摘要:

Theoretical calculations supported by numerical simulations show that utilization of the nonlinear dependence of the index of refraction on intensity makes possible the transmission of picosecond optical pulses without distortion in dielectric fiber waveguides with group velocity dispersion. In the case of normal dispersion (∂2&ohgr;/∂k2< 0) discussed here [the case of anomalous dispersion (∂2&ohgr;/∂k2> 0) was discussed in an earlier letter], the stationary pulse is a ``dark'' pulse or envelope shock. Numerical simulations show that such pulses are stable under the influence of small perturbations, white noise, or absorption. Important considerations relating to the practical applications of both ``bright'' and ``dark'' pulses are also discussed.

ISSN:0003-6951    

DOI:10.1063/1.1654847

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Efficient up‐conversion of near‐infrared energy was realized by confinement of infrared energy in an optical cavity containing a BaY2F8: Yb,Er single crystal. The lifetime of the ytterbium excited state showed a marked increase and, in a typical instance, became as long as 3.6 msec. Combined with 8% efficiency GaAs : Si diode, an over‐all conversion efficiency of nearly 0.04% was obtained for a 50‐mA diode‐exciting current.

ISSN:0003-6951    

DOI:10.1063/1.1654848

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

We describe a high‐speed deflector‐modulator based on an electro‐optically induced thick phase grating in optical waveguides of single‐crystal epitaxial ZnO film on Al2O3substrates. 40% of the beam is diffracted into first order with response times of 3 nsec. The extinction ratio in the deflected beam is greater than 95%. We predict 80% diffraction, response times of < 1 nsec, and power requirements of approximately 1 mW/MHz for an optimized geometry.

ISSN:0003-6951    

DOI:10.1063/1.1654849

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Quantitative studies of third‐harmonic generation in the all‐trans &bgr;‐carotene molecule and of third‐harmonic generation and the optical Kerr effect in &bgr;‐carotene glass are reported. The large values of the optical nonlinearities are attributed to the broadly delocalized &Pgr; electrons.

ISSN:0003-6951    

DOI:10.1063/1.1654850

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

This paper reports the first continuous operation of GaAs&sngbnd;Ga1 −xAlxAs double‐heterostructure (DH) junction lasers for periods of time in excess of 1000 h in a 30 °C ambient. One laser which has operated at a constant direct current for more than 1000 h has degraded only 10% from its initial 20‐mW light output. At 1000 h, the differential quantum efficiency remained essentially unchanged, but the threshold and the mode structure changed appreciably.

ISSN:0003-6951    

DOI:10.1063/1.1654851

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Two MIS versions have been fabricated employing rf‐sputtered dual insulator structures comprised of 1000 Å HfO2‐20 Å SiO2and 1000 Å SrTiO3‐20 Å SiO2. The high‐dielectric‐constant insulators in combination with a 20‐Å layer of silicon dioxide permit the transfer of charge by tunneling into traps at the dual‐insulator interface to occur at considerably lower voltages than comparable structures employing silicon nitride or aluminum oxide. It was found that trap density and, hence, the degree of flat‐band voltage shift could be altered by sputtering 50‐Å layers of selected materials at the insulator‐SiO2interface. The devices employing hafnium dioxide show promise in an application as a nonvolatile electrically alterable memory element. Although the strontium titanate devices exhibit a low threshold voltage for onset of charge transfer, the charge retention characteristics are poor.

ISSN:0003-6951    

DOI:10.1063/1.1654852

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The properties of heterojunctions betweenn‐ andp‐type crystalline silicon and certain threshold‐type amorphous chalcogenide films have been investigated. Low‐field and high‐fieldI‐Vcharacteristics, switching properties, and photoelectric behavior have all been studied. Devices fabricated with silicon substrates of opposite types are distinctly different; device characteristics at low voltages were found to be influenced appreciably by interface states. Short‐circuit photocurrent data imply band models which explain theI‐Vproperties in both the absence and the presence of light.

ISSN:0003-6951    

DOI:10.1063/1.1654853

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Two possibilities for observing the infrared absorption of residual phosphorus inp‐type silicon are discussed. Experimental results show that inp‐type silicon the pairing of Mg, presumably with boron and/or oxygen, produces donor complexes with ionization energy less than that of phosphorus. The integrated intensity of the phosphorus lines of the sample after Mg diffusion indicates a phosphorus concentration of ∼ 1.5 × 1013atoms/cm3.

ISSN:0003-6951    

DOI:10.1063/1.1654854

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The characteristic formation of dark filamentary features during the rapid degradation mode of AlxGa1−xAs double‐heterostructure lasers has been observed in material with no contacts, with or without ap‐njunction, and in minimal‐strain mounting configurations. The degradation was observed in optically pumped cw lasing and nonlasing conditions with active region temperatures near and above room temperature.

ISSN:0003-6951    

DOI:10.1063/1.1654855

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

An experimental condition has been found for the CO chemical laser where it would appear that vibration‐vibration relaxation processes (V‐V) compete with stimulated emission to force the laser to operate in essentially a single line &ngr; = 10–9,P(17). No frequency‐selective element has been used in the laser cavity. Experimental data and results of computations on a laser model are presented to support this suggestion. A cw power of 7 W has also been achieved in this longitudinal flow system with the addition of cold CO (300 °K) for the chemical efficiency of ∼ 3.2%, one of the highest values for any system reported at the present time.

ISSN:0003-6951    

DOI:10.1063/1.1654856

出版商:AIP    

年代:1973

数据来源: AIP