Nonlinear light-current characteristics of narrow stripe geometry lasers

Abstract

Over the last few years it has become clear that single-mode stable operation of planar gain-guided lasers requires a narrow current injection or, to be more precise, the profile of the injected current should be sharper than that of the near-field distribution of the fundamental mode . In this case the mode shape remains relatively stable because of the balance of guiding and anti-guiding effects, despite the fact that the electron distribution markedly depends on the output power . The slightly nonlinear light-current characteristics are common features of these narrow-stripe lasers . The low-power differential quantum efficiency is 10 to 15% less than that of their counterparts with broader stripe, but this difference decreases with increasing output power . The narrower the stripe width, the more conspicuous is this effect [1, 2] . Several physical effects are known in laser diodes which may induce nonlinear light-current characteristics. It will be shown that the electron distribution arising from the high-level stimulated recombination is sufficient to explain satisfactorily the observed discrepancy . The analysis is based on the following one-dimensional continuity equation for charge carriers n(X) Jo '(x) = r(n(x)) + NphI,(x)G(n(x)) _ D d2n(x) (1) Ldq Ld dx -