M. Reinhardt

Bio: M. Reinhardt is an academic researcher. The author has contributed to research in topics: Laser diode & Molecular beam epitaxy. The author has an hindex of 1, co-authored 1 publications receiving 46 citations.

Room-temperature operation of GaInAsN/GaAs laser diodes in the 1.5 /spl mu/m range

Abstract: GaInAsN-GaAs double quantum-well (DQW) laser structures emitting in the 1.5-/spl mu/m range were grown by solid source molecular beam epitaxy using a radio frequency plasma source for nitrogen activation. Lasing operation in the 1.5-/spl mu/m wavelength region has been realized for fabricated ridge waveguide laser diodes (LDs) under pulsed condition up to record high temperatures of 80/spl deg/C resulting in an emission wavelength of 1540 nm. This is the highest emission wavelength for laser diode operation based on GaAs. In addition, to investigate the optical properties of the active region, photoluminescence studies of underlying GaInAsN-GaAs QW structures emitting at wavelengths up to 1.55 /spl mu/m are presented.

GaInNAs long-wavelength lasers: progress and challenges

Abstract: Research to realize long-wavelength, GaInNAs quantum well lasers has been intense in the past three years. The results have been very promising considering the relative immaturity and challenges of this new materials system. This paper reviews both the materials challenges and progress in growth of the metastable GaInNAs alloys required to reach the 1.3–1.55 μm communication wavelengths and the challenges and progress in device design for both vertical-cavity surface-emitting lasers and higher power edge-emitting lasers.

Tunable long-wavelength vertical-cavity lasers: the engine of next generation optical networks?

Abstract: The incredible growth of the Internet and data transmission are pushing the bandwidth requirements for fiber networks and expansion of metro and local area networks at an unprecedented pace. One of the key requirements for a great expansion of optical networks is low cost, high-performance tunable lasers that are easily packaged and coupled to fiber. The paper reviews the terrain of both materials and device technologies that are currently driving this optical revolution and speculates on the future directions and if a single, all encompassing technology, the "Holy Grail," might be realized by any of the contenders.

GaInNAsSb for 1.3-1.6-/spl mu/m-long wavelength lasers grown by molecular beam epitaxy

Abstract: High-efficiency optical emission past 1.3 /spl mu/m of GaInNAs on GaAs, with an ultimate goal of a high-power 1.55-/spl mu/m vertical-cavity surface-emitting laser (VCSEL), has proven to be elusive. While GaInNAs could theoretically be grown lattice-matched to GaAs with a very small bandgap, wavelengths are actually limited by the N solubility limit and the high In strain limit. By adding Sb to the GaInNAs quaternary, we have observed a remarkable shift toward longer luminescent wavelengths while maintaining high intensity. The increase in strain of these new alloys necessitates the use of tensile strain compensating GaNAs barriers around quantum-well (QW) structures. With the incorporation of Sb and using In concentrations as high as 40%, high-intensity photoluminescence (PL) was observed as long as 1.6 /spl mu/m. PL at 1.5 /spl mu/m was measured with peak intensity over 50% of the best 1.3 /spl mu/m GaInNAs samples grown. Three QW GaIn-NAsSb in-plane lasers were fabricated with room-temperature pulsed operation out to 1.49 /spl mu/m.

Development of GaInNAsSb alloys : Growth, band structure, optical properties and applications

Abstract: In the past few years, GaInNAsSb has been found to be a potentially superior material to both GaInNAs and InGaAsP for communications wavelength laser applications. It has been observed that due to the surfactant role of antimony during epitaxy, higher quality material can be grown over the entire 1.2 – 1.6 µm range on GaAs substrates. In addition, it has been discovered that antimony in GaInNAsSb also works as a constituent that significantly modifies the valence band. These findings motivated a systematic study of GaInNAsSb alloys with widely varying compositions. Our recent progress in growth and materials development of GaInNAsSb alloys and our fabrication of 1.5 – 1.6 µm lasers are discussed in this paper. We review our recent studies of the conduction band offset in (Ga,In) (N,As,Sb)/GaAs quantum wells and discuss the growth challenges of GaInNAsSb alloys. Finally, we report record setting long wavelength edge emitting lasers and the first monolithic VCSELs operating at 1.5 µm based on GaInNAsSb QWs grown on GaAs. Successful development of GaInNAsSb alloys for lasers has led to a much broader range of potential applications for this material including: solar cells, electroabsorption modulators, saturable absorbers and far infrared optoelectronic devices and these are also briefly discussed in this paper.

Comparison of electronic band structure and optical transparency conditions of In x Ga 1 − x As 1 − y N y ∕ Ga As quantum wells calculated by 10-band, 8-band, and 6-band k ∙ p models

Abstract: We have investigated the electronic band structure and optical transparency conditions of ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{As}}_{1\ensuremath{-}y}{\mathrm{N}}_{y}∕\mathrm{Ga}\mathrm{As}$ quantum well (QW) using 10-band, 8-band and 6-band $\mathbf{k}∙\mathbf{p}$ models. The transition energy calculated by the 8-band model agrees very well with the values calculated by the 10-band model, especially in the range of high indium composition (35%). Electron effective mass $({m}_{e}^{*})$ predicated by band anticrossing model, with nitrogen-related enhancement weakened as indium composition increases, was used in the 8-band model and was favored compared to the heavier value predicted by the phenomenological relationship. We have calculated the optical transition matrix element $({Q}_{i}^{{n}_{c}{n}_{v}})$ using the Bloch wave functions for the $\mathbf{k}∙\mathbf{p}$ models and discovered that the inclusion of nitrogen-related energy level $({E}_{N})$ into the calculation of the conduction band by the 10-band $\mathbf{k}∙\mathbf{p}$ model yields lower differential gain $(dG∕dN)$ than that calculated by the 8-band $\mathbf{k}∙\mathbf{p}$ model on the same structure. Contrary to earlier reports that the reduction of $dG∕dN$ in ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{As}}_{1\ensuremath{-}y}{\mathrm{N}}_{y}∕\mathrm{Ga}\mathrm{As}$ QW and thus the lower obtainable optical gain is due to the increase in ${m}_{e}^{*}$, we have concluded that the reduction was due to the increased interaction between the $\ensuremath{\mid}S⟩$ conduction-band state and $\ensuremath{\mid}{S}_{N}⟩$ nitrogen-related energy state, which weaken the optical transition matrix elements between valence band and conduction band. Our results also show that if ${m}_{e}^{*}$ is very large (as predicted by the phenomenological model), $dG∕dN$ will increase monotonously with nitrogen composition. Moreover, neglecting valence band and conduction band interaction in $\mathbf{k}∙\mathbf{p}$ models will result in the prediction of higher $dG∕dN$ which is not accurate.