a data‐line pre‐charge function helps achieve accurate current programming at low brightness. A 1.9‐in. 120 × 136‐pixel AMOLED display using these circuits was demonstrated.     

Pulsed oscillation of GaAlAs/GaAs surface-emitting injection laser

We report the fabrication and lasing properties of the first GaAlAs/GaAs surface-emitting injection laser. The threshold current was 330 mA for 20 ?m? electrode at 77 K under pulsed conditions (? = 7960 ?). In some devices we achieved room temperature pulsed oscillation.     

1.17-μm highly strained GaInAs-GaAs quantum-well laser

Excellent lasing properties and temperature characteristic of a highly strained 1.17-μm GaInAs-GaAs double-quantum-well laser are reported. We show that a strained buffer layer, which is employed in the device, has no tradeoff on the device performance. For a 1500-μm-long laser with cleaved facets a threshold current density of 200 A/cm² is achieved. A transparency current density of 180 A/cm² is estimated for as cleaved devices. A record high characteristic temperature in this wavelength range of 150 K is achieved