排序方式: 共有56条查询结果,搜索用时 340 毫秒
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Martini R. Bethea C. Capasso F. Gmachl C. Paiella R. Whittaker E.A. Hwang H.Y. Sivco D.L. Baillargeon J.N. Cho A.Y. 《Electronics letters》2002,38(4):181-183
Experimental results for an optical free-space high-speed link using direct modulated mid-infrared (λ = 8.1 μm) quantum cascade lasers are presented. A total of 800 digitally encoded multimedia channels were transmitted. The reliability of the system against weather influence (fog) was experimentally compared to that of a near-infrared (λ = 0.85 μm) link 相似文献
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Zhijun Liu Gmachl C.F. Liwei Cheng Fow-Sen Choa Towner F.J. Xiaojun Wang Jenyu Fan 《Quantum Electronics, IEEE Journal of》2008,44(5):485-492
Temperature-dependent optical gain and waveguide loss have been measured for continuous-wave operated quantum-cascade lasers with wavelengths between 8.2 and 10.2 mum up to room temperature using the Hakki-Paoli method. The gain coefficient decreases with increasing temperature, and is close to the designed value for vertical transition lasers, but smaller than the designed value for diagonal transition lasers. The waveguide loss, however, is two to three times higher than calculated from free carrier absorption, and can be nearly constant, increase or decrease with temperature depending on sample design, which indicates that it is dominated by another mechanism other than plain free carrier absorption. One likely factor resulting in high waveguide loss is intersubband resonant absorption into higher lying states. 相似文献
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Sensitive absorption spectroscopy with a room-temperature distributed-feedback quantum-cascade laser 总被引:6,自引:0,他引:6
Namjou K Cai S Whittaker EA Faist J Gmachl C Capasso F Sivco DL Cho AY 《Optics letters》1998,23(3):219-221
We report what we believe are the first spectroscopic measurements to be made with a room-temperature quantum-cascade distributed-feedback laser. Using wavelength modulation spectroscopy, we detected N(2)O and CH(4) in the chemical fingerprint wavelength range near 8microm . The noise equivalent absorbance for our measurement was 5 parts in 10(5), limited by excess amplitude modulation on the laser output, which corresponds to a 1-Hz bandwidth detection limit of 250 parts N(2)O in 10(9) parts N(2) in a 1-m path length. 相似文献
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Martini R. Paiella R. Gmachl C. Capasso F. Whittaker E.A. Liu H.C. Hwang H.Y. Sivco D.L. Baillargeon J.N. Cho A.Y. 《Electronics letters》2001,37(21):1290-1292
High-speed mid-infrared quantum cascade lasers with direct modulation bandwidth of approximately 7 GHz have been developed. Error-free digital data transmission at 2.5 Gbit/s is demonstrated with devices emitting at 8 μm and operating at temperatures up to 85 K 相似文献
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Photoacoustic spectroscopy using quantum-cascade lasers 总被引:1,自引:0,他引:1
Paldus BA Spence TG Zare RN Oomens J Harren FJ Parker DH Gmachl C Cappasso F Sivco DL Baillargeon JN Hutchinson AL Cho AY 《Optics letters》1999,24(3):178-180
Photoacoustic spectra of ammonia and water vapor were recorded by use of a continuous-wave quantum-cascade distributed-feedback (QC-DFB) laser at 8.5 mum with a 16-mW power output. The gases were flowed through a cell that was resonant at 1.6 kHz, and the QC-DFB source was temperature tuned over 35 nm for generation of spectra or was temperature stabilized on an absorption feature peak to permit real-time concentration measurements. A detection limit of 100 parts in 10(9) by volume ammonia at standard temperature and pressure was obtained for a 1-Hz bandwidth in a measurement time of 10 min. 相似文献
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We discuss new approaches to monolithic integration of quantum cascade lasers with resonant intersubband nonlinearities. We show that the proposed approaches can greatly enhance the performance of quantum cascade lasers and give rise to new functionalities. Examples considered include extreme frequency up-or down-conversion and wide-range electric tuning. 相似文献
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Gagliardi G Borri S Tamassia F Capasso F Gmachl C Sivco DL Baillargeon JN Hutchinson AL Cho AY 《Isotopes in environmental and health studies》2005,41(4):313-321
We report the development of a novel laser spectrometer for high-sensitivity detection of methane and nitrous oxide. The system relies on a quantum-cascade laser source emitting wavelength of around 8.06 microm, where strong fundamental absorption bands occur for the considered species and their isotopomers. The detection technique is based on audio-frequency and radio-frequency modulation of laser radiation. First experimental tests have been performed to estimate the achievable detection limits and the signal reproducibility levels in view of possible measurements of (13)C/(12)C, (18)O/(16)O, (17)O/(16)O and (15)N/(14)N isotope ratios. 相似文献
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Kohler R. Gmachl C. Capasso F. Tredicucci A. Sivco D.L. Cho A.Y. 《Photonics Technology Letters, IEEE》2000,12(5):474-476
Widely tunable, single-mode quantum cascade distributed feedback (QC-DFB) lasers based on a complex coupling scheme and operating in the wavelength range of the CO2 laser (λ≈9.5-10.5 μm) are reported. Dynamic single-mode emission up to high current levels is obtained. The continuous single-mode tuning range is 150 nm, while the tuning range of the equivalent Fabry-Perot laser is ~400 nm. By homogeneously reducing all layer thicknesses by 10%, the wavelength coverage of a single QC-laser design can be extended to cover one entire regular band of the fundamental CO2 laser spectrum 相似文献
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High-quality superlattice structures of GaN/AlGaN were grown on (0 0 0 1) sapphire substrates by molecular beam epitaxy. The threading dislocation density was reduced by growing low-temperature AlN layers in between the high-temperature GaN. In addition, in situ monitoring of the growth rate was achieved using pyrometric interferometry. Cross-sectional transmission electron microscopy of the superlattice structures revealed abrupt interfaces between GaN/AlGaN and excellent layer uniformity. We observed intersubband absorption at wavelengths as short as 1.52 μm in the GaN/AlGaN material system. A range of intersubband absorption peaks was observed between 1.52 and 4.2 μm by varying the well thickness and barrier Al content. In addition, the distribution of the built-in electric field between the well and barrier layers was also found to affect the intersubband transition wavelength. 相似文献