1,720,991 research outputs found
II-VI infrared microcavity emitters with 2 postgrowth dielectric mirrors
No full textWe report on optically pumped resonant cavity emitters and vertical cavity surface-emitting lasers based on epitaxial CdHgTe material. The Fabry–Pérot resonator is constituted by two postgrowth dielectric mirrors. Room temperature emission is observed at 1.57, 2.63 and 3.18 μm. A laser threshold of 6 kW/cm2 at 300 K is obtained for the 1.57 μm emitter
Novel piezoelectric-barrier heterostructures for all-optical light modulation
No full textWe present preliminary new results on multiperiod piezoelectric-barrier all-optical modulators. It is shown first on single period structures that an incident beam of a few W/cm2 is able to create a space-charge field of approximately 20 kV/cm in the structure, inducing a 10 meV shift in the photoluminescence (PL) spectrum. We discuss then a multiperiod structure showing similar optically-driven PL shifts. Even though the multiperiod structure was not optimized for transmission modulation experiments, we observed a 12% transmission variation at 760 nm induced by a 10 W/cm2 optical beam
Laser emission in CdHgTe in the 2-3.5 μm range
No full textStimulated emission from HgCdTe separate confinement heterostructure waveguides embedding quantum wells as gain medium is studied. We explore the effect of composition grading in the barriers as well as that of using strained quantum wells on the temperature evolution of the laser threshold. The main effect of barrier grading is to suppress carrier trapping at low temperatures, leading to an improved excitation transfer from the barriers to the quantum wells, and to an intrinsic exponential dependence of the threshold on the temperature. For the strained quantum well structures, a two-fold reduction of the threshold is obtained, as compared with similar band gap unstrained structures. The threshold dependence on photon energy points out the importance of Auger type nonradiative recombinations. We determine the Auger constant in our structures, and compare them with published data. An exponential dependence of the Auger constants on the band gap, valid for type I heterostructures, is shown. A comparison of the published operating temperatures in competing devices is done. It appears that III–V type II and unipolar lasers are largely ahead of II–VI lasers. The future of HgCdTe could lie in vertical cavity, surface emitting lasers
Room temperature electro-optic effect in CdHgTe multiple quantum well heterostructures at 1.5μm
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