Spatiotemporal Stabilization of PT-Symmetric BAS Lasers

Summary form only given. Broad Area Semiconductor (BAS) lasers are promising and reliable light sources, used in many applications due to their compactness and high conversion efficiency. However, their major drawback is the relatively low spatial and temporal beam quality, see Fig.1 [1]. We propose to control and improve the spatiotemporal dynamics in BAS lasers applying a global P-symmetric and local PT-symmetric potential [2] which may localize energy at the P-symmetry leading to a narrow and enhanced beam emission. This approach produces a two-fold benefit: the reduction of transverse mode number and the control the spatiotemporal dynamics improving the laser stability. The resulting narrow, bright and stable beam emission is shown in Fig.1.d,e,f. The dynamics of electric field amplitude (A) and carrier density (N) for the proposed PT-symmetric BAS laser may be described by the paraxial equations: ∂A /∂z= i / (2k₀n)(∂²A) /(∂ x²) + s[(1+ih) N - (1+ α)]A+iΔn (x,z)k₀; (Eq.1.1) ∂N /∂t= γ(-N-(N-1))|A|² + p₀+ Δp (x,z)+ D∇²N)(Eq.1.2). Where Δn(x, z) = m₂ cos(q_x | x |) + m₃ sin(q_x | x |) is the complex potential and Δp(x, z) = m₁ sinfe I x I) the axial pump modulation, other parameters are the same as in ref. [3]. The laser pump modulation, with symmetry axis at x = 0, induces in-phase gain and refractive index modulations due to the Hemy factor which are spatially dephased to obtain local PT-symmetiy by the corresponding index profile, An. We consider forward and backward A components with cavity boundary conditions.