摘要:

The improvement of efficiency and threshold of visible AlGaInP/GaInP laser diodes, which use buried AlAs native oxides for carrier and optical confinement, is described. Annealing of completed laser bars in an inert atmosphere lowers the threshold current and dramatically increases the external differential quantum efficiency. The characteristic temperature of the devices also increases from 74.8 to 125 K, indicating that the electron confinement is greatly enhanced in the annealed lasers, resulting in the observed improved performance. Secondary-ion mass spectrometry measurements reveal a reduction in hydrogen concentration in the laser cladding regions. This suggests that the improved electron confinement can be attributed to increased acceptor activation due to reduced hydrogen passivation. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118900

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

This work demonstrates that the technique of guiding atoms through hollow optical fiber escorted by evanescent light is useful as a novel scheme of optical atom deposition. To show the feasibility of fabricating micron-sized structures with nanometric depth on a substrate, we measure the spatial distribution of the guided atom flux with a hot-wire detector. Moreover, precise control of the deposition rate is illustrated with a 1.4-&mgr;m-hollow fiber via photoionization spectroscopy. The ratio of the guided atom flux relative to the background transmission is enhanced up to 80-fold with a slightly tilted hollow fiber. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118901

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We demonstrated an experimental observation of self-trapping and self-deflection of a two-dimensional optical beam by the photorefractive effect at telecommunication wavelengths under an applied dc field. Self-trapping is effective for an intensity range related to the intensity-temperature resonance known for two-wave mixing in InP:Fe. The photorefractive index change giving rise to the trapping is measured at10−4,while the photorefractive space-charge field is measured at about 50 kV/cm, ten times higher than the applied field. We show experimentally that this index change creates a waveguide that can be used to guide a second beam at 1.55 &mgr;m. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118902

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Densely packed arrays (76&percent; volume fraction) of 10 &mgr;m diameter parallel indium wires exhibit an enhanced transmission, of∼103,relative to an indium foil of equal thickness for far-infrared(k<80 cm−1)propagating along the wire length. The absorption increases ask0.45±0.07and is explained by the dynamic Maxwell–Garnett model, which includes eddy current dissipation. The effective surface conductivity is depressed fiftyfold with respect to the bulk. The implications for plasmons in metal wire microstructures and for developing simultaneously transmissive and conductive composites are discussed. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118903

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Optical absorption, photoluminescence, and luminescence lifetimes ofCr3+inLiTaO3were studied. It was found that a relatively sharp absorption band assigned previously to the no-phonon4A2–2Etransition shifted by68 cm−1when temperature decreased from 300 to 5 K. A sharp, four-component emission band recorded at low temperature was assigned on the basis of lifetime measurements to the no-phonon2E–4A2transitions ofCr3+ions inLi+andTa5+sites. Frequencies of these transitions are lower than that of the sharp absorption band at the same temperature implying that the latter band is not the no-phonon4A2–2Eline but it may be associated with a phonon satellite of the4T2state. Strong thermal quenching of broad band luminescence ofCr3+was observed. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118904

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The refractive indices of diluted magnetic semiconductorCd1−xMnxTefilms on sapphire substrates have been determined bym-linespectroscopy to precision 0.001 at the wavelengths &lgr;=670, 785, and 1150 nm. Using these data, we designed double-layerCd1−xMnxTestructures on a GaAs substrate, achieving the integration of the magneto-optical waveguide on a semiconductor substrate. Good optical confinement of the waveguide mode was confirmed. ©1997 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.118905

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Grating coupling for surface-emitting intersubband light-emitting diodes (LEDs) and lasers are analyzed with a numerical method. The grating efficiency is calculated as functions of the grating periodicity and filling factor, and the vertical confinement thickness. The coupling loss is related linearly with the grating efficiency, which should be maximized for LEDs to couple out the spontaneous emission, but kept low for lasers to reduce the lasing threshold. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118906

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Spectrally resolved streak camera measurements of picosecond pulses emitted by hybridly colliding pulse mode-locked (CPM) laser diodes are presented in this letter. Depending on the modulation frequency both blue-chirped (upchirped) and red-chirped (downchirped) pulses can be observed. The two different regimes and the transition between them are characterized experimentally and the behavior is explained on the basis of our model for the CPM laser dynamics. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119086

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The nonlinear properties relevant to second harmonic generation inLaBGeO5:Nd3+are reported. This work focuses on the infrared region of the spectrum leading to blue-green laser radiation by self-frequency doubling, but covers a wide spectral range useful for other lanthanideLn3+rare-earth doping ions. Phase matching conditions, walk-off angle, and thermo-optic tuning sensitivity for second harmonic generation are reported. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118907

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Orthogonal polarizations within vertical-cavity surface-emitting lasers (VCSEL) lase at slightly different wavelengths. We describe the use of optical feedback to confine polarization variations to reproducible injection currents. An external cavity is used to select specific wavelengths that reflect back into the VCSEL, hence, changing the cavity Q for the different polarization states. With this control, we can change the polarization state of the laser output. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118908

出版商:AIP    

年代:1997

数据来源: AIP