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An experimental method for determining the transparency current density of semiconductor quantum well lasers is demonstrated in a strained-layer InGaAs/GaAs single quantum well laser system. The experimental results are then used as a practical guide to the study of ultralow threshold lasers. A threshold current as low as 0.75 mA is observed. [ABSTRACT FROM AUTHOR]

A tandem combination of a uniform gain broad-area semiconductor laser and a (lateral) periodic gain section displays a stable, near-diffraction-limited single-lobed far-field pattern. The GaAs/GaAlAs quantum well lasers display a high degree of coherence across 60-μm-wide apertures provided that the broad-area section is sufficiently long. [ABSTRACT FROM AUTHOR]

We demonstrate that, as predicted, (Al,Ga)As single quantum well (SQW) lasers have substantially narrower spectral linewidths than bulk double-heterostructure lasers. We have observed a further major reduction (>3×) in the linewidth of these SQW lasers when the facet reflectivities are enhanced. This observation is explained theoretically on the basis of the very low losses in coated SQW lasers and the value of the spontaneous emission factor at low threshold currents. We also report on the modulation frequency response parameter of these SQW lasers. [ABSTRACT FROM AUTHOR]

The lasing wavelength of a strained-layer InGaAs/GaAs single quantum well laser has been found to depend strongly on the cavity length. The relationship between the lasing wavelength and the cavity length was established experimentally and a cavity length tuning mechanism for a quantum well laser is thus made possible. [ABSTRACT FROM AUTHOR]

Very high power levels (330 mW) were obtained from single waveguide, single quantum well InGaAs/GaAs lasers. The lasers are shown to possess superior current threshold, temperature and optical damage characteristics. [ABSTRACT FROM AUTHOR]

Superluminescent diodes (SLDs) employing single and multiple quantum wells were investigated. The diode structure includes a monolithic window and a gain and absorber section. Spectral widths 2–3 times that of conventional SLDs were demonstrated. [ABSTRACT FROM AUTHOR]

We report on low threshold current strained InGaAs/AlGaAs single quantum well lasers grown by molecular beam epitaxy. Broad-area threshold current densities of 114 A/cm2 at 990 nm were measured for 1540-μm-long lasers. Threshold currents of 2.4 mA at 950 nm were obtained for an uncoated buried-heterostructure device with a 2-μm-wide stripe and 425-μm-long cavity. With reflective coatings the best device showed 0.9 mA threshold current (L=225 μm). Preliminary modulation measurements show bandwidths up to 5.5 GHz limited by the detector response. [ABSTRACT FROM AUTHOR]

Low-temperature (T = 30 K) photoluminescence (PL) and post thermal annealing effects on 150 KeV proton irradiated GaInAsN bulk, single quantum well and triple quantum well structures (Eg ~ 1.0 eV) have been investigated. The nitrogen proportion of the samples was confirmed by high-resolution X-ray diffraction (HR-XRD) measurement as 0.26%, 0.30% and 0.20% for GaInAsN bulk, SQW, and MQW samples, respectively. The result shows that the PL intensity of GaInAsN materials degraded seriously by proton irradiation. The PL intensity enhancement were observed for all three types of sample after thermal annealing at 650 °C for 5 min, and MQW sample was recovered by the factor bigger than 100. The irradiation induced red-shift and thermal annealing induced blue-shift phenomena were analyzed by SRIM simulation result and theoretical models of InGaAs band structure. • LT-PL and post thermal annealing effects on MBE grown 150 KeV proton irradiated InGsAsN have been investigated • PL intensity of all GaInAsN samples degraded seriously by proton irradiation. • The PL intensity enhancement were observed for all GaInAsN samples after five minutes thermal annealing. • The degradation of PL intensity is linearly depending on the total thickness of the GaInAsN material. • Proton irradiation caused red-shift of PL peak can be explained by the replacement of As atoms by N atoms. • After 650 °C annealing for five minutes, the annealing enhancement of PL peak intensity are observed in all samples. • PL peak positions are blue-shifted due to the inter-diffusion and short-range ordering of N and nearby atoms in InGaAsN. [ABSTRACT FROM AUTHOR]