摘要:

A new method to measure the tip’s true vibrational amplitude in the shear force microscopy is demonstrated. The measurements are based on modifications of the beam diffraction method. In addition to the dither vibration, the equilibrium position of the tip is set to move along the direction of the vibration. The ratio of ac amplitude to the derivative of dc amplitude gives the tip’s vibration. The sensitivity of this method is determined by the size of the laser focal spot times the ratio of the ac to dc signals of the diffracted light. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115289

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The effect of beam thickness in a two‐dimensional Cherenkov laser is investigated on the basis of the fluid model for the electron beam. In the analysis, the transverse variation of the drift velocity for the electron beam is taken into account. The numerical simulation shows that there exists an optimum beam thickness for an efficient use of the electron beam in the Cherenkov laser. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115290

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report the pump wavelength tuning of a low thresholdN‐(4‐nitrophenyl)‐L‐prolinol based nanosecond pulsed optical parametric oscillator in the near infrared. A broad tuning range from 1 to 1.5 &mgr;m corresponds to a limited pump wavelength excursion from 583 to 590 nm and a record low oscillation threshold of the order of 0.5 MW cm−2. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115291

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Recent optical heterodyne measurements with distributed‐Bragg‐reflector diode‐laser pumps demonstrate that low‐temperature‐grown (LTG) GaAs photomixers will be useful in a compact all‐solid‐state terahertz source. Electrical 3 dB bandwidths as large as 650 GHz are measured in mixers with low electrode capacitance. These bandwidths appear to be independent of pump‐laser wavelength over the range 780–850 nm. Shorter wavelength pumping results in a significant reduction of the bandwidth. The best LTG‐GaAs photomixers are used to generate coherent continuous‐wave output radiation at frequencies up to 5 THz. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115292

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Annealed and nonannealedp‐contact metallization for asymmetric cladding separate confinement heterostructure lasers with a thinp‐cladding layer is reported. Ti–Au and annealed Ti–Pt–Aup‐type contacts are demonstrated to improve the adhesion over a pure gold contact and allow annealing of the metallization to thinp‐cladding laser structures at the expense of an increase in the optical loss. The increased optical loss is due to the decreased conductivity of titanium and platinum as compared to gold. As little as 10 A˚ of titanium is adequate for an adhesion layer and only increases the optical loss by 1.6 cm−1over a pure gold metallization which has an optical loss of 10.0 cm−1. A metallization of 15 A˚ Ti−15 A˚ Pt−1500 A˚ Au is adequate for an anneal at 410 °C for 10 s and increases the optical loss by 7.0 cm−1. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115293

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Nonlinear optical absorption in solid films of poly(3‐octylthiophene) (P3OT) sensitized with methanofullerene was investigated for wavelengths from 620 to 960 nm. The nonlinear absorption is enhanced over that in either of the component materials by more than two orders of magnitude at 760 nm. The large nonlinearity results from efficient photoinduced intermolecular charge transfer from P3OT to methanofullerene, followed by absorption in the charge separated excited state. P3OT/fullerene films are promising as optical limiters; the transmission clamps at an average fluence of approximately 0.1 J/cm2. The damage threshold was 15 &mgr;J/pulse (≊1 J/cm2in average fluence), above which there is a permanent change in the linear transmission. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115294

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report that organic electroluminescence devices with a distyrylarylene (DSA) emitting layer including a new dopant realized highly efficient and bright emission in blue region. This dopant was amino‐substituted DSA. The luminous efficiency was obtained to be 1.5 lm/W. The external quantum efficiency was estimated to be 2.4%, which is one of the highest efficiencies ever reported in blue emitting organic EL devices. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115295

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report the observation of self‐induced gratings or noise gratings in an acrylamide photopolymer for use in real time holography. The possibilities of this noise source as an optimization technique for this type of material are pointed out. Noise gratings in these polymer films were created upon exposure to a He–Ne laser collimated beam at 633 nm without any subsequent processing step. The influence of intensity on recording noise gratings and angular selectivity are reported showing its influence on the recording of this type of noise source in real time holographic materials. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115296

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Direct‐write lithography on a 100 nm scale has been carried out using the near‐field optical interaction between an uncoated tapered fiber tip and a layer of photoresist. This allows both lithography and shear force microscopic examination of the surface, which reveals morphological changes in the photoresist before development. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115297

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The initial degradation of II–VI light emitting devices, namely the ⟨100⟩ dark line defect formation in CdZnSe quantum well structures formed during laser or light emitting diode (LED) operation, has been investigated. Optically degraded quantum well structures exhibiting dark line defects were investigated via transmission electron microscopy. The observable dislocation networks have been determined to be conglomerations of dislocation loops confined to the quantum well region having an associated Burgers vectors ofa[100] anda[010]. The discovery and identification of initial dark line defects may prove useful in identifying the defect mechanism in II–VI light emitters. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115298

出版商:AIP    

年代:1995

数据来源: AIP