摘要:

It was recently reported that a surface wave transducer could produce a beam of bulk waves whose tangential wave number was twice the fundamental wave number of the transducer; the wave numbers in the transducer's electric field are odd multiples of the fundamental. In this investigation it is found that the extra beam comes from mode conversion of rays reflected at the ends of the sample; the beam is not directly generated by the transducer.

ISSN:0003-6951    

DOI:10.1063/1.1655407

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

An electric field deforming a nematic slab becomes inhomogeneous because of dielectric or conductive anisotropy. An investigation of the latter regime indicates that the Fre´edericksz transition first becomes steeper and finally gives way to hysteresis as the conductive anisotropy is increased.

ISSN:0003-6951    

DOI:10.1063/1.1655408

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A high‐speed Bragg‐type electro‐optic modulator with modified interdigital electrodes has been constructed using a Li out‐diffused waveguide layer in LiNbO3. The thickness of the layer is about 7 &mgr;m and only two modes, TE0and TE1, are supported. For the TE0mode, a maximum modulation index of about 70% is obtained up to 900 MHz with an applied voltage of 18 V.

ISSN:0003-6951    

DOI:10.1063/1.1655409

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

We show that surface acoustic signals can be stored in and read from electron traps at the surface of a semiconductor that is adjacent to the piezoelectric on which the surface wave propagates. The observed memory action is explained by the large‐signal dynamics of the charging and discharging of the traps near a slightly depleted surface. The storage of the signal is accomplished by creating a zero‐frequencykpattern which fills the traps. The reading of the signal can be done by either correlation or convolution with another surface acoustic signal. This correlation device with internal memory does not require precise signal timing, operates with all signals at the same frequency, and does not require external time inversion of the reference signal.

ISSN:0003-6951    

DOI:10.1063/1.1655410

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Light reflecting from a laser‐produced plasma was measured as a function of plasma density. Light pulses of a Nd‐glass laser (100‐psec duration and 1014−W/cm2intensity) were focused on a high‐pressure gas jet as a target. A distinct reflectivity maximum of 0.3 was observed for helium at a density value 30% below the critical density. The results are interpreted in terms of stimulated Brillouin scattering.

ISSN:0003-6951    

DOI:10.1063/1.1655411

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A model on the preionization requirements for initiating a volume‐stabilized glow discharge is proposed. The basic requirement of the model is that the preionized electron density be large enough to cause appreciable spatial overlap of the primary avalanches and consequent smoothing of space‐charge field gradients at the stage when streamer formation would otherwise occur. A minimum required preionization electron density of ∼ 104cm−3is predicted for a typical CO2TEA laser discharge and is consistent with experimental observations.

ISSN:0003-6951    

DOI:10.1063/1.1655412

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

SEM photographs of regions of breakdown produced in vacuum (10−3Torr) are exhibited for four basic Al&sngbnd;SiO2&sngbnd;(100)Si configurations:psubstrate, field plate + and field plate ‐, andnsubstrate, field plate + and field plate ‐. Withp‐Si and field plate +, the geometry of the breakdown region reflects the anisotropic conductivity of hot electrons in Si along the (100) plane of the substrate wafer. Some properties of the breakdown correlate with the nature of the substrate surface channel (inversion versus accumulation); other properties correlate with the field‐plate polarity.

ISSN:0003-6951    

DOI:10.1063/1.1655413

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The signal and idler outputs from a proustite parametric oscillator have been difference mixed in a CdSe crystal to produce infrared radiation tuned continuously from 9.4 to 24.3 &mgr;m. Difference‐frequency powers, monitored by a pyroelectric detector, range from 10 W at 10 &mgr;m to 100 mW at 22 &mgr;m.

ISSN:0003-6951    

DOI:10.1063/1.1655414

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

We report the observation of laser action in an organic scintillator dye vapor (POPOP). The dye was heated in a suitable oven and the vapor excited with the 3371‐Å radiation from a pulsed N2laser. 30 kW of laser output at 3930 Å was obtained at a dye temperature of 330°C.

ISSN:0003-6951    

DOI:10.1063/1.1655415

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

We report the growth and fabrication of LPE multilayer InxGa1 −xAs homojunction LEDs. Junction edge emission in the 1.0–1.1‐&mgr;m wavelength range was obtained with external efficiencies of ∼1%. An important feature of the device structure is the incorporation of simple stepwise compositional grading for lattice matching of the substrate andp‐njunction layers.

ISSN:0003-6951    

DOI:10.1063/1.1655416

出版商:AIP    

年代:1974

数据来源: AIP