摘要:

Very large third-order optical nonlinearity,&khgr;(3)∼2.5×10−6esu, measured by a degenerate four wave mixing method using a short pulse (70 picosecond) laser, has been found in the rapid-thermal annealed Au:SiO2composite films at concentrations below the Au percolation threshold. The dependence of the&khgr;(3)on Au concentration,p, follows a cubic power law. The maximum figure of merit,&khgr;(3)/&agr;(with &agr; being the absorption coefficient) is about10−11esu cm. We explain this result as due to local field enhancement arising from the Mie resonance of the Au nanoclusters, with strong interaction between the nanoclusters further promoting the effect. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119291

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Using a laser diode modulated at 250 and 500 MHz, dependence of enhanced absorption on both sample length and temperature was investigated in an erbium doped yttrium aluminum garnet crystal. The transmitted laser intensity decreased with a decay time of 300 ps for sample lengths greater than 3.0 mm and temperatures higher than 50 K when the incident laser intensity increased. In addition, an emission peak was observed near 835 nm corresponding to the transition from the4S3/2level to the4I13/2inEr3+.It was suggested that the enhanced absorption was caused by stimulated emission in three excited states. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119302

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

This letter describes a method for producing in-fiber gratings that reduces the effects of mechanical and optical instabilities limiting other methods. In this technique, opaque lines formed on the outside of the fiber using a procedure known as microcontact printing, serve as an amplitude photomask for exposure to ultraviolet light. Long-period fiber optic attenuators formed by ths technique demonstrate its advantages. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119313

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Integrated intracavity quasi-phase-matched second harmonic generation (QPM-SHG) has been demonstrated in a periodically domain invertedNd:LiTaO3crystal which functions simultaneously as a gain and nonlinear medium. Lasing at 1.082 &mgr;m and simultaneous QPM-SHG at 541 nm has been established by pumping near 806 nm. The effect of doping on the domain reversal voltage ofLiTaO3and the photorefractive effect have also been investigated. It is found that optical damage can be avoided by heating above 80 °C. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119321

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We report on measurements of the spontaneous emission factor for oxide-confined InGaAs vertical cavity surface emitting lasers. The spontaneous emission factor is determined as a function of the active layer volume from the measurement of small-signal harmonic distortion at threshold. For a 3×3 &mgr;m oxide aperture device we obtain spontaneous emission factor of4.2⋅10−2at room temperature. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119288

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We have demonstrated soft x-ray short pulse generation from femtosecond laser-produced plasma with much lower debris using metal-doped glass as a target. Soft x-ray emission (50–200 Å) from a gold-doped glass target was about 40&percent; of that from a solid gold target while the density of gold in the doped-glass was less than 0.001 vol &percent; and the target was transparent at the wavelength of the laser light. Due to the low metal density, the particulate deposition, which is one of the serious obstacles to putting laser-produced plasma x-ray into practical use, was greatly reduced by the use of metal-doped glass as a target. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119289

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A modified Sagnac interferometer-based fiber temperature sensor is proposed. Polarization independent operation and high temperature sensitivity of this class of sensors make them cost effective instruments for temperature measurements. A comparison of the proposed sensor with Bragg grating and long-period grating fiber sensors is derived. A temperature-induced spectral displacement of 0.99 nm/K is demonstrated for an internal stress birefringent fiber-based Sagnac interferometer. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119290

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A simple technique is described for optically imaging the lateral distribution of normal forces exerted onto a flat surface. It is based on the detuning of a silicone rubber planar waveguide by the forces to be investigated. The method is demonstrated by imaging the contact line force of a sessile water droplet on the surface, with a force resolution better than &mgr;N. It is shown that the lateral resolution may be much better than the decay length of the waveguide modes used. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119292

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A Rhodamine 6 G solid solution in a copolymer of 2 hydroxyethyl methacrylate and methyl methacrylate have been flash-lamp pumped in an untuned laser cavity. The pumping energy threshold to obtain laser emission is 20 percent higher than in equivalent methanol solutions. With a flash-lamp electrical excitation average energy of 150 joules per pulse, no photodegradation was observed in the laser emission after more than 30 pumping pulses. There was an absence of local irregular fluctuations found typically in high Fresnel number dye lasers. An interpretation based on the assumption of stereospecificity in the lodging cavity of dye molecules, is consistent with the high photostability and the absence of local fluctuations obtained with this polymeric solid-state laser. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119293

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A new approach to the calculation of current noise in single quantum well infrared photodetectors is proposed. The modulation noise due to the fluctuation of the emitter barrier potential is taken into account by considering the correlation between the elementary pulses constituting the excess current injected from the emitter when the quantum well is depleted by electrons. A simple relationship between the noise gain and the photoconductive gain of the device is obtained. A comparison with experiments is also reported. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119294

出版商:AIP    

年代:1997

数据来源: AIP