Antiguided semiconductor laser array with edge reflectors

Abstract

In a semiconductor laser array structure in which antiguided regions between high effective refractive index waveguide regions experience greater gain then the waveguide regions, structures introduced at the sides of the array, next to the edgemost waveguides and not on the array period, reflect laterally transmitted radiation back toward the center of the array. The edge reflecting structures may be waveguide regions having widths of (m'+1/2) half-wavelengths, where 'm'' is zero or a positive integer, compared to array waveguides with width m, where 'm' is an integer not necessarily equal to 'm''. The edge reflecting structures may also be stacks of such waveguides, where the regions between the edge waveguides are of a width substantially equal to (n'+1/2) half-wavelengths, compared to antiguide element widths of n half-wavelengths. The two integers n and n' may be, but are not necessarily, equal. Alternatively, the edge reflectors can be mirrors fabricated at the side edges of the array or by disordering the active region beyond the edgemost waveguides to form a refractive index step. The mirrors should be positioned a distance substantially a/2 from the edgemost emitters, where 'a' is the array period.