Linear laser diode arrays for improvement in optical disk recording for space stations

The design and fabrication of individually addressable laser diode arrays for high performance magneto-optic recording systems are presented. Ten diode arrays with 30 mW cW light output, linear light vs. current characteristics and single longitudinal mode spectrum were fabricated using channel substrate planar (CSP) structures. Preliminary results on the inverse CSP structure, whose fabrication is less critically dependent on device parameters than the CSP, are also presented. The impact of systems parameters and requirements, in particular, the effect of feedback on laser design is assessed, and techniques to reduce feedback or minimize its effect on systems performance, including mode-stabilized structures, are evaluated

AlGaAs heterojunction lasers

The characterization of 8300 A lasers was broadened, especially in the area of beam quality. Modulation rates up to 2 Gbit/sec at output powers of 20 mW were observed, waveform fidelity was fully adequate for low BER data transmission, and wavefront measurements showed that phase aberrations were less than lamda/50. Also, individually addressable arrays of up to ten contiguous diode lasers were fabricated and tested. Each laser operates at powers up to 30 mW CW in single spatial mode. Shifting the operating wavelength of the basic CSP laser from 8300 A to 8650 A was accomplished by the addition of Si to the active region. Output power has reached 100 mW single mode, with excellent far field wave front properties. Operating life is currently approx. 1000 hrs at 35 mW CW. In addition, laser reliability, for operation at both 8300 A and 8650 A, has profited significantly from several developments in the processing procedures

Improving the Reliability and Modal Stability of High Power 870 nm AlGaAs CSP Laser Diodes for Applications to Free Space Communication Systems

The operating characteristics (power-current, beam divergence, etc.) and reliability assessment of high-power CSP lasers is discussed. The emission wavelength of these lasers was optimized at 860 to 880 nm. The operational characteristics of a new laser, the inverse channel substrate planar (ICSP) laser, grown by metalorganic chemical vapor deposition (MOCVD), is discussed and the reliability assessment of this laser is reported. The highlights of this study include a reduction in the threshold current value for the laser to 15 mA and a degradation rate of less than 2 kW/hr for the lasers operating at 60 mW of peak output power

High-power AlGaAs channeled substrate planar diode lasers for spaceborne communications

A high power channeled substrate planar AlGaAs diode laser with an emission wavelength of 8600 to 8800 A was developed. The optoelectronic behavior (power current, single spatial and spectral behavior, far field characteristics, modulation, and astigmatism properties) and results of computer modeling studies on the performance of the laser are discussed. Lifetest data on these devices at high output power levels is also included. In addition, a new type of channeled substrate planar laser utilizing a Bragg grating to stabilize the longitudinal mode was demonstrated. The fabrication procedures and optoelectronic properties of this new diode laser are described

Arkansas Soybean Performance Tests 2020

Soybean variety and strain performance tests are conducted each year in Arkansas by the University of Arkansas System Division of Agriculture’s Arkansas Crop Variety Improvement Program. The tests provide information to companies developing varieties and/or marketing seed within the State, and aid the Arkansas Cooperative Extension Service in formulating variety recommendations for soybean producers

Arkansas Corn and Grain Sorghum Performance Tests 2020

Corn and grain sorghum performance tests are conducted each year in Arkansas by the University of Arkansas System Division of Agriculture. The tests provide information to companies marketing seed within the state and aid the Arkansas Cooperative Extension Service in formulating recommendations for producers. The 2020 corn performance tests contained 85 hybrids and were conducted at the Northeast Research and Extension Center (NEREC) at Keiser, the Lon Mann Cotton Research Station (LMCRS) near Marianna, the Bell Farming Company (BFC) near Des Arc, the Pine Tree Research Station (PTRS) near Colt, the Rohwer Research Station (RRS) near Rohwer, and the Rice Research and Extension Center (RREC) near Stuttgart.The 2020 grain sorghum performance tests contained 15 hybrids and were conducted at the NEREC, the LMCRS, the RRS, and the RREC. Test location maps for grain sorghum and corn can be found on page 36 and inside the back cover, respectively

Arkansas Soybean Performance Tests 2022

Soybean variety and strain performance tests are conducted each year in Arkansas by the University of Arkansas System Division of Agriculture’s Arkansas Crop Variety Improvement Program. The tests provide information to companies developing varieties and/ or marketing seed within the state, and aid the Arkansas Cooperative Extension Service in formulating variety recommendations for soybean producers

Arkansas Corn and Grain Sorghum Performance Tests 2022

Corn and grain sorghum performance tests are conducted each year in Arkansas by the University of Arkansas System Division of Agriculture. The tests provide information to companies marketing seed within the state and aid the Arkansas Cooperative Extension Service in formulating recommendations for producers. The 2022 corn performance tests contained 68 hybrids and were conducted at the Northeast Rice Research and Extension Center (NERREC) at Harrisburg, the Northeast Rice Research and Extension Center (NEREC) at Keiser, the Lon Mann Cotton Research Station (LMCRS) near Marianna, the Rohwer Research Station (RRS) near Rohwer, and the Rice Research and Extension Center (RREC) near Stuttgart. The 2022 grain sorghum performance tests contained 24 hybrids and were conducted at the NERREC, the NEREC, the LMCRS, the RRS, and the RREC locations. The test location map for grain sorghum and corn can be found on page 42

Arkansas Soybean Performance Tests 2021

Soybean variety and strain performance tests are conducted each year in Arkansas by the University of Arkansas System Division of Agriculture’s Arkansas Crop Variety Improvement Program. The tests provide information to companies developing varieties and/ or marketing seed within the state, and aid the Arkansas Cooperative Extension Service in formulating variety recommendations for soybean producers

Arkansas Corn and Grain Sorghum Performance Tests 2021

Corn and grain sorghum performance tests are conducted each year in Arkansas by the University of Arkansas System Division of Agriculture. The tests provide information to companies marketing seed within the state and aid the Arkansas Cooperative Extension Service in formulating recommendations for producers. The 2021 corn performance tests contained 70 hybrids and were conducted at the Northeast Research and Extension Center (NEREC) at Keiser, the Lon Mann Cotton Research Station (LMCRS) near Marianna, the Bell Farming Company (BFC) near Des Arc, the Rohwer Research Station (RRS) near Rohwer, and the Rice Research and Extension Center (RREC) near Stuttgart. The 2021 grain sorghum performance tests contained 17 hybrids and were conducted at the NEREC, the LMCRS, the RRS, and the RREC locations. Test location maps for grain sorghum and corn can be found on page 40 and inside the back cover, respectively