摘要:

The reliability of uncoated InGaAsP/GaAs high‐power diode lasers emitting at 808 nm wavelength has been studied. 47 W of quasicontinuous wave output power (pulse width 200 &mgr;s, frequency 20 Hz) have been obtained from a 1‐cm‐wide laser bar. A single‐stripe diode without mirror coating has been life tested at 40 °C for emitting power of 800 mW continuous wave (cw) and showed no noticeable degradation and no change of the lasing wavelength after 6000 h of operation. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113404

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Optical bistability in a single quantum well waveguide resonator in the InP/InGaAsP material system is demonstrated. High contrast ratio (≳3:1) and switching at low power (≊1.5 mW) was obtained by using a single quantum well at a wavelength near the maximum nonlinear refractive index change and by depositing a reflective coating on the rear end of the waveguide. Clear optical bistability is observed in a wide wavelength range of 1480–1525 nm. Due to the low input power, cw operation of the device was possible at room temperature. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113405

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We study the temperature sensitivity of the Auger recombination rates in 1.55 &mgr;m InP‐based strained‐layer (SL) quantum‐well (QW) lasers on the basis of the band structures obtained by the self‐consistent numerical solution of the Poisson equation, the scalar effective‐mass equation for the conduction band, and the multiband effective mass equation for the valence band. The results of the theoretical analysis are then compared with the recent experimental results to clarify the basic physical mechanism which determines the Auger recombination rates in SL‐QW lasers. It is shown that the recent temperature sensitivity measurements of Auger recombination coefficients can be consistently explained in terms of the direct band‐to‐band Auger process in the quasi‐two‐dimensional system. We demonstrate that the Auger recombination process in 1.55 &mgr;m InP‐based SL‐QW lasers is mainly dominated by the direct band‐to‐band Auger process regardless of QW structures in the temperature range of 273–398 K. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113406

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A resonant cavity light emitting diode is fabricated which makes use of a Ag mirror/contact and a buried AlxOy/GaAs Bragg reflector. The buried AlxOyis formed by the selective conversion of AlAs. The differential light output efficiency is measured and found to be ∼5.5% when the AlxOy/GaAs reflector is present versus ∼2.5% for a control device without the AlxOy/GaAs mirror. The measured efficiencies are compared with calculations. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113614

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The electro‐optic response in a cross‐linked nonlinear optical polymer has been determined as a function of the extent of curing that takes place after coating and drying a film of the material but prior to poling it. It was found that although the value of the electro‐optic coefficient was reduced by partially curing the film before poling, the decrease was minimal even in a fully cured film. Furthermore, the thermal stability of the electro‐optic response was unaffected by the extent of curing before poling. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113615

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Second‐harmonic generation (SHG) properties of two novel organic crystals, i. e., 2,5‐ bis(benzylidene)cyclopentanone (BBCP) and 2,6‐bis( p‐methylbenzylidene)‐4‐tert‐butylcyclo‐ hexanone (MBBCH), were studied. Based on an x‐ray structural analysis, their SHG coefficientsdijat 1.06 &mgr;m are determined by the Maker‐fringe method asd14=7 pm/V for BBCP, andd31=15 pm/V,d32=12 pm/V, andd33=4 pm/V for MBBCH, respectively. Measurements on the refractive indices reveal that angle‐tune phase matching in the form of both types I and II is possible, in particular, with a large efficiency for MBBCH,deff∼12 pm/V, which was confirmed experimentally. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113616

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The fracture strength of free‐standing chemically vapor‐deposited diamond films was assessed by four‐point bending. A two‐parameter Weibull analysis was performed on 130 &mgr;m thick films resulting in a Weibull modulus of 4.3 and a statistical scaling stress of 626 MPa. The residual stress in films was measured from the free‐standing film curvature to be 384±10 MPa. The fracture surface chemistry was examined using scanning Auger spectroscopy. The fracture did not occur preferentially along grain boundaries. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113617

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Heteroepitaxial InP films grown on GaAs substrates by metalorganic chemical vapor deposition are demonstrated to have a higher concentration of zinc occupying interstitial sites than do equivalent homoepitaxial InP layers. A zinc interstitial‐related donor‐to‐acceptor photoluminescence peak is observed in heteroepitaxial InP films which is absent in the homoepitaxial sample spectra. Capacitance–voltage measurements yield a lower hole concentration in the heteroepitaxial layers versus the homoepitaxial layers, which is attributable to a higher fraction of zinc in interstitial sites within the heteroepitaxial layers. Additionally, the hole concentration of the heteroepitaxial layers is found to be lower near the heterojunction as compared with the film surface region, correlating with a higher dislocation density near the heterojunction as seen by transmission electron microscopy. We conclude that the increased zinc interstitial concentration and the reduced hole concentration are due to dislocation‐zinc solute interactions. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113618

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

High‐temperature high‐vacuum electrostatic levitation (HTHVESL) and differential scanning calorimetry (DSC) were combined to determine the hemispherical total emissivity &egr;T, and the specific heat capacitycp, of the undercooled liquid and throughout the glass transition of the Zr41.2Ti13.8Cu12.5Ni10.0Be22.5bulk metallic glass forming alloy. The ratio ofcp/&egr;Tas a function of undercooling was determining from radiative cooling curves measured in the HTHVESL. Using specific heat capacity data obtained by DSC investigations close to the glass transition and above the melting point, &egr;Tandcpwere separated and the specific heat capacity of the whole undercooled liquid region was determined. Furthermore, the hemispherical total emissivity of the liquid was found to be about 0.22 at 980 K. On undercooling the liquid, the emissivity decreases to approximately 0.18 at about 670 K, where the undercooled liquid starts to freeze to a glass. No significant changes of the emissivity are observed as the alloy undergoes the glass transition. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113619

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Flat, clean, essentially defect‐free GaAs(001) surfaces were produced at 570 °C in an As4overpressure using 1 keV Ar ion bombardment at an impingement angle &fgr; of 15° from the surface plane and a dose of 2.3×1016ions/cm2. Ion bombardment smoothened the surfaces leading to minimum roughness values of ≊0.3 nm and reflection high‐energy electron diffraction (RHEED) patterns that showed streaks with a 2×4 reconstruction. GaAs films grown by molecular beam epitaxy on the sputter cleaned surfaces exhibited strong RHEED oscillations. Cross‐sectional transmission electron microscope images showed that the epitaxial layers and substrates were defect‐free except for 2–3‐nm diam dislocation loops observed 10–20 nm below the substrate surface, separated by ≳100 nm along the interface. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113620

出版商:AIP    

年代:1995

数据来源: AIP