摘要:

A combined atomic force and scanning near‐field optical microscope is presented. The critical component of the instrument is a single crystal silicon, microfabricated force‐sensing cantilever with an integrated photodiode. Near‐field optical images are obtained by monitoring variations in the optical power detected by the photodiode while the cantilever tip is scanned in an evanescent optical field created by illuminating the sample by total internal reflection. Near‐field optical power was detected at tip‐sample spacings of one‐quarter wavelength. Atomic force and scanning near‐field optical microscope images of the same samples show corresponding features as small as 25 nm. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116504

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A method to determine the losses and the gain of aQ‐switched four‐level laser is presented. For an end‐pumped system with an additional measurement of relaxation oscillation frequencies the pumping‐beam and laser mode overlap can be determined. Since no resonator changes are necessary, the measurement is very easy to perform. With losses, gain, and overlap determined, everything is known to optimize the system. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116505

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Particles of cuprous oxide with 20 nm sizes have been precipitated from borosilicate glasses. The absorption spectra show distinct changes in glasses given different heat treatments. Only very weak nonlinear effects are observed. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116506

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Pulsed probe degenerate four wave mixing experiments were performed on GaN epilayers using 13 ps pulses at 532 nm. Intensity and time response of the scattering efficiency was studied. Intensity dependence of the observed signal suggests carrier generation by both single and two photon effects. The absolute scattering efficiency was measured and related to pump‐induced nonlinear index change. The nonlinear refractive coefficient found was 1×10−3cm2/GW which is greater than an order of magnitude larger than the expected value. Time response of the signal was found to be dictated by carrier lifetimes. Double‐exponential decays to trap levels with lifetimes of 100 ps and 1.1 ns are suggested as the dominant recombination processes. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116476

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report measurements of the transient multimode dynamics of vertical cavity surface emitting lasers excited by short (100–200 ps rise times, 1 ns duration) electrical pulses. Fast changes on the spatial distribution of the output power and strong mode competition are observed. Numerical simulations show that the observed dynamics are due to the partial overlap of the different transverse modes through spatial hole burning. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116477

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report on the lasing action of modified rhodamine 6G dyes copolymerized with methacrylic monomers. The laser samples were transversely pumped with a N2laser at 337 nm. Lasing efficiencies similar to those found for rhodamine 6G in ethanol solution have been achieved. Important increases in photostability, with lifetimes in excess of 20 000 shots at 2 Hz, have been obtained. By using a rotating mechanism, a stable output with no sign of degradation after half a million shots has been demonstrated. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116478

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The thermodynamics of the rapid boiling of a liquid on a solid surface heated by an excimer laser pulse is studied experimentally. The dynamics of bubble nucleation, growth, and collapse is detected by probing the optical specular reflectance. The transient temperature field is measured by monitoring the reflectance of a thin film with calibrated optical properties. The metastability behavior of the liquid and the criterion for the liquid‐vapor phase transition in nanosecond time scale are obtained for the pressure from 1 atmosphere to 3.3 MPa. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116479

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

First order gain and index coupled distributed feedback (DFB) gratings were realized in ZnSe‐based laser structures using direct implantation with a focused ion beam for gain‐modulated structures and conventional electron beam lithography for index modulation. With both technologies, gratings with periods below 90 nm could be achieved, permitting DFB emission in the blue spectral range. Fine tuning of the emission wavelength in steps of 0.14 nm is demonstrated by sampled DFB gratings based on a periodic modulation of the resonator period. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116480

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report on efficient frequency upconversion in Er3+‐doped fluoroindate glasses. The process is observed under 1.48 &mgr;m laser diode excitation and results in the generation of strong blue (∼407 nm), green (∼550 nm), and red (∼670 nm) radiation. The main mechanism that allows for upconversion appears to be the energy transfer among Er3+ions in excited states. The results illustrate the large potential of this new class of glasses for photonic applications. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116481

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report details of mirror grading profiles for high efficiency vertical cavity surface emitting lasers. The mirrors provide low vertical resistance in conjunction with improvements in optical reflectivity, thermal conductivity, and lateral electrical conductivity in comparison to earlier grading profiles. The enhancement of these properties is verified by a comparison of thermal resistance and total electrical resistance for lasers of varying size. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116482

出版商:AIP    

年代:1996

数据来源: AIP