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A vertical cavity surface emitting semiconductor laser is described which uses zinc diffusion and partial disordering of the epitaxial output mirror to provide waveguiding for lateral mode control. Mode suppression ratios against higher order transverse modes as high as 36 dB have been observed.<> 相似文献
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Hsin W. Du G. Gamelin J.K. Malloy K.J. Wang S. Whinnery J.R. Yang Y.J. Dziura T.G. Wang S.C. 《Electronics letters》1990,26(5):307-308
A surface emitting laser diode (SELD) with two distributed Bragg reflectors (DBR) and semiconductor multilayer air-bridge-supported top mirror is fabricated. A low threshold current of 1.5 mA is achieved under room temperature CW operation. The spectrum shows a strong peak at 891 nm with a FWHM of 10 AA. With light emission from the top Bragg reflector instead of from the back side of the substrate, laser arrays are easily formed with this novel structure.<> 相似文献
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Interstitial-free Fe-P alloys (0.083, 0.23 and 0.40 at. pct P) and a rephosphorized low-carbon steel were strained 4 pct in
tension, aged isothermally at temperatures between 373 and 723 K, then strained to fracture at room temperature. The yield
strength increment of the Fe-P alloys increases with aging time, reaches a maximum, then decreases. As with other substitutional
solutes, only the first stage of strain aging was seen; the UTS and elongation remained unchanged. Phosphorus is more effective
than other substitutional solutes in causing strain aging. Because of the limited solubility of P in α-Fe, increasing creasing
the P content from 0.083 to 0.40 at. pct had only a slight effect on strain aging. The activation energy for strain aging
is about 220 kJ/mole, indicating that aging is controlled by lattice diffusion of P. When both interstitial and substitutional
solutes are present, as in the rephosphorized steel, aging by interstitials masks any aging by P.
E. J. DZIURA, formerly Graduate Student, Department of Materials and Metallurgical Engineering, University of Michigan, is
now with the 相似文献
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The steady-state and dynamic behavior of a bistable laser resonator containing two semiconductor elements is examined theoretically. We derive necessary conditions for the bistable operation of the cavity and the constraints on the amplifier and absorber element characteristics imposed by these conditions. Our rate equation model demonstrates turn-on and turn-off of the output via current pulses, overshoot and ringing using fast rise time pulses, and critical slowing down when either the absorber or amplifier is switched. We give numerical results on switching. 相似文献
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Yang Y.J. Dziura T.G. Wang S.C. Fernandez R. Wang S. 《Electron Devices, IEEE Transactions on》1991,38(12):2691
Summary form only given. Continuous-wave GaAs mushroom structure surface emitting laser (MSEL) operation at a threshold current as low as 1.6 mA, an output power >2.0 mW, and a single transverse mode up to three times threshold current is reported. The relatively large CW output power was achieved by reducing the series resistance using a selective zinc diffusion. The low threshold current and single-mode operation are attributed to good lateral current confinement in a small constricted region formed by mesa undercutting. The complete device was mounted junction-side up on a chip carrier and tested CW at room temperature. Some results are given 相似文献
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The steady-state output of semiconductor lasers containing saturable absorbers is calculated using a model that includes transverse mode variation, high gain and absorption coefficient, and high mirror transmission. The results are compared to the predictions of the mean field theory, and they show that the mean field formulas underestimate the amount of hysteresis and overestimate the required amount of absorption compared to the high gain formulas. 相似文献
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Mushroom structure vertical cavity surface emitting lasers with a 0.6-μm GaAs active layer sandwiched by two Al0.6Ga0.4 As-Al0.08Ga0.92As multilayers as top and bottom mirrors are discussed. The lasers exhibit a 15-mA pulses threshold current at 880 nm. Single longitudinal and single transverse mode operation was achieved on lasers with a 5-μm-diameter active region of current levels near 2×l th. The light output above threshold current was linearly polarized with a polarization ratio of 25:1 相似文献
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Dziura T.G. Yang Y.J. Fernandez R. Bardin T. Wang S.C. 《Photonics Technology Letters, IEEE》1993,5(11):1270-1272
The high-speed modulation characteristics of helium-implanted zinc-diffused vertical cavity surface emitting semiconductor lasers are measured. Devices with a nominal active region diameter of 10 and 20 μm exhibit a move-out rate of 4.5-6.5 GHz/mW1/2 and a K factor of 0.65-0.85 ns. Maximum modulation frequency is limited by ohmic heating to approximately 5.5 GHz for 10-μm diameter lasers and to 2.7 GHz for 20-μm diameter lasers. A rolloff in the response below the relaxation oscillation frequency is observed and is explained well by a diffusion capacitance model 相似文献
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