FOCUSING CHARACTERISTICS OF A WIDE-STRIPED LASER-DIODE INTEGRATED WITH A MICROLENS

We developed a wide-striped laser diode integrated with a microlens th at provides good focusing characteristics through a small focusing spo t. We calculated and demonstrated that a 60-mum-wide core and a 1.9-mu m-high ridge is the best structure for fundamental index-guiding mode oscillation of a wide-striped laser diode. We integrated a wide-stripe d laser diode with the developed microlens in the Fresnel diffraction field, and demonstrated that a device with a 60-mum-wide core has a mi nimum focusing spot width of 2.0 mum in the horizontal direction. Also , we estimated the wavefront in the Fresnel diffraction field from the working distance error of a lens designed for a collimated incident b eam, and showed that the working distance error, focusing spot width, and sidelobe can be improved by this estimated wavefront.