摘要:

This Letter reports the generation of coherent radiation with voltage‐biased superconducting point contacts at both 30 MHz and 10 KMHz. The method of voltage biasing stabilizes the frequency of the emitted radiation against external noise sources and is tunable over a wide frequency range. We have optimized the electromagnetic coupling of the superconducting generator to the receiver and detected at least 5% of the generated power at 30 MHz. The relation1V= &PHgr;0&ngr;, where &PHgr;0is the flux quantum, is satisfied. Furthermore, we have observed harmonics,V=n&PHgr;0&ngr;, and subharmonics,nV= &PHgr;0&ngr;, of this relation. The frequency stability of the emitted radiation was limited by the stability of the bias supply and was measured to be 10−5at 30 MHz.

ISSN:0003-6951    

DOI:10.1063/1.1754609

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

Polarized infrared radiation was used to study the birefringence surrounding localized thermal strains in single‐crystal silicon due to electron beam bombardment. These localized spots had previously exhibited four‐lobed rosette stress patterns when examined by x‐ray topography. The interest lies in the crystal optics effects relating these observed phenomena.

ISSN:0003-6951    

DOI:10.1063/1.1754610

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A measurement of the signal‐to‐noise ratio and minimum detectable power for heterodyne detection of scattered radiation at 10.6 &mgr;m has been made. Using photoconductive Ge:Cu as the detector, the observed minimum detectable power, at a frequency of 70 kHz and in a bandwidth of 270 kHz, was 3.5 × 10−14W. This corresponds to a minimum detectable power of 1.3 × 10−19W in a 1‐Hz bandwidth, which is within a factor of 10 of the theoretically perfect photon counter.

ISSN:0003-6951    

DOI:10.1063/1.1754611

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A two‐wavelength He:Ne laser heterodyne system has been successfully used to measure electron number densities in the range from 4 × 1012cm−3to 1011cm−3, over a path length of 24 cm. These experiments were performed on a single‐shot basis in pulsed argon discharges. The spatially resolved laser measurements compared quite favorably with integrated electron density measurements made with a microwave cavity operating in theTM010mode.

ISSN:0003-6951    

DOI:10.1063/1.1754612

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

Following cleavage throughp‐njunctions on degeneraten‐type andp‐type germanium in liquid nitrogen, a large additional exponential contribution to the excess current has been observed. It is established that this excess is associated with the clean surface at the junction. Inversion layer conduction is shown to be negligible. Experimental evidence supports the interpretation that the surface excess is due to tunneling via surface states.

ISSN:0003-6951    

DOI:10.1063/1.1754613

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

Defects in siliconp‐on‐nsolar cells with a lithium‐diffusednregion, produced by electron irradiation and spontaneously annealed at room temperature, are interpreted as lithium atoms.

ISSN:0003-6951    

DOI:10.1063/1.1754614

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

The radial variation of electron temperature and density with partial gas pressures in a CO2&sngbnd;N2&sngbnd;He laser discharge is measured using double‐probe and microwave resonance techniques. In a 22‐mm‐diam discharge tube the optimum partial gas pressures for maximum laser power correspond to an electron temperature of 3 eV and a density of 3 × 109cm3. The radial electron density profile is compatible with measured gain profiles. The results indicate that the role of He in the excitation mechanism is not due to a reduction in electron temperature.

ISSN:0003-6951    

DOI:10.1063/1.1754615

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

The amplitude and time behavior of the pulsed output from a 10.6‐&mgr; CO2&sngbnd;N2&sngbnd;He laser is investigated as a function of partial gas pressures and discharge current. Nearly two orders of magnitude increase in output power is obtained compared to CW operation. The time behavior of the laser pulse indicates that electron excitation processes dominate in populating the upper laser level.

ISSN:0003-6951    

DOI:10.1063/1.1754616

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

It is found that efficient conversion from longitudinal acoustic waves to shear waves is possible in YAG by surface conversion at an incline surface, with both the input and output waves traveling along crystal axes. Using this process, existing efficient longitudinal‐wave transducers are applicable to shear‐wave generation. Laser beam probe measurements indicate that the surface conversion loss is of the order of 0.1 dB at 1461 MHz, and that the shear wave column has approximately the expected cross‐sectional shape.

ISSN:0003-6951    

DOI:10.1063/1.1754617

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

The Duguay, Hargrove, Jefferts frequency translation experiment is analyzed in terms of superposition of side bands. It is shown that a Gaussian input pulse leads, in a good approximation, to a Gaussian output pulse translated in frequency, so long as the modulation index is not so large as to lead to a translation, in units of the inter‐mode spacing, of the order of the cube of the number of modes of appreciable amplitude in the input pulse.

ISSN:0003-6951    

DOI:10.1063/1.1754618

出版商:AIP    

年代:1966

数据来源: AIP