Room-temperature continuous-wave operation of the In(Ga)As/GaAs quantum-dot VCSELs for the 1.3 µm optical-fibre communication

Abstract

Efficient room-temperature (RT) continuous-wave (CW) lasing operation of the 1.3 μm MBE (molecular-beam epitaxy) In(Ga)As/GaAs quantum-dot (QD) top-emitting oxide-confined vertical-cavity surface-emitting diode lasers (VCSELs) for the second-generation optical-fibre communication has been achieved. In their design, a concept of a QD inside a quantum well (QW) has been utilized. The proposed In(Ga)As/GaAs QD active region is composed of five groups of three 8 nm In 0.15 Ga 0.85 As QWs, each containing one InAs QD sheet layer. In each group located close to successive anti-node positions of the optical standing wave within the 3λ cavity, QWs are separated by 32 nm GaAs barriers. Besides, at both active-region edges, additional single InGaAs QWs are located containing single QD layers. For the 10 μm diameter QD VCSELs, the RT CW threshold current of only 6.2 mA (7.9 kA cm −2 ), differential efficiency of 0.11 W A −1 and the maximal output power of 0.85 mW have been recorded. The experimental characteristics are in excellent agreement with theoretical ones obtained using the optical-electrical-thermal-recombination self-consistent computer model. According to this, for the 10 μm devices, the fundamental linearly polarized LP 01 mode remains the dominating one up to the current of 9.1 mA. The lowest RT CW lasing threshold below 5 mA is expected for 6 μm devices.

Comparative analysis of lasing performance of oxide-confined and proton-implanted vertical-cavity surface-emitting diode lasers

“…between various optical, electrical, thermal and recombination processes, taking place within the VCSEL volume, which requires a fully self-consistent iterative approach and which is included in our model, is much more important for model accuracy than some its shortcomings of probably minor importance. Besides, the validity of our model has been confirmed experimentally [19].…”

Sensitivity of a VCSEL threshold performance to inaccuracies in its manufacturing

“…2), is much more important for model accuracy than some its shortcomings of probably minor im− portance. Besides, validity of our model has been confirmed experimentally [14]. …”

Numerical Self-Consistent Analysis of VCSELs

“…Reaching such self-consistency is especially important for modelling high-power and/or high-temperature VCSEL operation. Such a comprehensive VCSEL model has been reported by Sarzała and Nakwaski [3] and Sarzała [4], and its validity has been confirmed experimentally for QD VCSELs in [5]. Above the lasing threshold, the spatial-holeburning (SHB) effect should also be taken into account [6][7][8].…”

“…Such operation is required in several VCSEL applications as, for example, telecommunications and gas detection. Single mode operation can only be achieved for small aperture in standard index-guided VCSELs, which limits the available singlemode output [5]. Higher-output large-size index guided VCSELs usually exhibit multimode operation, especially at higher temperatures.…”

“…Higher-output large-size index guided VCSELs usually exhibit multimode operation, especially at higher temperatures. This results from the considerable current-crowding effect near the active-region edges, which-despite the smooth radial carrier diffusion profile in the active region-still favours higher-order transverse modes [5,8]. In gain-guided VCSELs, on the other hand, single-mode operation is possible for broader active regions, at the expense of higher threshold currents.…”