摘要:

Air‐ and vacuum‐cleaved rocksalt crystals have been treated with H2O vapor and with a mixture of H2O vapor and CO2gas in order to study the influence of such contaminations on the epitaxial growth of gold films on NaCl crystals. Hydroxide surfaces resulting from the treatment with pure H2O vapor yielded epitaxial gold films on both vacuum‐ and air‐cleaved specimens and these were very similar in nature to those epitaxial films normally grown on air‐contaminated NaCl substrates. Bicarbonate surfaces resulting from the further treatment with a mixture of H2O vapor and CO2gas yielded polycrystalline gold films on both the air‐ and vacuum‐cleaved specimens.

ISSN:0003-6951    

DOI:10.1063/1.1652831

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Simultaneous mode‐locking and quasi cw second‐harmonic generation (SHG) in high‐temperature lithium niobate or barium sodium niobate of a Nd3+:YAG laser have been accomplished by electro‐optic modulation of the nonlinear medium. This technique will be useful for obtaining ``100% conversion efficiencies,'' which would not be possible by the standard intracavity method, with nonlinear crystals that are either too short or have too low a nonlinear coefficient to achieve optimum coupling of the laser.

ISSN:0003-6951    

DOI:10.1063/1.1652836

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

AlxGa1−xAs injection lasers have been fabricated over the compositional range in which the alloy has a direct bandgap transition (0 <x≤ 0.34). At 300°K the threshold current density increases withxfrom 12 000 A/cm2(&lgr;L= 8600 Å) to 56 000 A/cm2(&lgr;L= 7340 Å) in uncoated devices with cavity lengths of about 10 mils. In the same range ofxthe external differential quantum efficiency gradually decreases from 40 to 16%. These are the highest efficiencies and lowest threshold current densities ever reported for room‐temperature lasers emitting in the same spectral range. The improvement is due to utilization of the newp+‐pheterojunction structure previously used by the authors in GaAs lasers to sharply reduce the internal optical loss by improving the optical confinement and reducing the absorption coefficient in thep+material adjoining the active region. At 77°K lasing has been achieved to 6450 Å and cw operation to 6900 Å with the emission of 0.4 W per diode.

ISSN:0003-6951    

DOI:10.1063/1.1652837

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Experimental demonstration of the sum and difference frequency generation of surface acoustic waves on &agr;‐quartz is reported. Individually calibrated interdigital transducers were used to generate and detect the waves. The absolute level of the nonlinearly generated acoustic power was measured for various interaction lengths and found to agree with a theory based on nonlinear coupled amplitude equations.

ISSN:0003-6951    

DOI:10.1063/1.1652822

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Optically excited recombination radiation is observed inn‐type single crystals of the II–V compound Cd3P2. Line narrowing characteristic of stimulated emission is induced at high excitation intensities.

ISSN:0003-6951    

DOI:10.1063/1.1652823

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

It has been established that diffusion of photogenerated carriers into the electrode can be an important limitation of the collection efficiency of surface‐barrier‐limited photoconductors.

ISSN:0003-6951    

DOI:10.1063/1.1652824

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Two nonlinear effects of laser propagation in dense plasmas have been analytically investigated, viz., laser penetration into an overdense plasma and the self‐focusing of a laser beam. It is concluded that for laser powers currently being used, both these effects can be quite important.

ISSN:0003-6951    

DOI:10.1063/1.1652825

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Our measurements of the small signal conductance of a GaAs Gunn diode at low field values do not show the frequency dependence reported by K. Matsuno.

ISSN:0003-6951    

DOI:10.1063/1.1652826

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A theoretical application of the Weinreich relationship is presented which is valid for an acoustic signal of duration less than its transit time through the medium. The acoustoelectric field produced by a piezoelectrically active acoustic wave propagating through cadmium sulphide is calculated, and excellent agreement is demonstrated between experiment and theory with the crystal both amplifying and attenuating.

ISSN:0003-6951    

DOI:10.1063/1.1652827

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

cw laser action has been observed at 3250 Å in Cd II, 6453 and 6844 Å in Sn II, and 7479 and 7588 Å in Zn II. Laser action occurred in He‐metal‐vapor discharges at pressures of several Torr He and much lower partial pressures of the metal vapor. The first four transitions have similar operating characteristics and are believed to be excited by Penning collisions between metastable He atoms and neutral metal‐vapor atoms (similar to the mechanism for exciting the 4416 Å cw transition in Cd II). The 3250 Å transition is the first cw uv laser that can be built and operated with relatively simple techniques, similar to those used in He&sngbnd;Ne lasers.

ISSN:0003-6951    

DOI:10.1063/1.1652828

出版商:AIP    

年代:1969

数据来源: AIP