Intracavity frequency-doubled electrically-injected VECSEL
ABSTRACT We have previously demonstrated an intra-cavity frequency doubled optically pumped vertical external cavity surface emitting laser (VECSEL) based on a top emitting epitaxial structure. In this paper we report on a similar device, an InGaAs MQW VECSEL that is electrically-injected and bottom emitting. The bottom emitting structure allows for better current spreading and more efficient heat extraction from the active region at the expense of increased intracavity absorption from the substrate region.
- Thyroid 06/1998; 8(5):423-5. · 3.54 Impact Factor
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ABSTRACT: The chief clinical characteristics of Graves' disease are hyperthyroidism and ophthalmopathy. The relation between the two and the effect of treatment for hyperthyroidism on ophthalmopathy are unclear. We studied 443 patients with Graves' hyperthyroidism and slight or no ophthalmopathy who were randomly assigned to receive radioiodine, radioiodine followed by a 3-month course of prednisone, or methimazole for 18 months. The patients were evaluated for changes in the function and appearance of the thyroid and progression of ophthalmopathy at intervals of 1 to 2 months for 12 months. Hypothyroidism and persistent nyperthyroiaism were promptly corrected. Among the 150 patients treated with radioiodine, ophthalmopathy developed or worsened in 23 (15 percent) two to six months after treatment. The change was transient in 15 patients, but it persisted in 8 (5 percent), who subsequently required treatment for their eye disease. None of the 55 other patients in this group who had ophthalmopathy at base line had improvement in their eye disease. Among the 145 patients treated with radioiodine and prednisone, 50 (67 percent) of the 75 with ophthalmopathy at base line had improvement, and no patient had progression. The effects of radioiodine on thyroid function were similar in these two groups. Among the 148 patients treated with methimazole, 3 (2 percent) who had ophthalmopathy at base line improved, 4 (3 percent) had worsening of eye disease, and the remaining 141 had no change. Radioiodine therapy for Graves' hyperthyroidism is followed by the appearance or worsening of ophthalmopathy more often than is therapy with methimazole. Worsening of ophthalmopathy after radioiodine therapy is often transient and can be prevented by the administration of prednisone.New England Journal of Medicine 02/1998; 338(2):73-8. · 54.42 Impact Factor
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ABSTRACT: The pathogenesis of thyroid-associated ophthalmopathy is thought to be autoimmune, although environmental and genetic factors are also considered to be important. As the morbidity of thyroid-associated ophthalmopathy is considerable and treatment often unsatisfactory, there a need to identify possible predisposing factors. The study was undertaken in order to ascertain the relationship between age, gender and severity of thyroid-associated ophthalmopathy. One hundred and one consecutive patients with thyroid-associated ophthalmopathy who presented over a period of 5 years to a combined thyroid-eye clinic. Patients were assessed by grading their inflammatory signs and degree of diplopia, and by measurement of exophthalmos, palpebral aperture, differential intraocular pressure, and visual acuity. On the basis of the above an ophthalmopathy index was devised to grade the overall severity of eye disease. The mean age was 49.2 years (SD 13.4), the female-to-male ratio was 4.05, and mean ophthalmopathy index 6.49 (SD 3.3). Optic nerve compression was present in 9.9% of patients. There was a positive relationship between age and ophthalmopathy index (P < 0.001); after correcting for age, males had an average ophthalmopathy index 41% greater than that of females. There is an association between severity of thyroid-associated ophthalmopathy and (i) advancing age and (ii) female-to-male ratio, which has not been previously described. Patients over the age of 60 (particularly males) with Graves' disease appear to be at risk of developing severe eye disease.Clinical Endocrinology 04/1993; 38(4):367-72. · 3.40 Impact Factor