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15 May 1976

Volume 28, Issue 10, pp. 571-637

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Torque curves and rotational hysteresis in a smectic C liquid crystal

P. J. Flanders

Appl. Phys. Lett. 28, 571 (1976); http://dx.doi.org/10.1063/1.88594 (3 pages) | Cited 16 times

Online Publication Date: 28 August 2008

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Static torque curves in 4,4′‐terephthal‐bis (butylaniline) (TBBA) as a function of temperature are reported. In the smectic A phase (between 173 and 199 °C) a simple sinusoidal torque curve is observed as expected. In the smectic C phase (between 144 and 173 °C) the torque curves are no longer sinusoidal. The torque maximum shifts from π/4 measured from the easy axis to larger angles as the temperature is decreased. Also, rotational hysteresis appears and minor loops are observed. As in the smectic A phase the shape of the torque curves is essentially independent of field, with the torque scaling as the square of the magnetic field. The observed magnetic properties can be understood in terms of the multidomain model for the smectic C phase. Comparison of the calculation with the experimental data allows a determination of the temperature‐dependent cone angle from the torque curves. Assuming a rotational model, the calculated hysteresis is found to be larger than the experimental value.
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81.05.-t Specific materials: fabrication, treatment, testing, and analysis
61.30.-v Liquid crystals

Attenuation of Rayleigh surface waves by surface roughness

A. A. Maradudin and D. L. Mills

Appl. Phys. Lett. 28, 573 (1976); http://dx.doi.org/10.1063/1.88595 (3 pages) | Cited 11 times

Online Publication Date: 28 August 2008

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We have carried out a calculation of the attenuation of Rayleigh surface waves by surface roughness, in the limit where the amplitude of the roughness is small. A Green’s function method has been employed in the work. In this letter, we present a summary of our method along with some principal results.
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62.30.+d Mechanical and elastic waves; vibrations
63.20.-e Phonons in crystal lattices
68.35.Gy Mechanical properties; surface strains
68.35.Iv Acoustical properties

Capillary liquid epitaxial growth of LiNbO3 and LiTaO3 single‐crystal thin films

T. Fukuda and H. Hirano

Appl. Phys. Lett. 28, 575 (1976); http://dx.doi.org/10.1063/1.88596 (3 pages) | Cited 9 times

Online Publication Date: 28 August 2008

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A new technique using capillary action, capillary liquid epitaxial (CLE) technique, is described for growing a high‐quality LiNbO3 thin film onto a LiTaO3 substrate. A LiTaO3 single‐crystal film, 2 μm in thickness, was also successfully grown with good epitaxy onto a LiNbO3 substrate by this technique. Evaluation of these films by x‐ray measurements and preliminary experimental results on optical waveguide are reported.
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68.55.-a Thin film structure and morphology
81.20.-n Methods of materials synthesis and materials processing
42.79.Gn Optical waveguides and couplers

Single‐crystal work‐function and evaporation measurements of LaB6

L. W. Swanson and T. Dickinson

Appl. Phys. Lett. 28, 578 (1976); http://dx.doi.org/10.1063/1.88597 (3 pages) | Cited 37 times

Online Publication Date: 28 August 2008

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Retarding potential and Richardson work functions of 2.28±0.03 and 2.47±0.06 eV, respectively, have been measured for the (100) face of LaB6. Auger electron spectra of the thermally cleaned surface gave a B/La ratio of 2.3–2.6. Mass spectrometric measurements showed the evaporating species from a clean LaB6 (100) surface to be atomic La and B in near‐stoichiometric proportions. Activation energies for the vaporization of La and B were 6.3±0.3 and 6.8±0.3 eV, respectively.
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79.40.+z Thermionic emission
73.40.Cg Contact resistance, contact potential
64.70.Hz Solid-vapor transitions

Attachment‐dominated electron‐beam‐ionized discharges

J. D. Daugherty, J. A. Mangano, and J. H. Jacob

Appl. Phys. Lett. 28, 581 (1976); http://dx.doi.org/10.1063/1.88598 (3 pages) | Cited 40 times

Online Publication Date: 28 August 2008

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In this letter we derive the stability criterion in discharges where two‐step ionization is dominant. For stable equilibrium the attachment rate has to be greater than or equal to twice the ionization rate. Two‐step ionization is often dominant in discharge‐pumped visible lasers because of the relatively large number of electronically excited states. Analysis of the KrF laser discharge indicates that two‐step ionization is dominant.
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52.80.-s Electric discharges
42.55.Lt Gas lasers including excimer and metal-vapor lasers

Laser light absorption measurements in an interaction‐produced plasma column

P. A. Pincosy, P. Bournot, D. Dufresne, J. P. Caressa, and M. Autric

Appl. Phys. Lett. 28, 583 (1976); http://dx.doi.org/10.1063/1.88599 (3 pages) | Cited 2 times

Online Publication Date: 28 August 2008

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100 J of 10.6‐μ laser energy produced in a 1.5‐μs pulse was focused to a 2‐mm‐diam spot by a 50‐cm‐focal‐length mirror. A plasma was created by breakdown in the 70‐ns gain‐switched peak of the pulse where the light flux becomes greater than 1010 W/cm2. The plasma column subsequently created in 5–20 Torr of hydrogen by the absorbed light energy was observed by 5‐ns exposure and streak photographs. The aspect of beam trapping is demonstrated by measurements of the transmitted light intensity radial distribution and significant energy absorption is shown by the measurement of transmitted energy.
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52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.25.Os Emission, absorption, and scattering of electromagnetic radiation

A new class of efficient low‐pressure gas discharges with high radiation output per unit volume

J. Hasker

Appl. Phys. Lett. 28, 586 (1976); http://dx.doi.org/10.1063/1.88600 (3 pages) | Cited 6 times

Online Publication Date: 28 August 2008

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A considerable increase of the axial electric field together with a modest increase of the electron temperature can be obtained by the introduction of a recombination structure (e.g., glass wool) into the discharge space. The effect is shown by experiments on mercury–rare‐gas discharges and interpreted in terms of enhanced recombination of ions and electrons. As an application, it is shown that the luminous flux per unit volume of usual fluorescent lamps can be doubled, while maintaining high over‐all luminous efficacy. Moreover, the construction of efficient fluorescent lamps with approximately the dimensions of an incandescent lamp has become feasible.
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85.60.Jb Light-emitting devices
52.80.-s Electric discharges
51.50.+v Electrical properties (ionization, breakdown, electron and ion mobility, etc.)
52.25.Os Emission, absorption, and scattering of electromagnetic radiation

Strength of 0.04–50‐m lengths of coated fused silica fibers

C. R. Kurkjian, R. V. Albarino, J. T. Krause, H. N. Vazirani, F. V. DiMarcello, S. Torza, and H. Schonhorn

Appl. Phys. Lett. 28, 588 (1976); http://dx.doi.org/10.1063/1.88601 (3 pages) | Cited 22 times

Online Publication Date: 28 August 2008

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Tensile strength measurements have been made on coated fused silica fibers at gage lengths up to 50 m. At gage lengths between 0.04 and 10 m, the average strength is essentially constant at about 5 GN/m2 (700 ksi). At gage lengths greater than 20 m the length dependence becomes important and by 50 m the strength has decreased to about 2 GN/m2 (300 ksi). The minimum strength recorded in the testing of samples taken continuously from a length of 1031.6 m was 0.43 GN/m2 (64 ksi). A ’’weakest link’’ model appears to be obeyed.
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81.40.-z Treatment of materials and its effects on microstructure, nanostructure, and properties
42.81.-i Fiber optics
46.50.+a Fracture mechanics, fatigue and cracks

Observation of dark line defects in GaP green LED’s under an external uniaxial stress

M. Iwamoto and A. Kasami

Appl. Phys. Lett. 28, 591 (1976); http://dx.doi.org/10.1063/1.88575 (2 pages) | Cited 21 times

Online Publication Date: 28 August 2008

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Dark line defects (DLD’s) have been observed in GaP green LED’s under an external mechanical stress. Excitation of minority carriers is essential to DLD formation. DLD is revealed to grow along the 〈110〉 direction and to correspond to an array of dislocation etch pits. A ’’traveling dark spot’’ was observed for the first time. It moves as fast as 1 mm/sec and becomes trapped at the edge of DLD, which results in DLD growing. DLD generation depends on both the forward current magnitude and external stress.
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85.60.Jb Light-emitting devices
78.60.Fi Electroluminescence
78.20.hb Piezo-optical, elasto-optical, acousto-optical, and photoelastic effects
78.55.-m Photoluminescence, properties and materials

Photovoltaic properties of n‐CdSe/p‐ZnTe heterojunctions

Fredrik Buch, Alan L. Fahrenbruch, and Richard H. Bube

Appl. Phys. Lett. 28, 593 (1976); http://dx.doi.org/10.1063/1.88576 (3 pages) | Cited 4 times

Online Publication Date: 28 August 2008

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Measurements of the diffusion potential, depletion layer width, and bias dependence of quantum efficiency for n‐CdSe/p‐ZnTe heterojunctions are used to construct a band diagram for the junction and to propose a current transport model. A new value of the electron affinity of CdSe is indicated by measurements of the open‐circuit voltage at low temperatures and high intensities. The saturation current density J0 is controlled by a thermal activation energy of 0.8 eV, corresponding to electron flow to the interface where recombination occurs through interface states. Performance as photovoltaic cells is limited by the short diffusion length of holes in CdSe.
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72.40.+w Photoconduction and photovoltaic effects
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
72.80.Ey III-V and II-VI semiconductors

GaAs‐Ga1‐xAlxAs double‐heterostructure injection lasers with distributed Bragg reflectors

Won‐Tien Tsang and Shyh Wang

Appl. Phys. Lett. 28, 596 (1976); http://dx.doi.org/10.1063/1.88577 (3 pages) | Cited 19 times

Online Publication Date: 28 August 2008

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Laser oscillation in injection‐pumped GaAs‐Ga1−xAlxAs double‐heterostructure distributed Bragg reflector (DBR) lasers is reported. Current threshold density as low as 890 A/cm2 in pulsed operation has been obtained at 183 °K. In this laser diode, the corrugations are placed outside the active part of the laser in the form of an end pair of parallel Bragg reflectors. The observed characteristics of the DBR lasers are found to agree well with the theory.
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42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
42.82.-m Integrated optics

Red‐light‐emitting laser diodes operating cw at room temperature

H. Kressel and F. Z. Hawrylo

Appl. Phys. Lett. 28, 598 (1976); http://dx.doi.org/10.1063/1.88578 (3 pages) | Cited 14 times

Online Publication Date: 28 August 2008

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Heterojunction laser diodes of AlGaAs have been prepared with threshold current densities substantially below those previously achieved at room temperature in the 7200–8000‐Å spectral range. These devices operate cw with simple oxide‐isolated stripe contacts to 7400 Å, which extends cw operation for the first time into the visible (red) portion of the spectrum.
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42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
85.60.Jb Light-emitting devices

Theory of elasto‐optic coefficients in polycrystalline materials

M. Flannery and J. Marburger

Appl. Phys. Lett. 28, 600 (1976); http://dx.doi.org/10.1063/1.88579 (2 pages) | Cited 2 times

Online Publication Date: 28 August 2008

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We estimate strain‐optic coefficients for polycrystalline laser window materials, and show that they deviate appreciably from the single‐crystal values. p11−p12 may change sign and grow in magnitude relative to the single‐crystal value.
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78.20.hb Piezo-optical, elasto-optical, acousto-optical, and photoelastic effects

XeBr exciplex laser

S. K. Searles

Appl. Phys. Lett. 28, 602 (1976); http://dx.doi.org/10.1063/1.88580 (2 pages) | Cited 4 times

Online Publication Date: 28 August 2008

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Laser emission from the recently discovered XeBr exciplex laser was investigated as a function of the partial pressures of Xe and Br2. An optical loss process appears to limit high‐pressure operation.
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42.55.Lt Gas lasers including excimer and metal-vapor lasers

Spin‐flip Raman laser at wavelengths up to 16.8 μm

C. K. N. Patel, T. Y. Chang, and V. T. Nguyen

Appl. Phys. Lett. 28, 603 (1976); http://dx.doi.org/10.1063/1.88581 (3 pages) | Cited 4 times

Online Publication Date: 28 August 2008

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An InSb spin‐flip Raman (SFR) laser is pumped with an optically pumped NH3 laser line at 780.515 cm−1 to obtain tunable first Stokes laser radiation at wavelengths up to 16.8 μm. We report results on the power output, tunability, and preliminary spectroscopy of UF6. Scaling of the primary CO2 pump laser as well as the NH3 laser together with the SFR laser appears possible for potential application of this system to uranium isotope separation.
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42.65.Dr Stimulated Raman scattering; CARS
42.65.Es Stimulated Brillouin and Rayleigh scattering
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
28.60.+s Isotope separation and enrichment
33.20.Ea Infrared spectra
33.20.Fb Raman and Rayleigh spectra (including optical scattering)

Laser‐induced breakdown and nonlinear refractive index measurements in phosphate glasses, lanthanum beryllate, and Al2O3 

W. Lee Smith and J. H. Bechtel

Appl. Phys. Lett. 28, 606 (1976); http://dx.doi.org/10.1063/1.88582 (2 pages) | Cited 7 times

Online Publication Date: 28 August 2008

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We present results of measurements of the laser‐induced dielectric breakdown threshold in two phosphate composition laser glasses, in lanthanum beryllate:Nd, and in Al2O3. The nonlinear refractive indices for these materials are also presented. The measurements were made with single 30‐psec 1.064‐μm pulses. The results are compared with those for other laser materials in the 1.06‐μm spectral region.
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79.20.Ds Laser-beam impact phenomena
77.22.Jp Dielectric breakdown and space-charge effects
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
42.65.-k Nonlinear optics

cw Brillouin laser

K. O. Hill, B. S. Kawasaki, and D. C. Johnson

Appl. Phys. Lett. 28, 608 (1976); http://dx.doi.org/10.1063/1.88583 (2 pages) | Cited 40 times

Online Publication Date: 28 August 2008

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The observation of efficient continuous‐wave Brillouin laser action in an optical‐fiber ring resonator is reported. Internal laser conversion efficiencies of 50% and a Brillouin‐shifted output of 20 mW have been achieved.
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42.50.-p Quantum optics
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.65.Dr Stimulated Raman scattering; CARS
42.65.Es Stimulated Brillouin and Rayleigh scattering
42.81.-i Fiber optics

Infrared absorption limits of HF and DF laser windows

M. Hass, J. A. Harrington, D. A. Gregory, and J. W. Davisson

Appl. Phys. Lett. 28, 610 (1976); http://dx.doi.org/10.1063/1.88584 (2 pages) | Cited 6 times

Online Publication Date: 28 August 2008

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The infrared absorption coefficients of NaCl, KCl, NaF, CaF2 and BaF2 have been determined by calorimetric techniques at the laser wavelengths 1.06, 2.7, and 3.8 μm. The absorption level of the best crystals can be 10−5 cm−1 or lower at l.06 μm, but no crystal with a coefficient lower than 10−4 cm−1 at 2.7 and 3.8 μm has been found. Possible reasons for these results are discussed.
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78.30.Hv Other nonmetallic inorganics
78.40.Ha Other nonmetallic inorganics
42.70.-a Optical materials
42.79.Fm Reflectors, beam splitters, and deflectors
42.79.Ls Scanners, image intensifiers, and image converters
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Temporal stability of unstable resonator with crossflow

Harold Mirels

Appl. Phys. Lett. 28, 612 (1976); http://dx.doi.org/10.1063/1.88585 (2 pages) | Cited 4 times

Online Publication Date: 28 August 2008

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The temporal stability of the output from a cw laser that contains an unstable resonator with crossflow is investigated for cases where the population inversion is partially due to a pumping mechanism within the resonator. For resonator magnification M near 1, the output is shown to be stable when G0(1) <1 and dP/dζ⩾0, where G0(1) is the ratio of inlet to optical axis gain, and (−dP/dζ) is the steamwise gradient of the volumetric pumping. For arbitrary M and ϕ≫1, laser output fluctuations are at most of order ϕ−1, where ϕ is a measure of the net gain due to pumping divided by the threshold gain. by the threshold gain. by the threshold gain.
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42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.55.Lt Gas lasers including excimer and metal-vapor lasers

Diffraction from laser‐induced deformation on reflective surfaces

Jackson C. Koo and Richart E. Slusher

Appl. Phys. Lett. 28, 614 (1976); http://dx.doi.org/10.1063/1.88586 (3 pages) | Cited 33 times

Online Publication Date: 28 August 2008

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Diffraction from laser‐induced deformations on reflective surfaces is described as a model for an observed decrease in surface reflectivity immediately preceding surface damage. Experimental measurements of reflected laser radiation at large angles from copper and silicon surfaces are in qualitative agreement with this diffraction model.
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79.20.Ds Laser-beam impact phenomena
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation

Low‐loss GaAs p+n−n+ three‐dimensional optical waveguides

F. J. Leonberger, J. P. Donnelly, and C. O. Bozler

Appl. Phys. Lett. 28, 616 (1976); http://dx.doi.org/10.1063/1.88587 (4 pages) | Cited 14 times

Online Publication Date: 28 August 2008

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Two types of low‐loss single‐mode p+n−n+ GaAs three‐dimensional waveguides have been successfully fabricated and their attenuation coefficients measured. The devices are an optical stripline and a new device, the channel‐stop strip guide. The channel‐stop strip guides have losses of 0.8 cm−1 at 1.06 μm and 1.1 cm−1 at 0.920 μm; the losses for the optical striplines are 1.2 cm−1 at 1.06 μm and 1.7 cm−1 at 0.920 μm. A first‐order loss calculation has yielded attenuation coefficients within 25% of these measured values. Both structures have an n+ substrate, an n− epitaxial layer for guiding, and p+ regions to laterally confine the light. The p+ regions have a uniform concentration and are formed by multiple‐energy Be+‐ion implantation; the p+n− junctions show sharp high‐voltage breakdowns at average electric fields in the n− layer of 1.5×105 V/cm.
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42.79.Gn Optical waveguides and couplers
42.82.-m Integrated optics
42.79.Sz Optical communication systems, multiplexers, and demultiplexers

Improved efficiency of MIS‐silicon solar cells by HF treatment of the oxide layer

A. H. M. Kipperman and M. H. Omar

Appl. Phys. Lett. 28, 620 (1976); http://dx.doi.org/10.1063/1.88588 (2 pages) | Cited 10 times

Online Publication Date: 28 August 2008

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Low‐temperature processes, which can be used for MIS structures, are very applicable for polysilicon solar cells. An HF treatment of the insulating oxide layer in single‐crystal MIS‐silicon solar cells turned out to enhance the short‐circuit current such that the AM1 efficiency appeared to be more than 10% without antireflection coating. A low surface recombination is indicated by the response to the blue part of the solar spectrum.
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84.60.Jt Photoelectric conversion
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
72.40.+w Photoconduction and photovoltaic effects

Transparent electrode properties of cadmium stannate

G. Haacke

Appl. Phys. Lett. 28, 622 (1976); http://dx.doi.org/10.1063/1.88589 (2 pages) | Cited 46 times

Online Publication Date: 28 August 2008

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Thin films of semiconducting n‐type cadmium stannate (Cd2SnO4) have been coated onto different substrate materials by rf sputtering. The films are transparent in the visible and near‐infrared part of the optical spectrum and electrically conductive. Conductivities as high as 6500 Ω−1 cm−1 have been achieved. Transparent electrode coatings can be prepared which have 1 Ω/square electrical sheet resistance and 85% average optical transmission between 5000 and 6500 Å.
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73.61.Cw Elemental semiconductors
73.61.Ey III-V semiconductors
73.61.Ga II-VI semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors
78.20.-e Optical properties of bulk materials and thin films
42.79.Wc Optical coatings

First phase nucleation in silicon–transition‐metal planar interfaces

R. M. Walser and R. W. Bené

Appl. Phys. Lett. 28, 624 (1976); http://dx.doi.org/10.1063/1.88590 (2 pages) | Cited 239 times

Online Publication Date: 28 August 2008

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What is the first compound that nucleates in planar solid silicon–transition‐metal binary couple reactions whose members form bulk equilibrium compounds? We propose, for couples annealed at low temperatures, the following simple rule: The first compound nucleated in planar binary reaction couples is the most stable congruently melting compound adjacent to the lowest‐temperature eutectic on the bulk equilibrium phase diagram. The predictions of this rule are compared with experimental results.
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68.55.-a Thin film structure and morphology
73.40.-c Electronic transport in interface structures
81.10.Aj Theory and models of crystal growth; physics and chemistry of crystal growth, crystal morphology, and orientation
82.60.Nh Thermodynamics of nucleation

High‐power integrated optic ir modulator at microwave frequencies

P. K. Cheo and M. Gilden

Appl. Phys. Lett. 28, 626 (1976); http://dx.doi.org/10.1063/1.88591 (2 pages) | Cited 7 times

Online Publication Date: 28 August 2008

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Optical sideband power of 40 mW has been generated in a 25‐μm‐thick GaAs waveguide modulator at 16‐GHz offset from a 4‐W CO2 laser carrier by applying a microwave power of 20 W. The electrode is in the form of a microstrip transmission line, 2.8 cm long and 1 mm wide. The measured modulation bandwidth is 1 GHz at the sideband half‐power points.
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42.79.Hp Optical processors, correlators, and modulators
42.82.-m Integrated optics
42.79.Gn Optical waveguides and couplers
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