Fabrication and Characterization of GaSb-Based Monolithic Resonant-Cavity Light-Emitting Diodes Emitting Around 2.3 μm and Including a Tunnel Junction

In this paper, the process of fabrication of GaSb-based electrically injected resonant-cavity LEDs near 2.3 mum is detailed. The electrical and optical properties of these diodes operating in continuous wave at room temperature are also presented. The different tested monolithic structures have similar designs with two doped AlAsSb/GaSb Bragg mirrors and an active region with eight GaInAsSb quantum wells. Performances of devices containing or not an n⁺⁺-InAsSb/p⁺⁺-GaSb tunnel junction (TJ) can be compared. The large improvements of electrical resistance as well as output power, observed when a TJ is included, demonstrate all the advantages to use such a technology for the realization of electrically injected vertical cavity structures emitting in the mid-IR on GaSb substrate.     

Recent Advances on InAs/InP Quantum Dash Based Semiconductor Lasers and Optical Amplifiers Operating at 1.55 μm

This paper summarizes recent advances on InAs/InP quantum dash (QD) materials for lasers and amplifiers, and QD device performance with particular interest in optical communication. We investigate both InAs/InP dashes in a barrier and dashes in a well (DWELL) heterostructures operating at 1.5 mum. These two types of QDs can provide high gain and low losses. Continuous-wave (CW) room-temperature lasing operation on ground state of cavity length as short as 200 mum has been achieved, demonstrating the high modal gain of the active core. A threshold current density as low as 110 A/cm² per QD layer has been obtained for infinite-length DWELL laser. An optimized DWELL structure allows achieving of a T₀ larger than 100 K for broad-area (BA) lasers, and of 80 K for single-transverse-mode lasers in the temperature range between 25degC and 85degC. Buried ridge stripe (BRS)-type single-mode distributed feedback (DFB) lasers are also demonstrated for the first time, exhibiting a side-mode suppression ratio (SMSR) as high as 45 dB. Such DFB lasers allow the first floor-free 10-Gb/s direct modulation for back-to-back and transmission over 16-km standard optical fiber. In addition, novel results are given on gain, noise, and four-wave mixing of QD-based semiconductor optical amplifiers. Furthermore, we demonstrate that QD Fabry-Perot (FP) lasers, owing to the small confinement factor and the three-dimensional (3-D) quantification of electronic energy levels, exhibit a beating linewidth as narrow as 15 kHz. Such an extremely narrow linewidth, compared to their QW or bulk counterparts, leads to the excellent phase noise and time-jitter characteristics when QD lasers are actively mode-locked. These advances constitute a new step toward the application of QD lasers and amplifiers to the field of optical fiber communications