The role of Auger recombination in the temperature-dependent output characteristics (T0=∞)(T0=∞) of pp-doped 1.3 μm quantum dot lasers

Temperature invariant output slope efficiency and threshold current (T0=∞)(T0=∞) in the temperature range of 5–75 °C have been measured for 1.3 μm pp-doped self-organized quantum dot lasers. Similar undoped quantum dot lasers exhibit T0=69 KT0=69 K in the same temperature range. A self-consistent model has been employed to calculate the various radiative and nonradiative current components in pp-doped and undoped lasers and to analyze the measured data. It is observed that Auger recombination in the dots plays an important role in determining the threshold current of the pp-doped lasers.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71264/2/APPLAB-85-22-5164-1.pd

40 GHz small-signal cross-gain modulation in 1.3m quantum dot semiconductor optical amplifiers

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Appl. Phys. Lett. 93, 051110 (2008) and may be found at https://doi.org/10.1063/1.2969060.Small-signal cross-gain modulation of quantum dot based semiconductor optical amplifiers (QD SOAs), having a dot-in-a-well structure, is presented, demonstrating superiority for ultrahigh bit rate wavelength conversion. Optimization of the QD SOA high speed characteristics via bias current and optical pump power is presented and a small-signal 3 dB bandwidth exceeding 40 GHz is demonstrated. The -doped samples investigated here enable small-signal wavelength conversion within a range of 30 nm, limited mainly by the gain bandwidth.DFG, 43659573, SFB 787: Halbleiter - Nanophotonik: Materialien, Modelle, BauelementeEC/FP6/027638/EU/Transparent Ring Interconnection Using Multiwavelngth PHotonic switches/TRIUMPHEC/FP6/500101/EU/Self-Assembled semiconductor Nanostructures for new Devices in photonics and Electronics/SANDI

Submonolayer Quantum Dots for High Speed Surface Emitting Lasers

We report on progress in growth and applications of submonolayer (SML) quantum dots (QDs) in high-speed vertical-cavity surface-emitting lasers (VCSELs). SML deposition enables controlled formation of high density QD arrays with good size and shape uniformity. Further increase in excitonic absorption and gain is possible with vertical stacking of SML QDs using ultrathin spacer layers. Vertically correlated, tilted or anticorrelated arrangements of the SML islands are realized and allow QD strain and wavefunction engineering. Respectively, both TE and TM polarizations of the luminescence can be achieved in the edge-emission using the same constituting materials. SML QDs provide ultrahigh modal gain, reduced temperature depletion and gain saturation effects when used in active media in laser diodes. Temperature robustness up to 100 °C for 0.98 μm range vertical-cavity surface-emitting lasers (VCSELs) is realized in the continuous wave regime. An open eye 20 Gb/s operation with bit error rates better than 10−12has been achieved in a temperature range 25–85 °Cwithout current adjustment. Relaxation oscillations up to ∼30 GHz have been realized indicating feasibility of 40 Gb/s signal transmission

Nonlinear optics and saturation behavior of quantum dot samples under continuous wave driving

The nonlinear optical response of self-assembled quantum dots is relevant to the application of quantum dot based devices in nonlinear optics, all-optical switching, slow light and self-organization. Theoretical investigations are based on numerical simulations of a spatially and spectrally resolved rate equation model, which takes into account the strong coupling of the quantum dots to the carrier reservoir created by the wetting layer states. The complex dielectric susceptibility of the ground state is obtained. The saturation is shown to follow a behavior in between the one for a dominantly homogeneously and inhomogeneously broadened medium. Approaches to extract the nonlinear refractive index change by fringe shifts in a cavity or self-lensing are discussed. Experimental work on saturation characteristic of InGa/GaAs quantum dots close to the telecommunication O-band (1.24-1.28 mm) and of InAlAs/GaAlAs quantum dots at 780 nm is described and the first demonstration of the cw saturation of absorption in room temperature quantum dot samples is discussed in detail