摘要:

In this study we report a novel strained InGaAsP/InGaAsP/InAsP multiquantum well structure for electroabsorption modulators giving high power saturation together with polarization insensitivity. A careful design of the structure in terms of band‐gap engineering has been performed to fulfil both requirements. The polarization sensitivity is less than 0.5 dB for the on‐state and for a wide range of wavelengths. The carrier escape time, even at very low field, is estimated at lower than 20 ps. The transmitted power for different wavelengths is linear up to 16 dBm. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117836

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report phase‐matched second‐harmonic generation in KNbO3channel waveguides. The guides were fabricated by one single homogeneous He+ion irradiation and specially structured photoresist on the KNbO3crystals serving as an implantation mask. The mask enabled the formation of channel guides with a trapezoidal‐shaped cross section providing simultaneous confinement of both TE and TM modes. 2.6 mW second‐harmonic blue‐light at 441 nm was generated in a 5.8‐mm‐long guide for an incident fundamental power of 280 mW. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117837

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A picosecond‐range all‐optical modulation based on the nonlinear interaction between interband‐ and intersubband‐resonant light in GaAs/AlGaAs multiple quantum wells was demonstrated. A free electron laser (FEL) with a very short pulse width (<10 ps) was used for the intersubband excitation. The dependence of the modulation depth on the wavelength of the intersubband‐resonant light was investigated by utilizing the wide tunability of the FEL. The result is in good agreement with the intersubband absorption spectrum of the multiple quantum wells measured by FT‐IR spectroscopy, which indicates that the observed modulation is indeed based on the intersubband transition induced by the FEL. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117838

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Phase‐matched second harmonic generation over 7 mm is demonstrated using the modal dispersion of a composite 4‐dimethylamino‐4′‐nitrostilbene/polyetherimde channel waveguide. For a 1‐mm‐long sample a record figure of merit for polymers of &eegr;=P2&ohgr;/(P&ohgr;L2)=14%/W cm2was measured at 1550 nm. This is comparable to the value reported for LiNbO3at that wavelength. The efficiency in longer samples is limited by fundamental and harmonic waveguide losses. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117839

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Polarization‐resolved four‐wave mixing spectroscopy is used to study interwell carrier dynamics in an alternating‐strain multiquantum‐well optical amplifier. The experimental data are found to be in good agreement with a simple model based on quantum capture/escape and diffusion processes. The results suggest that the interwell transport in this structure is mainly limited by carrier escape, and give an estimate of 16 ps for the overall transport lifetime. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117840

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Femtosecond hyper‐Rayleigh scattering has recently been used to determine the spatial correlation length between nonlinear optical chromophores in polymer films [G. Olbrechtsetal., Chem. Phys. Lett.253, 135 (1996)]. This correlation length corresponds to the effective interaction length for frequency doubling in waveguide format, as derived from phase‐matching curves. The temporal characteristics of this correlation length have now been studied and compared with thermal relaxation times, obtained with coherent second‐harmonic generation. The correlation length decays much faster than the second‐harmonic intensity, indicating that the efficiency of a second‐order waveguide process could decay much faster than generally anticipated. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117841

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Visible photoluminescence (PL), optical transmission, and Raman scattering spectra of Si nanocrystals embedded in SiO2matrix have been studied. Films were deposited by rf magnetron sputtering of compound SiO2/Si targets. Films containing silicon in the form of nanocrystals clusters show intense luminescence at room temperature. Films containing only amorphous Si clusters show little or no PL. Annealing in vacuum or in specific atmosphere leads to strong change of the PL spectrum and its intensity. Results are explained by strong influence of the Si/SiO2interface state on integral PL emission. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116967

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report the observation of collisions between mutually incoherent, one‐dimensional, bright, steady‐state photorefractive screening solitons. Using the theory of planar dielectric waveguides together with the theory of photorefractive screening solitons, we explain how the collisions depend on the peak intensity of the solitons and the externally applied biased field. Finally, we compare the experimental results with direct numerical simulations. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116968

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Under certain conditions grating/waveguide structures have a resonant behavior with narrow spectral bandwidths. Several such structures were designed, fabricated, and evaluated, demonstrating resonances with narrow spectral bandwidths ranging to as low as 0.035 nm at full width at half maximum. These can be exploited as compact spectral filters having high finesse. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116969

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Optical waveguides can be fabricated in the nonlinear material potassium titanyl arsenate (KTiOAsO4) using ion exchange in a mixed RbNO3/Ba(NO3)2melt. The guiding properties of such waveguides were measured and the variation of these properties with changes in processing conditions was investigated. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116970

出版商:AIP    

年代:1996

数据来源: AIP