High-power single mode (>1W) continuous wave operation of longitudinal photonic band crystal lasers with a narrow vertical beam divergence

Abstract

We report on 980nm InGaAs∕AlGaAs lasers with a broad waveguide based on a longitudinal photonic band crystal concept. The beam divergence measured as full width at half maximum was as narrow as <5° (vertical). Broad area 100μm multimode devices demonstrated >15W pulsed operation as limited by the current source. Significantly increased modal spot size enabled stable single lateral mode operation in broad ridge 10μm stripes. Maximum continuous wave power in single mode regime of 1.3W for 10μm wide stripe lasers was obtained, being limited by the catastrophic degradation of the unpassivated laser facets.

High power single-sided Bragg reflection waveguide lasers with dual-lobed far field

“…Ref. [8] experimentally demonstrated the narrow FF distribution with FWHM as narrow as 5 • by 16.5-μm-thick Bragg reflector with a mode shape of Shape I, the similar results can also be found in Refs. [7] and [9].…”

“…Note that the structure of single-sided BRL studied here is very similar with that reported in Ref. [8], however, the FF of the BRL in Ref. [8] shows a narrow single lobe.…”

“…[8], however, the FF of the BRL in Ref. [8] shows a narrow single lobe. To clarify the backside intrinsic mechanism, more analysis is necessary.…”

“…The dual-lobed or multi-lobed FF patterns were thought as the nature of dual-sided BRL, and attributed to the dualsided transverse Bragg resonance based on the quarter-wave (QtW) Bragg condition [14]. On the contrary, the narrow single-lobed FF patterns were considered as the unique advantage of single-sided BRLs [7][8][9]14]. It seems that the lobe characteristic of FF is determined by the single-sided or dual-sided BRW structure.…”

“…The single-sided BRLs or the so-called longitudinal photonic bandgap crystal (PBC) lasers demonstrate the ultra-narrow vertical beam divergence of about 5-8 • [7][8][9], which are promising for the application of high-brightness lasers. The dual-sided BRLs demonstrate the low threshold (∼157 A/cm 2 ) [10] and high temperature stability [11] with two separated lobes in the vertical far field (FF), which are favored for the phasematched nonlinear BRW [12,13].…”