The Near-Diffraction-Limited Operation of Positive Index-Guided Submicrometer-Ridge Laser Arrays

Strong optical and electrical interactions can occur between optoelectronic devices when the element-size and inter-element spacing are significantly reduced. In this paper, we study these interactions in the closely packed, positive index-guided submicrometer-ridge laser arrays, with element size of ${\sim}0.8\ \mu$ m, operating at a wavelength of ${\sim}1.55\ \mu$m. From simulations, the structure is found to favor the in-phase lasing mode, which produces a single-main-lobe far-field profile. Next, this property is experimentally demonstrated in the fabricated device, which exhibits a near-diffraction-limited (beamwidth of 1.3 times diffraction-limit) single-main-lobe far-field operating at 2.6 times the threshold current.