低臨限電流與小發散角的脊型雷射的模擬分析

Abstract

本論文利用ISE-TCAD的模擬軟體來設計及分析InGaAs量子井雷射（發光波長980 nm）。加入低折射率層於漸變性折射率分開侷限異質結構(grad-index separate-confinement heterostructure)與覆蓋層之間，這樣的結構會使得光學場尾端能夠有效地的滲入覆蓋層，且光學場能夠被緊密的侷限於主動區。所以可以同時得到低的垂直遠場發散角度及臨限電流密度。 經過模擬及計算後，我們得到水平及垂直遠場發散角分別為6.58度、14.64度，臨限電流密度為444 。相較於傳統的雷射結構而言，垂直遠場發散角有效地被下降2倍以上，而臨限電流密度維持相同或者輕微的上升而已。

In this study, we used ISE-TCAD simulation tools to design and analyze low threshold current density and low divergence angle InGaAs quantum well lasers at wavelength of 980 nm. The main approach is to add two low index layers inserted between the grad-index separate-confinement heterostructure (GRINSCH) layers and the cladding layers in the ridge-type semiconductor lasers. The simulation results reveals that the optical field widely expanded in the cladding layers and the carriers and optical field are tightly confined in the active region. A ridge-type laser diode with small vertical far-field divergence angle and low threshold current density can thus be obtained. By the design with simulation results, we can get a ridge laser with horizontal divergence angle of 6.58 degree, vertical divergence angle of 14.64 degree, and threshold current density of 444 . The vertical divergence angle is about a half to that of the conventional structured diode lasers, while the threshold current densities are about the same for our designed lasers and the conventional ones.