Chirped arrays of diode lasers for supermode control

We propose nonuniform structures of phase-locked diode lasers, which make it possible to discriminate efficiently against all the higher order array supermodes (lateral modes). In these nonuniform arrays, the effective mode index in each channel varies across the array. Consequently, the envelopes of the various supermodes, including the highest order one, differ significantly from each other. Thus, by proper tailoring of the gain distribution across the array, one can conveniently select the fundamental supermode. Such fundamental supermode oscillation is essential in order to obtain single lobe, diffraction limited beams and minimal spectral spread from phase-locked laser arrays

Coupling mechanism of gain-guided integrated semiconductor laser arrays

It is shown that a gain-guided laser array couples via propagating fields rather than the evanescent mode coupling typically responsible for directional coupling in passive (directional couplers) and active (laser array) devices. We show that these phase-locked modes exhibit an interference pattern, in the junction plane, which arises from the curvature of the phase fronts of optical fields of the interacting lasers. The experimental results are interpreted with the aid of a simple theoretical model, and the effect of the observed mode pattern on the coupling of gain-guided lasers is discussed

Control of mutual phase locking of monolithically integrated semiconductor lasers

The mutual coherence of two coupled semiconductor lasers is investigated experimentally. It is demonstrated that by varying the gain in the overlap region, the degree of phase coherence can be continuously controlled. The quantitative characterization of the degree of phase coherence by fringe visibility is demonstrated

Single contact tailored gain phased array of semiconductor lasers

We demonstrate a single contact tailored gain-guided array in which the gain profile across the array is made strongly asymmetric by varying the width of the contact stripes. A proton isolated array of six (GaAl)As lasers with 5-µm separations and widths varying linearly between 3 and 8 µm had a single lobed far field 2° wide, close to the diffraction limit for a single supermode. Fabrication of this device is simple, and suited to large-scale processing techniques. We also show that in such an asymmetric gain-guided array the fundamental mode is favored over higher order modes, and that higher order modes can have single lobed far-field patterns differing only slightly from that of the fundamental

Study of effects of space power satellites on life support functions of the earth's magnetosphere

The effects of the Satellite Solar Power System (SSPS) on the life support functions of the earth's magnetosphere were investigated. Topics considered include: (1) thruster effluent effects on the magnetosphere; (2) biological consequences of SSPS reflected light; (3) impact on earth bound astronomy; (4) catastrophic failure and debris; (5) satellite induced processes; and (6) microwave power transmission. Several impacts are identified and recommendations for further studies are provided

Surgical Management of Massive Labial Edema in a Gravid Preeclamptic Diabetic

Background. Massive labial edema is a rare complication during pregnancy that can jeopardize vaginal delivery, as well as leading to maternal and fetal morbidity. It can be related to systemic pathologies, but has been commonly associated with preeclampsia and diabetes. This increased and sometimes longstanding pressure may result in a “labial compartment syndrome� leading to microvascular damage and tissue necrosis if not resolved in a timely fashion. Case. Massive labial edema was treated first conservatively and then surgically in a gravid diabetic patient with severe preeclampsia. Immediately after Cesarean section, the labial compartment syndrome was relieved surgically and resolved rapidly. Conclusion. When conservative attempts at management of labial edema fail, or rapid resolution is critical to maternal and fetal outcome, surgical alternatives should be considered

Far-field distribution of semiconductor phase-locked arrays with multiple contacts

Experimental results of far-field patterns of semiconductor laser arrays with multiple contacts are reported. It is found that, by tailoring the distribution of the currents through the array elements, narrow single-lobe patterns—which are more useful in most applications—can be obtained from arrays that usually operate in a double-lobe mode. A diffraction-limited 1.8°-wide far-field pattern was obtained from a three-element array

Salinity Tolerance of Selected Ectomycorrhizal Fungi (Pisolithus tinctorius Pers.) and Ectomycorrhizal Eucalypts

Increasing soil salinity has become a major problem worldwide. It has led to a reduction in the amount of arable land, has put at risk the supply of freshwater and threatens the existence of many natural habitats. The major increase in salinity has been attributed to human activities such as clearing of natural vegetation and large-scale irrigation programmes. The alleviation of this problem has focussed on changed management strategies. the most significant of which is the re-establishment of deep rooted plants in sail affected areas. This, however, is difficult because of the variation in salt tolerance of such plants and the problems created through nutrient deficiencies characteristic of such sites. This study investigated the role of ectomycorrhizal (ECM) associations in assisting eucalypts tolerate soil salt. The response of specific isolates of P. tinctorius Pers. To salinity in vitro was used to determine which may be the most effective when transferrred to saline soils. All isolates tested appeared to be at least tolerant or semi-tolerant to 150 mM NaCI. However, the different isolates produced different patterns of colony growth, making assessment of growth rates, and therefore salt tolerance, difficult. Inoculation of E. camaldulensis Dehnh. and E. diversicolor F. Muell. with spores of field collected Scleroderma species and Pisolithus tinctorius improved salt tolerance of E. camaldulensis but not E. diversicolor. Inoculation of E. diversicolor and E. camaldulensis seedlings and clones with P. tinctorius isolates used in in vitro studies, showed no significant growth response to salinity. This may be attributed to poor development of ECM structures within the root zone of these plants. Root and shoot proline content showed significant responses to both inoculation with ECM Fungi and salt treatment. These results did vary between experiments. Further research into the use of ECM to alleviate the problem of soil salinity is justified by this study. The development of new, and improvement of current techniques is discussed in light of these findings