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Limitations to beam quality of mid-infrared angled-grating distributed-feedback lasers
By: Bewley, W.W.; Manfra, M.J.; Turner, G.W.; Martinelli, R.U.; Lee, H.; Vurgaftman, I.; Meyer, J.R.; Felix, C.L.; Jurkovic, M.J.; Bartolo, R.E.;
2001 / IEEE
This item was taken from the IEEE Periodical ' Limitations to beam quality of mid-infrared angled-grating distributed-feedback lasers ' The far-field characteristics of mid-infrared angled-grating distributed-feedback (/spl alpha/-DFB) lasers with W active regions are studied as a function of etch depth, stripe width, and optical pumping intensity. Whereas near-diffraction-limited output is obtained for 50 /spl mu/m stripes at ten times threshold, the beam quality degrades rapidly when either the stripe width or the pump intensity is increased. A key finding is that most of the degradation may be attributed to the onset of Fabry-Perot-like lasing modes that propagate along the direct path normal to the facets. We further show that these parasitic modes may be effectively eliminated by using ion-bombardment to create angled virtual mesas surrounded by loss regions. The bombarded structures show substantial improvement of the beam quality for wide pump stripes and high pump intensities, although in this first demonstration the efficiency decrease was greater than expected.
Ion Beam Effects
Mid-infrared Angled-grating Distributed-feedback Lasers
Beam Quality Limitations
/spl Alpha/-dfb Lasers
W Active Regions
Optical Pumping Intensity
Fabry-perot-like Lasing Modes
Angled Virtual Mesas
Gasb/inas/alsb Quantum Wells
Alas/sub 0.08/sb/sub 0.92/-gasb
Distributed Feedback Lasers
Quantum Well Lasers
Photonics And Electrooptics
Engineered Materials, Dielectrics And Plasmas