How to launch 1 W into single-mode fiber from a single 1.48-Μmflared resonator

摘要

The operation of 1.48-Μm flared resonators is thoroughlynstudied, both experimentally and theoretically: the accuratendetermination of threshold condition as a function of geometrical andnmaterial parameters, the study of emission spectra and astigmatismnvariations as a function of optical power level allow us to betternunderstand the may these devices operate. The origin of modal distortionnis then analyzed, and an original solution is proposed to increase thensingle-transverse-mode power at high injection level: it is shown thatnimplanting the multiple-quantum-well active layer with protonsnefficiently enhances the filtering capability of the overall structure,nand particularly that of the ridge waveguide, by bringing additionalnlateral absorption losses. The explanation of the filtering mechanism isnsuccessfully confirmed by simulations using the beam-propagation method.nThis technique finally allowed more than 1.3 W of continuous wave (CW)ndiffraction-limited power at 6 A. Low-modal-gain structures were thennrealized to reduce modal optical absorption in the implanted structuresnwith a view to maintaining a high external efficiency and a reducednvertical divergence. Finally, a three-lens coupling system was designednand the effects of optical feedback minimized so as to obtain a verynhigh coupling efficiency: with an improved laser design, 1.12 W of CWnpower were then coupled into single-mode fiber at 6.6 A, whichnrepresents 65% of the power emitted by the laser chip