摘要:

An optical storage technique based on the characteristic absorption bands ofJaggregates of organic dyes is reported. The information is written by disordering the regular structures of cyanine dyeJaggregates with a laser beam. This technique gives high recording sensitivity, and the disordered dye molecules can be made to reform theJaggregate, which indicates that the recording process is reversible. TheJaggregates of cyanine dyes were formed by incorporating them in Langmuir–Blodgett (LB) films. The advantages of the narrow absorption bands ofJaggregates and of the controlled multilayer forming capability of LB films were combined to demonstrate multiple wavelength optical recording using two recording layers.

ISSN:0003-6951    

DOI:10.1063/1.97263

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Time‐resolved studies of intense, relativistic electron beams using a novel subnanosecond Cˇerenkov electro‐optic shutter are described. The technique is applied to the measurements of the electron beam emittance from a multielectrode field emission gun (1.6 MV, 1 kA, 30 ns), and to the study of the stability of a rotating relativistic electron ring (200 kV, 100 A, 1 &mgr;s).

ISSN:0003-6951    

DOI:10.1063/1.97264

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

We report the first observation of photochemically initiated I2(D’→A’) emission at 342 nm. Mixtures of I2and C3F7I or I2and O3were excited by a KrF laser at 248 nm photodissociating the C3F7I or O3. The process believed responsible for the intenseD’→A’emission is rapid energy transfer from the excited I(2P1/2) or O2(a 1&Dgr;) photodissociation products to I2(X,v‘=0) producing I2(X,v‘=25→43) which is optically pumped by 248 nm photons to I2(D 1∑+u) and I2(F 1∑+u). Rapid collisional redistribution results in theF,D→D’crossover. Gain of several percent per centimeter on theD’→A’transition may be possible with the appropriate gas mixture and pump source.

ISSN:0003-6951    

DOI:10.1063/1.97265

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

We propose a new type of current injection semiconductor laser with rare‐earth dopant in the active layer for achieving stable, single longitudinal mode operation. In this laser, the rare‐earth/semiconductor combination is chosen such that the wavelengths of the dominant emission from the trivalent rare‐earth ion internal 4f‐4f  transitions are shorter than that of the band‐edge emission of the host semiconductor. Spectrally, the narrow optical gain due to the rare‐earth ion transition will superimpose on top of the broad gain peak of the host semiconductor. Such laser diodes will attain lasing action at the rare‐earth transition wavelength resulting in single longitudinal mode operation with conventional Fabry–Perot cavity. Furthermore, reproducible precise lasing wavelength insensitive to temperature variation should be possible. Such a proposed rare‐earth/semiconductor injection laser was investigated with erbium doping in the GaInAsP (&lgr;=1.55 &mgr;m) active layer of the heteroepitaxial ridge‐overgrown laser. Stable, single longitudinal mode operation at 15 322 A˚ was obtained. Furthermore, this lasing line shifted at a slow rate of ≲1 A˚/°C with heat‐sink temperature. Initial results do appear to confirm this new proposed rare‐earth/semiconductor laser operation scheme.

ISSN:0003-6951    

DOI:10.1063/1.97266

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Newly observed features of quantum well lasers are presented and explained with the aid of a simple model. These involve lasing with gain contributions not only from the fundamental (n=1) state, but simultaneously from the second quantized (n=2) state as well. Experimental data for current pumped GaAlAs/GaAs single quantum well lasers are presented. Very high resonator losses (≳100 cm−1) force the lasers to augment their gain with major contributions from the second quantized state. The main signature ofn=2 lasing, a sudden and large increase in the lasing photon energy, is observed and explained by the theory.

ISSN:0003-6951    

DOI:10.1063/1.97267

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The responses of specially designed directional couplers built with Ti:LiNbO3in‐diffused guides were measured and found to be substantially better predicted by an improved version of the coupled‐mode theory than by the traditional one.

ISSN:0003-6951    

DOI:10.1063/1.97268

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

When laser‐generated Rayleigh pulses interact with surface breaking slots in metals, two distinct reflections are present in the captured waveform. While the first component is accepted as arising from the direct reflection of a Rayleigh pulse from the top of the defect, the origin and features of the second component have been the subject of some discussion. This letter presents evidence to show that the second component also propagates at the Rayleigh velocity, lending support to the suggestion that it originates at the base of the slot and can be used to measure the slot depth.

ISSN:0003-6951    

DOI:10.1063/1.97269

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

We report first results from a new collective accelerator experiment in which a laser‐controlled channel of ionization is used to control the propagation of the potential well at the front of an intense relativistic electron beam injected at currents above the space‐charge limit. The controlled acceleration of protons at the rate of 40 MeV/m over a distance of 45 cm is reported, in good agreement with experimental design values.

ISSN:0003-6951    

DOI:10.1063/1.97270

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Pure fused low‐OH silica (Tetrasil SE) has been studied by electron spin resonance (ESR) after it had been irradiated by 50 MeV/amu oxygen and 43 MeV/amu krypton ions at the GANIL accelerator. Paramagnetic defects have been observed which are closely related to intrinsic defects formed by &ggr;‐ray irradiation in amorphous SiO2, such as theE’center and the peroxy radical. ESR signatures of defects formed by heavy ions exhibit, however, specific features in comparison with those formed by other types of irradiation (&ggr;/x rays, electrons, or neutrons). The density of defects increases faster than the energy loss, so that the production of defects by heavy ion irradiation cannot be described by the total energy deposit alone. This is consistent with previous studies of latent ion tracks in insulating minerals using small angle x‐ray scattering and track etching techniques.

ISSN:0003-6951    

DOI:10.1063/1.97219

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Good quality ZnSe‐ZnS strained‐layer superlattice (SLS) has been successfully fabricated for the first time by low pressure metalorganic vapor phase epitaxy (MOVPE) using methylalkyls (dimethylzinc, dimethylselenide, and dimethylsulfide). The satellite peak observed by x‐ray diffraction measurements and the periodic behavior of the atomic profiles by secondary ion mass spectrometry measurements confirm the formation of the SLS structure. From the photoluminescence measurements, the quantum size effect has been evidenced by the relationship between the ZnSe well‐layer thickness and the peak energy shift of the light emission. Our results show that low pressure MOVPE using VI group alkyls can be quite useful for the growth of ZnSe‐ZnS SLS.

ISSN:0003-6951    

DOI:10.1063/1.97220

出版商:AIP    

年代:1986

数据来源: AIP