摘要:

Threshold current of 2 mA at room temperature cw operation is realized in a vertical distributed feedback surface‐emitting laser diode with lateral buried heterostructure (LBH). In this LBH structure, the vertical distributed feedback active region (AlGaAs/GaAs multilayer) is entirely surrounded withn‐ andp‐type AlGaAs cladding layers for minority‐carrier confinement. The far‐field angle is 7°. The beam shape is nearly circular. However, the lasing spectrum is broad (2–3 nm) compared with the conventional edge‐emitting laser. Major differences between the surface‐emitting laser diode presented here and the conventional edge‐emitting laser diode are discussed.

ISSN:0003-6951    

DOI:10.1063/1.98586

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Pulsed operation of an AlGaInP graded‐index separate confinement heterostructure laser grown by organometallic vapor phase epitaxy is reported. The laser active region consists of a single 100 A˚ Ga0.5In0.5P quantum well and 1600 A˚ graded index regions on both sides of the well. The graded index regions were produced by lattice‐matched graded composition (AlyGa1−y)0.5In0.5P quaternary alloys. This structure reduces the broad‐area threshold current compared to a double heterostructure laser, with pulsed thresholds as low as 1050 A/cm2. Total pulsed power of 1.4 W at 658 nm is available from an 80 &mgr;m×300 &mgr;m mesa‐stripe laser. A differential quantum efficiency of ∼56% is measured. By examining the cavity length dependence of the threshold current density and quantum efficiency, it is apparent that the quantum well gain has not saturated in these structures. This suggests that devices containing a thinner single quantum well active region may result in a further reduction in threshold current density for visible lasers.

ISSN:0003-6951    

DOI:10.1063/1.98534

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A bright white‐light electroluminescence (EL) is obtained in a thin‐film EL device with Ce‐ and Eu‐doped SrS phosphors. The device shows a luminance level of 1500 cd/m2with 5 kHz drive (500 cd/m2at 1 kHz). The dominant excitation process of the Eu2+centers is found to be due to an efficient nonradiative energy transfer from the Ce3+to the Eu2+centers.

ISSN:0003-6951    

DOI:10.1063/1.98535

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We demonstrate a dual‐wavelength laser constructed from a single quantum well structure. The device includes twin‐stripe waveguides which differ in width. The two constituent emitters in the device of appropriate cavity lengths operate at widely different wavelengths, which are based on the lowest (n=1) and the second (n=2) quantized state transitions. Lasing behavior is interpreted in terms of the difference of the internal cavity loss of the waveguides.

ISSN:0003-6951    

DOI:10.1063/1.98536

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

GaAlAs gain‐guided semiconductor lasers having a curved facet are fabricated by employing reactive ion beam etching. The use of the curved facet permits stabilization of transverse mode in the direction parallel to the junction plane, reduction of astigmatism, and multilongitudinal mode oscillation.

ISSN:0003-6951    

DOI:10.1063/1.98537

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We propose the use of a novel doped, stepped semiconductor quantum well structure as an optical nonlinear element. The large nonlinearity results from the change of many‐body effects on resonant excitation of electrons from the ground to the first excited subband. Self‐consistent calculations showed that the intersubband energy separation can be increased by up to 7 meV on intense illumination, compared to 1 meV for a conventional, square quantum well. We estimate that optical switching at powers below 1 W are feasible in an optimized structure, with switching times of about 1 ps.

ISSN:0003-6951    

DOI:10.1063/1.98538

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Light‐induced changes in the stretching mode absorption of Si‐H and Si‐H2have been studied for hydrogenated amorphous silicon (a‐Si:H) films. The absorption below 2000 cm−1decreases greatly, but a small change has been observed above 2100 cm−1. The magnitude of the overall change increases as the substrate temperature is lowered and little change is observed fora‐Si:H films deposited at above 200 °C. The change in boron‐dopeda‐Si:H is small compared with the undoped film deposited at the same substrate temperature. Based on experimental results, it is suggested that the hydrogen in the bulk ofa‐Si:H diffuses to the microvoids during light illumination.

ISSN:0003-6951    

DOI:10.1063/1.98539

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The far‐field pattern of a traveling‐wave amplifier made from a gain‐guided laser diode array consists of a nearly diffraction‐limited principal lobe with one or two side lobes when injected with a plane wave from a single‐mode diode laser. The observed patterns for varying angle of incidence and amplifier pump current are consistent with a model that treats the array as a diffracting aperture containing a complex volume grating having an amplitude that depends on the current. Some internal parameters of the array are extracted and the implications to broad area amplifiers and laser arrays are discussed.

ISSN:0003-6951    

DOI:10.1063/1.98540

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We report on the performance characteristics of InGaAs/GaAs strained‐layer superlattice coplanar ridge‐type directional couplers realized by molecular beam epitaxy. The measured power transfer characteristics with 1.15 &mgr;m incident photoexcitation demonstrate nonlinear coupling due to absorption associated with the tails of the excitonic resonances in the quantum wells. From a theoretical fit of the measured data, the nonlinear refractive index coefficient,n2, of the multiquantum well is found to be 2.25×10−7cm2/W. This agrees very well with a value ofn2=1.9×10−7cm2/W obtained independently on the same material from interferometric measurements.

ISSN:0003-6951    

DOI:10.1063/1.98541

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We report the first observation of efficient degenerate four‐wave mixing in a planar waveguide. Four‐wave mixing reflectivities near one percent were seen inside a single mode waveguide fabricated by ion exchange in a sample of semiconductor‐doped glass.

ISSN:0003-6951    

DOI:10.1063/1.98542

出版商:AIP    

年代:1987

数据来源: AIP