High-Power Ultralow Divergence Edge-Emitting Diode Laser With Circular Beam

Abstract

A recognized drawback of edge-emitting diode lasers is their high divergence and elliptical beam shape since the first diode laser was demonstrated. In this paper, we demonstrated the ultranarrow circular beam emission from the broad area diode laser based on a modified Bragg-like waveguide. The low vertical divergence of 9.8°with 95% power content and 4.91°with the full-width at half-maximum was realized in the devices with 150 μm stripe width. The maximum output power was 4.2 W under quasi-continuous-wave operation and presently limited by thermal rollover. The detailed design principle was presented and it was found that reducing the refractive index and thickness of the defect layer was able to improve the vertical divergence and achieve the stable circular beam emission by controlling the lateral current distribution using the deep stripe. The packaged device with 90 μm stripe width demonstrated a maximum continuous wave power of 4.6 W at 10°C. A direct fiber coupling efficiency of 90.6% had been achieved with a common fiber of 105 μm core diameter.Index Terms-Semiconductor lasers, photonic bandgap, lowbeam divergence, high-power diode lasers. 1077-260X

Control of lateral divergence in high-power, broad-area photonic crystal lasers

“…O ne-dimensional photonic bandgap crystal (PBC) lasers such as the longitudinal PBC lasers [1][2][3][4] and Bragg reflection waveguide lasers [5][6][7] have been developed for high-power and high-brightness operation. In these devices, light is confined by the photonic bandgap effect in the vertical direction rather than by total interface reflection (TIR).…”

“…In these devices, light is confined by the photonic bandgap effect in the vertical direction rather than by total interface reflection (TIR). Low vertical divergence and circular beams 5) have been demonstrated in single devices, which are a potential solution to the intrinsic drawbacks of diode lasers, i.e., their high divergence and elliptical beam. However, the PBC can only control the vertical divergence.…”

“…4(b)] have nearly circular FF patterns, which has been analyzed in our previous work. 5) On comparison with the W=O devices, the WT devices [Fig. 4(c)] have narrower FF patterns in the lateral direction.…”

Beam control of high-power broad-area photonic crystal lasers using ladderlike groove structure

“…here is an increasing demand for high-power and high-beam-quality diode lasers for applications such as material processing, pumping solid-state lasers or fiber lasers, and defense. Recently, diode lasers based on the one-dimensional photonic bandgap crystal (PBC) structure have been proposed and developed [1][2][3][4][5] to improve the beam quality of diode lasers. Low vertical divergence and circular beams 5) have been demonstrated in single devices, providing a potential solution for the intrinsic drawbacks of diode lasers, i.e., high divergence and elliptical beam shape.…”

“…Recently, diode lasers based on the one-dimensional photonic bandgap crystal (PBC) structure have been proposed and developed [1][2][3][4][5] to improve the beam quality of diode lasers. Low vertical divergence and circular beams 5) have been demonstrated in single devices, providing a potential solution for the intrinsic drawbacks of diode lasers, i.e., high divergence and elliptical beam shape. The PBC lasers can be designed to allow fundamental transverse-mode operation even at high output power.…”