摘要:

A model of the effect of the longitudinal optical phonon number distribution on the Rabi oscillations of the photons involved in the associated indirect transition in a semiconductor is presented. It is shown that a faster cavity photon revival rate is obtained given an initial squeezed thermal phonon state. This is the result of pairwise correlations of phonons due to squeezing and also holds true when phonons are in squeezed vacuum or in squeezed number states. It may be possible to use this effect to detect squeezing in phonons. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119209

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A 2 in. diam single crystal of lithium tetraborate(Li2B4O7)was successfully grown by the Czochralski method. The crystal was free from macrodefects and had a dislocation density as low as100/cm2.It had an excellent homogeneity of the refractive index and a wide transparency down to 170 nm. The optical damage threshold was 40GW/cm2.Second-harmonic generation and sum frequency generation were investigated in association with the generation of the fourth and fifth harmonics of aQ-switched Nd:YAG laser. The conversion efficiency of the second-harmonic generation from the green (532 nm) light was 20&percent;. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119210

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A pyroelectric infrared detector operating at room temperature and based on semiconducting Y-Ba-Cu-O was fabricated. The capacitor structure consisting of semiconducting Y-Ba-Cu-O layer sandwiched between two Nb electrodes was fabricated on top of a thermally isolated SiO2bridge. The polycrystalline Y-Ba-Cu-O layer was deposited by ambient-temperature sputtering while standard Si micromachining techniques were used to etch the silicon under the oxide bridge. The pyroelectric response of the material is characterized by the temperature coefficient of polarization(p=dP/dT)which was measured to be as high as 65 nC/K cm2without an externally applied electric field. The pyroelectric figure of meritFdfor the material was estimated to be 0.032 (cm3/J)1/2. Employing a radiometric infrared source, the room-temperature voltage responsivityRVand specific detectivityD*of the unbiased detector were measured to be over103V/W and108cm Hz1/2/W, respectively. This letter discusses the characteristics of this complementary metal-oxide semiconductor-compatible pyroelectric detector and suggests methods for the improvement for its figures of performance. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119211

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We propose a novel all-optical gate switch based on a frequency shift accompanied by the semiconductor band-filling effect. This all-optical switch is very simple in structure, yet is capable of ultra-high-speed and high-efficiency switching. The switching characteristics are numerically investigated with a rate equation model for nonlinear phase shift. Then, the principle of operation is experimentally verified by measuring the spectral and time-domain properties of the switch. Its switching time is nearly the same as the duration (600 fs in the present experiment) of a control pulse. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119212

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A novel concept of mode locking with a hybrid laser was demonstrated in an actively mode-locked hybrid neodymium (Nd) laser, which contains both Nd:YLF and Nd:glass in a single cavity. A small gain from Nd:YLF can control the spectrum of Nd:glass and ensure good phase coherence among the lasing axial modes, generating stable, coherent pulses of 11 ps. The broadband Nd:glass can facilitate spectral broadening and produce shorter pulses than by Nd:YLF alone under the same mode-locking force. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119213

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Temperature dependences of light-scattering intensity in silica glasses were measured over a wide temperature range from 300 to 1 900 K. It was found that in OH-free silica glass, the diffusive density fluctuations are completely “frozen-in” at the glass transition temperature, while in OH-containing glass, OH gives rise to the structural relaxation of these “frozen-in” density fluctuations over 400 K below the glass transition temperature. This structural relaxation, expected to be caused by the introduction of some dopants with the same role of OH, can be used for reduction of the light-scattering loss in silica fibers. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119214

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We describe an optical scanning probe technique (Interference Scanning Optical Probe Microscopy) with enhanced resolution possibilities not limited by the aperture size of the optical probe. This is realized using a substrate in the form of a microcavity and probe collection mode in reflection geometry. The microcavity consisting of an opaque and a transparent layer, is used to shift the phase of the wave scattered from the adsorbate with respect to the incident and reflected beams. Using this technique silver island films have been detected with resolution better than 40 nm with a nominal probe aperture size of 100 nm. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119215

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Laser ablation and associated bubble formation are known to damage biologic tissue. Imaging of tissue straining during ablation would further the understanding and control of laser-induced damage. We have investigated the use of polariscopic imaging to monitor the strain induced by holmium laser radiation. The laser energy was delivered via an optical fiber either within or 1.7 mm from the surface of a photoelastic tissue phantom, poly(acrylamide) gel, whose viscoelastic properties could be controlled to mimic various tissues. Our results demonstrate that dynamic polaroscopy is a sensitive method to probe the strain experienced by the tissue during pulsed laser irradiations. Only compressive strain is observed when the bubble is formed within the phantom, whereas significant tensile strain is induced when the bubble is formed at or next to the surface. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119216

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The ordering temperaturesTc1(disordered &bgr; toB2order) andTc2(B2toL21order) have been obtained in Cu–Al–Ni shape memory alloys with different concentrations by electrical resistivity. The dependence of the ordering temperatures on the concentration has been established. Also, a modification of the theoretical calculations has been proposed to predict the ordering temperatures in Cu–Al–Ni ternary alloys. A good agreement between the theoretical ordering temperatures and the experimental results has been found. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119217

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We proposed a method to enhance the characteristics of undoped ZnO films byH2post-treatment using photochemical vapor deposition. The resistivity of aH2-treated film decreased from1×10−2to2×10−3 &OHgr; cm,the haze ratio increased from 37&percent; to 48&percent;, and no degradation of total transmittance was observed. There are two possible explanations for these phenomena. First, hydrogen atoms assist the desorption of oxygen atoms from the film, resulting in decreased resistivity. Second, hydrogen atoms etch small grains growing among large ones on the surface of the film, resulting in a rough surface. ©1997 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.119218

出版商:AIP    

年代:1997

数据来源: AIP