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Soibel A. Capasso F. Gmachl C. Peabody M.L. Sergent A.M. Paiella R. Sivco D.L. Cho A.Y. Liu H.C. 《Quantum Electronics, IEEE Journal of》2004,40(3):197-204
We report the observation of stable pulse emission and enhancement of intracavity second-harmonic generation (SHG) in self-mode-locked quantum cascade (QC) lasers. Down-conversion of the detector signal by heterodyning with an RF signal allows the direct observation of the pulsed laser emission in the time domain and reveals a stable train of pulses characteristic of mode-locked lasers. The onset of self-mode locking in QC lasers with built-in optical nonlinearity results in a significant increase of the SHG signal. A pulse duration of /spl sim/12 ps is estimated from the measured increase of the SHG signal in pulsed emission compared to the power expected for the SHG signal in CW emission. This value is in good agreement with the pulse duration deduced from the optical spectral width. 相似文献
63.
Numerous organic and inorganic laboratory standards were gathered from nine European and North American laboratories and were analyzed for their delta(18)O values with a new on-line high temperature pyrolysis system that was calibrated using Vienna standard mean ocean water (VSMOW) and standard light Antartic precipitation (SLAP) internationally distributed reference water samples. Especially for organic materials, discrepancies between reported and measured values were high, ranging up to 2 per thousand. The reasons for these discrepancies are discussed and the need for an exact and reliable calibration of existing reference materials, as well as for the establishment of additional organic and inorganic reference materials is stressed. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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A multiwavelength laser array has been obtained through growth on patterened InP substrates using chemical beam epitaxy. This technique makes use of interfacet migration of reactant species to obtain compositional and/or thickness variation with position on a set of patterned ridges. Results obtained on 相似文献
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Morton P.A. Tanbun-Ek T. Logan R.A. Chand N. Wecht K.W. Sergent A.M. Sciortino P.F. Jr. 《Electronics letters》1994,30(24):2044-2046
25 GHz modulation bandwidth is achieved from a fully packaged 1.55 μm DFB laser, using devices with p-doped compressively strained MQW active regions and large negative wavelength detuning. Devices on submounts show a record bandwidth of 26 GHz, limited by device and bonding parasitics. Resonance frequencies of over 26 GHz are measured 相似文献
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A review is presented of the calculation of photoionization spectra, particularly in the spectral range where electron autoionization of diatomic molecules takes place. In addition to some interesting results obtained over years that compare favourably with experiment, the emphasis here is put on the relation between the methods developed for the calculation of observables associated with the continuum energy spectrum of the electrons and the Alchemy system of programs. This system of programs serves as a basis for initial and intermediate calculations. The examples presented show that diatomic molecules not only in gas phase but also oriented in space or physisorbed at surfaces may be studied readily. 相似文献
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