摘要:

The focal‐lengthfand beam‐diameterDdependence of threshold power for air breakdown has been investigated using focused ∼20‐psec 1.06‐&mgr; laser pulses. Primary spherical aberration is shown to be very important in determining the threshold power whenD/fis large. Diffusion‐type losses and self‐focusing played no part in the breakdown mechanism in the present work.

ISSN:0003-6951    

DOI:10.1063/1.1655141

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The spatial distribution of focal spots formed when laser beams self‐focus in materials is shown to originate from the growth of certain instability modes. These modes are determined by a simple mathematical relationship derived from instability theory, which has been verified experimentally. Because of these instabilities, the threshold power for self‐focusing is inversely proportional to the self‐focusing length for high‐power laser beams.

ISSN:0003-6951    

DOI:10.1063/1.1655142

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Measurements of the 9.6‐ and 10.6‐&mgr; CO2laser transition probabilities and optical cross sections have been made by using a tuneable CO2laser and room‐temperature absorption cell. In order to increase the accuracy of the resulting constants, two measurements, one in the combined Doppler‐and pressure‐broadened regime and one in the pure pressure‐broadened regime, provided data for the simultaneous solution of the transition rate and cross section. The 10.6‐&mgr; results are in general agreement with previous studies and knowledge of the 9.6‐&mgr; values permits performance predictions and quantitative use of gain data in this laser band.

ISSN:0003-6951    

DOI:10.1063/1.1655143

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A powerful excitation technique for mixtures of molecular gases using a combination of optical pumping and resonant energy transfer is described. By using an N2O&sngbnd;CO2mixture as an example, laser action in N2O at 10.5 and 10.8 &mgr;m has been achieved at total pressures up to 42 atm.

ISSN:0003-6951    

DOI:10.1063/1.1655144

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A comparison has been made of the minority‐carrier lifetime (77–300 K) in relatively pure InAs prepared by liquid phase epitaxy, vapor phase epitaxy, and from the melt. The data suggest that the lifetime is controlled by Auger recombination in the material prepared by liquid phase epitaxy. This is not the case for the other materials.

ISSN:0003-6951    

DOI:10.1063/1.1655145

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The detection and measurement of trace quantities of mercury in air by a magneto‐optic coherent forward‐scattering technique is described. The method is characterized by high sensitivity and selectivity, and is applicable to a broad class of elements.

ISSN:0003-6951    

DOI:10.1063/1.1655146

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Measurements of the intrinsic noise fluctuations in the light intensity from a stripe‐geometry double‐heterostructure junction laser operating continuously at room temperature are reported. The frequency spectrum of the fluctuations has been measured from 10 MHz to 4 GHz for currents both above and below threshold. The above‐threshold noise spectra show the resonant peak due to excitation of the spiking resonance by the quantum shot noise intrinsic to the lasing process. Near threshold the frequency of this resonance varies between 200 and 1000 MHz as a function of laser current. In addition, as the pumping current is increased above threshold, the low‐frequency (< 100 MHz) noise shows the pronounced reduction expected of an amplitude‐stabilized oscillator. However, over the same range of currents, the high‐frequency (> 2 GHz) noise continues to increase in apparent contradiction with theoretical predictions.

ISSN:0003-6951    

DOI:10.1063/1.1655147

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Low‐intensity picosecond optical pulses from a mode‐locked cw dye laser have been observed to be self‐phase modulated upon propagation through a CS2‐filled glass fiber. This self‐phase modulation occurs in the absence of self‐focusing and has several interesting consequences with respect to pulse shaping and ultrashort‐pulse propagation.

ISSN:0003-6951    

DOI:10.1063/1.1655148

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

We report the observation of efficient room‐temperature electroluminescence from InPp‐njunctions at wavelengths near the 1.05‐&mgr; window of low‐loss glass fibers. External efficiencies of 1% and peak wavelengths variable between 0.98 and 1.10 &mgr; have been obtained.

ISSN:0003-6951    

DOI:10.1063/1.1655149

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The fabrication and evaluation of corrugation grating filters with reflectivities better than 75% and bandwidths less that 2 Å is reported. Grating filters were fabricated on glass waveguides using standard interferometric and ion‐beam machining techniques and evaluated with a tunable dye laser. Measured and calculated filter responses are found to be in excellent agreement. Tolerances for realizing ideal filter performances are given.

ISSN:0003-6951    

DOI:10.1063/1.1655150

出版商:AIP    

年代:1974

数据来源: AIP