摘要:

TheX2&Sgr;+1/2→B2&Sgr;+1/2absorption band of HgBr has been observed in the afterglow of a pulsed Ne‐N2‐HgBr2discharge. Peaking in the ultraviolet (UV) near 350 nm, this continuum degrades slowly to the red and at 410 nm the absorption coefficient is 30% of its maximum value. Upon exciting theX→Bband with an XeF (351 nm) or frequency tripled Nd:YAG (355 nm) laser, intense lasing is observed in the blue‐green (&lgr;∼502 nm). For &lgr;pump=351 nm, the energy conversion efficiency (UV to green) is 22% which corresponds to aphotonconversion efficiency of 32%. The quantum efficiency for this four level system is 71%.

ISSN:0003-6951    

DOI:10.1063/1.96460

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Distributed Bragg reflector Pb1−xSnxSe/ Pb1−x−yEuySnxSe double heterostructure stripe geometry diode lasers were fabricated using molecular beam epitaxy. We observed cw single mode operation between the heat‐sink temperatures 66 and 81 K at &lgr;≊7.8 &mgr;m with an average tuning rate of 0.8 cm−1/K. Single mode continuous tuning over a relatively wide range of 6 cm−1, with an average tuning rate of 0.026 cm−1/mA, was obtained at 77 K.

ISSN:0003-6951    

DOI:10.1063/1.96461

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

We present a new technique for the detection of spectral holes or other strain‐sensitive spectral features using phase‐sensitive ultrasonic modulation. The spectral feature is directly modulated at MHz rates in synchrony with an applied rf ultrasonic field, hence the method offers zero background and the potential for high‐speed detection with sensitivity near the quantum limit. The technique is demonstrated for a model color center system, and the characteristic line shape is analyzed in detail. The method is more sensitive than laser FM (frequency modulation) spectroscopy for low modulation frequencies, and should be generally useful for the detection of strain‐sensitive spectral features.

ISSN:0003-6951    

DOI:10.1063/1.96462

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A novel technique, which employs a modified Twyman–Green interferometer, is used to measure the nonlinear index of a CdS0.9Se0.1‐doped glass at different wavelengths in the vicinity of the band gap at room temperature. The measuredn2values for the doped glass are compared with calculated values obtained by Kramers–Kronig transformation of the measured &Dgr;&agr;(&lgr;)=&agr;(I1,&lgr;)−&agr;(I2,&lgr;). A good agreement is achieved between the measured nonlinear dispersion and that obtained through the Kramers–Kronig relations.

ISSN:0003-6951    

DOI:10.1063/1.96463

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The third order nonlinear optical susceptibility has been measured by degenerate four wave mixing in a 33‐&mgr;m‐thick biaxial film of a conjugated aromatic heterocyclic polymer, poly‐p‐phenylenebenzobisthiazole, commonly known as PBT, which has a very high mechanical strength due to its rigid rod conformation as well as environmental stability and a high laser damage threshold. For the first time, the response of the optical nonlinearity in the &pgr;‐electron conjugated system has been experimentally verified to be in subpicoseconds. The value of &khgr;(3)is found to be about an order of magnitude larger than that of CS2. The measurement at two different wavelengths suggests that they are nonresonant &khgr;(3)values. The measured anisotropy of &khgr;(3)as a function of angular orientation at two different sets of laser polarization is explained by using the tensor properties of &khgr;(3)in an anisotropic medium.

ISSN:0003-6951    

DOI:10.1063/1.96464

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The continuous tunability of various coupled‐cavity semiconductor lasers has been investigated. Monolithic etched groove and cleaved coupled cavity (C3) geometries are included. Using a special method of modulating the laser currents, appreciable tuning ranges have been achieved (∼8 A˚) without mode hops. Also, electronic tuning of a laser with no amplitude variation is illustrated. A tuning range of 4 A˚ with <5% AM depth is observed. Review of the theory and a comparison of the different laser geometries are included.

ISSN:0003-6951    

DOI:10.1063/1.96465

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The Klein–Nishina differential cross section averaged over a relativistic Maxwellian electron distribution is analytically reduced to a single integral, which can then be rapidly evaluated in a variety of ways. This is, to our knowledge, the first correct computation of the Compton scattering kernel.

ISSN:0003-6951    

DOI:10.1063/1.96466

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The temperature effect of anode dielectric materials on ion beam turn‐on time is examined in a magnetically insulated pulsed ion diode. It is observed that the turn‐on time decreased with temperature increase. This effect may be explained by a simple model in which electrons bombard the anode surface to generate desorbed and evaporated gas and trigger surface flashover to produce an anode plasma.

ISSN:0003-6951    

DOI:10.1063/1.96467

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

LiInSe2films were grown on GaP substrates using a hot wall technique. Reflection high‐energy electron diffraction analysis showed that LiInSe2, having a &bgr;‐NaFeO2(wurtzitelike) structure, grows epitaxially on a ⟨111⟩Aoriented GaP at substrate temperatures ranging from 360 to 400 °C and at the wall temperature of 650 °C with the compensation of Se. The crystalline quality of the epitaxial layers on substrates was investigated by Rutherford backscattering (RBS). The depth profile of RBS‐aligned spectrum showed the relative low minimum yield of backscattered particles except for that near the interface. Auger electron spectroscopy measurements showed that the atomic concentration ratio of Se and In in films was 2.

ISSN:0003-6951    

DOI:10.1063/1.97010

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Both uniform and irregular artificially layered superlattice structures can exhibit a variety of misleading image artifacts in transmission electron microscopy when the layer normal is not perpendicular to the beam direction. These include apparent ‘‘layer dislocations,’’ and the origins of these and other artifacts, as observed in Cu/NiPd superlattices, are discussed.

ISSN:0003-6951    

DOI:10.1063/1.96468

出版商:AIP    

年代:1986

数据来源: AIP