The strong wavelength dependence of confinement in the proposed NAW structure: (a) refractive index, band gap, and modal intensity distribution at different wavelengths in the proposed NAW laser structure; (b) wavelength dependence of the active layer confinement factor in the proposed NAW structure for two optical confinement layer (OCL) thickness values (including the OCL and the quantum well (QW); (c) dependence of on the waveguide layer thickness in the proposed NAW (1 and ) and in symmetric (2, , 3, and ) waveguide structures. All curves in (c) are calculated for an OCL with an 8 nm thick GaAs QW active layer; the - and -cladding compositions are , (2 and ), and (3 and ). The solid curves 1,2, and 3 are for and the dashed curves , , and for . Note the much larger relative difference between values available with the asymmetric structure.
Material (a) and modal (b) gain curves for the proposed NAW laser structure at room temperature (1) and at an elevated temperature (2–4). Curves 1 and 2: (threshold carrier density at ); curve 3: (ensuring the same peak material gain as in curve 1); curve 4: (threshold value at , i.e., ensuring the same peak modal gain as in curve 1). Solid arrows illustrate the peak gain shift and dashed arrows the evolution of the spectrum under temperature increase and carrier density increase.
Material (1) and modal (2) gain peak shift in the proposed NAW laser structure with temperature increase.
Transverse far field profile and input efficiency for the proposed NAW structure at .
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