摘要:

The experimental observation of blue‐chirped pulses for passive mode‐locking and red‐chirped pulses for active mode‐locking is theoretically explained as a consequence of different &agr; parameters in the gain and absorber section. The influence of nonlinear gain due to carrier heating is also discussed. The knowledge of the chirp is crucial for the optimization of passively mode‐locked lasers for spectrally narrow emission or for the emission of linearly chirped pulses. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115062

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Gratings of different period spacings are fabricated on quantum well infrared photodetectors having two‐stack multiple quantum wells (MQW) to determine the grating coupling efficiency in multicolor detection. The peak wavelength of each MQW is 4.8 and 9.4 &mgr;m, respectively, covering the two atmospheric windows. 2D gratings of box‐shaped cavities with grating period either in 3 or 4.6 &mgr;m spacing are used to coupled normal incident light into the detector. Comparing detectors with and without gratings at either normal or 45° facet incidence, the detectors with an optimized grating show efficient light coupling for both wavelengths due to the fact that the longer wavelength in the present case is an integral multiple of the shorter wavelength. The optimized long wavelength grating couples the shorter wavelength through additional higher orders of diffraction. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115063

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Highly orienteda‐axis BaTiO3thin films were grown by pulsed laser deposition on (001) MgO substrates. The full width at half‐maximum of the (200) BaTiO3rocking curve was as narrow as 0.6°. A large hysteretic quadratic electro‐optic effect was observed in a transverse geometry at 6328 A˚. A birefringence shift up to 3×10−3was measured at an applied dc electric field of 1 kV/mm. It was found that laser repetition rate plays an important role on the surface morphology of the deposited films. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115064

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

An optical heterodyne technique has been used to demonstrate electro‐optic modulation up to 60 GHz, the highest reported to date, in polymer waveguide modulators. The frequency response of the device from 40 to 60 GHz was obtained by measuring the frequency down converted modulation signal with a low frequency photodetector. No rolling‐off was identifiable from the measured device response, indicating no fundamental material limitations in this frequency range for the polymer material which we used. Such an optical heterdyne system can be a powerful tool for modulator characterization at millimeter wave frequencies because of its high sensitivity and low frequency demands on photoreceivers. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115065

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The emission transients of optically excited high‐speed multiple quantum well laser diodes have been measured by up‐converting the emission in a nonlinear crystal. From the gain‐switched oscillation the intrinsic resonance frequency and damping factor are determined. The high temporal resolution allows us to observe additional short period oscillations with a frequency of about 170 GHz. Numerical solution of the traveling wave rate equations indicates that these high frequency oscillations arise due to inhomogeneous carrier injection. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115066

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A double layer of single domains with opposing polarizations has been formed on bothcfaces by rapid thermal annealing of proton‐exchangedz‐cut LiTaO3at above the Curie temperature. The formed top single‐domain layers have inward‐directed polarization and the single‐domain layers underneath have outward‐directed polarization. The domain structure development for an annealing range from 2 s to 10 min has been investigated. The results are discussed in relation to recently proposed models for the domain‐inversion mechanisms in LiTaO3and LiNbO3. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115067

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A laser diode pumped Tm3+‐doped ZBLAN fiber upconversion laser is demonstrated with blue output power levels up to 106 mW. Differential optical‐to‐optical conversion efficiencies up to 30% are measured with respect to pump power coupled into the upconversion fiber. A single spatial mode blue output beam is demonstrated, with anM2value of 1.4. ©1995 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.115412

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A new nonlinear optical crystal CsLiB6O10(CLBO), is described that can be grown from either stoichiometric melt or from solution. A large, high quality single crystal with dimensions of 14×11×11 cm3was obtained by the top‐seeded Kyropoulos method. Fourth harmonic and fifth harmonic generations of the 1.064 &mgr;m Nd:YAG laser radiation with type‐I phase matching were realized in the CLBO crystal. Output pulse energies obtained were 110 mJ at 266 nm and 35 mJ at 213 nm. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115413

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A passive TE to TM polarization mode converter is fabricated by using poled polymer waveguides. The optic axis of the poling induced waveguide is slowly rotated 90° by using a slowly varying structure of poling electrodes. Thus the polarization conversion is achieved as the guided mode propagates through the waveguide. TE to TM mode conversion is observed with a polarization extinction ratio higher than 30 dB, and the excess loss is less than 1 dB. The polarization conversion is relatively insensitive to wavelength since the device contains no periodic structures. These devices are easier to fabricate than others containing periodic structures. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115414

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A detailed physical model of pyrometric interferometry during molecular beam epitaxy growth of III–V layers is presented. The pyrometric radiation intensity is expressed as spatial convolution of the spontaneous emission rates and the propagation response of the sample. The new formalism, together with empirical modeling of background signal provide a generic framework for implementing a model‐reference closed‐loop control system for epitaxial growth of multilayer structures. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115415

出版商:AIP    

年代:1995

数据来源: AIP