摘要:

The possibility of generating extremely intense picosecond pulses at 5.3 &mgr;m by frequency doubling a strong CO2laser pulse in Te is demonstrated. It is shown that free carriers generated by two‐photon absorption at the leading edge of the second harmonic perturb the indices of refraction and greatly reduce the conversion efficiency for the remainder of the pump pulse.

ISSN:0003-6951    

DOI:10.1063/1.90247

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

A tunable amplification around 3600 A˚ has been demonstrated at low temperatures in the low‐energy side of the emission band of CaO crystals doped with F+centers. The pumping power was delivered by a pulsed nitrogen laser and the optical gain was measured in a coaxial configuration. The observed amplification fits the equations of the pumping cycle for this system reasonably well. The possibility of designing a tunable laser using this material is discussed in light of our experiments.

ISSN:0003-6951    

DOI:10.1063/1.90248

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The small‐signal gain of cw CO2and/or N2O mixing gasdynamic lasers has been measured by varying the cavity losses with the aid of two rotating coupled NaCl plates placed within the cavity and looking for the generation cutoff point. The saturation parameter has been determined on the basis of measured values of respective small‐signal gains by experimentally recovering the output power‐cavity losses relation. The measurements yielded &agr;0≃1.1 m−1andIs≃3.2 kW/cm2for CO2, and &agr;0≃1.0 m−1andIs≃3.0 kW/cm2for a cw N2O mixing gasdynamic laser.

ISSN:0003-6951    

DOI:10.1063/1.90249

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The spatial variation of minority‐carrier diffusion length in the vicinity of a grain boundary for a polycrystalline silicon sheet has been measured by the use of the EBIC technique. The effect of such a variation on solar‐cell output has then been computed as a function of grain size. Calculations show that the cell output drops considerably for grain size smaller than three times the bulk diffusion length.

ISSN:0003-6951    

DOI:10.1063/1.90250

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The catastrophic degradation of GaAlAs DH laser diodes is examined with the application of pulsed or dc current. The dependence of the pulsewidth on the degradation is measured using samples with or without facet coating. The light outputPDat which the catastrophic degradation occurs decreases with an increase in the pulsewidth in the pulsewidth range 100 nsec to 10–50 &mgr;sec, andPDis constant over the pulsewidth of 10–50 &mgr;sec. The sample with an Al2O3film coating has the highestPD. Photoluminescence patterns of the active layer in degraded samples both with and without facet coating show the growth of DLD’s in the ⟨110⟩ direction from the vicinity of a facet in the stripe region.

ISSN:0003-6951    

DOI:10.1063/1.90251

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

We have observed electroluminescence at then‐TiO2/electrolyte interface under strong polarization of TiO2electrodes above 8 V versus SCE. The quantum yield, obtained from current and intensity measurements at 10 V versus SCE, was in a range between 10−3and 10−4. The emission spectrum, measured by optical glass filters, was found to be distributed in a range between 450 and 800 nm, the spectrum peak being approximately 630 nm, which is equivalent to a photon energy of 2.0 eV. This luminescence has been attained to the radiative recombination of electrons in some surface states with holes created in the valence band by electron tunneling.

ISSN:0003-6951    

DOI:10.1063/1.90252

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Five optically coupled narrow stripe (3.5 &mgr;m) GaAs/GaAlAs semiconductor lasers on 8‐&mgr;m centers are operated as a spatially coherent phase‐locked laser array. Output beams with less than 2° divergence are observed up to 60 mW/facet output with a quantum efficiency of greater than 25%/facet. Significant nonlinearities do not appear until well over 100 mW/facet output.

ISSN:0003-6951    

DOI:10.1063/1.90253

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

A structure change from a polycrystal to single‐crystal layer in ion‐implanted Si samples has been obtained by single‐pulse ruby‐laser irradiation with a power density threshold of about 70 MW cm−2(pulse length 50 nsec). Under these conditions surface mechanical damage is produced. A laser pulse train shaping technique was adopted to reduce the residual disorder in the layer after laser irradiation and to prevent mechanical damage.

ISSN:0003-6951    

DOI:10.1063/1.90245

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The introduction of hydrogen during the MBE growth of GaAs is shown to produce a major improvement in the electrical properties of the epitaxial layers. The observed increase in 77 K electron mobilities reflects a significant decrease in total ionized impurity concentration. Evidence is presented that the dominant residual impurities in MBE‐grown GaAs are oxygen and carbon.

ISSN:0003-6951    

DOI:10.1063/1.90246

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

AninsituOhmic‐contact‐formation technique forn‐ andp‐GaAs of any resistivity by molecular beam epitaxy was described. The measured specific contact resistances lie between low‐10−6&OHgr; cm2and mid‐10−5 &OHgr; cm2. The contacts were Ohmic for currents in excess of 250 mA tested in both forward and reverse directions. Furthermore, the contact metallization was optically smooth as no sintering or alloying process was needed. Excellent uniformity of electrical quality of the Ohmic contacts on the same sample was obtained.

ISSN:0003-6951    

DOI:10.1063/1.90254

出版商:AIP    

年代:1978

数据来源: AIP