摘要:

Optical image scanning utilizing the transverse acoustoelectric effect induced by surface acoustic waves propagating on a basal plane of photoconductive cadmium sulfide is experimentally demonstrated. ’’Positive’’ high sensitivity is obtained by using a cadmium sulfide crystal known well to be an excellent photoconductor as well as a good piezoelectric material.

ISSN:0003-6951    

DOI:10.1063/1.88903

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A novel reflective image intensifier based on the twisted nematic electro‐optic effect is described. The device can be read out with intense actinic radiation without need for an optical blocking layer. Images of very high resolution and excellent tonal range can be obtained at voltage levels as low as 1.6 Vrms.

ISSN:0003-6951    

DOI:10.1063/1.88904

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

True hydrodynamic instabilities in nematic and weakly cholesteric liquids of positive dielectric anisotropy were observed under ac excitation. Static and dynamic periodic structures occur under two regimes. The low‐conductance mode is characterized by an instability threshold voltage which is independent of the driving frequency and almost independent of temperature until a transition frequency is reached. Above that transition frequency, the threshold is a field, proportional to the square root of the driving frequency and varying with temperature as the square root of the viscosity. The high‐conductance mode is characterized by a field threshold at all driving frequencies. The conductance mode type is determined by both the charge relaxation frequency and the electrode spacing. The existence of a cutoff frequency for the instability lends additional support to the identification of the phenomenon as a conductance mode.

ISSN:0003-6951    

DOI:10.1063/1.88905

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The thermal orientational fluctuations of nematic liquid crystals have been studied by analyzing the speckle transmission picture of a coherent laser light. The fluctuations’s suppression on the application of a biasing electric field follows a reciprocal square dependence.

ISSN:0003-6951    

DOI:10.1063/1.88906

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

By means of Richardson plots, low work functions of 2.3–2.4 eV have been measured for three cyrstal planes including (100) of single‐crystal LaB6. Modifying Smith’s model of a metallic surface, the work function of LaB6has been theoretically estimated for a jellium model at 2.31±0.05 eV which is in good agreement with experimental values.

ISSN:0003-6951    

DOI:10.1063/1.88907

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The free‐carrier plasma edge and plasma diffusion dynamics have been studied in Ge by monitoring rapid temporal variations of surface reflectivity at 10.6‐&mgr;m wavelength which occur after excitation by intense picosecond pulses at 1.6 &mgr;m. The results of such transient spectroscopy show that the method can be used as a sensitive diagnostic tool for the many semiconductor plasmas.

ISSN:0003-6951    

DOI:10.1063/1.88908

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The 337‐&mgr;m radiation of an HCN laser has been mixed with the radiation of a 3‐mm kylstron in a harmonic mixer employing various types of diodes. Beat notes resulting from different orders of mixing, occurring at frequencies as high as 4.5 THz, could be directly observed on the scope. Gallium arsenide appeared to be the most favorable diode material, whereas the Schottky barrier type produce slightly better results than the conventional GaAs point‐contact diodes. The performance of the heterodyne system at 891 GHz is given in terms of sensitivity (NEP) and conversion loss (Lc).

ISSN:0003-6951    

DOI:10.1063/1.88909

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Channeling measurements with MeV4He ions were used to investigate the disorder distributions produced in ⟨111⟩ and ⟨100⟩ Si samples by implantation at substrate temperatures from −180 to 300 °C. The results indicate that for high implantation doses (1015–1016ions/cm2) a deep stable disordered region is present in both orientations for the samples implanted at temperatures above room temperature but is absent for room‐temperature and lower implants. The colors that have been observed on the surface of samples with similar implants are found to be correlated with the thickness of a thin crystalline layer at the surface.

ISSN:0003-6951    

DOI:10.1063/1.88886

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Silicon samples with visible color bands have been produced by high beam currents and have been studied using optical reflectivity, Rutherford backscattering (channeling), and transmission electron microscopy. Backscattering shows crystalline or near‐crystalline layers at the surface, buried amorphous layers centered at the damage range, and a deeper damage peak. Complex interference spectra are successfully analyzed for two sets of fringes: a visible set primarily associated with the crystalline layer of index of refractionnxat the surface and an infrared set primarily associated with the buried amorphous layer (na≳nx). Interband transitions in the ultraviolet confirm the existence of crystalline layers at the surface. The deeper damage peak is composed of small dislocations as shown by electron microscopy.

ISSN:0003-6951    

DOI:10.1063/1.88887

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

GaAsp+n−n+electro‐optic directional‐coupler switches have been successfully fabricated and evaluated at 1.06 &mgr;m for use as components in integrated optical circuits. The devices were fabricated from a pair of closely spaced low‐loss [&agr;≈1 cm−1(4.3 dB/cm) at 1.06 &mgr;m] single‐modep+n−n+channel‐stop strip guides. They are operable both as passive directional couplers and as electro‐optic switches. The couplers have exhibited 98% power transfer and have an attenuation only about 0.1 dB/cm greater than that of a single guide having the same dimensions as one of the coupled guides. The switch performance was found to depend on the crystallographic direction chosen for light propagation. All devices were in the {100} plane, and 17‐dB (98%) power isolation in both the switched and unswitched states with constant total power output (≲0.2‐dB variation) was achieved for propagation along a [011] direction. These switches were 7.2 mm long, and had an optimum switching voltage of 43 V and a calculated power‐bandwidth ratio in a 50‐&OHgr; system of 110 mW/MHz.

ISSN:0003-6951    

DOI:10.1063/1.88888

出版商:AIP    

年代:1976

数据来源: AIP