Long-wavelength monolithic VCSEL arrays with high optical output power

Two-dimensional vertical-cavity surface-emitting laser (VCSEL) arrays at 1.55 /spl mu/m wavelength with parallel operation of single- or multimode devices are presented. 3/spl times/3 VCSEL arrays show maximum output powers beyond 30 mW and conversion efficiencies as high as 22%.     

Optically Active Binary Liquid Crystal Thermometry

Research on the biological effects and medical applications of non-ionizing electromagnetic fields often requires the use of nonmetallic non-perturbing temperature sensors. The highly temperature dependent optical activity observed in certain types of liquid crystals makes possible the construction of very sensitive non-perturbing fiberoptic thermometers. A knowledge of the effect of various parameters on the optical rotatory power of the chosen liquid crystal is essential for the construction of such a device. The dependence of the optical rotatory power on temperature, composition, and sample thickness in a binary mixture of a nematic (MBBA) and a cholesteric (Cholesteryl Oleate) liquid crystal was studied. The dependence of effective pitch on composition was determined. Application of the data on rotatory power and effective pitch to the construction of devices is discussed. Illinois under Grant USPHSCA 09067.     

Electrically pumped room temperature CW VCSELs with 2.3 /spl mu/m emission wavelength

Continuous wave (CW) operation at room temperature of electrically pumped InGaAlAs/InP vertical-cavity surface-emitting lasers (VCSELs) at emission wavelengths as high as 2.3 /spl mu/m is demonstrated for the first time. Devices with 15 /spl mu/m active region diameter show a maximum output power of 0.75 mW at 20/spl deg/C and a maximum CW operating temperature of 45/spl deg/C.     

2.5-mW single-mode operation of 1.55-/spl mu/m buried tunnel junction VCSELs

We present 1.55-/spl mu/m wavelength buried tunnel junction InGaAlAs-InP vertical-cavity surface-emitting lasers with low threshold current and high efficiency. An improved mirror design is accomplished with high-reflective low-loss epitaxial InGaAlAs-InAlAs and hybrid dielectric CaF/sub 2/-ZnS-Au layer stacks, respectively. Lasers with aperture diameters of only around 5 /spl mu/m exhibit continuous-wave single-mode output powers at room temperature well beyond 2 mW. Threshold voltages and series resistances as low as 0.9 V and 30-40 /spl Omega/ have been measured. The spectral behavior shows excellent performance over the relevant current and temperature range.     

Temperature dependent electron velocity-field characteristics for In0.53Ga0.47AS at high electric fields

The static electron velocity-field characteristics for n-In_0.53Gan_0.47AS have been measured at temperatures from 95 K to 300 K over a range of electric field strengths from about 10 kV/cm to beyond 100 kV/cm. The velocity decreases monotonically with increasing electric field at all temperatures over the range of field strengths investigated. The electron velocity-field curves for In_0.53Ga_0.47As exhibit a larger peak-to-valley ratio, lower high-field velocity, and a smaller high-field temperature dependence than those for GaAs measured using the same experimental technique.