摘要:

If a medium with an absorption constant that increases with light intensity is placed within a laser interferometer, then fluctuations in the power output of the laser can be decreased. In this manner the typical spiking behavior of a pulsed, solid‐state laser can be essentially reduced to a constant output power as a function of time. A material that has the desired property is one that is Rayleigh active, for once threshold is reached for the stimulated Rayleigh effect the absorption at the pump frequency increases with intensity. The threshold for the stimulated Rayleigh effect is low because most of the gain is provided by the laser medium. Spike suppression has been achieved for a pulsed ruby laser by placing a cell containing benzene within the laser interferometer.

ISSN:0003-6951    

DOI:10.1063/1.1755104

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Standing wave excitation of two‐photon fluorescence in solutions or organic molecules is reported. The observations allow the direct display and measurement of optical pulses as short as 1−2 × 10−2sec.

ISSN:0003-6951    

DOI:10.1063/1.1755105

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A new technique for the display and measurement of picosecond light pulses is demonstrated. Two picosecond pulses, of different optical frequencies, are sent on a collision course in a liquid. They produce strong two‐photon fluorescence only in the region where they overlap. This results in the direct display of the pulse shapes over a very weak background. In a different arrangement, the two pulses enter the liquid collinearly and simultaneously, and initially generate strong two‐photon fluorescence. Subsequently, as the pulses propagate through the liquid, dispersion causes one pulse to overtake the other and the two‐photon fluorescence diminishes. This results in amagnifieddisplay of the pulses.

ISSN:0003-6951    

DOI:10.1063/1.1755106

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Two‐photon absorption has been observed in alkali halide crystals with a 1 MW superradiant pulse at 3371 Å from a nitrogen gas laser. This multiple quantum process is equivalent to a single‐photon absorption in the fundamental absorption edge of the alkali halide with the formation of an exciton and its subsequent trapping at an imperfection to form anFcenter. The crystals were visibly colored in the regions of high laser flux density. These colored regions, similar to color centers produced by ultraviolet radiation in the exciton region, were bleached by radiation in theFcenter absorption band.

ISSN:0003-6951    

DOI:10.1063/1.1755107

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The etch‐decoration method developed to detect lattice vacancies in graphite has been extended to the detection of lattice vacancies in molybdenite. Observations indicate that vacancies occur at sites from which a molybdenum atom is missing and that etch pits developed from these vacancies may be several layers deep; however, gold decoration can reveal step heights one layer deep (6.15 Å).

ISSN:0003-6951    

DOI:10.1063/1.1755108

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

This Letter reports a new technique for making holograms which employs a reference beam that is totally reflected from the air emulsion boundary of the hologram plate. This type of recording permits a very close spacing between the object and the hologram and has several interesting properties. The properties are listed and discussed in this Letter.

ISSN:0003-6951    

DOI:10.1063/1.1755109

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The existence of a space‐charge layer on the surfaces of the crystallites in PbS photoconducting films is considered. Estimates indicate that observed Hall coefficients may be due to the surface layers rather than to low carrier concentration in the crystallites.

ISSN:0003-6951    

DOI:10.1063/1.1755110

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Second‐harmonic generation (&lgr; = 5.3 &mgr;) is observed when dc fields and CO2laser beams are applied simultaneously to narrow band‐gap semiconductors. The nonlinear mechanism responsible for the dc‐induced second harmonic is shown to be a mobile‐carrier effect, and is ascribed to the nonparabolicity of the conduction bands. The possible application of this effect to the modulation of optical beams is indicated.

ISSN:0003-6951    

DOI:10.1063/1.1755111

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The threshold power for stimulatedBrillouinscattering has been measured from 5° to 300°K in crystalline and fused quartz. There is only a small dependence on temperature. Further threshold measurements in 10 different substances show that instead the threshold depends on the photoelastic properties of the medium. Both facts were predicted by Kroll's dynamical theory. The threshold for stimulatedRamanscattering, however, may be strongly temperature dependent as demonstrated for calcite.

ISSN:0003-6951    

DOI:10.1063/1.1755112

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A new transparent tetragonal crystal, KSr2Nb5O15, of the tungsten bronze type has been found to be ferroelectric with a Curie temperature of ≈160°C. At room temperature the electro‐optic coefficient,r∥, is 1.3 × 10−8cm/V and &egr;∥is approximately 1,000.

ISSN:0003-6951    

DOI:10.1063/1.1755113

出版商:AIP    

年代:1967

数据来源: AIP