Effect of Index Variation in Active Layer on Transverse Mode for Vertical-Cavity Surface-Emitting Lasers

Abstract

The distribution of carrier density in an active layer of a vertical-cavity surface-emitting laser (VCSEL) produces a refractive index distribution, affecting the transverse-mode behavior of the VCSEL causing high-order-mode lasing. To achieve high-power fundamental-mode operation, we investigated the reduction in this effect by elongating the cavity. Experimental data show that the high-order mode started lasing immediately above a threshold in a lambda-cavity VCSEL with an active area large than 10 µm in diameter. By introducing a long monolithic cavity, high-order-mode lasing was suppressed. Theoretical results clearly show that such high-order-mode suppression is achieved because the effect of carrier-induced index change in the active layer is reduced by elongating the cavity.

Gain and coherence collapse condition for a laser diode with optoelectronic feedback using Volterra series

“…Laser diodes have three main characteristic quantities: gain [1][2][3], refractive index change [4][5][6], and linewidth enhancement factor [7][8][9]. These quantities have been studied many times theoretically [10][11][12][13][14][15], experimentally [16][17][18][19][20][21][22][23][24], and intelligently . In this current study, the characteristic quantity gain and coherence collapse condition with optoelectronic feedback are analysed and simulated with the use of Volterra series.…”