摘要:

Poled guest‐host polyquinoline thin films are shown to demonstrate both exceptionally large electro‐optic activity and long‐term stability. After an initial drop from 45 to 26 pm/V in the first 100 h, the electro‐optic coefficientr33at 26 pm/V remained for more than 2000 h. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115424

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

An asymmetricY‐junction wavelength demultiplexer, with a segmented branch, was realized in Ti:LiNbO3. The device was fabricated in a single‐step lithographical process. Wavelength demultiplexing operation in the range 633 nm<&lgr;<834 nm is demonstrated, with extinction ratios up to 30 dB. Insertion loss vary between a negligible value (far away from cutoff) up to 7 dB (near cutoff). Possible applications of the device are considered. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115425

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Crystalline beta barium borate (&bgr;‐BaB2O4) thin films have been prepared on silicon (001) and sapphire (001) substrates by the pulsed laser deposition technique. The crystallinity of these films was found to depend sensitively on the deposition temperature. At a deposition temperature around 800 °C and in the presence of 75 mTorr of O2gas, films grown on Si(100) substrates are typically polycrystalline with x‐ray diffraction peaks along (104) and (001) orientations while the film grown on a sapphire (001) substrate is highly textured with (001) orientation (caxis) normal to the film surface. The film grown on sapphire (001) substrate exhibits a maximum effective second harmonic generation coefficientdeffof 2.2 pm/V, which is comparable to that of bulk &bgr;‐BaB2O4single crystals. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115426

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A new form of frequency‐selective all‐optical heterodyning at the difference frequency of two modulated laser beams, related to stochastic resonance, is reported. A noise‐induced enhancement of the heterodyne signal and of the signal‐to‐noise ratio has been predicted and observed in an all‐optical bistable system for the beams at different wavelengths. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115427

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The grating spacing dependence of photorefractive diffraction efficiency in an organic polymer composite is presented and discussed. The analysis of the grating spacing dependence of the refractive index modulation with the standard model of photorefractive grating dynamics is shown to lead to inconsistencies in determination of the maximum attainable index change. It is shown that the effects resulting from orienting of the composite’s optically second‐order nonlinear chromophores in the periodic local field affect the formation of the refractive index grating. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115428

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A simple method to determine nonradiative recombination coefficients of vertical‐cavity surface‐emitting lasers is proposed and demonstrated. The dependence of the lateral spontaneous emission on the current density is used to determine the nonradiative recombination coefficients and the threshold carrier densities. In this scheme, the lateral spontaneous emission obtained from the nearest neighbor devices is analyzed. For 10‐&mgr;m diameter proton‐implanted vertical‐cavity surface‐emitting lasers, the obtained nonradiative recombination coefficient is about 1.8×108s−1, responsible for 25% of threshold current density. ©1995 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.115429

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Titanium doped sapphire (Ti:Al2O3) shows a 420 nm blue emission band whose corresponding excitation band lies at 244 nm. With the aim of ascertaining the origin of this blue emission, using synchrotron radiation we measured the vacuum ultraviolet to ultraviolet absorption spectrum of titanium doped sapphire. It is suggested that the blue emission is due to a center other than a trivalent Ti3+ion or a tetravalent Ti4+ion, most probably an F+‐type color center formed in the crystal. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115430

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We fabricated a periodic domain structure in a 0.5 mm thick slab of LiTaO3crystal by applying an external pulsed field at room temperature. Using a pulse dye laser with a pulsewidth of 8 ns and a repetition rate of 10 Hz, third‐order quasi‐phase‐matched second‐harmonic blue‐light generation is demonstrated by free propagation of a 862.6 nm fundamental Gaussian beam in a 4 mm long LiTaO3slab, with a single pulse energy of 0.072 mJ and an energy conversion efficiency of 5.7%. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115431

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The third‐order optical nonlinearity &khgr;(3)of porous silicon has been measured using theZ‐scan technique. Intensity dependent absorption was observed and attributed to a resonant two photon absorption process. The real and imaginary parts of &khgr;(3)have been measured at 665 nm and found to be 7.5×10−9esu and −1.9×10−9esu, respectively. This constitutes a significant enhancement over crystalline silicon. All optical switching based on nonlinear absorption is demonstrated. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115432

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Very intensive red light emission from C60trapped in 13X molecular sieve has been observed, and it is attributed to the active forbidden transition of C60anion due to the interaction of C60with the sketch structure of 13X molecular sieve. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115433

出版商:AIP    

年代:1995

数据来源: AIP