摘要:

We report the observation of second harmonic generation and acoustic‐wave convolution for surface waves onYZ‐cut lithium niobate where the nonlinearity originates with the charge‐particle dynamics in a nearby semiconductor. The second harmonic generation is 28 dB above that obtained from LiNbO3alone, and the convolution output is 24 dB above reports for LiNbO3alone.

ISSN:0003-6951    

DOI:10.1063/1.1654153

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

The development of filamentary structure associated with the self‐focusing of ultrashort pulses in the presence of dielectric relaxation is examined. Numerical solutions to the equations of self‐focusing and relaxation display filament formation, although filament stabilization is strongly dependent on power. This suggests that further ingredients may be required for a complete theory of filament formation.

ISSN:0003-6951    

DOI:10.1063/1.1654154

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Gamma spectra were taken at room temperature with devices fabricated from semi‐insulating CdTe. A resolution of 8 keV (FWHM) was found for241Am (60 keV), 10 keV for57Co (122 keV), 30 keV for137Cs (662 keV), and 75 keV for60Co (1.33 MeV). The photoelectric absorption coefficient at a photon energy of 122 keV was measured to be 5.4 ± 0.4 cm−1in CdTe. The escape of the photoelectron at higher photon energies degraded the spectra and lowered the absorption coefficients below their theoretical values. Devices were also encapsulated within probes and their efficiency to photoelectric events was compared with that of a silicon detector. Ratios of 150:1 for57Co and 12:1 for241Am were found favoring CdTe.

ISSN:0003-6951    

DOI:10.1063/1.1654155

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

For mixing in a Josephson junction at infrared frequencies, we have shown that the available power from the junction increases as the intermediate frequency is increased. Following this result an infrared receiver has been developed incorporating a 9‐GHz maser preamplifier at the i.f. Using this system, the beat between the 401st harmonic of a high‐quality microwave source and a 3.8‐THz infrared laser has been observed. Also, for low‐order mixing at 3.8 THz, a comparison of beat signals from a Josephson junction and a room‐temperature mixer has been made.

ISSN:0003-6951    

DOI:10.1063/1.1654156

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Energy transfer in LaF3; Er, Yb is studied by observing the lifetimes of Er3+in excited states and the excitation spectra both at room temperature and at 77 °K. It is found that the energy transfer from Er3+(4S3/2→4I13/2) to Yb3+(2F7/2→2F5/2) is associated with the emission of three phonons of about 350 cm−1, and that the energy transfer from Er3+(2H9/2→4F9/2) to Yb3+accompanied by the absorption of phonons takes place.

ISSN:0003-6951    

DOI:10.1063/1.1654157

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Numerical calculations utilizing a realistic carrier velocity vs electric field relationship have been carried out for the dc current‐voltage characteristics and small‐signal ac response of abrupt Sip+np+,p+nvp+,n+pn+, andn+p&pgr;n+barrier injection transit time (BARITT) devices. The small‐signal ac response of these devices can be represented accurately by the depletion capacitance either in parallel with a negative conductance or in series with a negative resistance. The negative conductance has maximum amplitude for transit angles of approximately 1.55&pgr; and dc current density biases of 20–100 A/cm2. A distinct advantage was found in small‐signal applications forp+np+devices overp+nvp+devices and forn+pn+devices overn+p&pgr;n+devices.

ISSN:0003-6951    

DOI:10.1063/1.1654158

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

An experimental study of the constitution of the As&sngbnd;Te glasses has been carried out, using glass‐forming‐ability measurements, high‐angle diffraction, differential thermal analysis, and other thermodynamic determinations. Evidence is definitely given for a difference of valency between crystalline and glassy states. A model is suggested for the structural units in the glass and for the modifications induced by an excess of arsenic or tellurium with respect to the critical As2Te3composition.

ISSN:0003-6951    

DOI:10.1063/1.1654159

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

We report the observation of higher‐order disftributed‐feedback (DFB) laser oscillation using sinusoidal susceptibility modulation. For higher‐order DFB oscillation the period of the susceptibility modulation is a multiplemof one‐half the lasing wavelength. We have obtained tunable DFB oscillation form=2 andm=3 by pumping rhodamine 6G with interference fringes. A discussion of two possible mechanisms which could account for our observations is presented. Higher‐order DFB operation reduces the resolution required for fabricating a DFB laser.

ISSN:0003-6951    

DOI:10.1063/1.1654160

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

The absolute vibrational population distribution of a cooled CO&sngbnd;He laser plasma has been measured and is in excellent agreement with theoretical predictions based onV‐Vanharmonic exchange relaxation, particularly when measured values of electron density are considered. The population distribution was obtained from small‐signal‐gain measurements at the line centers of 21 vibration‐rotation transitions in a wavelength‐selective laser oscillator.

ISSN:0003-6951    

DOI:10.1063/1.1654161

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

A structure is described which yields uniform polarization in the emitted light from an array of GaAs lasers. The exterior cleaved faces define a standard Fabry‐Perot structure, and a 2‐&mgr; air space within the cavity inclined at the Brewster angle provides the necessary discrimination in gain between orthogonal modes to produce TE polarization (within ± 3°) for all lasers in the array.

ISSN:0003-6951    

DOI:10.1063/1.1654162

出版商:AIP    

年代:1972

数据来源: AIP