Multiple-Wavelength Vertical-Cavity Surface-Emitting Lasers by Grading a Spacer Layer for Short-Reach Wavelength Division Multiplexing Applications

摘要

We propose and demonstrate a simple and unique method to fabricate the multiple-wavelength vertical-cavity surface-emitting lasers (VCSELs) emitting at 980 nm by grading only the first low-index spacer layer of SiO_2/Ta_2O_5 dielectric mirror. A multi step exposure to UV lithography followed by selective wet chemical etching has been applied to create spacer layer gradients. We have successfully realized equally spaced four-channel VCSELs with wavelength span exceeding 30.0 nm by grading a 230.0 nm spacer layer and achieved single mode lasing with a side mode suppression ratio in excess of 30.0 dB.