RESUMO
We report a case of accidental thermal injury due to improper use of a laser pointer obtained outside of the United States. A 13-year-old received a laser pointer as a gift and looked at a reflection of the beam. The patient underwent full ophthalmologic examination with fundus photography, spectral domain optical coherence tomography, and fluorescein angiography. Visual acuity in the left eye was 20/100 at presentation. Fundus examination and ancillary tests were consistent with thermal macular injury. The laser pointer was analyzed and found to be a green diode laser with average power output of 154 mW.
Assuntos
Lasers Semicondutores/efeitos adversos , Macula Lutea/lesões , Doenças Retinianas/etiologia , Epitélio Pigmentado da Retina/patologia , Escotoma/etiologia , Administração Oral , Adolescente , Atrofia , Glucocorticoides/uso terapêutico , Humanos , Masculino , Prednisona/uso terapêutico , Doenças Retinianas/diagnóstico , Doenças Retinianas/tratamento farmacológico , Escotoma/diagnóstico , Escotoma/tratamento farmacológico , Tomografia de Coerência Óptica , Acuidade VisualRESUMO
We demonstrate experimentally and numerically that, by spectrally filtering the delayed optical feedback into a semiconductor laser, one can elicit novel dynamics in the frequency of the laser output light on a time scale that is set by the delay time of the feedback. In particular, we show that through a judicious choice of the filter bandwidth, and its frequency relative to that of the laser, one can produce controlled oscillations in the frequency of light from the laser.
RESUMO
We investigate the influence of quantum noise on the highly complex nonlinear dynamics that arise in a single-mode semiconductor laser subject to filtered optical feedback. Our numerical study, which utilizes rate equations that are augmented by Langevin noise terms to account for the spontaneous-recombination noise, shows that for relatively broad filters the noise may lead to qualitatively different dynamics than predicted by a deterministic analysis. In particular, we find that certain attractors that are predicted in the absence of noise may no longer be available when the effects of noise are correctly incorporated. For narrow bandwidth filters we demonstrate optical-injection-like behavior and identify locking of the semiconductor laser to the relaxation oscillation side peaks. In general, the results indicate that shot noise in the laser can influence the dynamics quite substantially.
