Title :
Design of tapered waveguides for improved output coupling
Author :
Hadley, G. Ronald
Author_Institution :
Sandia Nat. Labs., Albuquerque, NM, USA
Abstract :
Waveguides whose width increases linearly with distance are shown to be an excellent means for decreasing the beam divergence of the guided mode and thus improving output coupling, provided the taper angle is carefully chosen. Such tapered waveguides can provide nearly diffraction-limited output while incurring virtually no energy penalty. Beam propagation calculations together with a dimensional analysis allow the first quantitative prediction of output beam divergence for a wide range of input parameters. Performance is shown to be optimal for taper angles of about 0.4 times the input beam´s full width at half maximum (FWHM) divergence angle, subsequently reducing the latter by a factor of five.<>
Keywords :
integrated optics; optical design techniques; optical losses; optical waveguide theory; reflectivity; beam divergence; beam propagation calculations; dimensional analysis; divergence angle; energy penalty; guided mode; improved output coupling; input beam´s full width; nearly diffraction-limited output; output beam divergence; output coupling; quantitative prediction; taper angle; taper angles; tapered waveguide design; Diffraction; Diode lasers; Laser beams; Optical coupling; Optical fibers; Optical reflection; Optical waveguides; Photonics; Waveguide theory; Waveguide transitions;
Journal_Title :
Photonics Technology Letters, IEEE
